JP2014219027A - Relief valve structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a relief valve structure capable of controlling/switching the discharge pressure and the flow rate of oil within the individual low/medium/high rotation number regions of an engine properly in the individual optimum states, and making the structure extremely simple.SOLUTION: A relief valve structure comprises: a valve body B including discharge openings at a large diameter cylindrical part 4, a small diameter head 5 and a rear end side, and a communication hole 62 for communicating an in-valve passage 61 and the outside of the small diameter head 5; a valve housing A1 having a valve element passage 11, a first relief discharge hole 2 and a second relief discharge hole 3 formed therein; and an elastic member 7 for biasing the valve body B toward the side of a relief passage 12 of a valve element passage 11. In a low rotation range of the engine, the small diameter head part holds the relief passage 12 in a closed state; in an intermediate rotation area, the valve body B moves so that the small diameter valve head 5 leaves the relief passage to open the relief passage 12 thereby to provide the communication between the in-valve passage 61 and the first relief discharge hole 2; and, in a high rotation area, the large diameter cylindrical part 4 brings the second relief discharge hole 3 into the open state.

Description

  The present invention provides an oil pump for a vehicle engine or the like, which can appropriately control and switch the oil discharge pressure and flow rate to an optimum state in each of low, medium and high engine speed ranges. The present invention relates to a relief valve structure that can be extremely simplified.

  A relief valve structure for performing pressure control is mounted on an oil pump that supplies lubricating oil to an automobile engine. In the relief valve structure, when the supply oil becomes high pressure in the oil pump, the oil is allowed to escape to another route in order not to adversely affect the equipment, and the oil pressure is maintained below a certain level.

  In recent years, finer control has been required for oil pumps, and oil relief (discharge) is properly performed according to the situation in each of the low, medium and high engine speed ranges. There are more things to stop. In order to satisfy such a demand, the applicant previously invented the content disclosed in Patent Document 1.

  In Patent Document 1, an oil pump is wasted by performing an appropriate amount of oil relief and properly stopping oil relief in each region of the low, medium and high engine speeds. It has been achieved to eliminate work.

JP 2010-107036 A

  By the way, Patent Document 1 has been able to solve many of the various problems in the conventional relief operation. However, there are still some points to be improved. To be specific, the structure of the device is somewhat complicated and therefore expensive.

  Further, further downsizing is required for the structure of the spring and the valve element disposed in the valve passage in the valve housing. Therefore, an object of the present invention (technical problem to be solved) is to satisfy the above-mentioned demand.

  In view of this, the inventor has intensively and researched to solve the above-mentioned problems. A valve body formed of a communication hole that communicates the flow path in the valve and the outside of the small-diameter valve head; a first relief discharge hole in the valve body passage having a relief flow path formed at one end; and the first relief A valve housing having a second relief discharge hole positioned closer to the relief flow path than the discharge hole, and an elastic member that urges the valve body toward the relief flow path of the valve body passage. In the low rotation speed range, the small diameter valve head closes the relief flow path, and in the medium rotation speed range, the small diameter valve head is separated from the relief flow path by the movement of the valve body. And opening the communication hole, the valve passage, and the first relief. It communicates the Deana, in the high speed range, by the large-diameter cylindrical portion has a relief valve structure formed as open state the second relief discharge hole, the above-mentioned problems are eliminated.

  The invention of claim 2 includes a large-diameter cylindrical portion, a small-diameter valve head, a valve passage in which the rear end side is a discharge opening, and a communication hole that communicates the valve passage and the outside of the small-diameter valve head. A first relief discharge hole and a second relief discharge hole located closer to the relief flow channel than the first relief discharge hole are formed in a valve body passage having a relief flow channel formed at one end thereof. A valve housing and an elastic member that urges the valve body toward the relief flow path side of the valve body passage, and the minimum distance from the relief opening position of the relief flow path to the second relief discharge hole is The small-diameter valve head is formed longer than the entire axial length, and the maximum distance from the relief opening position to the second relief discharge hole is shorter than the entire length of the valve body, and the large-diameter cylindrical portion The length of the first relief discharge hole and the second relief By having a relief valve structure in which is shorter than the minimum distance between the full discharge hole, the above-mentioned problems are eliminated.

  The invention of claim 3 includes a large-diameter cylindrical portion, a small-diameter valve head, a valve passage in the rear end that is a discharge opening, and a communication hole that communicates the valve passage and the outside of the small-diameter valve head. A first relief discharge hole and a second relief discharge hole located closer to the relief flow channel than the first relief discharge hole are formed in a valve body passage having a relief flow channel formed at one end thereof. A valve housing and an elastic member that urges the valve body toward the relief flow path side of the valve body passage, and the small-diameter valve head of the valve body abuts around the relief opening of the relief flow path The large diameter cylindrical portion closes the second relief discharge hole, the small diameter valve head is separated from the relief flow path, the communication hole, the valve flow path, The large-diameter cylindrical portion is communicated with the first relief discharge hole and moves the valve body to By having a relief valve structure formed as a state to open the second relief discharge hole, the above-mentioned problems are eliminated.

  According to a fourth aspect of the present invention, there is provided the relief valve structure according to any one of the first, second, and third aspects, wherein the first relief discharge hole is also used as a back pressure relief hole. Solved. According to a fifth aspect of the present invention, in any one of the first, second, third, and fourth aspects, a conical passage slope step portion is formed at an end portion of the valve body passage near the relief flow path. A chamfered portion is formed at the tip of the small-diameter valve head, and the chamfered portion has a relief valve structure in surface contact with the passage slope stepped portion, thereby solving the above problems. The invention according to claim 6 is the relief valve structure according to claim 5, wherein the relief opening of the relief flow path is formed to have the same or smaller diameter than the minimum diameter of the chamfered portion of the small diameter valve head. The above problem has been solved.

  In the first aspect of the invention, the relief is stopped and operated accurately in the low engine speed range, medium engine speed range, and high engine speed range. Then, in the middle speed range, the communication hole of the valve body, the flow path in the valve, and the first relief discharge hole are communicated to perform oil relief, thereby achieving low oil pressure, so that relief in the middle speed range is achieved. It can reduce unnecessary work and improve fuel efficiency.

  Further, the valve body is provided with an internal valve flow path having a discharge opening on the rear end side in the axial direction, and a coil spring or the like for elastically biasing the valve body toward the relief flow path side. A part of the elastic member can be accommodated so as to be loosely inserted. Therefore, the valve body and the elastic member have a portion that overlaps in the axial direction, and can be shorter than the sum of the axial lengths of the valve body and the elastic member. The axial length of the passage can be set short and compact.

  In the invention of claim 2, the valve body can use the small-diameter valve head as a pressure receiving surface that receives the pressure of the relief oil in the relief flow path. It serves to store a part of the elastic member as a coil spring. In this way, the relief valve structure capable of two-stage hydraulic pressure can be made into an extremely simple structure with little machining on the valve body side and almost no machining on the valve housing side.

  Further, the length of the large-diameter cylindrical portion of the valve body is formed shorter than the minimum distance between the first relief discharge hole and the second relief discharge hole, so that in the high engine speed range of the engine, When the large-diameter cylindrical portion is positioned between the first relief discharge hole and the second relief discharge hole, the first relief discharge hole and the second relief discharge hole are opened, and the oil is discharged from the first relief. It can be performed in both the discharge hole and the second relief discharge hole, and the relief operation at high rotation can be made extremely efficient.

  The valve body is provided with an in-valve channel having a discharge opening on the rear end side in the axial direction. The in-valve channel has a discharge opening on the rear end side in the axial direction of the valve body, and serves as both an oil channel and a function of housing an elastic member. An elastic member such as a coil spring for elastically urging the valve body toward the relief flow path is configured such that a part thereof can be loosely inserted into the valve flow path.

  For this reason, since the valve body and the elastic member have portions that overlap in the axial direction, the sum of the axial lengths of the valve body and the elastic member can be made shorter. The axial length can be set short and compact. The invention of claim 3 has the same effects as the inventions of claims 1 and 2.

  In the invention of claim 4, since the first relief discharge hole is also used as a back pressure relief hole, it is not necessary to form the first relief discharge hole and the back pressure relief hole separately, and one through hole is provided. It is possible to reduce the size of the valve housing with a very simple structure simply by forming the valve housing.

  In the invention of claim 5, a conical passage slope step portion is formed at the end of the valve body passage near the relief flow path, and a chamfered portion is formed at the tip of the small diameter valve head. Since the portion is configured to be in surface contact with the passage slope step portion, the contact area between the chamfered portion of the small diameter valve head and the passage slope step portion of the valve body passage is widened, and the relief channel is closed. This can be done even more reliably. Further, the entire surface of the pressure receiving top part and a part of the chamfered part serve to receive the oil pressure, and the operability of the valve body can be improved.

  In a sixth aspect of the invention, the diameter of the relief opening of the relief flow path is formed to be the same as or smaller than the minimum diameter of the chamfered portion of the small diameter valve head. The pressure receiving top portion excluding the portion is effectively used, and a reliable relief operation can be achieved.

(A) is a plan view of a pump body provided with the relief valve structure of the present invention, (B) is an enlarged sectional view taken along the line X1-X1 in (A), and (C) is an enlarged view of part (A) in (B). (D) is the (a) part enlarged view except the valve body of (B). (A) is a perspective view of the valve body, (B) is an enlarged longitudinal side view of the valve body, and (C) and (D) are longitudinal side views showing the positional relationship between the valve body passage and the valve body. (A) is a vertical side view in the low engine speed range, (B) is a vertical side view in the medium engine speed area (previous term), and (C) is a vertical side view in the medium engine speed range (late stage). (D) is a longitudinal side view in a high engine speed range. (A) is a principal part enlarged view which shows the relief state in the low-speed area | region of an engine, (B) is the (a) part enlarged view of (A). (A) is a principal part enlarged view which shows the relief state in the middle-rotation-speed area | region (previous term) of an engine, (B) is the (c) part enlarged view of (A). (A) is a principal part enlarged view which shows the relief state in the engine rotation speed range (late stage), (B) is a (D) enlarged view of (A). (A) is a principal part enlarged view which shows the relief state in the high engine speed area | region, (B) is the (e) part enlarged view of (A). It is a graph which shows the characteristic of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The relief valve structure in the present invention is mainly composed of a valve housing A1 and a valve body B (see FIG. 1B). Although the relief valve structure may be incorporated on the engine block side, it is often incorporated into a part of the pump body A (see FIG. 1A).

  Hereinafter, the relief valve structure will be described as an embodiment incorporated in the pump body A. In addition, the relief in this invention means discharging | emitting a part of the oil out of a circuit, when the pressure of the oil in the oil circuit in which the relief valve structure of this invention was integrated exceeds a preset value.

  The valve housing A1 is formed in a part of the pump body A [see FIG. 1 (A)]. A valve body passage 11 and a relief flow path 12 are provided inside the valve housing A1, and the valve body passage 11 and the relief flow path 12 are formed continuously in the axial direction. Specifically, the valve body passage 11 has a structure in which one axial end of the valve body passage 11 communicates with the relief flow path 12 (see FIGS. 1B, 2D, 2C, and 2D). Here, in the valve body passage 11, the side communicating with the relief flow path 12 in the axial direction is the front side of the valve body passage 11, and the opposite side of the relief flow path 12 in the axial direction is the rear side of the valve body passage 11. And

  The valve housing A1 is formed to bulge and form a substantially halved cylinder at a predetermined position in the pump body A. A valve body B is disposed in the valve body passage 11, and the valve body B reciprocates between the front side and the rear side along the axial direction of the valve body passage 11.

  The relief flow path 12 communicates with a discharge branch flow path 15 a from an oil pump discharge port 15 provided in the pump body A. When the oil discharged to the discharge port 15 exceeds a predetermined value and becomes a high pressure, the valve body B is caused by the force due to the pressure applied to the valve body B mounted in the valve housing A1 from the discharge branch flow path 15a. The valve body passage 11 is moved from the front side toward the rear side, and oil is fed into the valve body passage 11 through the relief flow path 12 to perform a relief operation.

  Unlike the inner diameter D1 of the valve body passage 11 and the inner diameter D2 of the relief passage 12, the relief passage 12 is formed with a smaller inner diameter than the valve body passage 11 (see FIG. 1D). The valve body passage 11 communicates with the relief flow path 12 via a step surface. The step surface becomes a conical passage slope step portion 11a whose diameter gradually decreases toward the relief flow path 12 (see FIGS. 1D and 2D).

  In addition, the passage slope step portion 11a has a portion with the largest diameter located on the valve body passage 11 side, and a portion with the smallest diameter becomes a boundary with the relief flow path 12 side [FIG. )reference〕. This boundary is the position of the relief opening 12 a of the relief flow path 12. The passage slope step portion 11a is a portion with which a chamfered portion 53 of the valve body B, which will be described later, comes into contact, and the state where the valve body B is stationary in this state is the initial position state of the valve body B [FIGS. FIG. 3 (A), FIG. 4].

  A first relief discharge hole 2 and a second relief discharge hole 3 are formed at a substantially intermediate position in the axial direction of the valve body passage 11 in the valve housing A1. As shown in FIG. 1, the first relief discharge hole 2 and the second relief discharge hole 3 are arranged along the axial direction of the valve body passage 11 and are formed at different positions in the axial direction. 1 (B), see FIG. 2 (C), (D)]. The range of the substantially intermediate position of the valve body passage 11 is the entire range except for the vicinity of both ends in the passage direction.

  The first relief discharge hole 2 and the second relief discharge hole 3 are portions that communicate the inside and the outside of the valve body passage 11 in the valve housing A1. The positional relationship between the first relief discharge hole 2 and the second relief discharge hole 3 is such that the second relief discharge hole 3 is located in front of the first relief discharge hole 2 and closer to the relief flow path 12. [Refer to FIG. 1 (A), FIG. 2 (C), FIG. 3 (C), FIG. 4 etc.)].

  That is, the second relief discharge hole 3 is located closer to the relief flow path 12 than the first relief discharge hole 2. The first relief discharge hole 2 is formed as a through hole communicating with the valve housing A1 between the inside and the outside of the valve body passage 11.

  There is an embodiment in which the first relief discharge hole 2 is also used as a back pressure relief hole. The back pressure relief hole that also serves as the first relief discharge hole 2 is also referred to as a breathing hole. In the axial reciprocation of the valve body passage 11 of the valve body B, the valve body B passes through the valve body passage 11 by the pressure of oil. When trying to move to the side opposite to the relief flow path 12, the resistance pressure caused by the air in the valve body passage 11 is discharged from the valve body passage 11 to the outside of the valve housing A1, so that the valve body B moves smoothly. It plays a role.

  The second relief discharge hole 3 is a through hole and has a larger area than the first relief discharge hole 2 and may be circular, rectangular, or trapezoidal. Further, as shown in FIG. 1 (A), two through holes are arranged substantially symmetrically at an appropriate interval in the direction orthogonal to the axial direction of the valve housing A1, that is, in the width direction. See FIG. 1A].

  Inside the pump body A, a rotor chamber 13 constituting the pump is formed. An inner rotor 81 provided with external teeth in the rotor chamber 13 and an outer rotor 82 provided with internal teeth are eccentrically housed while meshing with each other.

  The inner rotor 81 and the outer rotor 82 are disclosed by an imaginary line (two-dot chain line) in FIG. Specifically, the inner rotor 81 is of a trochoid type. Then, the oil is sucked from the suction port 14 formed in the rotor chamber 13, and the oil is discharged from the discharge port 15 and circulated to the equipment.

  Next, the valve body B is mainly composed of a large-diameter cylindrical portion 4, a small-diameter valve head 5, a valve passage 61, and a communication hole 62 (see FIGS. 2A and 2B). Here, the valve body B has a front side and a rear side in the axial direction. The front side is the side on which the small-diameter valve head 5 is formed, and the rear side is the side on which the large-diameter cylindrical portion 4 is formed. The small-diameter valve head 5 is composed of a cylindrical portion 51 and a pressure receiving top portion 52 (see FIGS. 2A and 2B).

  A chamfered portion 53 is formed between the cylindrical portion 51 and the pressure receiving top portion 52. The chamfered portion 53 is a portion formed as a conical slope, and the chamfered portion 53 is formed at an inclination angle equivalent to the passage slope step portion 11 a of the valve body passage 11. When the valve body B is in the initial position state, the chamfered portion 53 of the small-diameter valve head 5 abuts on the passage slope step portion 11a of the valve body passage 11, and the relief flow path 12 and the valve body passage 11 The oil flow is shut off and the relief flow path 12 is closed (see FIGS. 3A and 4).

  The chamfered portion 53 is in surface contact with the passage slope step portion 11 a of the valve body passage 11 and closes the relief opening 12 a of the relief flow path 12. The diameter D5 of the pressure receiving top 52 at the tip of the small diameter valve head 5 is the same as the diameter D2 of the relief opening 12a of the relief flow path 12, or the diameter D5 of the pressure receiving top 52 at the tip of the small diameter valve head 5 is The relief channel 12 is formed slightly larger than the diameter D2 of the relief opening 12a.

  In particular, when the chamfered portion 53 of the small-diameter valve head 5 comes into surface contact with the passage slope step portion 11a of the valve body passage 11, the diameter D5 is formed slightly larger than the diameter D2, so that the pressure receiving top portion 52 is formed. The area can be increased. The small-diameter valve head 5 is smaller in diameter than the large-diameter cylindrical portion 4, and the small-diameter valve head 5 is formed with a conical valve slope stepped portion 54 continuous with the large-diameter cylindrical portion 4.

  As described above, the large-diameter cylindrical portion 4 slides in the valve body passage 11 so as to be reciprocally movable between the front side and the rear side in the axial direction. Is formed slightly smaller than the inner diameter of the valve body passage 11 so that the valve body B can slide smoothly. Specifically, the magnitude relationship between the diameter D4 of the large-diameter cylindrical portion 4 and the inner diameter D1 of the valve body passage 11 is the same as the fitting structure of the gap fitting that slides relatively in a close contact state at about several tens of μm. It is.

  The cylindrical portion 51 has a cylindrical shape having the same diameter at any position along the axial direction. The axial length of the small-diameter valve head 5 is referred to as an axial total length Lt. The total axial length Lt is a length including the cylindrical portion 51, the chamfered portion 53, the pressure receiving top portion 52, and the valve slope step portion 54. The pressure receiving top 52 of the small-diameter valve head 5 serves to move the valve element B itself in the valve element passage 11 by receiving the pressure of the oil flowing into the relief flow path 12 (see FIGS. 3 to 7). ).

  The state in which the small-diameter valve head 5 of the valve body B abuts around the relief opening 12 a of the relief channel 12 is defined as the closed state of the relief channel 12. Specifically, in a state where the chamfered portion 53 of the small-diameter valve head 5 is in contact with the passage slope step portion 11a, the oil flowing into the relief passage 12 from the discharge branch passage 15a is directed to the valve body passage 11 side. There is no spillage. That is, the relief flow path 12 is closed and the inflow of oil to the valve body passage 11 is blocked.

  Inside the valve body B, an in-valve channel 61 is formed along the axial direction. The in-valve channel 61 has a discharge opening 61a formed at the axially rear end portion of the large-diameter cylindrical portion 4, and becomes a closed wall surface by the pressure receiving top portion 52 on the small-diameter valve head 5 side on the axially front side. [See FIG. 1 (C), FIG. 3 (A), etc.].

  A communication hole 62 is formed in the cylindrical portion 51 of the small diameter valve head 5. The communication hole 62 communicates with the valve flow path 61 inside the valve element B (see FIG. 2B). The valve body B communicates the outside on the front side of the small-diameter valve head 5 and the discharge opening 61 a of the valve passage 61 through the communication hole 62 and the valve passage 61.

  As a result, the outside of the large-diameter cylindrical portion 4 communicates from the outside of the small-diameter valve head 5 via the communication hole 62, the in-valve channel 61, and the discharge opening 61a. Oil flows into the communication hole 62 from the outside of the small-diameter valve head 5, flows into the valve passage 61 from the communication hole 62, and is discharged from the discharge opening 61a of the valve passage 61. The oil flows into the valve body passage 11 as it is (see FIGS. 3C and 3D).

  One or more communication holes 62 are formed in the cylindrical portion 51 of the small diameter valve head 5. When there are a plurality of communication holes 62, they are arranged at equal intervals (equal angles) along the outer periphery of the cylindrical portion 51. Specifically, the number of communication holes 62 is preferably about 2, 3 or 4.

  The valve body B housed in the valve body passage 11 of the valve housing A1 is arranged with the small-diameter valve head 5 facing the relief flow path 12 side. An elastic member 7 is attached to the valve body passage 11, and the valve body B is always elastically biased to the front side of the valve body passage 11, that is, the relief flow path 12 side by the elastic member 7. . Specifically, a coil spring is used for the elastic member 7 (see FIG. 1B). The elastic member 7 is fixed by a support member 16 mounted at a position on the rear side in the axial direction of the valve body passage 11, that is, on the side opposite to the relief flow path 12.

  The valve body B is referred to as an initial position of the valve body B when the valve body A1 is in an unloaded state where no relief pressure is applied in the valve housing A1. In this initial position, the chamfered portion 53 of the small-diameter valve head 5 of the valve body B abuts the passage slope step portion 11a in the valve body passage 11, and the relief flow path 12 is closed. Become.

  In the present invention, the axial total length Lt of the small-diameter valve head 5 of the valve body B is shorter than the minimum distance between the relief opening 12a near the valve body passage 11 in the relief flow path 12 and the second relief discharge hole 3. It is set (see FIG. 2C). The minimum distance is a portion closest to the relief opening 12a of the relief flow path 12 at the periphery of the second relief discharge hole 3 having a hole shape.

である。 The magnitude relationship between the minimum distance La between the relief opening 12a of the relief passage 12 near the valve body passage 11 and the second relief discharge hole 3 and the axial total length Lt of the small diameter valve head 5 is as follows.

It is.

である。 Further, the axial length Ls of the large-diameter cylindrical portion 4 of the valve body B is set to be shorter than the minimum distance Lb between the first relief discharge hole 2 and the second relief discharge hole 3 [FIG. )reference〕. Specifically, the magnitude relationship between the axial length Ls of the large-diameter cylindrical portion 4 of the valve body B and the minimum distance Lb between the first relief discharge hole 2 and the second relief discharge hole 3 is:

It is.

である。 Further, the overall length Lf of the valve body B is set to be larger than the maximum distance La ′ between the relief opening 12 a of the relief flow path 12 near the valve body passage 11 and the second relief discharge hole 3. That is, the magnitude relationship between the maximum distance La ′ between the relief opening 12a of the relief flow path 12 near the valve body passage 11 and the second relief discharge hole 3 and the overall length Lf of the valve body B is as follows.

It is.

  With the above configuration, in the initial position of the valve body B in the valve housing A1, that is, in a state where the valve body B is disposed at a position near the relief flow path 12 of the valve body passage 11, the following occurs. That is, the relief flow path 12 is closed, and the second relief discharge hole 3 is closed by the large-diameter cylindrical portion 4 (see FIGS. 1B, 3A, and 4). Moreover, the 1st relief discharge hole 2 is an open state.

  Next, the relief operation in the low engine speed range, medium engine speed range, and high engine speed range of the present invention will be described. Here, the elastic member 7 in the present invention is a coil spring, and elastically biases the valve body B at the initial position from the rear side of the valve body passage 11 toward the relief opening 12a on the front side. .

  And the force by the pressure at the time of the relief which the valve body B receives shall not shrink a coil spring unless it exceeds the predetermined elastic force which the elastic member 7 made into a coil spring has. That is, as long as the force due to the oil pressure does not exceed a predetermined value, the valve body B is brought into an immobile state by the elastic member 7.

  In the case of a low engine speed range (including an idling state) from the start of the engine, as shown in FIGS. 3A and 4, the discharge pressure is low even if the pump is operated. Therefore, since the elastic force by the elastic member 7 exceeds the force due to the pressure received by the pressure receiving top 52 of the valve body B, the valve body B is maintained in the initial position in the valve body passage 11. Therefore, relief (oil discharge) is not performed. The second relief discharge hole 3 is closed by the large diameter cylindrical portion 4 of the valve body B, and the chamfered portion 53 of the small diameter valve head 5 is in contact with the passage slope step portion 11a.

  The rotational speed increases within the range of the low rotational speed range of the engine, and the pressure received by the pressure receiving top portion 52 of the valve body B also increases. However, the elastic force of the elastic member 7 exceeds the force due to this pressure. Is set as follows. Therefore, in the low rotation speed range, the valve element B is maintained in an immobile state at the initial position.

  Therefore, the relief flow path 12 remains closed in the low rotational speed range (see FIG. 4), and in the low rotational speed range, the hydraulic pressure by the pump is approximately proportional to the rotational speed as shown in the graph of FIG. To rise.

  Next, in the middle speed range of the engine, the first period (see FIGS. 3B and 5) and the second period (see FIGS. 3C and 6) will be described separately. The first half of the middle rotation speed range is the range from immediately after changing from the low rotation speed range to the middle rotation speed range to the middle rotation speed of the middle rotation speed range, and the second half is the middle rotation of the middle rotation speed range. This is the range from the number to just before the change to the high speed range.

  First, in the first half of the middle rotation speed range, the force due to the pressure received from the relief flow path 12 of the pressure receiving top portion 52 of the valve body B at the same time as entering the middle rotation speed range from the low rotation speed range exceeds the elastic force of the elastic member 7. The valve element B is moved toward the rear side in the axial direction of the valve element passage 11 (opposite to the relief flow path 12), and the chamfered portion 53 of the small-diameter valve head 5 is brought into contact with the passage slope step portion 11a. From the contact state to the separation state, the relief opening 12a of the relief flow path 12 opens and communicates with the valve element passage 11 (see FIGS. 3B and 5).

  Then, the oil enters the valve body passage 11 from the relief flow path 12 in a state where the cylindrical portion 51 is separated from the relief flow path 12. Further, the rear side of the valve body passage 11 is blocked by the large-diameter cylindrical portion 4 of the valve body B.

  Therefore, the oil that has flowed into the valve body passage 11 flows into the in-valve channel 61 through the communication hole 62 formed in the cylindrical portion 51 of the small-diameter valve head 5, and is discharged from the in-valve channel 61. Oil is discharged from the opening 61a to the rear side of the valve body passage 11 (see FIGS. 3B and 5).

  In this way, in the middle rotation speed range, the small diameter valve head 5 is opened apart from the relief flow path 12 by the movement of the valve element B, and the communication hole 62 and the in-valve flow path 61 are opened. And the first relief discharge hole 2 communicate with each other. As a result, the oil relief operation is started.

  The relief operation in the first half of the middle rotation speed range is from when the small-diameter valve head 5 starts to be separated from the relief flow path 12. Immediately after the start of the first half, the relief flow 12 enters the valve body passage 11. The oil inflow is very small.

  In particular, immediately after the cylindrical portion 51 immediately after the relief start is separated from the relief flow path 12, the chamfered portion 53, the cylindrical portion 51 and the valve slope step portion 54 of the valve body B, the valve body passage 11 and the passage slope step. The gap S formed by the portion 11a is very small (see FIG. 5B). Therefore, the amount of oil flowing into the gap S is extremely small, and therefore the relief amount is very small.

  Next, in the latter period of the middle rotation speed range (see FIGS. 3C and 6), the force due to the pressure received by the small-diameter valve head 5 of the valve element B increases, Continue moving toward the rear. As a result, the space on the front side of the valve body passage 11 is expanded, the amount of oil flowing through the communication hole 62 of the small-diameter valve head 5, the in-valve channel 61, and the first relief discharge hole 2 is increased, and the relief amount is increased. .

  In the relief operation from the first period to the second period in the middle rotation speed range, the oil that has flowed into the valve body passage 11 from the relief flow path 12 first flows into the communication hole 62 of the valve body B. Since the communication hole 62 is a small-diameter through hole having a diameter of about several millimeters formed in the small-diameter valve head 5, the amount of inflow of oil is small, and therefore the relief amount gradually increases from the previous period to the latter period. There are, however, few in total. This state is disclosed in the middle rotation speed range of the graph of FIG.

  Next, when the engine is in a high speed range, when the transition from the latter half of the middle speed range to the high speed range occurs, the oil pressure increases and the valve element B moves, so that the large-diameter cylindrical portion 4 The second relief discharge hole 3 is moved to the rear side from the position of the second relief discharge hole 3 to open the second relief discharge hole 3 (see FIGS. 3D and 7). Then, the oil is discharged from the second relief discharge hole 3. At the same time, the oil that flows through the communication hole 62 of the valve body B and the flow passage 61 in the valve and is discharged from the discharge opening 61 a is also discharged from the first relief discharge hole 2.

  That is, relief is performed from both the second relief discharge hole 3 and the first relief discharge hole 2 [see FIGS. 3D and 7]. In the high engine speed range, the pump oil discharge amount increases and the oil relief amount also increases. This state is shown in the high speed range in the graph of FIG.

  In addition, although the relief valve structure of this invention was demonstrated as what is comprised with an oil pump, it can also be applied to various hydraulic equipment independently as a relief valve.

A1 ... valve housing, B ... valve body, 11 ... valve body passage, 11a ... passage slope step,
12 ... relief flow path, 2 ... first relief discharge hole, 3 ... second relief discharge hole,
4 ... Large diameter cylindrical part, 5 ... Small diameter valve head, 51 ... Cylindrical part, 52 ... Pressure receiving top part, 53 ... Chamfering part,
54 ... Valve slope step part, 61 ... Valve flow path, 62 ... Communication hole, 7 ... Elastic member.

Claims (6)

  A valve body comprising a large-diameter cylindrical portion, a small-diameter valve head, a valve flow passage having a discharge opening on the rear end side, a communication hole communicating the flow passage in the valve and the outside of the small-diameter valve head, and one end A first relief discharge hole in a valve body passage having a relief flow channel formed on the side thereof, a valve housing having a second relief discharge hole positioned closer to the relief flow channel than the first relief discharge hole, An elastic member that urges the valve body toward the relief flow path side of the valve body passage, and the small-diameter valve head closes the relief flow path in a low engine speed range, and As the valve body moves, the small-diameter valve head is separated from the relief flow path to open the relief flow path, and communicates the communication hole, the valve flow path, and the first relief discharge hole. In the high rotation speed range, the large-diameter cylindrical portion opens the second relief discharge hole. A relief valve structure characterized by comprising as a state.   A valve body comprising a large-diameter cylindrical portion, a small-diameter valve head, a valve flow passage having a discharge opening on the rear end side, a communication hole communicating the flow passage in the valve and the outside of the small-diameter valve head, and one end A first relief discharge hole in a valve body passage having a relief flow channel formed on the side thereof, a valve housing having a second relief discharge hole positioned closer to the relief flow channel than the first relief discharge hole, An elastic member that biases the valve body toward the relief flow path side of the valve body passage, and the minimum distance from the relief opening position of the relief flow path to the second relief discharge hole is an axis of the small-diameter valve head The maximum distance from the position of the relief opening to the second relief discharge hole is formed to be shorter than the total length of the valve body, and the length of the large diameter cylindrical portion is the first length. Minimum relief discharge hole and second relief discharge hole A relief valve structure characterized by comprising is shorter than away.   A valve body comprising a large-diameter cylindrical portion, a small-diameter valve head, a valve flow passage having a discharge opening on the rear end side, a communication hole communicating the flow passage in the valve and the outside of the small-diameter valve head, and one end A first relief discharge hole in a valve body passage having a relief flow channel formed on the side thereof, a valve housing having a second relief discharge hole positioned closer to the relief flow channel than the first relief discharge hole, An elastic member that biases the valve body toward the relief flow path side of the valve body passage, and the small-diameter valve head of the valve body is in a closed state in contact with the periphery of the relief opening of the relief flow path, The large diameter cylindrical portion closes the second relief discharge hole, and the communication hole, the in-valve flow path, and the first relief discharge hole are in a state where the small diameter valve head is separated from the relief flow path. The large-diameter cylindrical portion communicates with the second relief discharge hole by the movement of the valve body. A relief valve structure characterized by comprising a state opened.   4. The relief valve structure according to claim 1, wherein the first relief discharge hole also serves as a back pressure relief hole.   5. The end of the valve body passage near the relief flow path is formed with a conical passage slope step portion at the tip of the small-diameter valve head according to claim 1. The relief valve structure according to claim 1, wherein a chamfered portion is formed, and the chamfered portion is in surface contact with the passage slope step portion.   6. The relief valve structure according to claim 5, wherein the diameter of the relief opening of the relief flow path is the same as or smaller than the minimum diameter of the chamfered portion of the small diameter valve head.

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