JP2021156327A - Relief valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress or avoid generation of abnormal noise due to movement of a spool valve body of a relief valve. SOLUTION: A tubular sleeve 2 and a spool valve body 3 which receives a fluid pressure in the sleeve 2 and slides relative to the sleeve 2 along the axial direction A of the sleeve 2 to advance and retreat. A drain port 22 that penetrates the peripheral wall of the sleeve 2 in an oblique B direction that is not orthogonal to the axial center A direction of the sleeve 2 and allows excess fluid to escape, and an opening degree of the drain port 22 through the spool valve body 3. A relief valve 1 including a spring 4 elastically urged in a direction of reducing the pressure is configured. [Selection diagram] Fig. 3

Description

The present invention relates to a relief valve. In particular, the present invention relates to internal lubrication of an internal combustion engine for a vehicle and those incorporated in a lubricating oil system that supplies hydraulic pressure to various hydraulic devices associated therewith.

In an internal combustion engine for a vehicle, lubricating oil stored in an oil pan (oil tank) is pumped by an oil pump to lubricate each part of the engine. At the same time, lubricating oil is also supplied to the hydraulic pressure devices such as the variable valve timing mechanism and the chain tensioner as the hydraulic pressure for operating them. The oil pump rotates by receiving rotational driving force from the crankshaft of the internal combustion engine, and sucks and discharges lubricating oil.

Generally, a relief valve is incorporated as a safety valve in the hydraulic circuit. As is well known, the relief valve opens when the pressure of the fluid in the circuit exceeds a predetermined set pressure (relief pressure) and releases a part of the high-pressure liquid to release the pressure of the fluid in the circuit. It works to suppress the pressure below the set pressure.

In the vehicle-mounted lubricating oil system, at least sufficient hydraulic pressure is required to operate the variable valve timing mechanism and the like regardless of the engine speed. The capacity of the oil pump is designed to provide this required hydraulic pressure at all times. In addition, in the operating region where the engine speed is high, in order to prevent seizure of the engine, it is required to further increase the pressure of the lubricating oil flowing through the lubricating oil system and supply a larger amount of lubricating oil to each part of the engine.

With a simple relief valve, the set pressure is uniquely determined. If the set pressure is set to the pressure required in the high rotation operating region, the oil pump will continue to pump the lubricating oil at an unnecessarily high pressure in the low to medium rotation operating region, leading to mechanical loss. In order to reduce such loss, it is conceivable to adopt a relief valve having two stages of set pressure, that is, a high set pressure required at high rotation speed and a low set pressure required at low to medium rotation speed.

In a known spool type relief valve (for example, refer to the patent document below), a plurality of drain ports are provided on the peripheral wall of the sleeve including the spool valve body, and only the first-stage drain port is opened at low and medium rotations to open the high. It is configured to open the second drain port together with the first drain port when rotating.

Japanese Unexamined Patent Publication No. 2005-069352

The drain port of the conventional relief valve is formed through the peripheral wall of the sleeve in the axial direction of the sleeve, that is, in the direction orthogonal to the direction in which the spool valve body slides forward and backward. Therefore, at the moment when the spool valve body is displaced and the land opens the drain port, the fluid suddenly flows into the drain port and the flow rate suddenly changes. This sudden change in flow rate can cause abnormal noise.

Moreover, the spool valve body of the relief valve is constantly moving in response to fluctuations in the pressure of the fluid in the circuit, and the movement becomes large and the drain port (especially the first-stage drain port) opens unintentionally, which is different. Sound was sometimes produced and perceived by the user.

The present invention made by paying attention to the above problems is intended to suppress or avoid the generation of abnormal noise due to the movement of the spool valve body of the relief valve.

In the present invention, a tubular sleeve, a spool valve body that receives fluid pressure in the sleeve and slides in and out of the sleeve relative to the sleeve in the axial direction of the sleeve, and a peripheral wall of the sleeve. The sleeve is provided with a drain port that penetrates in an oblique direction not orthogonal to the axial direction of the sleeve and allows excess fluid to escape, and a spring that elastically biases the spool valve body in a direction that reduces the opening degree of the drain port. Relief valve was constructed.

Further, in the present invention, a tubular sleeve, a spool valve body that receives fluid pressure in the sleeve and slides in and out of the sleeve relative to the sleeve in the axial direction of the sleeve, and the sleeve. The opening that penetrates the peripheral wall and appears on the inner peripheral surface of the peripheral wall forms an oval shape in which the inner dimension of the opening in the direction parallel to the axial direction of the sleeve is larger than the inner dimension in the direction perpendicular to that direction. A relief valve including a drain port for allowing excess fluid to escape and a spring for elastically urging the spool valve body in a direction of reducing the opening degree of the drain port is configured.

According to the present invention, it is possible to suppress or avoid the generation of abnormal noise due to the movement of the spool valve body of the relief valve.

The cross-sectional view which shows the structure of the relief valve and the hydraulic pressure circuit of one Embodiment of this invention. The figure which shows the arrangement of the relief valve provided in the oil pump cover in the same embodiment. The cross-sectional view which shows the structure of the relief valve of the same embodiment.

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the relief valve 1 of the present embodiment and the hydraulic circuit of the lubricating oil system of the in-vehicle internal combustion engine to which the relief valve 1 is applied. The oil pump 7 sucks and discharges lubricating oil, which is a fluid stored in the oil pan 8. The oil pump 7 is, for example, a known trochoid type hydraulic pump, which receives rotational driving force from the crankshaft of an internal combustion engine and rotates in accordance with the crankshaft. As a general rule, the discharge pressure and discharge flow rate of the lubricating oil by the oil pump 7 increase as the engine speed increases.

The lubricating oil discharged by the oil pump 7 is for the purpose of lubricating a high-load lubricating portion 9 such as around the camshaft of an internal combustion engine and a low-load lubricating portion 9 around the crankshaft and the outer circumference of the piston (inner circumference of the cylinder bore). Supplied. Not only that, hydraulic devices such as a variable valve timing mechanism that adjusts the rotational phase difference between the crankshaft and camshaft, and a chain tensioner that adjusts the tension of the timing chain that transmits power between the crankshaft and camshaft. 0 is also supplied as the hydraulic pressure.

The relief valve 1 incorporated in the hydraulic pressure circuit plays a role of adjusting the pressure of the lubricating oil pumped from the oil pump 7 toward the lubricating portion 9 and the hydraulic pressure device 0 to a desired set pressure. The oil pump 7 is assembled to, for example, a front cover (timing chain cover, chain case) that covers a timing chain, a chain tensioner, or the like of an internal combustion engine. Then, as shown in FIG. 2, the relief valve 1 is provided on the oil pump cover 5 which is fixed to the front cover and covers the oil pump 7.

On the inner surface of the oil pump cover, there is a region 51 facing the oil pump chamber facing the suction port 61 of the oil pump 7, a region 52 facing the oil pump chamber facing the discharge port 62 of the oil pump 7, and these regions. It is provided with a partition wall 53 that separates 51 and 52. On top of that, an introduction port 21 that introduces the hydraulic pressure on the discharge port 62 side, and a first-stage drain port (relief passage) 22 that allows a part of the hydraulic pressure on the discharge port 62 side to flow back to the suction port 61 side to escape. A second-stage drain port 23 is formed so that a part of the hydraulic pressure on the discharge port 62 side is returned to the suction port 61 side to escape.

In the lubricating oil system, at least sufficient hydraulic pressure is required to operate the variable valve timing mechanism and the like regardless of the engine speed. The capacity of the oil pump 7 is designed so that this liquid pressure can be supplied at all times. In addition, in the operating region where the engine speed is high, in order to prevent seizure of the engine, it is required to further increase the pressure of the lubricating oil flowing through the lubricating oil system and supply a large amount of lubricating oil to the lubricating unit 9.

In order to meet the above-mentioned request, the relief valve 1 of the present embodiment has a low set pressure necessary and sufficient to operate the hydraulic pressure device 0 such as the variable valve timing mechanism in the operation region of low to medium rotation, and high rotation. It has a two-stage set pressure with a high set pressure that can reliably lubricate the lubrication unit 9 in the operating region.

As shown in FIGS. 1 and 3, the relief valve 1 of the present embodiment has a tubular sleeve 2 and a spool valve that slides in the sleeve 2 along the axial center A direction of the sleeve and advances and retreats. The body 3 includes a plurality of drain ports 22 and 23 penetrating the peripheral wall of the sleeve 2, and a spring 4 elastically urging the spool valve body 3 in a direction of reducing the opening degree of the drain ports 22 and 23. ..

The inner circumference of the spool 2 has a substantially cylindrical shape, and an introduction port 21 is open on one end side thereof. The oil pump 7 discharges from the introduction port 21, and high-pressure lubricating oil flowing through the hydraulic circuit flows in. The pressure of the lubricating oil presses the spool valve body 3 in the direction of increasing the opening degree of the drain ports 22 and 23.

The drain ports 22 and 23 are connected to the upstream of the oil pump 7 or the flow path leading to the oil pan 8, respectively.

The spool valve body 3 has a substantially cylindrical land whose outer periphery abuts or is extremely close to the inner circumference of the spool 2, and plays a role of closing the drain ports 22 and 23 by the land. Then, the opening / closing of the drain ports 22 and 23 is expanded / contracted through the advancing / retreating operation along the axial center A direction of the spool valve body 3.

As the pressure of the lubricating oil introduced into the sleeve 2 from the introduction port 21, that is, the discharge pressure of the oil pump 7 increases, the spool valve body 3 resists the elastic urging force exerted by the spring 4 and is shown in FIG. It is displaced so as to be separated from the indicated initial position (that is, the introduction port 21). When the pressure of the lubricating oil introduced from the introduction port 21 exceeds the lower set pressure, as shown in FIG. 3, the first-stage drain port 22 closed in the relief valve 1 opens, and excess lubricating oil is discharged. It is released from the introduction port 21 to the upstream of the oil pump 7 or the downflow path to the oil pan 8 through the first-stage drain port 22. As a result, the lubricating oil supply to the lubricating unit 9 and the hydraulic pressure device 0 of the internal combustion engine is controlled in the vicinity of the low set pressure in the operating region of low to medium rotation.

When the pressure of the lubricating oil introduced from the introduction port is less than the higher set pressure, the second drain port remains closed. However, when the pressure of the lubricating oil exceeds a high set pressure, the first-stage drain port 22 that has already been opened in the relief valve 1 and the second-stage drain port 23 that has been closed also open, resulting in excess lubricating oil. Is released from the introduction port 21 to the upstream of the oil pump 7 or the flow path to the oil pan 8 through both the first-stage drain port 22 and the second-stage drain port 23.

Therefore, in the relief valve 1 of the present embodiment, as shown in FIG. 3, the first-stage drain port 22 has an obliquely inclined shaft whose peripheral wall of the sleeve 2 is not orthogonal to the axial center A direction of the sleeve 2. It is formed by penetrating in the B direction. As a result, the shape of the opening 221 of the drain port 22 that appears on the inner peripheral surface of the peripheral wall of the sleeve 2 becomes an oval shape (oval shape, elliptical shape, elongated hole shape, etc.). The inner dimension of the opening 221 in the direction parallel to the axial center A direction is larger than the inner dimension in the direction perpendicular to the same direction.

Therefore, when the spool valve body 3 is displaced from the initial position to open the closed first-stage drain port 22, the opening of the first-stage drain port 21 with respect to the increase in the pressure of the lubricating oil introduced from the introduction port 21. The amount of expansion of the area becomes smaller (the expansion becomes slower) as compared with the conventional relief valve, and the sudden change in the flow rate of the lubricating oil through the drain port 22 of the first stage is suppressed. As a result, it is possible to preferably suppress or avoid the generation of abnormal noise due to the movement of the spool valve body 3.

In addition, suppressing sudden changes in the flow rate and pressure of the lubricating oil improves the responsiveness and accuracy of the control of the various hydraulic devices 0, and further increases the discharge amount of the lubricating oil by the oil pump 7 unnecessarily. It also leads to not letting it. All of these can contribute to improving the fuel efficiency of the internal combustion engine.

The second-stage drain port 23 may be formed by penetrating the peripheral wall of the sleeve 2 in a direction orthogonal to the axial center A direction of the sleeve 2.

The present invention is not limited to the embodiments described in detail above. The specific configuration of each part can be variously modified without departing from the spirit of the present invention.

1 ... Relief valve 2 ... Sleeve 21 ... Introduction port 22 ... First stage drain port 221 ... Opening 23 ... Second stage drain port 3 ... Spool valve body 4 ... Spring 5 ... Oil pump cover A ... Sleeve axial direction B … Diagonal direction not orthogonal to the axial direction of the sleeve

The inner circumference of the sleeve 2 has a substantially cylindrical shape, and an introduction port 21 is opened on one end side thereof. The oil pump 7 discharges from the introduction port 21, and high-pressure lubricating oil flowing through the hydraulic circuit flows in. The pressure of the lubricating oil presses the spool valve body 3 in the direction of increasing the opening degree of the drain ports 22 and 23.

The spool valve body 3 has a substantially cylindrical land whose outer periphery abuts or is extremely close to the inner circumference of the sleeve 2, and plays a role of closing the drain ports 22 and 23 by the land. Then, the opening / closing of the drain ports 22 and 23 is expanded / contracted through the advancing / retreating operation along the axial center A direction of the spool valve body 3.

Therefore, in the relief valve 1 of the present embodiment, as shown in FIG. 3, the first-stage drain port 22 has an obliquely inclined shaft whose peripheral wall of the sleeve 2 is not orthogonal to the axial center A direction of the sleeve 2. It is formed by penetrating in the B direction. As a result, the shape of the opening of the drain port 22 that appears on the inner peripheral surface of the peripheral wall of the sleeve 2 becomes an oval shape (oval shape, elliptical shape, elongated hole shape, etc.). The inner dimension of the opening in the direction parallel to the axial center A direction is larger than the inner dimension in the direction perpendicular to the same direction.

Claims (2)

Cylindrical sleeve and
A spool valve body that slides in the sleeve along the axial direction of the sleeve relative to the sleeve under the pressure of a fluid and moves forward and backward.
A drain port that penetrates the peripheral wall of the sleeve in an oblique direction that is not orthogonal to the axial direction of the sleeve and allows excess fluid to escape.
A relief valve including a spring that elastically biases the spool valve body in a direction that reduces the opening degree of the drain port. Cylindrical sleeve and
A spool valve body that slides in the sleeve along the axial direction of the sleeve relative to the sleeve under the pressure of a fluid and moves forward and backward.
The opening that penetrates the peripheral wall of the sleeve and appears on the inner peripheral surface of the peripheral wall has an oval shape in which the inner dimension of the opening in the direction parallel to the axial direction of the sleeve is larger than the inner dimension in the direction perpendicular to the direction. A drain port that allows excess fluid to escape,
A relief valve including a spring that elastically biases the spool valve body in a direction that reduces the opening degree of the drain port.

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