JPH0718329B2 - Engine oil pump structure - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement in an oil pump structure of an engine.

(Prior Art) Conventionally, in an oil pump as a single article,
For example, as disclosed in Japanese Utility Model Publication No. 48-34002, a recirculation passage that connects the discharge side and the suction side of an oil pump is provided, and when the discharge pressure exceeds a predetermined value,
There is one in which the discharged oil is returned to the suction side of the oil pump through the recirculation passage to improve the efficiency of the oil pump.

On the other hand, in an engine, as disclosed in, for example, Japanese Patent Laid-Open No. 57-131808, a cover for covering a conduction band such as a timing chain or belt is detachably attached to the outer surface of the engine body, and the cover is attached to the cover. It is known that an oil pump that is driven by a crankshaft or the like is integrally provided. In this case, when the pressure of the oil discharged from the oil pump (discharge pressure) exceeds a predetermined value, the discharged oil is returned to the oil pan to control the discharge pressure.

(Problems to be solved by the invention) However, in the case where the oil pump is not a single article but is provided integrally with the engine such as the conduction band cover as described above, the discharge oil is discharged through the recirculation passage. The structure of returning to the suction side has not been put to practical use. This is because if the recirculation passage is made up of a pipe arranged outside the cover, the passage length becomes longer, so the pressure of the discharge oil returned to the suction side drops significantly due to the passage resistance. Because the pressure of the discharged oil that has been returned to the oil tank may hinder sucking the oil from the oil pan into the oil pump, the efficiency of the oil pump cannot be improved even if the discharged oil is returned to the suction side. Is.

The present invention has been made in view of the above points, and an object of the present invention is to provide a recirculation that connects the discharge side and the suction side of an oil pump in the case where the oil pump is provided integrally with the engine. Make the passage as short as possible to suppress the pressure drop due to the passage resistance of the discharge oil returned from the discharge side to the suction side, while preventing the pressure of the discharge oil returned to the suction side from obstructing the oil suction from the oil pan. None, the efficiency of the oil pump can be effectively increased by returning the discharged oil to the suction side.

(Means for Solving the Problems) In order to achieve the above object, the means for solving the problems of the present invention has the following structure as an oil pump structure of an engine.
That is, a member that constitutes an oil pump body is integrally provided on the outer surface of the engine body, and a recirculation passage that connects the discharge side and the suction side of the oil pump is provided along a guide wall that guides the pump rotor. Has been formed. Further, the suction passage for sucking oil from the oil pan is communicated with the suction chamber of the oil pump substantially in the center in the circumferential direction, while the recirculation passage is provided on the trailing side of the suction chamber (in the pump rotor rotation direction). It is configured such that the opening is on the delayed side when viewed.

(Operation) With the above configuration, in the present invention, the recirculation passage that connects the discharge side and the suction side of the oil pump is formed along the guide wall, and is close to the trailing side of the suction chamber, that is, the discharge chamber. Since the passage length is extremely short due to the opening in the portion, the pressure drop due to the passage resistance of the discharge oil returned from the discharge side to the suction side hardly occurs. Moreover, since the recirculation passage is open to the trailing side away from the position (approximately the center in the circumferential direction) of the suction chamber with which the suction passage communicates, the discharge returned to the suction chamber via this passage. The suction of the oil from the oil pan through the suction passage is not hindered by the pressure of the oil, so that the oil can be sucked well.

(Example) Hereinafter, the Example of this invention is described based on drawing.

1 and 2 show an engine having an oil pump structure according to an embodiment of the present invention, 1 is a cylinder block, 2 is an oil pan attached to a lower portion of the cylinder block 1, and 3 is a cylinder block 1. A pulley 4 is attached to an end portion of the crank shaft disposed inside the crank shaft 3 and extending toward the front of the cylinder block 1, and a chain 5 is wound around the pulley 4.

A chain cover 12 is arranged on the front outer surface of the cylinder block 1 to cover the chain 5. The chain cover 12 is located on the cylinder block 1 side of the pulley 4 and is formed into an inner member 13 that is detachably attached to the cylinder block 1 and a bag shape that opens rearward (toward the inner member 13). An outer member 14 detachably attached to the member 13 and joined to the member 13 in an oil sheet state.
And the chain 5 is housed between the inner member 13 and the outer member 14.

An oil pump housing 20 is formed on the inner member 13 of the chain cover 12 corresponding to the crankshaft 3, and an oil pump 21 driven by the crankshaft 3 is housed in the housing 20. Above oil pump
Reference numeral 21 denotes an internal gear type having an external tooth drive gear 22 and an internal tooth driven gear 23 as a pump rotor. The external tooth drive gear 22 is fitted and fixed to the crankshaft 3 and is driven by the internal tooth driven gear. The gear 23 is rotatably fitted in the housing 20.

The structures of the inner member 13 of the chain cover 12 and the oil pump housing 20 formed on the inner member 13 are shown in detail in FIGS. 3 to 15. FIG. 3 is a front view of the inner member 13 as seen from the front (outer member 14 side), and FIG. 4 is a rear view of the inner member 13 as seen from the rear (cylinder block 1 side). In addition, FIG. 5, FIG. 6, FIG. 7, and FIG.
FIG. 9 and FIG. 9 are respectively arrows B, C, D, E of FIG.
FIG. 10 is a view from the direction of the arrow and the arrow F, and FIG.
It is sectional drawing in the GG line of a figure. Figure 11, Figure 12, Figure 1
Figures 3, 14 and 15 are the HH line and I- of Figure 4, respectively.
FIG. 3 is a sectional view taken along line I, line JJ, line KK, and line LL.

3 to 10, a joint surface 24 for joint connection with the outer member 14 and a plurality of bolt bosses 25, 25 having screw holes are formed on the front surface side of the inner member 13 and the inner member 13 is formed. A flange portion 26 projecting forward from the joint surface 24 is formed at the lower end of the member 13, and the flange portion 26 is formed.
As shown in FIG. 1, the upper end of the front edge of the oil pan 2 is attached to the bolt 26 by a bolt 27. Further, on the rear surface side of the inner member 13, a joint surface 28 for joining and connecting to the cylinder block 1 and a plurality of bolt bosses 29, 29 having screw holes or bolt insertion holes are formed, and at the lower side. An oil pump housing 20 is formed around the crankshaft penetration portion 30.

The oil pump housing 20 is a space (pump chamber) for accommodating the oil pump 21 in which the peripheral edge of the oil pump cover 31 is attached to the outer peripheral wall 20a with bolts 32.
Are formed. A suction port 34 is opened at a substantially central portion in the circumferential direction on the suction chamber 33 (right half portion of the pump chamber in FIG. 4) side of the housing 20, and the suction port 34 is formed as shown in FIG. The oil that is in communication with the suction passage 35 formed in the inner member 13 and the introduction pipe 36 (see FIG. 1) connected to the suction passage 35, and collects at the bottom of the oil pan 2 is the introduction pipe.
The air is sucked into the suction chamber 33 of the housing 20 via the suction passage 36 and the suction passage 35. On the other hand, a discharge port 38 is opened substantially at the center in the circumferential direction on the discharge chamber 37 (left half of the pump chamber in FIG. 4) side of the housing 20, and the discharge port 38 is shown in FIG. 12 and FIG. As also shown in Fig. 4, the oil that is communicated with the discharge passages 39a and 39b formed in the inner member 13 and whose pressure is increased by the operation of the oil pump 21 in the housing 20 is discharged from the discharge port.
The gas is discharged from the inner member 13 through the discharge passages 39a and 39b.

In the upper half of the oil pump housing 20, the outer peripheral wall portion 20a rotatably guides the internal gear driven gear 23 of the oil pump 21, while in the lower half portion thereof, the inner peripheral wall portion 20a has a predetermined inner surface. The inner tooth driven gear 23 is rotatably guided by a guide wall 40 provided at a distance, and a space extending along the guide wall 40 is provided between the guide wall 40 and the outer peripheral wall portion 20a. A circulation passage 41 is formed. The recirculation passage
One end of 41 is opened to the trailing side of suction chamber 33 (the delay side when viewed in the rotation direction of the pump rotor) through the opening 41a formed in guide wall 40, while the other end is A communication hole 43 is formed in the valve housing 42 formed in the member 13.
Are communicated via. The valve housing 42 is
As shown in FIG. 14 and FIG. 15, a relief valve 44 is provided inside the discharge port 38 and communicates with the discharge port 38. The relief valve 44 includes a valve body 45 slidably fitted in the valve housing 42, an adjusting screw 46 screwed into an opening of the valve housing 42, and the valve body
A compression spring 47 is provided between the adjustment screw 45 and the adjustment screw 46, and the spring 47 is opened when the pressure of the oil discharged from the discharge port 38 exceeds a predetermined value.

Incidentally, 48 is an oil boss having an oil supply passage 49 formed by being hung from the side edge of the inner member 13 to the upper end side of the oil pump housing 20, and oil is provided on the front side surface of the oil boss 48 (side surface on the outer member 14 side). A pair of oil jet connection holes 50, 50 communicating with the supply passage 49 are provided.
Oil is jetted toward the chain 5 from an oil jet (not shown) connected to 0. Further, the oil supply passage 49 is communicated with an oil supply passage 51 formed in the cylinder block 1 as shown in FIG. 1, and the oil is supplied to the crank bearing portion of the cylinder block 1 through the both oil supply passages 49.51. Supplied.

Next, the operation and effect of the above embodiment will be described. In the oil pump 21 in which the housing 20 is formed integrally with the inner member 13 of the chain cover 12, the pressure of the oil discharged from the discharge port 38 is When the (discharge pressure) exceeds a predetermined value, the relief valve 44 facing the discharge port 38 is opened to discharge the discharge oil.
The gas flows into the recirculation passage 41 from the inside of the valve housing 42 and the communication hole 43 from the valve 38, passes through the recirculation passage 41, and is returned from the opening 41a to the trailing side of the suction chamber 33.

In this case, the recirculation passage 41 has the guide wall 40 for guiding the internal gear driven gear 23 as the pump rotor.
Since the opening 41a is formed along the trailing side of the suction chamber 33, that is, the portion closest to the discharge port 38, the length of this passage 41 is such that the recirculation passage is outside the inner member 13. This is much shorter than the case where it is configured by a pipe disposed in the above, and the pressure drop due to the passage resistance of the discharged oil hardly occurs. In addition, the recirculation passage 41 has a suction chamber 33 through which the suction passage 35 is communicated.
Since it is opened at a portion (trailing side) away from the suction port 34 (approximately the center in the circumferential direction), the oil pan 2 is caused by the pressure of the discharge oil returned to the suction chamber 33 through the recirculation passage 41. Therefore, the suction of the oil into the suction chamber 33 through the suction passage 35 is not hindered, and the oil can be sucked well. The discharge oil can be effectively used by preventing the pressure drop of the discharge oil and maintaining the oil suction in good condition, and the efficiency of the oil pump can be effectively increased.

In the above embodiment, the present invention has been described in the case where the chain cover 12 covering the chain 5 is composed of the inner member 13 and the outer member 14, and the oil pump 21 is integrally provided on the inner member 13. In the case where one cover is detachably attached to the engine body by covering the conduction band such as a chain and a belt, and an oil pump driven by a crankshaft is integrally provided on the cover, or in the cylinder block 1 itself. It is needless to say that the same can be applied to the case where is provided.

(Effects of the Invention) As described above, according to the engine oil pump structure of the present invention, the recirculation passage that connects the discharge side and the suction side is formed along the guide wall, and the trailing side of the suction chamber is formed. Since the recirculation passage is very short, there is almost no pressure drop due to the passage resistance of the discharged oil that is returned to the suction side. It is possible to effectively improve the efficiency of the oil pump by returning the discharged oil to the suction side without hindering the oil suction.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, and FIG.
2 is an enlarged sectional view taken along the line AA, FIG. 2 is a vertical sectional front view of a chain portion of an engine, FIG. 3 is a front view of an inner member, FIG. 4 is a rear view of the same, and FIG. 5, FIG. 7 and 8
FIG. 9 and FIG. 9 are respectively arrows B, C, D in FIG.
It is the arrow line view seen from E arrow and F arrow direction. 10 is a sectional view taken along the line GG in FIG. 3, and FIG. 11, FIG.
Figures 13, 14, and 15 are the HH of Figure 4, respectively.
FIG. 4 is a cross-sectional view taken along the line II, the line JJ, the line KK, and the line LL. 12 ... Chain cover, 21 ... Oil pump, 33 ... Suction chamber,
35 ... suction passage, 40 ... guide wall, 41 ... recirculation passage.

Claims (1)

[Claims] 1. A guide wall in which a member constituting an oil pump body is integrally provided on an outer surface of an engine body, and a recirculation passage communicating between a discharge side and an intake side of the oil pump guides a pump rotor. The suction passage for sucking oil from the oil pan is communicated with the suction chamber of the oil pump at a substantially central portion in the circumferential direction, while the recirculation passage is provided on the trailing side of the suction chamber. The oil pump structure of the engine, which is open to the.