JP5215959B2 - Oil pump relief valve - Google Patents

Description

  The present invention relates to a relief valve provided in an oil pump for supplying oil for lubrication / cooling to each part of an engine to suppress an excessive increase in oil discharge pressure.

  An automobile engine is provided with an oil pump that sucks oil from an oil reservoir and supplies it to each part of the engine. This oil pump is driven by the power of the crankshaft, and as the engine speed increases, the oil discharge pressure increases, and the oil discharge pressure also increases in a low temperature state where the oil fluidity decreases.

  In this oil pump, when the oil discharge pressure is higher than necessary, the power of the crankshaft is wasted. Therefore, a relief valve is provided that opens a relief hole that communicates the discharge side and the suction side of the oil pump when the oil discharge pressure becomes high. It is possible to suppress wasteful consumption.

  In such a relief valve for an oil pump, two relief holes are formed apart from each other in the lift direction of the valve body, and the two relief holes are sequentially opened according to the lift operation of the valve body. The thing provided with the relief mechanism of a type | formula is known (refer patent document 1).

  Moreover, what was provided with the relief hole which makes an ellipse shape is known (refer patent document 2). In this configuration, the relief hole can be fully opened at a stage where the lift amount of the valve body is small compared to a perfectly circular relief hole having the same opening area, and the opening area is the same when the lift amount is the same. Since it becomes large, the flow rate of oil can be increased at an early stage, and an increase in the discharge pressure of the oil pump can be suppressed with good response.

Noto 2587580 gazette JP-A-8-158842

  However, even in a relief valve equipped with a two-stage relief mechanism, it is desirable to devise the shape of the relief hole to suppress an increase in the discharge pressure of the oil pump with good response. In the configuration formed in an elliptical shape, even when the valve body is in a state immediately before the relief valve is fully closed, the opening area is large, so the oil flow rate is low, and accordingly the passage speed of foreign matter in the oil is also low. There is a problem that the possibility of occurrence of biting of foreign matter is increased.

  The present invention has been devised to solve such problems of the prior art, and its main purpose is to suppress an excessive increase in the discharge pressure of the oil pump with good response. And it is providing the relief valve of the oil pump comprised so that the biting of a foreign material could be suppressed.

A first aspect of the invention made to solve the above-described problem is that a cylindrical valve housing portion (23) having a relief hole in the side wall that communicates the discharge side and the suction side of the oil pump, and the axial direction thereof. A valve body (24) that opens and closes to open and close the relief hole; and a spring (25) that urges the valve body toward a fully closed position, and the valve housing portion includes a first relief hole (21) and An oil pump having a second relief hole (22) spaced apart in the axial direction so that the first relief hole and the second relief hole are sequentially opened in accordance with the lift operation of the valve body. The oil pump includes a bypass chamber (12) between the suction chamber (7) and the discharge chamber (9), and the valve housing portion faces the bypass chamber. Side walls are provided, and the first relief hole and the second relief hole are provided. In addition to opening the bypass chamber, the pressure in the discharge chamber is applied to the pressure receiving surface (24a) of the valve body through the introduction hole (26) communicating the inside of the valve housing portion with the discharge chamber. The first relief hole is provided at a position close to the pressure receiving surface of the valve body in the fully closed position, and the first relief hole has a circular shape and has the same diameter. A plurality of the second relief holes are formed in a substantially trapezoidal shape with an end portion on the introduction hole side having an acute angle .

  According to this, in the configuration in which one circular first relief hole is provided, the size of the first relief hole in the axial direction is smaller than when the size is set so that the total opening area is the same. Since it becomes short, the lift amount of the valve body required to fully open the first relief hole is shortened. And the opening area in the same lift amount becomes large, and the flow volume of oil can be increased rapidly. Further, the amount of bending of the spring until the first relief hole is fully opened is reduced, and the first relief hole can be fully opened in a region where the spring force is weak. Therefore, the lift speed of the valve body is also increased. For this reason, it can suppress with sufficient responsiveness that the discharge pressure of oil rises excessively.

  In addition, in the configuration in which one first relief hole having an elliptical shape is provided and the size is set so that the total opening area is the same, the lift amount of the valve body is near the fully closed position. In a small state, the opening area can be reduced even with the same lift amount. For this reason, when the valve body is closed, the oil flow rate increases immediately before the valve body fully closes the first relief hole, and the passage speed of the foreign matter in the oil increases accordingly. Can be suppressed.

Particularly, in the configuration in which the first relief hole has a circular shape as in the first invention, the first relief hole can be easily formed with high accuracy by drilling with a drill .

  As described above, according to the present invention, the lift amount of the valve body required to fully open the first relief hole is shortened, and the opening area with the same lift amount is increased, and the first relief hole is fully opened. Therefore, when the valve body closes, the valve body immediately before the relief hole is fully closed can be suppressed. In this state, since the oil flow rate is high, it is possible to suppress biting of foreign matter.

It is sectional drawing which shows an example of the oil pump to which the relief valve by this invention was applied. It is a front view of the relief valve shown in FIG. It is sectional drawing which shows the operation | movement condition of the relief valve shown in FIG. It is a principal part front view which shows the relief valve which concerns on the 1st Embodiment of this invention. It is a front view which shows the opening condition of the 1st relief hole shown in FIG. 4, and the 1st relief hole by a conventional structure. It is a principal part front view which shows the relief valve which concerns on the 2nd Embodiment of this invention. It is a principal part front view which shows the relief valve which concerns on the 3rd Embodiment of this invention. It is a graph which shows the change situation of oil pressure and friction according to engine speed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, an oil pump 1 to which the present invention is applied is a trochoid pump, and includes an outer rotor 2 and an inner rotor 3, and the pump is interposed between inner teeth of the outer rotor 2 and outer teeth of the inner rotor 3. Chamber 4 is defined. In the housing 5, there are formed a suction chamber 7 that guides oil flowing from the suction port 6 to the pump chamber 4 and a discharge chamber 9 that guides oil discharged from the pump chamber 4 to the discharge port 8.

  The oil pump 1 is driven by the power of the crankshaft. Specifically, the torque of a crankshaft (not shown) is input to the inner rotor 3. Accordingly, the oil discharge pressure increases as the engine speed increases, and the oil discharge pressure increases even in a low temperature state where the fluidity of the oil decreases.

  Furthermore, this oil pump 1 is provided with a relief valve 11 according to the present invention in order to avoid wasting power of the crankshaft due to pressurization of oil when the oil discharge pressure becomes higher than necessary. When the relief valve 11 is opened, the oil in the discharge chamber 9 is returned to the suction chamber 7 via the bypass chamber 12.

  The housing 5 is composed of an engine-side housing divided body (not shown) having a fastening surface with the engine side, and a housing divided body (not shown) that holds the outer rotor 2 and the inner rotor 3, and by combining the two divided bodies, The storage chamber of the outer rotor 2 and the inner rotor 3, the discharge chamber 9, the suction chamber 7, and the bypass chamber 12 are sealed.

  As shown in FIG. 2, the relief valve 11 includes a cylindrical valve housing portion 23 in which relief holes 21 and 22 communicating with the discharge chamber 9 and the bypass chamber 12 are formed in the side wall, and is advanced and retracted in the axial direction thereof. A valve body 24 that opens and closes the relief holes 21 and 22 and a spring 25 that biases the valve body 24 toward the fully closed position are provided.

  The inside of the valve accommodating part 23 is connected with the discharge chamber 9 through the introduction hole 26, and when the pressure of the discharge chamber 9 acts on the pressure receiving surface 24a of the valve body 24 and the pressure of the discharge chamber 9 increases excessively. The valve body 24 lifts away from the valve seat 28 against the urging force of the spring 25 to open the relief holes 21 and 22, so that the oil in the discharge chamber 9 flows from the introduction hole 26 to the valve accommodating portion 23. Is discharged from the relief holes 21 and 22 and flows into the bypass chamber 12.

  In particular, here, the first relief hole 21 and the second relief hole 22 are formed on the side wall of the valve accommodating portion 23 so as to be separated from each other in the axial direction. The second relief hole 22 is sequentially opened to provide a two-stage relief mechanism, whereby the oil flow rate is adjusted stepwise according to the pressure level in the discharge chamber 9.

  That is, in the region where the pressure in the discharge chamber 9 is relatively low, as shown in FIG. 3A, both the first relief hole 21 and the second relief hole 22 are fully closed. When the pressure is increased, as shown in FIG. 3B, the first relief hole is fully opened and the second relief hole is fully closed, and when the pressure in the discharge chamber 9 is further increased, FIG. ), The first relief hole 21 and the second relief hole 22 are both fully opened.

  The first relief hole 21 and the second relief hole 22 have different total opening areas, the total opening area of the first relief hole 21 is set to be smaller than that of the second relief hole 22, and the engine speed is high. While the pressure in the discharge chamber 9 is high, a large amount of oil is discharged from the second relief hole 22 to suppress an excessive increase in the oil discharge pressure, while the engine speed is low and the pressure in the discharge chamber 9 is compared. Even in a relatively low state, a small amount of oil is discharged from the first relief hole 21 to keep the oil discharge pressure within an appropriate range, and to suppress wasteful consumption of the crankshaft power.

  As shown in FIG. 2, an air vent hole 27 that communicates the inside of the valve housing portion 23 and the bypass chamber 12 is formed below the second relief hole 22 on the side wall of the valve housing portion 23. Thereby, it is possible to prevent the air accumulated in the valve housing portion 23 from inhibiting the lift operation of the valve body 24, and the oil enters the inside of the valve housing portion 23 from the air vent hole 27, Oil can be supplied to the spring 25.

<First Embodiment>
As shown in FIG. 4, in the relief valve 11 according to the first embodiment of the present invention, the first relief hole 21 has a circular shape and the same diameter is the circumferential direction of the valve housing portion 23, that is, A plurality (two in this case) are formed side by side in a direction orthogonal to the advancing / retreating direction (axial direction) of the valve body 24.

  In the relief valve 11, as the valve body 24 performs a lift operation, the fully closed state shown in FIG. 5 (A- 1) is passed through the intermediate opening shown in FIG. 5 (A- 2). 5 (A-3), the first relief hole 21 is partially closed by the valve body 24 at the intermediate opening shown in FIG. Defined.

  Here, the configuration according to the present invention and a conventional first relief hole 51 having a circular shape as shown in FIGS. 5 (B-1), (B-2), and (B-3) are provided. The configuration is compared with the case where the size is set so that the total opening area is the same.

  First, since the diameter of the first relief hole 21 according to the present invention is smaller than that of the first relief hole 51 and the plurality of first relief holes 21 are arranged in the circumferential direction of the valve accommodating portion 23, FIG. -3) As shown in (B-3), the lift amount a1 of the valve body 24 required to fully open the first relief hole 21 is shorter than the lift amount a2 in the case of the first relief hole 51. And as shown to FIG. 5 (A-2) * (B-2), in the 1st relief hole 21 by this invention, the opening area in the same lift amount b becomes larger than the case of the 1st relief hole 51. FIG. The oil flow rate can be increased rapidly. Further, in the first relief hole 21 according to the present invention, the amount of bending of the spring 25 until the first relief hole 21 is fully opened is smaller than that in the case of the first relief hole 51, and the first relief hole 21 can be fully opened in a region where the spring force is weak. Therefore, the lift speed of the valve body 24 is also increased. For this reason, it can suppress with sufficient responsiveness that the discharge pressure of oil rises excessively.

  Next, the configuration according to the present invention and the conventional configuration in which one elliptical first relief hole 52 is provided as shown in FIGS. 5 (C-1), (C-2), and (C-3). Then, the case where the size is set so that the total opening area is the same is compared.

  In the first relief hole 21 according to the present invention, as shown in FIGS. 5 (A-2) and (C-2), when the lift amount of the valve body 24 is small near the fully closed position, the same lift amount b. However, the opening area can be made smaller than in the case of the first relief hole 52. For this reason, when the valve body 24 is closed, the oil flow rate increases immediately before the valve body 24 fully closes the first relief hole 21, and accordingly, the passage speed of foreign matter in the oil also increases. Therefore, it is possible to suppress biting of foreign matter.

  As shown in FIG. 1, the first relief hole 21 is provided in the engine-side housing divided body shown in the housing 5 and is aligned with a housing divided body (not shown) (disposed on the front side in the figure). It is provided so as to face the surface side (front side in the figure), thereby improving workability when forming the first relief hole 21 by drilling or the like. The same applies to the second and third embodiments described later.

  Moreover, the 1st relief hole 21 can also be made into an elliptical shape other than a perfect circle shape. In this case, if an elliptical shape with a large flatness ratio is used, the effect of suppressing the biting of foreign matter when the valve body 24 is closed is reduced, and therefore an elliptical shape close to a perfect circular shape with a small flatness ratio is preferable. Incidentally, since the side wall of the valve housing part 23 has a cylindrical shape, when drilling is performed from the direction intersecting with the axis line of the valve housing part 23, it becomes a perfect circle, but the axis line of the valve housing part 23 When drilling is performed from a direction that does not intersect, an elliptical shape is obtained. For this reason, in consideration of workability, when drilling the plurality of first relief holes 21 from the same direction, the plurality of first relief holes 21 are brought as close as possible so that the drilling direction of the drill is set to the valve housing portion 23. The first relief hole 21 close to a perfect circle shape can be opened.

  In addition, a plurality (two in this case) of the second relief holes 22 are formed in the circumferential direction of the valve accommodating portion 23. The second relief holes 22 have a substantially trapezoidal shape with an upper end having an acute angle, and the two second relief holes 22 are center lines as viewed from the mating surface side (front side in the figure) of the divided body of the housing 5. Are formed in a symmetrical shape.

<Second Embodiment>
As shown in FIG. 6, in the relief valve 61 according to the second embodiment of the present invention, the first relief hole 62 has a substantially triangular shape, and the apex portion 63 is in the closed side, that is, in the fully closed position. It is located on the pressure receiving surface 24a side of the valve body 24 and is formed so that the axial dimension L1 is shorter than the circumferential dimension L2.

  In particular, here, the first relief hole 62 has an isosceles triangular shape symmetrical with respect to the axial center line when viewed from the mating surface side (front side in the figure) of the divided body of the housing 5, and the apex portion 63 is formed. It is arranged at the center position in the circumferential direction. The opening edge portion of the apex angle portion 63 is formed in an arc shape. When the lift amount of the valve body 24 is small, a split-circle-shaped opening portion is defined by the opening edge portion of the apex angle portion 63 having an arc shape. Is done. The opening edge of the bottom corner 64 is also formed in an arc shape.

  In this configuration, similarly to the first embodiment shown in FIG. 5, the size is set so that the entire opening area is the same in the configuration in which one circular first relief hole 51 is provided. Compared to the case, the axial dimension of the first relief hole 62 according to the present invention can be shortened, so that the lift amount of the valve body 24 required to fully open the first relief hole 62 is shortened. And the opening area in the same lift amount becomes large, and the flow volume of oil can be increased rapidly. Further, the amount of bending of the spring 25 until the first relief hole 62 is fully opened is reduced, and the first relief hole 62 can be fully opened in a region where the spring force is weak, so the lift speed of the valve body 24 is also increased. For this reason, it can suppress with sufficient responsiveness that the discharge pressure of oil rises excessively.

  Further, in the first relief hole 62 according to the present invention, compared with the case where the size is set so that the total opening area is the same in the configuration in which the first relief hole 52 having an elliptical shape is provided, In the state where the lift amount of the valve body 24 is small in the vicinity of the closed position, the opening area can be reduced even with the same lift amount. For this reason, when the valve body 24 is closed, the oil flow rate increases immediately before the valve body 24 fully closes the first relief hole 62, and accordingly, the passage speed of foreign matter in the oil also increases. Therefore, it is possible to suppress biting of foreign matter.

<Third Embodiment>
As shown in FIG. 7, in the relief valve 71 according to the third embodiment of the present invention, the first relief hole 72 has a substantially hemispherical shape, and the bent center portion 73 is closed from the end portion 74. That is, the valve body 24 is located on the pressure receiving surface 24a side in the fully closed position, and the axial dimension L1 is shorter than the circumferential dimension L2.

  In particular, here, the first relief hole 72 has a symmetrical shape with respect to the axial center line when viewed from the mating surface side (front side in the figure) of the divided body of the housing 5, and the central portion 73 is in the circumferential direction. A pair of slit-like portions 75 that are disposed at the center position and extend straight in a direction inclined with respect to the circumferential direction are formed symmetrically with respect to the axial center line. The opening edge on the closed side of the central portion 73 is formed in an arc shape, and when the lift amount of the valve body 24 is small, a split-circle opening portion is defined at the opening edge portion of the arc-shaped central portion 73. Made. The opening edge portion of the end portion 74 is also formed in an arc shape. The slit-shaped portion 75 has a constant width (dimension in the direction orthogonal to the extending direction) L3.

  In this configuration, similarly to the first embodiment shown in FIG. 5, the size is set so that the entire opening area is the same in the configuration in which one circular first relief hole 51 is provided. Compared to the case, the axial dimension of the first relief hole 72 according to the present invention can be shortened, so that the lift amount of the valve body 24 required to fully open the first relief hole 72 is shortened. And the opening area in the same lift amount becomes large, and the flow volume of oil can be increased rapidly. Further, the amount of bending of the spring 25 until the first relief hole 72 is fully opened is reduced, and the first relief hole 72 can be fully opened in a region where the spring force is weak, so that the lift speed of the valve body 24 is also increased. For this reason, it can suppress with sufficient responsiveness that the discharge pressure of oil rises excessively.

  Further, in the first relief hole 72 according to the present invention, compared to the case where the size is set so that the total opening area is the same in the configuration in which the first relief hole 52 having an elliptical shape is provided, In the state where the lift amount of the valve body 24 is small in the vicinity of the closed position, the opening area can be reduced even with the same lift amount. For this reason, when the valve body 24 is closed, the oil flow rate increases immediately before the valve body 24 fully closes the first relief hole 72, and accordingly, the passage speed of foreign matter in the oil also increases. Therefore, it is possible to suppress biting of foreign matter.

  By the way, as shown in the first embodiment, that is, as shown in FIG. 4, a configuration in which two first relief holes 21 having a circular shape are provided by a two-stage relief mechanism (Example 1) and one relief hole are provided. A configuration with the provided one-stage relief mechanism (Comparative Example 1) and a configuration in which one circular first relief hole 51 is provided with the two-stage relief mechanism as shown in FIG. 5 (Comparative Example 2). As shown in FIG. 8, an experiment was conducted to measure the discharge pressure of the oil pump and the friction down effect.

  In the first embodiment, as shown in FIG. 8A, in the region where the engine speed is low to medium, the increase in hydraulic pressure is effectively suppressed as compared with Comparative Example 1 as well as Comparative Example 1. In addition, as shown in FIG. 8 (B), the friction (load), which is a measure of the amount of power consumption of the crankshaft due to the pressurization of oil, is greatly reduced as compared with Comparative Example 2. The effectiveness of the present invention has been demonstrated.

  In addition, as shown in 2nd Embodiment, ie, FIG. 6, the structure provided with one 1st relief hole 62 which makes a substantially triangular shape with a 2 step | paragraph relief mechanism, or 3rd Embodiment, ie, FIG. As shown in Fig. 1, when a similar experiment was performed on a configuration in which one first relief hole 72 having a substantially square shape was formed by a two-stage relief mechanism, Example 1 (first embodiment) The effectiveness of the present invention was demonstrated.

DESCRIPTION OF SYMBOLS 1 Oil pump 5 Housing 7 Suction chamber 9 Discharge chamber 11 Relief valve 12 Bypass chamber 21 1st relief hole 22 2nd relief hole 23 Valve accommodating part 24 Valve body, 24a Pressure receiving surface 25 Spring 26 Introduction hole 61 Relief valve 62 1st relief Hole 63 Vertical corner portion 64 Bottom corner portion 71 Relief valve 72 First relief hole 73 Center portion 74 End portion 75 Slit portion

Claims (1)

A cylindrical valve housing portion having a relief hole in the side wall that communicates between the discharge side and the suction side of the oil pump, a valve body that moves forward and backward in its axial direction to open and close the relief hole, and this valve body A spring urging toward the closed position, and a first relief hole and a second relief hole are formed in the valve accommodating portion so as to be separated from each other in the axial direction, and the first relief hole and the second relief hole are formed according to a lift operation of the valve body. 1 is a relief valve of an oil pump in which one relief hole and the second relief hole are sequentially opened,
The oil pump includes a bypass chamber between the suction chamber and the discharge chamber, and a side wall of the valve housing portion is provided so as to face the bypass chamber, and the first relief hole and the second relief hole are provided. While opening to the bypass chamber, the pressure of the discharge chamber is applied to the pressure receiving surface of the valve body through an introduction hole communicating the inside of the valve housing portion with the discharge chamber,
The first relief hole is provided at a position close to the pressure receiving surface of the valve body in the fully closed position, and the first relief hole has a circular shape and the same diameter is the circumference of the valve housing portion. Formed side by side in the direction ,
The relief valve for an oil pump, wherein the second relief hole is formed in a substantially trapezoidal shape with an end portion on the introduction hole side having an acute angle .

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