JP2021156270A - Oil pump of engine - Google Patents

Abstract

To suppress noise which is generated resulting from air column resonance from a point of a relief valve at a cold start by a simple structure. A leak hole 29 is formed at a bulkhead 27 for partitioning a flow-in chamber 18 and a flow-out chamber 19 of an oil pump, and a valve arrangement cylinder part 28 is formed while continuing to the bulkhead 27. A valve body 31 which is pushed by a spring 32 is arranged at the valve arrangement cylinder part 28, and when pressure exceeds a prescribed value, the valve body 31 retreats while withstanding the spring 32. Then, oil which has leaked is discharged from a first oil escape hole 35 to the outside of a cover housing 10, and flows down into oil in an oil pan. Bubbles are generated when the leaked oil falls down into the oil in the oil panel, the mixture of the fine bubbles into the oil can be promoted, and an air column resonance phenomenon can be thereby erased before the oil is spread to an engine.SELECTED DRAWING: Figure 4

Description

The present invention relates to an oil pump provided in an engine (reciprocating internal combustion engine) for automobiles and the like.

The reciprocating engine is equipped with an oil pump as an indispensable device. There are various structures and arrangement positions of the oil pump, but there is a type that is incorporated in the front cover that covers the timing chain.

That is, the oil pump includes a pump housing and a cover housing, and in the case of a trochoid pump, the inner rotor and the outer rotor are arranged in the pump chamber formed between the two housings, but the pump housing is front. There is a type that is integrated with the cover and the inner rotor is directly connected to the crankshaft. This type has the advantage that the weight of the engine can be reduced because a part of the oil pump is also used as the front cover.

Any type of oil pump is provided with a relief valve, but abnormal noise may be generated from the relief valve. For example, pulsation may occur in the oil to be relieved due to a change in the speed of the rotation of the crankshaft, and a countermeasure against this is disclosed in Patent Document 1.

Japanese Unexamined Patent Publication No. 2014-118852

By the way, when the engine is started from a state where the temperature is completely lowered as in cold start, the relief valve is opened due to the high viscosity of the oil and some oil is returned to the pump chamber, but the inventor of the present application observed. However, with respect to the above-mentioned oil pump with an integrated front cover, an abnormal noise such as a monotonous electronic sound may be generated for several tens of seconds when the engine is started.

This abnormal noise at the time of starting is not continuous and disappears after several tens of seconds, but it is jarring and should be prevented or suppressed. Therefore, when the inventor of the present application studied the cause of the generation of abnormal noise, it was found that the phenomenon of air column resonance occurred when the oil passed through the passage of the relief valve.

Next, the reason why the phenomenon of air column resonance disappears in several tens of seconds is that the time during which abnormal noise continues to occur is almost the same as the time during which oil reaches the engine. Is presumed to affect the bubble ratio (or density) of the oil.

That is, when the engine is stopped, the oil that fills the oil passage of the engine returns to the oil pan, and the fine bubbles contained in the oil escape with time, and the density does not contain bubbles at the next start. Large oil is sucked up by the oil pump and pumped to each part of the engine, but when the oil goes around each part of the engine, it takes in the air that was present in the oil passage and the oil goes from the oil drop hole to the oil pan. After a certain amount of time has passed, the oil sucked up by the oil pump becomes a state containing fine bubbles and the density decreases due to the air entering the oil due to the bubbling phenomenon when flowing down, and as a result, the leak passage It is presumed that the air column resonance phenomenon of the oil pump disappears.

The present invention has been made based on such research and knowledge, and is intended to suppress abnormal noise at the time of starting by a simple structure.

The invention of the present application relates to the improvement of an oil pump, and this oil pump is
"It is located on the opposite side of the timing chain from the cylinder block, one end of the oil pan is located below, and it has a built-in relief valve."
In the configuration
"The relief valve includes a first oil relief hole that opens at a preset first pressure and a second oil relief hole that opens at a second pressure that is stronger than the first pressure. An oil relief hole opens outward to allow leaked oil to flow down the oil pan. "
It has the feature.

In the present invention, the oil released from the first oil relief hole may be simply returned to the oil pan, or is ejected toward the timing chain as in the embodiment, hits the timing chain, and then flows down to the oil pan. You may let me.

In the present invention, the oil leaked from the first oil relief hole of the relief valve at the time of starting flows down to the oil pan without circulating in the pump chamber, but when the flowing oil falls into the oil of the oil pan, a bubbling phenomenon occurs. Therefore, fine bubbles can be generated in the oil of the oil pan. As a result, the bubble content of the oil sucked up from the oil pan before the oil is distributed throughout the engine can be increased, and the phenomenon of air column resonance generated in the passage of the relief valve can be quickly eliminated.

Further, since the present invention has a configuration that only changes the opening mode of the oil leaking hole from the relief valve, the structure is not complicated. Therefore, the abnormal noise generated at the time of starting can be suppressed by a simple structure.

When the leaked oil is applied to the timing chain as in the embodiment, it is not necessary to separately provide a chain jet, so that the structure can be further simplified, which is preferable. In this case, if the oil is ejected from below toward the timing chain as in the embodiment, the timing chain can be prevented from getting too wet with the oil, and the height of the oil falling into the oil pan becomes high, so that the oil pan It can be said that it can contribute to the early extinction of air column resonance by improving the foaming in.

In order to promote the effect of the present invention, it is preferable that the leaked oil flows down as close to the strainer as possible.

It is a front view (front view) of a front cover. It is a rear view (rear view) of a front cover with a cover housing attached. It is a rear view of the front cover with the cover housing removed. (A) is a front view (front view) of the cover housing, (B) is a sectional view taken along line BB of (A), and (C) is a partially enlarged view of (B) in a leaked state. 2 is a schematic cross-sectional view taken along the line VV of FIGS. 2 and 4 (A).

Next, an embodiment of the present invention will be described with reference to the drawings. The present invention is applied to an automobile engine. In the following, the front-back and left-right terms are used to specify the direction, but the front-back direction is the crank axis direction, and the left-right direction is the direction orthogonal to the crank axis and the cylinder bore axis. For the front and rear, the direction from the crank chamber to the timing chain is forward, and the direction from the crank chamber to the mission case is backward. As a precaution, the directions are shown in FIGS. 1 to 4 (A).

(1). Overview The basic structure of the engine is the same as before, and the front of the engine body is composed of a front cover (timing chain cover) 1. The front cover 1 has a shallow tray-like shape that opens rearward, and overlaps the front surface of the cylinder block 2 shown in FIG. 5 and the front surface of the cylinder head and the head cover (not shown). It is fixed with bolts. Therefore, as shown in FIGS. 1 to 3, a large number of bolt insertion holes 3 are formed in the peripheral edge of the front cover 1.

In FIG. 5, the cylinder block 2 is viewed from the VV viewing direction of FIG. 2, and therefore, although the cross section appears strictly, the lower surface is roughly displayed without displaying the cross section. A crank cap 4 is fixed to the lower surface of the front wall of the cylinder block 2 with bolts 5, and the front journal 6a of the crankshaft 6 is rotatably held by the crank cap 4. In FIG. 5, reference numeral 7 is a bearing metal, and reference numeral 8 is a crank arm.

The alternate long and short dash line indicated by reference numeral A in FIG. 2 is the overlapping surface of the cylinder block 2 and the oil pan 8. As can be understood from the position of the overlapping surface A, the lower portion of the front cover 1 partially overlaps the front surface of the oil pan 8.

As described above, the front cover 1 is open rearward. Therefore, a peripheral wall overlapping the cylinder block 2 and the like is formed on the outer peripheral portion, and a bolt insertion hole 3 is formed in the peripheral wall. In FIGS. 2 and 3, the end faces of the peripheral walls are indicated by parallel diagonal lines (therefore, the parallel diagonal lines in FIGS. 2 and 3 are not representations of the cross section). Further, as shown in FIGS. 2 and 3, a large number of reinforcing ribs 9 are provided inside (recessed portion) of the front cover 1.

As is clearly shown in FIG. 2, the cover housing 10 constituting the oil pump is laminated and fixed to the rear surface of the front cover 1 by a large number of screws (bolts) 11. On the other hand, as shown in FIG. 3, a pump housing 12 constituting an oil pump is integrally formed on the front cover 1.

As shown by the alternate long and short dash line in FIG. 2 and the solid line in FIG. 5, the main sprocket 13 is fixed to the portion of the crankshaft 6 between the cylinder block 2 and the cover housing 10, and the timing chain 14 is wound around the main sprocket 13. I'm hanging. The main sprocket 13 is arranged above the front portion of the oil pan 8. Therefore, directly below the main sprocket 13 is an oil sump of the oil pan 8. Needless to say, the timing chain 14 is also wound around a driven sprocket provided on the camshaft.

(2). Oil pump As can be understood from the comparison of FIGS. 3 and 4 (A), the output holes 16 through which the front end of the crankshaft 6 penetrates are opened in the front and rear of both housings 10 and 12. A pump chamber 17 centered on the output hole 16 is formed on the opposite surfaces of the housings 10 and 12. Further, an inflow chamber 18 and an outflow chamber 19 are formed with the pump chamber 17 interposed therebetween. Although not shown, an inner rotor directly connected to the crankshaft 6 and an outer rotor meshed with the inner rotor are arranged in the pump chamber 17, and oil flows out from the inflow chamber 18 due to the rotation of both rotors. It is pumped to the chamber 19.

The inflow chamber 18 and the outflow chamber 19 are generally formed in a height relationship in which the inflow chamber 18 is at the bottom and the outflow chamber 19 is at the top, and the pump chamber 17 is sandwiched between the inflow chamber 18 and the outflow chamber 19 so as to be separated into left and right. To be precise, the engine is mounted in the engine room with the crankshaft 6 placed horizontally long in the vehicle width direction, but the inflow chamber 18 is located on the right side (front side in the vehicle forward direction) with the pump chamber 17 in between. The outflow chamber 19 is located on the left side (rear side in the vehicle forward direction) with the pump chamber 17 in between.

As shown in FIG. 4A, the inflow port 20 communicates with the lower end of the inflow chamber 18 in the cover housing 10, and as shown in FIG. 2, the inflow port 20 opens behind the cover housing 10. doing. An oil strainer (not shown) is attached to the inflow port 20 by screwing or the like.

The oil strainer includes a horizontal portion connected to the inflow port 20 and a suction cylinder portion extending downward from the tip thereof, and the lower end of the suction cylinder portion is directly below the main sprocket 13 shown in FIG. Nearby, it is immersed in the oil accumulated in the oil pan 8.

As shown in FIG. 1, a receiving seat 21 for mounting an oil filter (not shown) is formed on the left side of the front surface of the front cover 1 slightly above the output hole 16. The receiving seat 21 is formed with a central screw cylinder 22 for screwing an oil filter and an entrance port 23 located below the central screw cylinder 22. Therefore, in the present embodiment, the outlet port 24 is opened in the central screw cylinder 22.

As shown in FIG. 4, the entrance port 23 is open to the rear surface of the front cover 1, and as shown in FIG. 4A, the outflow chamber 19 of the cover housing 10 has a protruding portion 19a communicating with the entrance port 23. Is formed. Further, as shown in FIG. 3, the outlet port 24 is open to the rear surface of the front cover 1, and as shown in FIGS. 3 and 4 (A), one end is provided on the rear surface of the front cover 1 and the front surface of the cover housing 10. A substantially left-right longitudinal arc groove 25 is formed so as to communicate with the outlet port 24, and a discharge port 26 opened on the rear surface of the cover housing 10 is formed at the other end of the arc groove 25.

A portion of the cover housing 10 provided with the discharge port 26 overlaps the front surface of the cylinder block 2, and a main gallery (not shown) communicating with the discharge port 26 is formed in the cylinder block 2.

As shown in FIGS. 3 and 4 (A), the inflow chamber 18 and the outflow chamber 19 are separated by a wide partition wall 27 at a portion on the left side. The partition wall 27 is inclined with respect to the cylinder bore axis so as to shift to the left as it goes upward, and as shown in FIG. 4 (B), the partition wall 27 is orthogonal to the partition wall 27 as a part of the relief valve device on the cover housing 10. A long valve arrangement cylinder portion 28 is formed in the direction in which the valve is arranged.

A leak hole 29 communicating with the valve arrangement cylinder 28 is opened in the partition wall 27, and a second oil relief hole (main oil relief hole) 30 communicating with the inflow chamber 18 is opened in the valve arrangement cylinder 28. There is. Further, the valve arrangement cylinder portion 28 is opened downward, and the valve body 31 and the spring 32 opened downward are inserted from below, and the spring 32 is supported by the spring receiver 33 screwed and mounted from below. A back pressure relief hole 34 communicating with the inflow chamber 18 is formed in a portion of the valve arrangement cylinder 28 below the main oil relief hole 30 in order to allow the valve body 31 to move backward.

The valve body 31 is a member forming the core of the relief valve, and the tip portion thereof penetrates to the middle part of the partition wall 27 (therefore, the valve hole into which the valve body 31 slides extends to the partition wall 27). Then, a first oil relief hole (outward oil relief hole) 35 opened obliquely upward toward the main sprocket 13 is bored in a portion of the partition wall 27 where the tip end portion of the valve body 31 enters. ing.

(3). Summary By the way, when the engine is cold-started, the discharge pressure often rises above the set pressure due to the high viscosity of the oil. Then, the valve body 31 is pushed down, and the leaked oil is released from the first oil relief hole 35, so that the pumping loss can be reduced. Further, when the oil discharge pressure further rises due to the engine rotating at high speed or the like, the valve body 31 further retracts against the spring 32, and most of the leaked oil is discharged from the second oil relief hole 30 to the inflow chamber 18 Return to. Therefore, when the pressure of the oil is excessively increased, a considerable part of the oil circulates between the inflow chamber 18 and the outflow chamber 19.

Then, at the time of cold start, the oil returns to the oil pan 8 and the air bubbles are released for a long time to increase the density. Therefore, when passing through the leak hole 29, an abnormal noise is generated due to the air column resonance phenomenon. May occur.

However, in the present embodiment, the oil leaked from the partition wall 27 is discharged from the first oil relief hole 35 and flows down to the oil pan 8, so that a bubbling phenomenon occurs when the oil falls into the oil of the oil pan 8 and the oil is released. The oil that enters the oil pump can contain fine bubbles before it reaches the entire engine. As a result, the abnormal noise can be quickly eliminated. In the experiment of the inventor of the present application, the generation time of abnormal noise could be reduced by half.

When the first oil relief hole 35 is directed toward the main sprocket 13 from diagonally below as in the embodiment, it can be replaced with a chain jet, so that the structure of the engine can be simplified and the cost can be reduced (oil during engine operation). Is frequently discharged from the first oil relief hole 35, so that the lubrication of the timing chain 14 is not incomplete.) In FIG. 5, the oil discharged from the first oil relief hole 35 hits the timing chain 14 and then flows down to the front side orthogonal to the paper surface.

Further, the oil released from the first oil relief hole 35 rises high once and then falls into the oil of the oil pan 8 to promote foaming when falling into the oil tank of the oil pan 8, so that the oil can be added to the oil. It is possible to promote the mixing of air bubbles and promote the disappearance of air column resonance. In this case, since the viscosity of the oil is high at the time of cold start, the showering of the oil is suppressed and the tapping action of the oil pan 8 against the oil is enhanced. Therefore, it can be said that it is possible to promote the generation of air bubbles particularly at the time of starting and contribute to the early suppression of the air column resonance phenomenon.

The invention of the present application can be embodied in various ways other than the above-described embodiments. For example, leaked oil may be returned to the oil pan without hitting the timing chain. Further, it is not always necessary to use a part of the front cover as a part of the oil pump, and the entire oil pump may be configured to have a structure independent of the front cover.

The present invention can be embodied in an engine oil pump. Therefore, it can be used industrially.

1 Front cover 2 Cylinder block 6 Crank shaft 8 Oil pan 10 Cover housing that composes the oil pump 12 Pump housing that composes the oil pump 13 Driven sprocket 14 Timing chain 16 Output hole 17 Pump chamber 18 Inflow chamber 19 Outflow chamber 20 Inflow port 21 Oil filter receiving seat 26 Discharge port 27 Partition wall 28 Valve arrangement cylinder 29 Leak hole 30 Second oil relief hole (main oil relief hole)
31 Valve body that composes the relief valve 32 Spring that composes the relief valve 35 First oil relief hole (outward oil relief hole)

Claims (1)

It is arranged on the opposite side of the timing chain from the cylinder block, one end of the oil pan is located below, and it has a built-in relief valve.
The relief valve includes a first oil relief hole that opens at a preset first pressure and a second oil relief hole that opens at a second pressure stronger than the first pressure, and the second oil. The relief hole is open outward so that the leaked oil can flow down into the oil pan.
Engine oil pump.

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