Title of Invention

A DIRECT INJECTION TYPE COMBUSTION CHAMBER OF DIELSEL ENGINE

Abstract

ABSTRACT A cavity 7 is arranged at a mid portion of the piston head top surface 4, and a valve recess 6 is arranged near to a peripheral edge of the piston head top surface 4. The cavity 7 and the valve recess 6 are communicated with each other, so that a swirl flow 23 can be inducted into the cavity 7 under the guide of a valve recess inner peripheral surface 12. A raised portion 10 is formed from a mid portion of an inner bottom of the cavity 7 toward the cylinder head 1.

Full Text

The present invention relates to a direct injection type combustion chamber of a diesel engine. As a prior art of a direct injection type combustion chamber of a diesel engine there has been known a one as shown in Fig. 4 This includes the following basic construction similarly to the present invention. That is, a cylinder head 101 is provided with a fuel injection nozzle 102 and a swirl port 103, a piston head top surface 104 has a valve recess 106 and a combustion cavity 107 concaved therein leaving a squish surface 105, so that a fuel 108 can be injected from the fuel injection nozzle 102 into the cavity 107. The cavity 107 is arranged at a mid portion of the piston head top surface 104, and the valve recess 106 is arranged near to a peripheral edge of the piston head top surface 104. The cavity 107 and the valve recess 106 are communicated with each other, so that a swirl flow 123 can be inducted into the cavity 107 under the guide of a valve recess inner peripheral surface 112. In this combustion chamber, since the swirl flow 123 rotating about a cylinder center axis 109 is produced within a cylinder by a suction air inducted from the swirl port 103 into the cylinder during a suction stroke and the piston head top surface 104 approaches the cylinder head 101 at an end of a compression stroke, the swirl flow 123 is inducted rapidly into the cavity 107 under the guide of a valve recess inner peripheral surface 112, a rotating flow 124 rotating about a cavity center axis 122 is produced within the cavity 107 as well as a squish flow 125 is produced by the squish surface 105 within the cavity 107, so that the air and the fuel 108 can be mixed by those rotating flow 124 and squish flow 125 within the cavity 107. In this prior art, since an inner bottom surface of the cavity 107 is flat, a stagnant air portion on which the rotating flow 124 can't act tends to remain at a mid portion of the cavity 107. Accordingly, the present invention provides a direct injection type combustion chamber of a diesel engine which injects fuel from a fuel injection nozzle into a combustion cavity of a piston head top surface, comprising: a cylinder head being provided with the fuel injection nozzle and a swirl port; the said piston head top surface having a valve recess and the said combustion cavity being concaved therein leaving a squish surface, so that the fuel can be injected from the fuel injection nozzle into the said combustion cavity; the said combustion cavity being located at a mid portion of the piston head top surface, and the valve recess being located near to a peripheral edge of the piston head top surface; the said combustion cavity and the said valve recess having a communication with each other, so that a swirl flow is inducted into the cavity under the guide of a valve recess inner peripheral surface; a raised portion being provided from a mid portion of an inner bottom of the said cavity toward the cylinder head; only one valve recess being provided, and when observing in parallel to a cylinder center axis and assuming a recess center pointing radial imaginal line extending from the cylinder center axis toward a recess center axis of the valve recess, a reference radial imaginal line extending from the cylinder center axis in a direction opposed to the recess center pointing radial imaginal line, a lower-limit radial imaginal line advanced in angle from the reference radial imaginal line in the turning direction of the swirl flow and an upper-limit radial imaginal line further advanced in angle from the lower-Hmit radial imaginal line in the turning direction of the swirl flow; and an advancement angle of the lower-limit radial imaginal hne with respect to the reference radial imaginal line being set to 30 degrees and an advancement angle of the upper-limit radial imaginal line with respect to the reference radial imaginal line being set to 150 degrees, so that a cavity center axis offset relative to the cylinder center axis is arranged within a sector range having a central angle of 120 degrees defined between the lower-limit radial imaginal line and the upper-limit radial imaginal line. SUMMARY OF THE INVENTION It is an object of the present invention to provide a direct injection type combustion chamber of a diesel engine which is capable of increasing a combustion efficiency. For accomplishing the above-mentioned object, the present invention employs the following construction. For example, as shown in Fig. 1(A) or Fig. 3 corresponding to embodiments of the present invention, in a direct injection type combustion chamber of a diesel engine, a cylinder head 1 is provided with a fuel injection nozzle 2 and a swirl port 3, a piston head top surface A has a valve recess 6 and a combustion cavity 7 concaved therein leaving a squish surface 5, so that a fuel 8 can be injected from the fuel injection nozzle 2 into the cavity 7, the cavity 7 is arranged at a mid portion of the piston head top surface h and the valve recess 6 is arranged near to a peripheral edge of the piston head top surface 4, the cavity 7 and the valve recess 6 are communicated with each other, so that a swirl flow 23 can be inducted into the cavity 7 under the guide of a valve recess inner peripheral surface 12. Therein, a raised portion 10 is formed from a mid portion of an inner bottom of the cavity 7 toward the cylinder head \ . According to the present Invention, the following advantages can be obtained owing to the above-mentioned construction. That is, in this combustion chamber, as shown in Fig. 1 (A) or Fig. 3, since the swirl flow 23 rotating about a cylinder center axis 9 is produced within a cylinder by a suction air inducted from a swirl port 3 into the cylinder during a suction stroke and the piston head top surface 4 approaches the cylinder head 1 at an end of a compression stroke, the swirl flow 23 is inducted rapidly into the cavity 7 under the guide of a valve recess inner peripheral surface 12, a rotating flow Ik rotating about a cavity center axis 22 is produced within the cavity 7 as well as a squish flow 25 is produced by the squish surface 5 within the cavity 7, so that the air and the fuel 8 can be mixed by those rotating flow 24 and squish flow 25 within the cavity 7. Then, in the present invention, since the raised portion 10 is formed from the mid portion of an inner bottom of the cavity 7 toward the cylinder head, the stagnant air portion on which the rotating flow 24 doesn't act doesn't exist at the mid portion of the cavity 7. BRIEF DESCRIPTION OF THE DRAWING Fig. 1 is an explanatory view of a combustion chamber in a first embodiment of the present invention, Fig. 1(A) is a front view of a piston head top surface. Fig. 1(B) is a sectional view taken along the B - B line in Fig. 1(A), Fig-1(C) is a sectional view taken along the C - C line in Fig* 1(A), and Fig. 1(D) is a sectional view taken along the D-D line in Fig. 1 (B); Fig. 2 is an explanatory view of a principal portion of an engine provided with the combustion chamber in the first embodiment. Fig. 2(A) is a vertical sectional view, and Fig. 2(B) is a sectional view taken along the B - B line in Fig. 2(A); Fig. 3 is a front view of a piston head top surface for use in a combustion chamber in a second embodiment of the present invention; and Fig. 4 is an explanatory view of a combustion chamber of a prior art, Fig. A(A) is a front view of a piston head top surface, and Fig. A(B) is a sectional view taken along the B - B line in Fig. A(A). DESCRIPTION OF THE PREFERRED EMBODIMENT Embodiments of the present invention will be explained with reference to the drawings. In a first embodiment illustrated in Figs. 1 and 2, a single-cylinder horizontal diesel engine is exemplified. A construction of this engine is as follows. That is, as shovm in Fig. 2 (A), a cylinder 30 is mounted horizontally into a cylinder block 29, and a cylinder head 1 is assembled to one end of the cylinder block 29. A piston head 32 is internally fitted into the cylinder 30. A push rod insertion bore 34 is opened through both the cylinder block 29 ^nd the cylinder head 1, and a push rod 35 is inserted thereinto. The cylinder head 1 is provided with a suction air swirl port 3, an exhaust port 31 and a nozzle insertion port 33, and a fuel injection nozzle 2 is inserted into the nozzle insertion port 33 and fixedly secured therein. As shown in Fig. 1, a piston head top surface 4 has a valve recess 6 and a combustion cavity 7 concaved therein leaving a squish surface 5, so that a fuel 8 can be injected from the fuel injection nozzle 2 into the cavity 7. The cavity 7 is arranged at a mid portion of the piston head top surface 4 and the valve recess 6 is arranged near to a peripheral edge of the piston head top surface 4. The cavity 7 and the valve recess 6 are communicated with each other, so that a swirl flow 23 can be inducted into the cavity 7 under the guide of a valve recess inner peripheral surface 12. In this combustion chamber, since the swirl flow 23 rotating about a cylinder center axis 9 is produced within a cylinder by a suction air inducted from a swirl port 3 into the cylinder during a suction stroke and the piston head top surface ^ approaches the cylinder head ] at an end of a compression stroke, the swirl flow 23 is inducted rapidly into the cavity 7 under the guide of a valve recess inner peripheral surface 12, a rotating flow 24 rotating about a cavity center axis 22 is produced within the cavity 7 as well as a squish flow 25 is produced by the squish surface 5 within the cavity 7, so that the air and the fuel 8 can be mixed by those rotating flow 24 and squish flow 25 within the cavity 7. In this embodiment, in order to increase a combustion efficiency, a raised portion 10 is formed from a mid portion of the inner bottom of the cavity 7 toward the cylinder head ]. Therefore, a stagnant air portion on which the rotating flow 24 doesn't act doesn't exist at the mid portion of the cavity 7, and the mixing of the air and the fuel within the cavity 7 is promoted to increase the combustion efficiency. The valve recess 6 is round. This valve recess 6 is used for a suction valve, but there is not provided any valve recess for an exhaust valve. The fuel 8 injected from the fuel injection nozzle 2 is directed from a location near to the cavity center axis 22 to the cavity inner peripheral surface 11. The cavity 7 has the cavity center axis 22 parallel to the cylinder center axis 9, and the cavity inner peripheral surface 11 is formed like a truncated conical surface of which diameter increases gradually as it approaches the inner bottom surface of the cavity 7. A peripheral surface of the raised portion 10 is formed like a conical surface of which diameter decreases gradually as it approaches the cylinder head 1. As shown in Fig. 1 (D), since the cavity inner peripheral surface 11 and the peripheral surface of the raised portion 10 appear as coaxial circles about the cavity center axis 22 in an imaginal section perpendicular to the cylinder center axis 9, the rotating flow 24 rotates under a little resistance within the cavity 7. In this first embodiment, as shown in Fig. 1(A), only one valve recess 6 is arranged, and when observing in parallel to a cylinder center axis 9 and assuming a recess center pointing radial imaginal line 15 extending from the cylinder center axis 9 toward a recess center axis 14 of the valve recess 6, a reference radial imaginal line 16 extending from the cylinder center axis 9 in the opposed direction to the recess center pointing radial imaginal line 15, a lower-limit radial imaginal line 17 advanced in angle from the reference radial imaginal line 16 in the turning direction of the swirl flow and an upper-limit radial imaginal line 18 further advanced in angle from the lower-limit radial imaginal line 17 in the turning direction of the swirl flow, an advancement angle 19 of the lower-limit radial imaginal line 17 with respect to the reference radial imaginal line 16 is set to 30 degrees and an advancement angle 20 of the upper-limit radial imaginal line 18 with respect to the reference radial imaginal line 16 is set to 150 degrees, so that a cavity center axis 22 offset relative to the cylinder center axis 9 is arranged within a sector range 21 having a central angle of 120 degrees defined between the lower-limit radial imaginal line 17 and the upper-limit radial imaginal line 18. According to the above-mentioned construction, in case that the squish surface 5 is divided into a fore half portion 26 ranging from the valve recess 6 to the reference radial imaginal line 16 along the swirl flow rotating direction and a rear half portion 27 ranging from the reference radial imaginal line 16 to the valve recess 6 along the swirl flow rotating direction, when an offset distance of the cavity center axis 22 from the cylinder center axis 9 is constant as well as the cavity center axis 22 is located on an orthogonal radial imaginal line 28 advanced by an angle of 90 degrees from the reference radial imaginal line 16 toward the downstream side of the swirl flow 23, an area of the fore half portion 26 becomes maximum and an area of the rear half portion 27 becomes minimum. Therefore, when the cavity center axis 22 is disposed within a sector range 21 having a central angle of 120 degrees extending evenly from the orthogonal radial imaginal line 28 to both the upstream side and the downstream side of the swirl flow 23 respectively, the area of the fore half portion 26 becomes large sufficiently and the area of the rear half portion 27 becomes small sufficiently, so that a speed of the squish flow 25 produced in the fore half portion 26 is increased and a speed of the squish flow 25 produced in the rear half portion 27 is decreased correspondingly to that increased speed. Thereupon, the rotating flow 24 having a strong rotating force just after the induction from the valve recess 6 into the cavity 7 and the high-speed squish flow 25 can be compounded in well-balanced manner as well as the rotating flow 24 having slightly decreased its rotating force after the rotation of about half perimeter within the cavity 7 and the low-speed squish flow 25 are compounded in well-balanced manner, so that the rotating flow 24 is hardly disturbed by the squish flow 25 and the decreasing of its rotation force is restrained. Accordingly, the mixing of the air and the fuel 8 within the cavity 7 is further promoted and the combustion efficiency is further increased. More preferably, an advancement angle 19 of the lower-limit radial imaginal line 17 with respect to the reference radial imaginal line 16 is set to 45 degrees, an advancement angle 20 of the upper-limit radial imaginal line 18 with respect to the reference radial imaginal line 16 is set to 135 degrees, so that a cavity center axis 22 offset relative Co the cylinder center axis 9 is arranged within a sector range 21 having a central angle of 90 degrees defined between the lower-limit radial imaginal line 17 and the upper-lirait radial imaginal line 18. In a second embodiment of the present invention illustrated in Fig. 3, the first embodiment illustrated in Figs. ] and 2 is modified so that the cavity inner peripheral surface 11 and the valve recess inner peripheral surface 12 are connected to each other through a swirl flow guide surface 13 directed tangentially with respect to both those inner peripheral surfaces 11, 12. Other constructions are the same as those in the first embodiment, and in Fig. 3, the same component members as those in the first embodiment are designated by the same symbols. According to this construction, the swirl flow 23 inducted into the valve recess 6 is guided rapidly into the cavity 7 along the swirl guide surface 13, so that the speed of the rotating flow 24 within the cavity 7 is increased. Therefore, the mixing of the air and the fuel 8 within the cavity 7 is further promoted and the combustion efficiency is further increased. WE CLAIM: I. A direct injection type combustion chamber of a diesel engine which injects fuel (8) from a fuel injection nozzle (2) into a combustion cavity (7) of a piston head top surface (4), comprising: a cylinder head (1) being provided with the fuel injection nozzle (2) and a swirl port (3); the said piston head top surface (4) having a valve recess (6) and the said combustion cavity (7) being concaved therein leaving a squish surface (5), so that the fuel (8) can be injected from the fuel injection nozzle (2) into the said combustion cavity (7); the said combustion cavity (7) being located at a mid portion of the piston head top surface (4), and the valve recess (6) being located near to a peripheral edge of the piston head top surface (4); the said combustion cavity (7) and the said valve recess (6) having a communication with each other, so that a swirl flow (23) is inducted into the cavity (7) under die guide of a valve recess inner peripheral surface (12); a raised portion (10) being provided from a mid portion of an inner bottom of the said cavity (7) toward the cylinder head (1); only one valve recess (6) being provided, and when observing in parallel to a cylinder center axis (9) and assuming a recess center pointing radial imaginal line (15) extending from the cylinder center axis (9) toward a recess center axis (14) of the valve recess (6), a reference radial imaginal line (16) extending from the cylinder center axis (9) in a direction opposed to the recess center pointing radial imaginal line (15), a lower-limit radial imaginal line (17) advanced in angle from the reference radial imaginal line (16) in the turning direction of the swirl flow and an upper-limit radial imaginal line (18) further advanced in angle from the lower-limit radial imaginal line (17) in the turning direction of the swirl flow; and an advancement angle (19) of the lower-limit radial imaginal line (17) with respect to the reference radial imaginal line (16) being set to 30 degrees and an advancement angle (20) of the upper-limit radial imaginal line (18) with respect to the reference radial imaginal line (16) being set to 150 degrees, so that a cavity center axis (22) offset relative to the cylinder center axis (9) is arranged within a sector range (21) having a central angle of 120 degrees defined between the lower-limit radial imaginal line (17) and the upper-limit radial imaginal line (18). 2. A direct injection type combustion chamber of a diesel engine which injects fuel (8) from a fuel injection nozzle (2) into a combustion cavity (7) of & piston head top surface (4), comprising: a cylinder head (1) being provided with the fuel injection nozzle (2) and a swirl port (3); the S3id piston head top surface (4) having a valve recess (6) and the said combustion cavity (7) being concaved therein leaving a squish surface (5), so that the fuel (8) can be injected from the fuel injection nozzle (2) into the said combustion cavity (7); the said combustion cavity (7) being located at a mid portion of the piston head top surface (4), and the valve recess (6) being located near to a peripheral edge of the piston head top surface (4); the said combustion cavity (7) and the said valve recess (6) having a communication with each other, so that a swirl flow (23) is inducted into the cavity (7) under the guide of a valve recess inner peripheral surface (12); a raised portion (10) being provided from a mid portion of an inner bottom of the said cavity (7) toward the cylinder head (1); only one valve recess (6) being provided, and when observing in parallel to a cylinder center axis (9) and assuming a recess center pointing radial imaginal line (15) extending from the cylinder center axis (9) toward a recess center axis (14) of the valve recess (6), a reference radial imaginal line (16) extending from the cylinder center axis (9) in a direction opposed to the recess center pointing radial imaginal line (15), a lower-limit radial imaginal line (17) advanced in angle from the reference radial imaginal line (16) in the turning direction of the swirl flow and an upper-limit radial imaginal line (18) further advanced in angle from the lower-limit radial imaginal line (17) in the turning direction of the swirl flow; and the advancement angle (19) of the lower-limit radial imaginal line (17) with respect to the reference radial imaginal line (16) being set to 45 degrees and the advancement angle (20) of the upper-limit radial imaginal line (18) with respect to the reference radial imaginal line (16) being set to 135 degrees, so that the cavity center axis (22) offset relative to the cylinder center axis (9) is arranged within the sector range (21) having the central angle of 90 degrees defined between the lower-limit radial imaginal line (17) and the upper-limit radial imaginal line (18). 3. The direct injection type combustion chamber of a diesel engine as claimed in claim 1 or 2, wherein the valve recess inner peripheral surface (12) is connected to a cavity inner peripheral surface (11) through a swirl flow guide surface (13) directed tangentially with respect to both of those inner peripheral surfaces (11), (12). 4. A direct injection type combustion chamber of a diesel engine, substantially as herein described with reference to the accompanying drawings.

Documents:

1788-mas-96 abstract-duplicate.pdf

1788-mas-96 abstract.pdf

1788-mas-96 claims-duplicate.pdf

1788-mas-96 claims.pdf

1788-mas-96 correspondence-others.pdf

1788-mas-96 correspondence-po.pdf

1788-mas-96 description (complete)-duplicate.pdf

1788-mas-96 description (complete).pdf

1788-mas-96 drawings.pdf

1788-mas-96 form-13.pdf

1788-mas-96 form-2.pdf

1788-mas-96 form-26.pdf

1788-mas-96 form-4.pdf

1788-mas-96 petition.pdf