Title of Invention

DRUM TYPE BRAKE AND STRADDLE TYPE VEHICLE

Abstract To provide a drum type brake and a straddle type vehicle,although simple in constitution, capable of effectively preventing brake squeak.An installation member 80 that is placed adjacent in the wheel shaft direction to a brake drum 30, installed on a shoe plate 40 for pivoting a brake shoe 50 for free turn, and having a first portion and a second portion 81A, 81B, the first portion 81A being fixed to the shoe plate 40 or another member, the second portion 81B being fixed to or pressed against the shoe plate 40, and the natural frequency of the portion between the first portion 81A and the second portion 81B being different from the natural frequency of the shoe plate 40 when the first portion is made a fixed point.
Full Text DRUM TYPE BRAKE AND STRADDLE TYPE VEHICLE
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a drum type brake for use in the straddle type vehicle such as the motorcycle, four-wheeled buggy, and snowmobile, and to the straddle type vehicle provided with this, and in particular relates to the drum type brake and the straddle type vehicle capable of preventing brake squeak although simple in constitution.
2. Description of the Related Art
In some of the straddle type vehicles such as the motorcycle, four-wheeled buggy, and snowmobile, the wheels are provided with the drum type brake. Generally the drum type brake has been of the constitution in which braking is made by friction by pressing a brake shoe against the inner surface of a rotating drum. There has been a problem of brake squeak with the drum type of brake constituted as described above : when the frictional vibration of the brake drum and the brake shoe matches the natural frequency of the brake components such as the brake drum, brake shoe, shoe plate, etc., resonance occurs, ending up in occurrence of uncomfortable noise.
Therefore, conventionally, prevention of brake squeak has been sought by adjusting the natural frequency of the brake components by changing weights of the brake components resonated
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by the above-mentioned frictional vibration. For example, JP-UM-A-62-92331 (Figs. 1 and 2) proposes a drum type brake provided with a brake squeak prevention device comprising a pair of vibration suppressing members made of strip members such as steel plates rounded in semicircular shape and a band made of annular elastic member with its inside round surface having a shallow groove. The vibration suppressing members are fit into the groove in the band which is fit around the outside round surface of the brake drum.
The convention drum type brake of the above constitution has prevented brake squeak by changing the weight of the brake drum thereby changing its natural frequency and preventing the brake drum from resonating with the frictional vibration.
SUMMARY OF THE INVENTION
However, as for the above-described conventional drum type brake, the brake squeak prevention device has been of the constitution with the metallic vibration suppressing member serving as the weight fit around the brake drum by means of the band of annular elastic member. As a result, there have been problems that the brake squeak prevention device cannot be attached later to the brake drum of the wheel with spokes assembled as JP-UM-A-62-92331, and in contrast, after the spokes are assembled, it is very difficult to service or replace the brake squeak prevention device once fit around the brake drum.
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There have been other problems: as the brake squeak prevention device is made up of a plural number of parts; a pair of vibration suppressing members and a band; the number of parts increases, assembling to the brake drum requires time and effort. There has been another problem: While it is necessary to increase the size of the weight or the vibration suppressing members in order to make the brake drum heavier, the outside round surface area of the brake drum the vibration suppressing members are attached to is limited. Therefore, there has been a certain limit to the increase in the size of the vibration suppressing members.
This invention has been made in view of the above problems with an object of providing a drum type brake and a straddle type vehicle, although simple in constitution, capable of effectively preventing brake squeak.
To accomplish the above obj ect, a drum type brake of the invention is constituted to have an installation member, with the installation member being placed adjacent in the wheel shaft direction to a brake drum, installed on a shoe plate for pivoting a brake shoe for free turn, and having a first portion and a second portion, the first portion being fixed to the shoe plate or another member, with the second portion being fixed to or pressed against the shoe plate, and the natural frequency of the portion between the first portion and the second portion being different from the natural frequency of the shoe plate
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when the first portion is made a fixed point.
Preferably, a constitution has portions of small amplitude and great amplitude when the shoe plate vibrates, in which the first portion of the installation member is fixed to the portion of small amplitude or fixed to another member located in the portion of small amplitude while the second portion of the installation member is fixed to or pressed against the portion of great amplitude.
Preferably, a constitution has portions of small amplitude and great amplitude when the shoe plate vibrates, in which the second portion of the installation member is fixed to or pressed against the portion of great amplitude, while the first portion of the installation member is fixed to a portion of the shoe plate apart from the second portion more than the wheel shaft in the diametral direction or to another member located in the portion of the shoe plate apart from the second portion more than the wheel shaft in the diametral direction.
Preferably, a constitution is made with the first portion of the installation member fixed to the wheel shaft, and more preferably, with the first portion of the installation member fixed to the wheel shaft through a cylindrical collar.
Preferably, a constitution is made with the installationmember provided with an installation plate having a first portion on one end and a second portion on the other end and the cylindrical collar fixed to the first portion, with the cylindrical collar
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attached to the wheel shaft while the second portion of the installation plate fixed to or pressed against the shoe plate.
Preferably, a constitution is made with the second portion of the installation member fixed to or pressed against a turn stop portion of the shoe plate, and more preferably, with the second portion of the installation member fixed to the turn stop portion with a tightening member.
Preferably, a constitution is made with a clearance formed between a main portion of the installation member excluding the portion between the first and second portions and the shoe plate so that the main portion and the shoe plate keep non-contact state even when the shoe plate vibrates.
Preferably, a constitution is made that the installation member is made a rear arm for supporting a rear wheel through the wheel shaft, the rear arm is provided with the first and second portions, the wheel shaft is passed through the first portion and fixed while the turn stop portion of the shoe plate is fixed to the second portion.
To accomplish the above object, a straddle type vehicle according to the invention is made of a constitution provided with any of the drum type brakes related to the above-described invention.
With the drum type brake and the straddle type vehicle of the invention, the natural frequency of the portion between the first and second portions of the installation member is
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different from the natural frequency of the shoeplate . Therefore, in case frictional vibration of the brake drum and the brake shoe occurs, vibration modes of the installation member and the shoe plate are different, friction occurs between the shoe plate and the second portion of the installation member, the vibration energy of the shoe plate is converted into frictional heat energy, and brake squeak can be prevented.
In this way, it is possible to attenuate shoe plate vibration and prevent brake squeak effectively by means of the installation member of a simple constitution.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a right side view of a straddle type vehicle related to the first embodiment of the invention.
Fig. 2 is an enlarged view of the drum type brake related to the first embodiment of the invention.
Fig. 3 is a vertical sectional view of the above drum type brake.
Fig. 4 is a front view of a shoe plate constituting the above drum type brake.
Fig. 5 is an oblique view of the drum type brake related to the second embodiment of the invention.
Fig. 6 is a side view of the installation member.
Fig. 7 is a front view of the installation member.
Fig. 8 is an enlarged view of the drum type brake related
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to the second embodiment of the invention.
Fig. 9 is an enlarged view of the drum type brake related to the third embodiment of the invention.
Fig. 10 partial enlarged view of the drum type brake related to the fourth embodiment of the invention.
Fig. 11 is a front view of the shoe plate and the installation member constituting the drum type brake related to the fifth embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFFERED EMBODIMENTS The drum type brake and the straddle type vehicle related to the embodiment of the invention is described hereinafter in reference to appended drawings. First, the straddle type vehicle provided with the drum brake related to the embodiment is described in reference to Fig. 1. Fig. 1 is a right side view of the straddle type vehicle (motorcycle) related to the embodiment.
In the same figure, a vehicle body frame 10 of a motorcycle 1 is a cradle type frame, with a front fork 11 attached rotatably to a steering head pipe 10a at the front end of the vehicle body frame 10. At the lower end of the front fork 11 is rotatably supported a front wheel WF, above which is provided a front fender for covering the front wheel WF. Handlebars 12 are attached to the upper end of the front fork 11.
To the steering head pipe 10a are connected left and right
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main frames 10b extending obliquely rear downward and left and right down tubes 10c extending downward, with an air-cooled type, four-stroke engine 14 mounted in a space surrounded with the main frames 10b and the down tubes 10c. The engine 14 has an upright type cylinder 14a slightly tilted forward. The engine 14 is also connected to an oil cooler 15 via a pipe (not shown) . The oil cooler 15 is attached to the down tubes 10c passing in front of the cylinder 14a and located in the upper front part of the cylinder 14a. The oil cooler 15 is surrounded with a shroud 16 made of plastic to introduce drive-induced wind to and cool the oil cooler 15.
Behind the main frame 10b are connected left and right seat rails lOd, lOd for supporting a seat 17. Back stays lOe are connected between the seat rails lOd and the rear portion of the main frame 10b to support the seat rails lOd. The seat rails lOd and the back stays lOe form a rear frame. While the rear frame is made as a combination of a plural number of pipes in this embodiment, it may be otherwise constituted with a single body, for example with Al casting.
A fuel tank 18 is placed in the connection area of the seat rails lOd and the main frame 10b, so that the fuel tank bridges both of them. The fuel tank 18 is located above the engine 14, with the seat 17 connected to the rear end of the fuel tank 18.
On the other hand, a pivot shat attachment bracket (not shown)
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is fixed to the rear lower portion of the main frame 10b, with a pivot shaft (not shown) supported with the pivot shaft attachment bracket. The front end of a rear arm 19 is supported with the pivot shaft, with the rear arm 19 supported for free swinging with a suspension 20. A movable fender 21 is fixed and tightened with an attachment bolt to the rear arm 19. At the rear end of such a rear arm 19 is rotatably supported a rear wheel WR via a wheel shaft 26. The rear wheel WR is provided with a drum type brake 3 related to this embodiment. The drum type brake is detailed later.
The area from below the rear part of the fuel tank 18 to below the front part of the seat 17 is covered with a side cover 22. The area below the area from the side to the rear part of the seat 17 is covered with a rear cover 23. Further, foot brackets 24, 24 are fixed to both left and right sides in the rear lower part of the main frame 10b. An exhaust pipe 25 extending toward the rear from the engine 14 is supported at the right hand foot bracket 24.
Next, the drum type brake related to the first embodiment of the invention is describe din reference to Figs. 1, 2 to 4. Fig. 2 is an enlarged view of the drum type brake related to the first embodiment of the invention. Fig. 3 is a vertical sectional view of the drum type brake. Fig. 4 is a front view of a shoe plate constituting the drum type brake.
As shown in Figs. 2 and 3, the drum type brake 3 of an inside
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expansion type is constituted mainly with: a brake drum 30, a shoe plate 40, a pair of brake shoes 50, 50, a cam lever 60, a back plate 70, and an installation member 80.
The brake drum 3 0 is made integral with the rear wheel WR and rotatably supported through paired left and right bearings 31 and 32 on the wheel shaft 26 installed in the rear arm 5. Thus, the brake drum 30 is adapted to rotate about the wheel shaft 26 together with the rear wheel WR. An inside space 30A for accommodating the brake shoes 50 is formed on one side (right side of the vehicle) of the brake drum 30, with the inside round surface of the inside space 30 serving as a friction surface 30B.
The opening of the inside space 30A of the brake drum 30 is covered with the shoe plate 40. The shoe plate 40 is as shown in Fig. 4 is a member of generally disk shape in front view, with a wheel shaft insertion hole 40A bored in the center, and with an integrally formed turn stop portion 40B of a step shape extending radially outward up to outside the radius from the wheel shaft layer insertion hole 40A. Such a shoe plate 40 is fixed to the rear arm 19 by inserting the wheel shaft 26 through the wheel shaft layer insertion hole 40A while tight-connecting the turn stop portion 40B to the rear arm 5 by means of a turn stop rod (not shown).
The inside of the shoe plate 40 is provided with a pivot shaft 41 extending toward the inside space 30A of the brake drum 30,
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with a pair of brake shoes 50, 50 pivoted for free turn on the pivot shaft 41. The shoe plate 40 is also provided with a cam shaft insertion hole 40C adjacent in radial direction to the wheel shaft insertion hole 40A, with a camshaft 42 rotatably held in the cam shaft insertion hole 40C. The camshaft 42 engages through its cam with both of the brake shoes 50 within the inside space 30 of the brake drum 30.
The brake shoes 50 are respectively placed in the vicinity of the friction surface 30B of the brake drum 30 in a semicircular shape extending along the friction surface 30B, opposite to each other in the circumferential direction around the wheel shaft 26. The brake shoes 50 are pivoted respectively at one end on the pivot shaft 41, and their other ends are free to turn (expand inside) about the pivot shaft 41 in the diametral direction of the brake drum 30. The other ends of the brake shoes 50 engage with the cams of the camshaft 42 as described above.
The brake shoes 50 are each provided with a pair of springs (not shown) to force them away from the friction surface 30B of the brake drum 30 and press respective other ends of the brake shoes 50 against the camshaft 42. Incidentally, the brake shoes 50 are known ones, their base portions are made of metal having sufficient strength and rigidity, and their surfaces on the friction surfaces 30B side have linings attached.
The cam lever 60 is attached to the other end of the camshaft
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42 projecting outward of the shoe plate 40, and extends outward in the diametral direction of the shoe plate 40. The tip of the cam lever 60 is connected to a rod (not shown) moving as interlocked with the brake pedal of the motorcycle 1 described above.
When the brake pedal is operated or depressed, the rod moves in a straight line as interlocked with the turn of the brake pedal, and the cam lever 60 turns as it receives the straight line motion. Then, the camshaft 42 makes interlocked motion with the cam lever 60, and the camshaft 42 makes interlocked motion with the cam lever 60, which causes respective brake shoes 50 engaging with the cams of the camshaft 42 to turn (make inside expansion) toward the friction surface 30B of the brake drum 30. As a result, brake force of the rotating rear wheel WR is produced.
At this time, if the frictional vibration of the brake drum 30 and the brake shoes 50 matches the natural frequency of the brake components, resonance occurs to produce uncomfortable brake squeak. This embodiment, however, prevents the brake squeak as the installation member 80 is provided. The installation member 80 will be detailed later.
On the other hand, the other end (vehicle's left side) is connected to the back plate 70. The back plate 70 is supported on the wheel shaft 26 for free turn via a bearing 71 installed in its shaft layer insertion hole 70A. A sprocket 90 is fixed
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to the outside face of the back plate 70 using a plural number of bolts 91, 91, .... The sprocket 90 engages through its cogs with a chain 92 for transmitting driving force from the engine 14 described above.
Such a back plate 70 turns as it receives driving force from the engine 14 via the sprocket 90 and the chain 92, and the rotation is transmitted to the brake drum 30 to rotate the rear wheel WR.
Next, the installation member for preventing brake squeak of the brake drum is described in reference to Figs. 2 to 4, and 5 to 7. Fig. 5 is an oblique view of the installation member attached to the drum type brake. Fig. 6 is a side view of the installation member. Fig. is a front view of the installation member.
First, the constitution of the installation member 80 is described in reference to Figs. 5 to 7 . The installation member 80 is mainly constituted with a metallic installation plate 81, with a cylindrical collar 82 welded to its one end. The installation plate 81, as shown in Figs. 2 and 4, is of a shape nearly the same as the contour of the turn stop portion 40B of the shoe plate 40, having a first portion 81A to be a fixing point to the shoe plate 40 and a second portion 81B. In the first portion 81A is bored an attachment hole 81a for the cylindrical collar 82, while in the second portion 81B is bored an attachment hole 81b matching a rod tight-connecting hole
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41B provided in the turn stop portion 40B.
Because the installation plate 81 as will be described later is to produce friction between itself and the shoe plate 40 vibrating at the second portion 81B and attenuate this vibration, it requires rigidity of an extent that does not follow the vibration of the shoe plate 40. Therefore, the higher the rigidity of the installation plate 81, the more effectively is produced friction with the vibrating shoe plate 40, so that vibration of the shoe plate 40 is efficiently attenuated.
On the other hand, the cylindrical collar 82 is a member for easily fixing the installation plate 81 to the wheel shaft 26, and is made in the shape of a thick-walled cylinder with its girth round-grooved. The inside diameter of the cylindrical collar 82 is approximately the same as the outside diameter of the wheel shaft 2 6, to be fit onto the wheel shaft 2 6 as shown in Fig. 3.
The first portion 81A of the installation plate 81 is fixed to the position of the wheel shaft insertion hole 40A of the shoe plate 40 by fitting the cylindrical collar 82 together with the rear arm 19 over the wheel shaft 2 6 and tightening the nut 2 6a screwed on one end of the wheel shaft 26. At this time, the second portion 81B of the installation plate 81 matches the fixing surface 40B2 of the turn stop portion 40B of the shoe plate 40. There, the second portion 81B of the installation plate 81 is fixed to the fixing surface 40B2 of the turn stop
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portion 40B by inserting a tightening bolt (not shown), for fixing the turn stop rod, into the attachment hole 81b and the rod tightening hole aligning with each other, and tightening the bolt.
Further, one end of the cylindrical collar 82 is formed with a stepped attachment portion 82a. Fitting the attachment hole 81a of the installation plate 81 to the stepped attachment portion 82a holds the installation plate 81, attached to the wheel shaft 2 6, at the height of the fixing surface 40B2 of the turn stop portion 40B. As shown in Fig. 3, the fixing surface 40B2 is formed to be slightly higher than other surface of the turn stop portion 40B other than that, so that the second portion 81B of the installation plate 81 comes into surface contact with only the fixing surface 40B2.
Such a constitution makes it possible to limit the contact surface between the installation plate 81 and the shoe plate 40 to the first and second portions 81A and 81B that are necessary for producing frictional heat energy and make other portion (main portion excluding the first and second portions 81A and 81B of the installation plate 81) to be free from contact. This makes it possible to prevent the installation plate 81 and the shoe plate 40 from contacting in unnecessary portions, vibrating, and producing new brake squeak.
Here, the principle of brake squeak prevention with the installation member 80 of the above constitution is described.
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The principle of brake squeak prevention of this invention is that the installation member 80 as a brake component, assumed to be in the state of being fixed at least at one point, different from the shoe plate 40 in natural frequency when receiving frictional vibration of the brake drum 30 and the brake shoe 50, is pressed against or fixed to the shoe plate 40 by surface contact to convert the vibration energy of the shoe plate 40 into frictional heat energy on the contact surface.
To cite an extreme, specific example, if an installation member 80 that does not vibrate at all is brought into surface contact with the shoe plate 40 that resonates with frictional vibration, friction occurs on the contact surface, the vibration energy of the shoe plate 40 is converted into frictional heat energy and attenuated.
Incidentally, the "natural frequency" in this invention does not mean the vibration due to input from outside when an object such as the shoe plate 40 and the installation member 80 is put to free state according to general definition. The "natural frequency" in this invention means the natural frequency of the portion between two portions, the first portion 81A and the second portion 81B.
To attenuate vibration of the shoe plate 40 effectively according to the above principle, the inventor measured vibration mode of the shoe plate 40. Specifically, as shown in Fig. 4, with the wheel shaft insertion hole 40A of the shoe plate 40
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made a fixed point pO, acceleration sensors (not shown) are placed at intersections PI to P9 of the phantom lines on the figure to measure the vibration mode of the shoe plate 40. As a result, it was found that the shoe plate 40 mainly vibrates to wave up and down in the direction of the wheel shaft 2 6 and that the amplitude is greater as the point is farther apart from the wheel shaft insertion hole 4 OA in the diametral direction.
Therefore, as for the installationmember 80 of this embodiment, as described above, the second portion 81B of the installation plate 81 is fixed to the end of the turn stop member 40B where amplitude is greater than other portion. This makes it possible to attenuate vibration at the point of greater amplitude and effectively prevent brake squeak.
Because the rod tightening hole 40B1 and the fixing surface 4 0B2 for fixing the turn stop rod are provided on the turn stop member 40B, there is also an advantage that the second portion 81B of the installation plate 81 may be fixed without providing an additional attachment portion on the shoe plate 40.
Next, choosing the fixing point of the first portion 81A of the installation plate 81 on the shoe plate 40 is described. First, as described above, in case the second portion 81B is fixed to a portion of greater amplitude as described above, fixing the first portion 81A to the vicinity of the fixing point P0, a location of small amplitude of the shoe plate 40 like this embodiment, or fixing to the vicinity of the wheel shaft
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insertion hole 40A, is effective for attenuating vibration. This is because it is possible to increase the displacement, due to difference in both natural frequency and vibration mode, of the portion between the first portion 81A and the second portion 81B of the installation plate 81 relative to the shoe plate 40.
On the other hand, in case the first portion 81A is fixed to a portion (a portion of small difference in amplitude phase) that vibrates in the same mode as the portion where the second portion 81B of the shoe plate 40 is fixed, it is thought that the installation plate undesirably follows the amplitude of the shoe plate 40, friction on mutual contact surfaces decreases, and the effect of vibration attenuation decreases.
For example, the points P5 and P9 on the shoe plate 40 shown in Fig. 4 are radially close to each other, both centered on the fixed point P0, and thought to vibrate in approximately the same mode. Therefore, in case the first portion 81A of the installation plate 81 is fixed to the point P5 and the second portion 81B is fixed to the point P9, it is thought that the installation plate 81 disadvantageously follows the amplitude of the points P5 and P9, and friction on mutual contact surfaces decreases.
In contrast, in case the first portion 81A is fixed to a portion of the shoe plate 40 that vibrates in a mode different from the portion (a portion of great amplitude phase difference)
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where the second portion 81B is fixed, it is thought that friction on mutual contact surfaces increases, and the effect of vibration attenuation increases.
For example in Fig. 4, the points P1 and P9 centered on the fixed point PO of the shoe plate 40 are radially apart from each other and thought to vibrate in different modes . Therefore, in case the first portion 81A of the installation plate 81 is fixed to the point P1 while the second portion 81B is fixed to the point P9, it is thought that the installation plate 81 does not follow the amplitude at these points P1 and P9, and friction on mutual contact surfaces increases.
As a result of the above vibration mode measurement, it became at least known that, on the shoe plate 40 of a disk shape as shown in Fig. 4, two points on both sides of a borderline, a diametral straight line passing the fixed point PO, are different from each other in vibration mode. Therefore, if the second portion 81B of the installation plate 81 is fixed to the point P9, it is thought that also in case the first portion 81A is fixed to one of the points P2, P3, P8, and P7 apart from the point P9 farther than the point PO, the installation plate 81 does not follow the amplitude of one of the points P2, P3, P8, and P7, and the friction on mutual contact surfaces increases.
In the drum type brake 3 related to this embodiment and the motorcycle (straddle type vehicle) 1 provided with the same brake, the natural frequency of the portion between the first
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portion 81A and the second portion 81B of the installation member 80 (installationplate 81) is different from the natural frequency of the shoe plate 40. Therefore, in case frictional vibration of the brake drum 30 and the brake shoe 50 occurs, the installation member 80 is different in natural vibration from the shoe plate 40 and friction occurs between the second portion 81B of the installation member 80 and the shoe plate 40 (fixed surface 40B2) . This makes it possible to convert vibration energy of the shoe plate 40 into frictional heat energy, attenuate vibration of the shoe plate 40, and prevent brake squeak.
Because the second portion 81B of the installation member 80 of this embodiment is fixed to the turn stop portion 40B of great amplitude of the shoe plate 40, it is possible to convert greater vibration of the shoe plate 40 into greater frictional heat energy and effectively prevent brake squeak effectively.
Further, as described above, the shoe plate 40 of approximate disk shape is the smallest in amplitude in the vicinity of the wheel shaft 2 6 and greater in amplitude at locations away from the wheel shaft 26 in radial direction. In case the first portion 81A and the second portion 81B of the installation member 80 are too close to each other, vibration modes of the shoe plate 4 0 in both portions end up in approximating each other, the installation member 80 ends up in following the vibration of the shoe plate 40, and friction of the installation member 80 and the shoe plate 40 in the secondportion 8 1B ends up in decreasing.
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Therefore, it is possible to effectively prevent brake squeak by producing greater frictional heat energy in the second portion 81B by fixing the second portion 81B of the installation member 80 to the portion of great amplitude of the shoe plate 40 while fixing the first portion 81A of the installation member 80 to the wheel shaft 2 6 affected less with the amplitude of the shoe plate 40.
The installation member 80 of this embodiment, although simple in constitution provided with the installation plate 81 and the cylindrical collar 82, is capable of preventing effectively squeak of the drum type brake 3 from occurring. It is also possible to easily attach the installation member 80 to the shoe plate 40 by fitting the cylindrical collar 82 over the wheel shaft 26, and easily retrofit the drum type brake 3 of existing motorcycles (straddle type of vehicles) 1 by later attachment.
This embodiment also makes it possible to fix easily the second portion 81B of the installation member 80 utilizing the existing turn stop portion (connecting portion of the turn stop rod) 40B and using a tightening member such as a bolt, and simplify the installation member 80 itself but also its installation structure.
In addition to this, in this embodiment, the contact points of the installation member 80 and the shoe plate 40 are limited
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to the first and second portion 81A and 81B necessary for producing frictional heat energy while other portion (main portion excluding the first and second portions 81A and 81B of the installation plate 81) is made free from contact. Owing to this, it is possible to prevent the installation plate 81 and the shoe plate 40 from contacting in unnecessary portions, vibrating, and producing new brake squeak.
Next, the drum type brake related to the second embodiment of the invention is described in reference to Fig. 8. Fig. 8 is an enlarge view of the drum type brake related to the second embodiment of the invention. Incidentally, in the second embodiment described below, the same parts as those of the first embodiment described above are provided with the same symbols and detailed description is omitted.
In the same figure, as for the drum type brake 4 related to this embodiment, the above installation member 80 (See Figs. 3 and 5) is assumed to be the rear arm 90 for supporting the rear wheel via the wheel shaft 26. The rear arm 90, is constituted like the installation member 80 to have a first and secondportions 90A and 90B, with the wheel shaft 26 inserted in and fixed to the first portion 90A, and with the turn stop portion 40B of the shoe plate 40 fixed to the second portion 90B.
The first portion 90A of the rear arm 90 is formed with an elongated hole 91 for inserting an end portion of the wheel shaft 26. The elongated hole 91 is for adjusting the slack
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or the like of a chain by moving the wheel shaft 2 6 in fore-and-aft direction of the vehicle. Similar to this, an elongated hole 92 extending in fore-and-aft direction of the vehicle is formed in the second portion 90B of the rear arm 90 so that the tightening position of the bolt 93 to be fixed to the turn stop portion 40B may be changed while following the displacement of the wheel shaft 26.
Like the first embodiment described above, the fixing surface 40B2 of the turn stop portion 40B is made slightly higher than other portion of the turn stop portion 40B other than that, so that the second portion 90b of the rear arm 90 comes into surface contact with the fixing surface 40B2 only.
With the drum type brake 4 of this embodiment like this, like with the first embodiment described above, the natural frequency of the portion between the first portion 90A and the second portion 90B is different from the natural frequency of the shoe plate 40. Due to this, in case frictional vibration of the brake drum 30 and the brake shoe 50 (Refer to Fig. 3) occurs, vibration modes of the rear arm 90 and the shoe plate 40 differ and friction occurs between the second portion 90B of the rear arm 90 and the shoe plate 40 (fixed surface 40B2) . Due to this, the vibration energy of the shoe plate 4 0 is converted to frictional heat energy, vibration of the shoe plate 40 is attenuated, and brake squeak is prevented.
It is also possible to make the rear arm 90 itself the installation
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member 80, so that brake squeak is effectively prevented without otherwise additionally providing an installation member 80 while reducing the number of parts.
Further, in case the portion between the first portion 90A and the shoe plate 40 is formed with a member that can be deemed to be almost rigid body vibrating together with the shoe plate, the same functional effect as with the first embodiment is provided even if the first portion 90A is not directly fixed to the shoe plate 40.
Next, the drum type brake related to the third embodiment of the invention is described in reference to Fig. 9. Fig. 9 is an enlarged view of the drum type brake related to the third embodiment of the invention. Incidentally, in the third embodiment described below, the same parts as those of the first or second embodiment described above are provided with the same symbols and detailed description is omitted.
In the same figure, the drumtypebrake related to this embodiment is constituted with the above installation member 80 (See Figs. 3 and 5) made the rear arm 100. In this embodiment, however, the turn stop portion 140 of the shoe plate 40 is changed in constitution.
First, the rear arm 100 has the first portion 100A in the
vicinity of the end portion of its side wall portion 101 and
also has the second portion 100B at its upper wall portion 102.
An elongate hole 101a extending in fore-and-aft direction of
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the vehicle is formed in the first portion 100A. The wheel shaft 26 inserted into the elongated hole 101a is tightened with a nut 26a.
On the other hand, in the second portion 100B is bored an attachment hole 102a passing through the upper wall portion 102. A nut 103 with its thread hole matching the attachment hole 102a is welded to the reverse side of the upper wall portion 102. The bolt 142 inserted into the turn stop portion 140 of the shoe plate 40 is tightened into the nut 103 to fix the turn stop portion 140 to the second portion 100B.
The turn stop portion 140 is made approximately parallel to the rear arm 100 of an inverted L plate shape in cross section integral with the shoe plate 40. The turn stop portion 140 has a fixing portion 141 in surface contact with the upper wall portion 102 of the rear arm 100. An elongated hole 141a for inserting the bolt 142 is formed in the fixing portion 141. The elongated hole 141a extends in fore-and-aft direction of the vehicle so that the tightening position of the bolt 142 for fixing the turn stop portion 140 may be changed following the displacement of the wheel shaft 2 6 when it is moved along the elongated hole 101a provided in the first portion 101A of the rear arm 100.
With the drum type brake 5 of this embodiment as described above, like with the first embodiment, the natural frequency of the portion between the first portion 100A and the second
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portion 100B of the rear arm 100 is different from the natural frequency of the shoe plate 40. Due to this, in case frictional vibration of the brake drum 30 and the brake shoe 50 (Refer to Fig. 3) occurs, the rear arm 100 and the shoe plate 40 are different in vibration mode, and friction occurs between the second portion 100B of the rear arm 100 and the shoe plate 40 (fixed portion 141) . Due to this, the vibration energy of the shoe plate 40 is converted to frictional heat energy, vibration of the shoe plate 40 is attenuated, and brake squeak is prevented.
Further, like in the second embodiment, the rear arm 100 itself may be made the installation member 80 to effectively prevent brake squeak while reducing the number of parts without additionally providing the installation member 80 separately.
Next, the drum type brake related to the fourth embodiment of the invention is described in reference to Fig. 10. Fig. 10 is an enlarged partial view of the drum type brake related to the fourth embodiment of the invention. Incidentally, in the fourth embodiment described below, the same parts as those of the first to third embodiments are provided with the same symbols and detailed description is omitted.
In the same figure, the drum type brake 6 of this embodiment is of a constitution provided with an installation member 110 made up of an installation plate 111 and a cylindrical collar 112. In particular, this embodiment is characterized in that the second portion 111B of the installation plate 111 is provided
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with a projecting, step-shaped press contact portion 111b, so that the press contact portion 111b is pressed against the surface of the shoe plate 40 with an urging force given to the installation plate 111.
As a means for giving the urging force to the press contact portion 111b, for example, in the state of before being fixed to the wheel shaft 26, the installation plate 111 is provided with a slight forward tilt in the direction opposite the projecting direction (the direction of arrow P in the figure) of the cylindrical collar 112. This results in that the installation plate 111 produces urging force in the direction of arrow P in the figure when the cylindrical collar 112 is fixed to the wheel shaft 26.
Further, to the first portion 111A of the installation plate 111 is fitted, like in the first embodiment, the step-shaped attachment portion 112a of the cylindrical collar 112, so as to keep the first portion 111A side of the installation plate 111 at the height of the contact portion 111b on the surface of the shoe plate 40 when the cylindrical collar 112 is fixed to the wheel shaft 26. This results in that only the contact portion 111b of the installation plate 111 comes into contact with the surface of the shoe plate 40.
With such a drum type brake 6 of this embodiment, like with the first embodiment, the natural frequency of the portion between the first portion 111A and the second portion 111B of the
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installation member 110 (installation plate 111) is different from the natural frequency of the shoe plate 40. As a result, when frictional vibration of the brake drum 30 and the brake shoe 50 (Refer to Fig. 3) occurs, vibration modes of the installation member 110 and the shoe plate 40 are different, and friction occurs between the contact portion 111b and the shoe plate 40 in the second portion 111B of the installation 110. Due to this, vibration energy of the shoe plate 40 is converted to frictional heat energy, vibration of the shoe plate 40 is attenuated, and it is possible to prevent brake squeak.
Since this embodiment is also constituted that the contact portion 111b is formed in the second portion 111B of the installation 110 and the contact portion 111b is pressed against the surface of the shoe plate 40, the second portion 111B need not be fixed with bolts and nuts, and attachment to the shoe plate 40 is further facilitated.
Next, the drum type brake related to the fifth embodiment of the invention is described in reference to Fig. 11. Fig. 11 is a front view of the shoe plate and the installation member that make up the drum type brake related to the fifth embodiment of the invention. Incidentally, in the fifth embodiment described below, the same parts as those of the first to fourth embodiments described above are provided with the same symbols and detailed description is omitted.
In the same figure, the drum type brake 7 of this embodiment
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is constituted with the shoe plate 40 and an installation member 12 0 of an approximately concentric arcuate shape. The installation member 120 has, on its both end sides, first and second portions 120A and 120B. These first and second portions 120A and 120B are provided with attachment holes 121 and 122 for passing through attachment bolts (not shown).
On the other hand, the shoe plate 4 0 is provided with two projecting attachment seat portions 40D and 40E corresponding to the attachment holes 121 and 122. Thread holes 40D1 and 4 0E1 for screw engagement with the above-mentioned attachment bolts are bored in the centers of the attachment seat portions 40D and 40E. The first and second portions 120A and 120B of the installation member 120 are placed on the attachment seat portions 40D and 40E, and the attachment bolts inserted into the attachment holes 121 and 122 are tightened into the thread holes 40D1 and 40E1, so that the first and second portions 120A and 120B are fixed to the attachment seat portions 40D and 40E.
Like this, like the first and second embodiments, the portion for fixing the first portion 120 A is not limited to the vicinity of the wheel shaft insertion hole 40A of the shoe plate 40 and the wheel shaft 26. In other words, as long as the natural frequency of the portion between the first portion 120A and the second port ion 12 0B of the installation member 120 is different from the natural frequency of the shoe plate 40, functional effect of vibration attenuation may be provided even if the
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first portion 120A of the installation member 120 is fixed to a portion other than the wheel shaft insertion hole 40A on the shoe plate 40, like in this embodiment.
With the drum type brake 7 of this embodiment constituted like this, the natural frequency of the portion between the first portion 120A and the second portion 12 OB of the installation member 12 0 is different from the natural frequency of the shoe plate 40. As a result, when frictional vibration of the brake drum 30 and the brake shoe 50 (Refer to Fig. 3) occurs, vibration modes of the installation member 110 and the shoe plate 40 are different, and friction occurs between the first and second portions 120A, 120B of the installation member 120 and the shoe plate 40 (attachment seat portions 40D, 40E). Due to this, vibration energy of the shoe plate 40 is converted to frictional heat energy, vibration of the shoe plate 40 is attenuated, and it is possible to prevent brake squeak.
Incidentally, the drum type brake and the straddle type vehicle of the invention are not limited to the above embodiments. For example, this invention makes it possible to prevent brake squeak in the drum type brake of not only inside expansion type according to the above embodiments, but also outside contact type, once frictional vibration occurs. In case of inside expansion type of drum type brake, this invention may be applied to both the double leading-shoe type and leading-and-trailing shoe type.
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In all the above embodiments, while the installation member is made a thin, light-weight, plate-shapedbody, it is not limited to the plate-shaped body but may be variously changed in many respects such as shape and weight.
Further, the straddle type vehicle as the object of applying the drum type brake related to this invention is not limited to the motorcycle 1 of the type shown in Fig. 1 but the object of application may be two-wheeled vehicles such as scooters, off-the-road vehicles, and tricycles, four-wheeled buggies (all-terrain vehicles), and straddle type vehicles such as snowmobiles.
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What is claimed is:
1. A drum type brake having an installation member, wherein the installation member is placed adjacent in the wheel shaft direction to a brake drum, installed on a shoe plate for pivoting a brake shoe for free turn, and having a first portion and a second portion, the first portion being fixed to the shoe plate or another member, the second portion being fixed to or pressed against the shoe plate, and the natural frequency of the portion between the first portion and the second portion being different from the natural frequency of the shoe plate when the first portion is made a fixed point.
2 . The drum type brake as claimed in Claim 1, having a portion of small amplitude and a portion of great amplitude when the shoe plate vibrates, wherein the first portion of the installation member is fixed to the portion of small amplitude or fixed to another member located in the portion of small amplitude, while the second portion of the installation member is fixed to or pressed against the portion of great amplitude.
3. The drum type brake as claimed in Claim 1, having a portion of small amplitude and a portion of great amplitude when the shoe plate vibrates, wherein the second portion of the installation member is fixed to or pressed against the portion of great amplitude, while the first portion of the installation
- 32 -

member is fixed to a portion of the shoe plate apart from the secondportionmore than the wheel shaft in the diametral direction or to another member located in the portion of the shoe plate apart from the second portion more than the wheel shaft in the diametral direction.
4. The drum type brake as claimed in Claim 1, wherein the
first portion of the installation member is fixed to the wheel
shaft.
5. The drum type brake as claimed in Claim 4, wherein the
first portion of the installation member is fixed through a
cylindrical collar to the wheel shaft.
6. The drum type brake as claimed in Claim 5, wherein the
installation member is provided with an installation plate having
a first portion on one end and a second portion on the other
end; and the cylindrical collar fixed to the first portion,
and the cylindrical collar is attached to the wheel shaft while
the second portion of the installation plate is fixed to or
pressed against the shoe plate.
7. The drum type brake as claimed in Claim 1, wherein the
second portion of the installation member is fixed to or pressed
against a turn stop portion of the shoe plate.
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8. The drum type brake as claimed in Claim 7, wherein the second portion of the installation member is fixed to the turn stop portion with a tightening member.
9 . The drum type brake as claimed in Claim 1, wherein a clearance is formed between a main portion of the installation member excluding the portion between the first and second portions and the shoe plate so that the main portion and the shoe plate keep non-contact state even when the shoe plate vibrates.
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10. The drum type brake as claimed in Claim 1, wherein the
installation member is made a rear arm for supporting a rear
wheel through the wheel shaft, the rear arm is provided with
the first and second portions, and the wheel shaft is passed
through the first portion and fixed while the turn stop portion
of the shoe plate is fixed to the second portion.
11. A straddle type vehicle provided with the drum type brake
as claimed in one of Claims 1 to 10.


Documents:

00837-kol-2006 abstract.pdf

00837-kol-2006 claims.pdf

00837-kol-2006 correspondence others.pdf

00837-kol-2006 description(complete).pdf

00837-kol-2006 drawings.pdf

00837-kol-2006 form-1.pdf

00837-kol-2006 form-2.pdf

00837-kol-2006 form-3.pdf

00837-kol-2006 form-5.pdf

00837-kol-2006 g.p.a.pdf

00837-kol-2006 priority documents.pdf

00837-kol-2006-correspondence-1.1.pdf

837-KOL-2006-(27-01-2012)-CORRESPONDENCE.pdf

837-KOL-2006-(27-01-2012)-FORM 27.pdf

837-KOL-2006-(27-01-2012)-PA.pdf

837-KOL-2006-ABSTRACT.pdf

837-KOL-2006-AMANDE CLAIMS.pdf

837-KOL-2006-AMANDED PAGES OF SPECIFICATION.pdf

837-KOL-2006-CORRESPONDENCE 1.1.pdf

837-kol-2006-correspondence.pdf

837-KOL-2006-DESCRIPTION (COMPLETE) 1.1.pdf

837-KOL-2006-DRAWINGS 1.1.pdf

837-kol-2006-examination report.pdf

837-KOL-2006-FORM 1 1.1.pdf

837-kol-2006-form 18.pdf

837-KOL-2006-FORM 2 1.1.pdf

837-KOL-2006-FORM 3 1.1.pdf

837-kol-2006-form 3-1.2.pdf

837-kol-2006-form 5.pdf

837-kol-2006-gpa.pdf

837-kol-2006-granted-abstract.pdf

837-kol-2006-granted-claims.pdf

837-kol-2006-granted-description (complete).pdf

837-kol-2006-granted-drawings.pdf

837-kol-2006-granted-form 1.pdf

837-kol-2006-granted-form 2.pdf

837-kol-2006-granted-letter patent.pdf

837-kol-2006-granted-specification.pdf

837-KOL-2006-INTERNATIONAL SEARCH REPORT.pdf

837-KOL-2006-OTHERS DOCUMENTS.pdf

837-KOL-2006-OTHERS PATENT DOCUMENTS.pdf

837-kol-2006-others-1.1.pdf

837-KOL-2006-OTHERS.pdf

837-KOL-2006-PETITION UNDER RULE 137-1.1.pdf

837-KOL-2006-PETITION UNDER RULE 137-1.2.pdf

837-KOL-2006-PRIORITY DOCUMENT.pdf

837-kol-2006-reply to examination report-1.1.pdf

837-KOL-2006-REPLY TO EXAMINATION REPORT.pdf

837-KOL-2006-TRANSLATED COPY OF PRIORITY DOCUMENT.pdf

abstract-00837-kol-2006.jpg


Patent Number 244387
Indian Patent Application Number 837/KOL/2006
PG Journal Number 50/2010
Publication Date 10-Dec-2010
Grant Date 06-Dec-2010
Date of Filing 21-Aug-2006
Name of Patentee YAMAHA HATSUDOKI KABUSHIKI KAISHA
Applicant Address 2500 SHINGAI, IWATA-SHI, SHIZUOKA-KEN
Inventors:
# Inventor's Name Inventor's Address
1 KAZUNORI MATSUMURA C/O. YAMAHA HATSUDOKI KABUSHIKI KAISHA, 2500, SHINGAI, IWAGA-SHI, SHIZUOKA 4388501
2 TAKAO L KOYA C/O. YAMAHA HATSUDOKI KABUSHIKI KAISHA, 2500, SHINGAI, IWAGA-SHI, SHIZUOKA 4388501
3 TOYOKATSU C/O. YAMAHA HATSUDOKI KABUSHIKI KAISHA, 2500, SHINGAI, IWAGA-SHI, SHIZUOKA 4388501
4 TATSUYA SASAKI C/O. YAMAHA HATSUDOKI KABUSHIKI KAISHA, 2500, SHINGAI, IWAGA-SHI, SHIZUOKA 4388501
PCT International Classification Number F 16 D 65/12
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2005-257051 2005-09-05 Japan