JP7114204B2 - Relief valve - Google Patents

Description

The present invention relates to relief valves. More particularly, it relates to a lubricating oil system that supplies working hydraulic pressure to internal lubrication of an internal combustion engine for a vehicle and to various hydraulic devices associated therewith.

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

In general, a hydraulic circuit incorporates a relief valve as a safety valve. As is well known, a relief valve opens when the pressure of the fluid in the circuit exceeds a predetermined set pressure (relief pressure) and releases part of the high-pressure liquid to relieve the pressure of the fluid in the circuit. is suppressed below the set pressure.

A vehicle-mounted lubricating oil system requires at least sufficient hydraulic fluid pressure to operate a 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 fluid pressure at all times. In addition, in the operating region where the engine speed is high, 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 in order to prevent engine seizure.

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

In a known spool-type relief valve (see, for example, the following patent document), a plurality of drain ports are provided on the peripheral wall of a sleeve that contains a spool valve body, and only the drain port at the first stage is opened at low and medium speeds, and high It is configured to open the second stage drain port together with the first stage drain port during rotation.

JP 2005-069352 A

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 perpendicular to the direction in which the spool valve body slides and advances and retreats. Therefore, at the moment when the spool valve body is displaced and the land opens the drain port, the fluid abruptly flows into the drain port, causing a sudden change in the flow rate. This sudden change in flow rate can cause abnormal noise.

Moreover, the spool valve element of the relief valve is constantly moving due to fluctuations in the pressure of the fluid in the circuit. A sound could be produced and perceived by the user.

SUMMARY OF THE INVENTION The present invention, which has been made in view of the above problems, is intended to suppress or avoid abnormal noise caused by movement of a spool valve element of a relief valve.

In the present invention, a sleeve having a cylindrical shape, a spool valve body that receives fluid pressure in the sleeve and slides relative to the sleeve along the axial direction of the sleeve to advance and retreat, and one end of the sleeve. an introduction port that is open to the side and introduces a fluid, and penetrates the peripheral wall of the sleeve in an oblique direction that is not orthogonal to the axial direction of the sleeve so as to move away from the introduction port as it goes from the inner peripheral side to the outer peripheral side of the sleeve. A first-stage drain port for releasing excess fluid and a second- stage drain port for releasing excess fluid penetrate through a portion of the peripheral wall of the sleeve that is farther from the introduction port than the first-stage drain port. and a spring that elastically biases the spool valve body in a direction to reduce the opening of the drain port.

The first-stage drain port has an opening that appears on the inner peripheral surface of the peripheral wall, and 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 that direction. can be made .

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

1 is a cross-sectional view showing the configuration of a relief valve and a hydraulic circuit according to one embodiment of the present invention; FIG. The figure which shows arrangement|positioning of the relief valve provided in an oil pump cover in the same embodiment. Sectional drawing which shows the structure of the relief valve of the same embodiment.

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

The lubricating oil discharged by the oil pump 7 is used for the purpose of lubricating the high-load lubricating parts 9 such as around the camshaft of the internal combustion engine and the low-load lubricating parts 9 such as around the crankshaft and the piston outer circumference (cylinder bore inner circumference). supplied. In addition, hydraulic devices such as a variable valve timing mechanism that adjusts the rotational phase difference between the crankshaft and the camshaft, and a chain tensioner that adjusts the tension of the timing chain that transmits power between the crankshaft and the camshaft. 0 is also supplied as hydraulic pressure.

The relief valve 1 incorporated in the hydraulic circuit plays a role of regulating the pressure of lubricating oil pressure-fed from the oil pump 7 toward the lubricating portion 9 and the hydraulic 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 the timing chain, chain tensioner, etc. of the internal combustion engine. As shown in FIG. 2 , the relief valve 1 is provided on an oil pump cover 5 that is fixed to the front cover and covers the oil pump 7 .

The inner surface of the oil pump cover has 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. and a partition wall 53 that separates 51 and 52 . In addition, an introduction port 21 for introducing the hydraulic pressure on the discharge port 62 side, and a first-stage drain port (relief passage) 22 for releasing part of the hydraulic pressure on the discharge port 62 side by recirculating to the suction port 61 side. , and a second-stage drain port 23 for recirculating a portion of the hydraulic pressure on the discharge port 62 side to the suction port 61 side to escape.

The lubricating oil system requires sufficient hydraulic pressure to operate at least 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 hydraulic pressure can be supplied at all times. In addition, in the operating region where the engine speed is high, 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 section 9 in order to prevent seizure of the engine.

In order to meet the above requirements, the relief valve 1 of the present embodiment has a low set pressure necessary and sufficient to operate the hydraulic device 0 such as a variable valve timing mechanism in the operating range of low to medium speed, and It has two levels of set pressure, one being a high set pressure that can reliably lubricate the lubricating portion 9 in the operating range.

As shown in FIGS. 1 and 3, the relief valve 1 of this embodiment includes a cylindrical sleeve 2 and a spool valve that slides in the sleeve 2 along the direction of the axis A of the sleeve. A body 3, a plurality of drain ports 22, 23 passing through the peripheral wall of the sleeve 2, and a spring 4 elastically biasing the spool valve body 3 in a direction to reduce the opening of the drain ports 22, 23. .

The inner periphery of the sleeve 2 has a substantially cylindrical shape, and an introduction port 21 is opened at one end thereof. High-pressure lubricating oil discharged from the oil pump 7 and flowing through the hydraulic circuit flows from the introduction port 21 . The pressure of the lubricating oil presses the spool valve body 3 in the direction of increasing the opening 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 downstream path leading to the oil pan 8, respectively.

The spool valve body 3 has a substantially cylindrical land whose outer periphery abuts or is very close to the inner periphery of the sleeve 2, and the land serves to close the drain ports 22 and 23. As shown in FIG. The opening degrees of the drain ports 22 and 23 are expanded and contracted through the forward and backward movement of the spool valve body 3 along the axial center A direction.

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 biasing force exerted by the spring 4, and the position shown in FIG. It is displaced away from the initial position shown (that is, the introduction port 21). When the pressure of the lubricating oil introduced from the introduction port 21 exceeds the low set pressure, as shown in FIG. The oil is released from the introduction port 21 to the upstream of the oil pump 7 or the downstream path leading to the oil pan 8 through the first stage drain port 22 . As a result, the lubricating oil pressure supplied to the lubricating section 9 and the hydraulic device 0 of the internal combustion engine is controlled to be close to the low set pressure in the low-to-middle speed operating range.

The second stage drain port remains closed when the pressure of the lubricating oil introduced through the inlet port is below the higher set pressure. However, when the pressure of the lubricating oil exceeds the high set pressure, the already open first stage drain port 22 and the closed second stage drain port 23 of the relief valve 1 also open, and excess lubricating oil is released from the introduction port 21 to the upstream of the oil pump 7 or the downstream path leading to the oil pan 8 through both the first-stage drain port 22 and the second-stage drain port 23 .

Thus, in the relief valve 1 of this embodiment, as shown in FIG. It is formed so as to penetrate in the B direction. As a result, the shape of the opening of the drain port 22 appearing on the inner peripheral surface of the peripheral wall of the sleeve 2 becomes an oval shape (oval shape, elliptical shape, long hole shape, etc.). The inner dimension of the opening in the direction parallel to the direction of the axis A 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 is reduced. The amount of expansion of the area is smaller than that of the conventional relief valve (the expansion is gradual), and a sudden change in the flow rate of lubricating oil through the drain port 22 of the first stage is suppressed. As a result, it is possible to suitably 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 furthermore, the amount of lubricating oil discharged by the oil pump 7 is increased unnecessarily. It also leads to not letting you. 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 perpendicular to the axial center A direction of the sleeve 2 .

The present invention is not limited to the embodiments detailed above. The specific configuration of each part can be modified in various ways without departing from the gist of the present invention.

1... Relief valve 2... Sleeve 21... Introduction port
22 First-stage drain port 23 Second-stage drain port 3 Spool valve element 4 Spring 5 Oil pump cover A Axial direction of sleeve B A diagonal direction not perpendicular to the axial direction of sleeve

Claims (2)

a cylindrical sleeve;
a spool valve body that receives fluid pressure in the sleeve and slides relative to the sleeve along the axial direction of the sleeve to advance and retreat;
an introduction port that opens at one end of the sleeve and introduces a fluid;
The peripheral wall of the sleeve is penetrated in an oblique direction that is not perpendicular to the axial direction of the sleeve so as to move away from the introduction port as it goes from the inner peripheral side to the outer peripheral side of the sleeve, and the first stage that allows excess fluid to escape. a drain port;
a second-stage drain port penetrating through a portion of the peripheral wall of the sleeve that is farther from the introduction port than the first-stage drain port and that allows excess fluid to escape;
and a spring that elastically biases the spool valve body in a direction to reduce the opening of the drain port. The first-stage drain port has an opening that appears on the inner peripheral surface of the peripheral wall, and 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 that direction. 2. The relief valve of claim 1, comprising:

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