Variable displacement oil pump and method for manufacturing variable displacement oil pump

Abstract

A variable displacement oil pump according to the present invention has a protrusion (46) that is partially formed on a spring contact surface (451) of an arm part (45) of a cam ring (4) so as to overlap with part of the outer circumference of a coil spring (SP). This protrusion (46) restricts tilting of the coil spring (SP) and makes it possible to suppress positional deviation of the coil spring (SP). Furthermore, because the protrusion (46) is provided partially on the spring contact surface (451) of the arm part (45) of the cam ring 4, the coil spring (SP) need only be pushed inward of the protrusion (46) when installing the coil spring (SP), thus making it possible to ensure ease of installation of the coil spring (SP).

Description

[Technical Field]

[0001] The present invention relates to a variable displacement oil pump and a method for manufacturing a variable displacement oil pump. [Background technology]

[0002] A known conventional variable displacement oil pump is, for example, that described in Patent Document 1 below.

[0003] In the variable displacement oil pump described in Patent Document 1, a cam ring that is swingably provided within a pump accommodating portion of a housing is biased in a direction that increases the amount of eccentricity by the biasing force of a coil spring that elastically contacts an arm that is provided on the opposite side of the swing fulcrum across the center of the cam ring. In this biasing mechanism, a cylindrical protrusion that protrudes from the spring abutment surface of the arm of the cam ring fits into the inner periphery of the coil spring, and the protrusion supports the inner periphery of one end of the coil spring (the end that seats on the cam ring), thereby suppressing positional displacement of the coil spring. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-019716 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional variable displacement oil pump, the protrusion is fitted to the inner periphery of the coil spring, which means that when assembling the coil spring, the protrusion must be fitted to the inner periphery of the coil spring while restoring the compressed coil spring, making the assembly of the coil spring difficult and leaving room for improvement.

[0006] Therefore, the present invention has been devised in consideration of the technical problems of the conventional variable displacement oil pumps described above, and aims to provide a variable displacement oil pump that can suppress positional deviation of the coil spring while ensuring ease of assembly of the coil spring. [Means for solving the problem]

[0007] In one aspect of the present invention, a cam ring is provided with a protrusion that is partially formed so as to extend from a spring contact surface against which the coil spring contacts in the longitudinal direction of the coil spring and overlap with a portion of the outer periphery of the coil spring. [Effects of the Invention]

[0008] According to the present invention, it is possible to ensure ease of assembly of the coil spring while suppressing positional deviation of the coil spring. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is an exploded perspective view of a pump body in a variable displacement oil pump according to the present invention; [Figure 2] 2 is a plan view of the pump body shown in FIG. 1, with the second housing omitted. [Figure 3] 1 is a vertical cross-sectional view of a control valve for a variable displacement oil pump according to the present invention. [Figure 4] FIG. 2 is an enlarged view of a main part of FIG. [Figure 5] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Figure 6] 5A and 5B are diagrams illustrating a manufacturing method of a variable displacement oil pump according to the present invention, in which (a) is a schematic diagram illustrating a coil spring arrangement step, and (b) is a cross-sectional view taken along line BB in FIG. 5A. [Figure 7] 1 is a diagram showing an operating state of a variable displacement oil pump according to the present invention, in which the amount of eccentricity of a cam ring is greatest. FIG. [Figure 8]1 is a diagram showing an operating state of a variable displacement oil pump according to the present invention, illustrating an operating state in which the eccentricity of a cam ring is at its smallest. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of a variable displacement oil pump according to the present invention will be described in detail below with reference to the drawings. In the following embodiment, an example is shown in which this variable displacement oil pump is applied as an oil pump for supplying lubricating oil to an internal combustion engine of an automobile. For convenience, the following description will define the direction along the rotational axis of the drive shaft 2 as the "axial direction," the direction perpendicular to the rotational axis of the drive shaft 2 as the "radial direction," and the rotational direction of the drive shaft 2 as the "circumferential direction."

[0011] (Oil pump configuration) Fig. 1 shows an exploded perspective view of a pump body PA of a variable displacement oil pump according to this embodiment. Fig. 2 shows a plan view of the pump body PA with the second housing 12 shown in Fig. 1 removed.

[0012] As shown in Fig. 1, the variable displacement oil pump has a pump body PA and a control valve SV (see Fig. 3) that controls the discharge rate (discharge pressure) of the pump body PA. The pump body PA has a drive shaft 2, a pump element 3 that is rotationally driven by the drive shaft 2, a cam ring 4 that is swingably provided on the outer periphery of the pump element 3, and a coil spring SP that biases the cam ring 4, all of which are housed inside a housing 1. In this embodiment, the pump body PA is fastened to an engine (not shown), more specifically to the side of a cylinder block (not shown), by bolts (not shown).

[0013] 1 and 2, the housing 1 has a cup-shaped first housing 11 that corresponds to the pump body, and a second housing 12 that is joined to the first housing 11 and corresponds to a cover member that closes the opening of the first housing 11. The first housing 11 and the second housing 12 are positioned by a positioning pin PN and fastened together by a screw SW. The first housing 11 and the second housing 12 are both integrally formed from a metal material, for example, an aluminum alloy.

[0014] The first housing 11 has a bottom wall 111 and a peripheral wall 112 that rises from the outer peripheral edge of the bottom wall 111 and continues circumferentially along the outer peripheral edge of the bottom wall 111. That is, the first housing 11 is open at one axial end that faces the second housing 12, and is closed at the other axial end by the bottom wall 111. In other words, the bottom wall 111 and the peripheral wall 112 define a cup-shaped pump accommodating portion 110 inside the first housing 11.

[0015] A joint surface 113 for joining to the second housing 12 is provided at an opening edge portion on one axial end side of the first housing 11. This joint surface 113 is provided so as to extend radially outward of the first housing 11 and is formed integrally with the peripheral wall 112. The joint surface 113 is also formed with a plurality of (two in this embodiment) female threaded holes 113a. The plurality of female threaded holes 113a are provided at intervals in the circumferential direction, and a plurality of screws SW for fastening the second housing 12 to the first housing 11 are screwed into each female threaded hole 113a. The joint surface 113 is also formed with a plurality of (four in this embodiment) first housing side mounting holes 113b. The plurality of first housing side mounting holes 113b are provided at intervals in the circumferential direction, and together with a second housing side mounting hole 121b provided in the second housing 12, form pump mounting holes for mounting the variable displacement oil pump to a cylinder block (not shown).

[0016] A first bearing hole (not shown) for rotatably supporting one end of the drive shaft 2 penetrates substantially at the center of a bottom wall 111 that constitutes one end wall of the pump housing portion 110. A first suction port 114 having a generally arc-like shape is formed on the inner surface of the bottom wall 111, on the outer circumferential side of the first bearing hole (not shown). The first suction port 114 opens into a region (hereinafter referred to as the "suction region") where the volumes of the plurality of pump chambers 30 described below increase as the pumping action of the pump element 3 increases. A first discharge port 115 having a generally arc-like shape is formed on the opposite side of the rotation center Z of the drive shaft 2 from the suction region. The first discharge port 115 opens into a region (hereinafter referred to as the "discharge region") where the volumes of the plurality of pump chambers 30 decrease. A first pin support groove 111b for swingably supporting the cam ring 4 via a generally cylindrical pivot pin 40 is formed on the inner surface of the bottom wall 111, on the outer circumferential side of the first discharge port 115. One axial end of the pivot pin 40 is press-fitted into the first pin support groove 111b.

[0017] The first suction port 114 is narrowest at its starting end and widest at its middle in the rotational direction D of the drive shaft 2, gradually narrowing from the middle to the terminal end. The middle portion of the first suction port 114 is connected to an suction port extension 114a extending radially outward. The suction port extension 114a is further provided with an suction port 114b (see FIG. 5) that penetrates the bottom wall 111 and opens to the outside. Oil stored in an oil pan (not shown) is introduced through the suction port 114a. The suction port 114b may be directly connected to the oil pan (not shown) via an oil strainer (not shown), or may be connected to the oil pan (not shown) via an suction passage (not shown).

[0018] 1 and 2, in the variable displacement oil pump, oil stored in an oil pan (not shown) is drawn into each pump chamber 30 located in the suction region through suction port 114b, first suction port 114, and second suction port 124 (described later) based on negative pressure generated by the pumping action of pump element 3. In this way, in the variable displacement oil pump according to this embodiment, the suction section is made up of suction port 114b, first suction port 114, and second suction port 124 (described later).

[0019] 2, the first discharge port 115 is formed so as to gradually expand from the starting end toward the middle portion and gradually decrease from the middle portion toward the terminal end portion in the rotation direction D of the drive shaft 2. The first discharge port 115 is also provided with a discharge opening (not shown) that penetrates the bottom wall 111 and opens to the outside.

[0020] 1 and 2, in the variable displacement oil pump, oil pressurized by the pumping action of pump element 3 and discharged to first discharge port 115 and second discharge port 125 (described later) is supplied from the discharge port (not shown) through a main gallery provided inside the cylinder block (not shown) to various sliding parts of the engine (not shown, for example, crank metal), an oil jet device (not shown) that serves to cool pistons of the engine (not shown), a valve timing control device (not shown), etc. In this way, in the variable displacement oil pump according to this embodiment, the discharge section is made up of first discharge port 115, second discharge port 125 (described later), and the discharge port (not shown).

[0021] Furthermore, a communication groove (not shown) that connects the first discharge port 115 and a first bearing hole (not shown) is provided in the bottom wall 111 of the first housing 11. That is, oil is supplied to the first bearing hole (not shown) via this communication groove, and also to the side portions of the rotor 31 and each vane 32 (described later), ensuring good lubrication of each sliding portion. Note that this communication groove is formed so as not to coincide with the direction in which each vane 32 (described later) appears and disappears, thereby preventing each vane 32 from falling off into the communication groove.

[0022] 2 with respect to a line M (hereinafter referred to as the "cam ring reference line") connecting the center Z of the first bearing hole 111a, which is the rotation center of the drive shaft 2, and the center Q of the first pin support groove 111b, which is the oscillation center of the cam ring 4. The first seal sliding surface 112a and the second seal sliding surface 112b, with which the first seal member S1 and the second seal member S2 provided on the outer periphery of the cam ring 4 can slide, are formed inside the peripheral wall 112 that constitutes the side wall of the pump housing portion 110. The first seal sliding surface 112a is formed in the shape of an arcuate surface having a curvature defined by a first radius R1 from the center Q of the first pin support groove 111b, and has a circumferential length set to allow the first seal member S1 to slide in contact within the oscillation range of the cam ring 4. Similarly, the second seal sliding surface 112b is formed as an arcuate surface having a curvature determined by a second radius R2 from the center Q of the first pin support groove 111b, and is set to a circumferential length that allows the second seal member S2 to slide within the swing range of the cam ring 4.

[0023] 2 with respect to the cam ring reference line M, there is formed a third seal sliding surface 112c, against which the third seal member S3 on the outer circumferential side of the cam ring 4 can slide. The third seal sliding surface 112c is formed as an arcuate surface having a curvature defined by a third radius R3 from the center Q of the first pin support groove 111b, and has a circumferential length set to allow the third seal member S3 to slide within the swing range of the cam ring 4.

[0024] 1, the second housing 12 functions as a cover member that closes the opening (pump accommodating portion 110) of the first housing 11, and is joined to the joining surface 113 of the first housing 11 via a screw SW. Specifically, the second housing 12 has a screw through hole 121a provided at a position corresponding to the female threaded hole 113a of the first housing 11. Then, the screw SW that passes through this screw through hole 121a is screwed into the female threaded hole 113a of the first housing 11, thereby fastening the second housing 12 to the first housing 11.

[0025] A second bearing hole 122a that rotatably supports the other end of the drive shaft 2 is formed through the second housing 12 at a position opposite the first bearing hole 111a of the first housing 11. A second suction port 124 and a second discharge port 125 that correspond to the first suction port 114 and the first discharge port 115 of the first housing 11 are also disposed on the inner surface of the second housing 12, facing the first suction port 114 and the first discharge port 115. A second pin support groove 122b is formed on the inner surface of the second housing 12 at a position opposite the first pin support groove 111b. The second pin support groove 122b press-fits and holds the other axial end of the pivot pin 40, and supports the pivot pin 40 in cooperation with the first pin support groove 111b.

[0026] As shown in FIGS. 1 and 2 , the drive shaft 2 has a general drive shaft portion 21 formed at one axial end thereof, which is rotatably supported in a first bearing hole 111a of the first housing 11. Meanwhile, a large-diameter drive shaft portion 22, which has a larger outer diameter than the general drive shaft portion 21, is rotatably supported in a second bearing hole 122a of the second housing 12 at the other axial end thereof. Furthermore, a drive shaft end portion 23 of the drive shaft 2, which is formed with a relatively smaller diameter at the other end thereof than the large-diameter drive shaft portion 22, is exposed to the outside through the first bearing hole 111a and is connected to a crankshaft of an engine (not shown) via a transmission member (not shown), such as a chain. That is, the drive shaft 2 rotates the pump element 3 in a rotational direction D in FIG. 2 based on the rotational force transmitted from the crankshaft (not shown). Here, a line N (hereinafter referred to as the "cam ring eccentric direction line") passing through the rotation center Z of the drive shaft 2 and perpendicular to the cam ring reference line M, as shown in FIG. 2, defines the boundary between the suction region and the discharge region.

[0027] 1 and 2, the pump element 3 has a generally cylindrical rotor 31 housed on the inner peripheral side of the cam ring 4 and driven to rotate by the drive shaft 2, and a plurality of vanes 32 housed so as to be able to protrude and retract within a plurality of slits 312 that open radially on the outer peripheral side of the rotor 31. In addition, a pair of ring members 33, 33 formed to have a smaller diameter than the rotor 31 and housed radially inside each vane 32 are disposed on both axial ends of the rotor 31.

[0028] The rotor 31 has a generally circular shaft through-hole 311 that passes through the center in the axial direction and through which the drive shaft general section 21 passes. The rotor 31 also has a plurality of slits 312 that are cut out radially from the center of the shaft through-hole 311 outward in the radial direction. At the bottom of each slit 312, a back pressure chamber 313 with a generally circular cross section that serves to introduce oil is provided. That is, the centrifugal force generated as the rotor 31 rotates and the pressure of the oil introduced into the back pressure chamber 313 push each vane 32 outward (toward the cam ring 4).

[0029] The plurality of vanes 32 housed in the rotor 31 are formed into a rectangular plate shape from a predetermined metal material, and as the rotor 31 rotates, the tip end surface of each vane comes into sliding contact with the inner circumferential surface of the cam ring 4 (the peripheral wall of a pump element housing portion 41, which will be described later). That is, as the tip end surface of each vane 32 comes into sliding contact with the inner circumferential surface of the cam ring 4, the rotor 31, a pair of circumferentially adjacent vanes 32, 32, and the cam ring 4 define a plurality of pump chambers 30 in the rotation direction D of the rotor 31. As the rotor 31 rotates, the base end surface of each vane 32 comes into sliding contact with the outer circumferential surfaces of a pair of ring members 33, 33, and the vanes 32 are pushed up radially outward from the rotor 31 by the pair of ring members 33, 33. As a result, even when the engine speed is low and the centrifugal force caused by the rotation of the rotor 31 and the oil pressure in the back pressure chamber 313 are small, the tip surface of each vane 32 slides against the inner surface of the cam ring 4, separating each pump chamber 30 liquid-tightly.

[0030] Cam ring 4 is formed in a generally annular shape from a sintered material and has a circular pump element accommodating portion 41 on its inner circumferential side that can accommodate pump element 3. Furthermore, on the outer circumferential side of cam ring 4, a circular groove-shaped swing support portion 42 is provided along the axial direction. This swing support portion 42 is in sliding contact with the outer circumferential surface of cylindrical pivot pin 40 that is supported by housing 1. That is, cam ring 4 is in sliding contact with the outer circumferential surface of pivot pin 40 that is supported by first pin support groove 111b and second pin support groove 122b, and is thereby swingably supported within pump accommodating portion 110 via pivot pin 40. Furthermore, swing support portion 42 is pressed against pivot pin 40 by discharge pressure P that acts on the inner surface of cam ring 4 (pump element accommodating portion 41) in the discharge region as pumping action by pump element 3 occurs.

[0031] Additionally, the outer circumferential side of cam ring 4 has first seal component 431, second seal component 432, and third seal component 433, which respectively face first seal sliding surface 112a, second seal sliding surface 112b, and third seal sliding surface 112c of first housing 11. First seal component 431 has a first seal surface 431a shaped like an arc concentric with first seal sliding surface 112a. Second seal component 432 has a second seal surface 432a shaped like an arc concentric with second seal sliding surface 112b. Third seal component 433 has a third seal surface 433a shaped like an arc concentric with third seal sliding surface 112c.

[0032] Furthermore, a first seal holding groove 431b is formed in the first seal surface 431a, extending along the axial direction and opening toward the first seal sliding contact surface 112a. A second seal holding groove 432b is formed in the second seal surface 432a, extending along the axial direction and opening toward the second seal sliding contact surface 112b. A third seal holding groove 433b is formed in the third seal surface 433a, extending along the axial direction and opening toward the third seal sliding contact surface 112c.

[0033] The first seal retaining groove 431b accommodates a first seal member S1 that comes into sliding contact with the first seal sliding surface 112a when the cam ring 4 pivots. The second seal retaining groove 432b accommodates a second seal member S2 that comes into sliding contact with the second seal sliding surface 112b when the cam ring 4 pivots. The third seal retaining groove 433b accommodates a third seal member S3 that comes into sliding contact with the third seal sliding surface 112c when the cam ring 4 pivots.

[0034] 1 and 4, the first seal member S1, the second seal member S2, and the third seal member S3 are all made of, for example, a fluorine-based resin material having low friction properties, and are formed linearly and elongated along the axial direction of the cam ring 4. Furthermore, as shown in Fig. 4, a rubber elastic member BR is disposed at the bottom of each of the first seal retaining groove 431b, the second seal retaining groove 432b, and the third seal retaining groove 433b. That is, the first, second, and third seal members S1, S2, and S3 elastically contact the first, second, and third seal sliding surfaces 112a, 112b, and 112c, respectively, with the elastic force of the elastic members BR, thereby providing a liquid-tight seal between the first, second, and third seal surfaces 431a, 432a, 433a and the first, second, and third seal sliding surfaces 112a, 112b, and 112c.

[0035] Furthermore, with the above-described configuration, a first control oil chamber PR1 is defined on the outer periphery of cam ring 4 by first seal member S1 in sliding contact with first seal sliding surface 112a and second seal member S2 in sliding contact with second seal sliding surface 112b. A first control oil pressure P1 is introduced to first control oil chamber PR1 via a first passage L1, one of two branches branched from a discharge pressure introducing passage Lb connected to the main gallery. The first control oil pressure P1 introduced to first control oil chamber PR1 is substantially the same as the discharge pressure P introduced to the main gallery. The first passage L1 is connected to a first control pressure introducing hole 118 penetrating the bottom wall 111 of first housing 11, and the first control oil pressure P1 is introduced directly to first control oil chamber PR1 via the first control pressure introducing hole 118. The first control oil pressure P1 introduced into the first control oil chamber PR1 acts on a first pressure-receiving surface 441 formed between the first seal component 431 and the second seal component 432 on the outer peripheral surface of the cam ring 4 facing the first control oil chamber PR1. The oil pressure acting on the first pressure-receiving surface 441 applies a moving force (oscillating force) to the cam ring 4 in a direction (hereinafter referred to as the "concentric direction") that reduces the eccentricity Δ of the cam ring 4 (the eccentricity Δ of the center O of the pump element accommodating portion 41 relative to the rotation center Z of the drive shaft 2).

[0036] Similarly, a second control oil chamber PR2 is defined on the outer circumferential side of the cam ring 4 by the swing support portion 42, which is in sliding contact with the pivot pin 40, and the second seal member S2, which is in sliding contact with the second seal sliding surface 112b. The second control oil pressure P2, which is reduced in pressure through the control valve SV, is introduced into the second control oil chamber PR2 from the other second passage L2, which branches off from the discharge pressure introducing passage Lb. The second control oil pressure P2 is also introduced into the second control oil chamber PR2 through a second control pressure introducing hole (not shown) that penetrates the second housing 12. The second control oil pressure P2 introduced into the second control oil chamber PR2 acts on a second pressure-receiving surface 442, which is formed between the swing support portion 42 and the third seal component 433, on the outer circumferential surface of the cam ring 4 facing the second control oil chamber PR2. The oil pressure acting on this second pressure-receiving surface 442 applies a moving force (oscillating force) to the cam ring 4 in a direction (hereinafter referred to as the "eccentric direction") that increases the eccentricity Δ of the cam ring 4 (the eccentricity of the center O of the pump element accommodating portion 41 relative to the center of rotation Z of the drive shaft 2).

[0037] The coil spring SP is accommodated in a spring accommodating portion 119 provided at a position facing the pivot pin 40 across the rotation center Z of the drive shaft 2. That is, the coil spring SP compressed with a predetermined preload (set load W1) is loaded into the spring accommodating portion 119 between an arm portion 45 extending toward the outer periphery of the cam ring 4 and one end wall 119a of the spring accommodating portion 119. Here, the spring accommodating portion 119 is formed by recessing the peripheral wall 112 of the pump accommodating portion 110 radially outward on the outer periphery of the first suction port 114 in the first housing 11. Furthermore, one end wall 119a of the spring accommodating portion 119 functions as a seating surface for the coil spring SP, while the other end wall 119b functions as a stopper for restricting the range of movement of the cam ring 4 in the eccentric direction. That is, the cam ring 4 is constantly biased in the eccentric direction by the coil spring SP, and the arm portion 45 abuts against the other end wall 119b of the spring accommodating portion 119, thereby maintaining the maximum eccentric state.

[0038] With the above configuration, when the biasing force based on the internal pressure of the first control oil chamber PR1 (first control oil pressure P1) is smaller than the set load W1 of the coil spring SP, the cam ring 4 moves in the eccentric direction based on the set load W1 of the coil spring SP, reaching the maximum eccentric state as shown in Figure 2. On the other hand, when the discharge pressure P increases and the biasing force based on the internal pressure of the first control oil chamber PR1 (first control oil pressure P1) exceeds the set load W1 of the coil spring SP, the cam ring 4 moves in the concentric direction in response to the discharge pressure P.

[0039] (Control valve configuration) FIG. 3 shows a vertical cross-sectional view of a control valve SV that controls the discharge amount (discharge pressure) of the variable displacement oil pump (pump body PA) according to this embodiment.

[0040] 3, the control valve SV is a solenoid valve that is driven and controlled by a control device (not shown) that controls the engine. Specifically, the control valve SV has a valve portion 5 that controls the opening and closing of the second passage L2, and a solenoid portion 6 that is provided at one end of the valve portion 5 and controls the opening and closing of the valve portion 5 based on an excitation current output by the control device (not shown).

[0041] The valve portion 5 is a so-called three-way valve that includes a valve case 51, a spool valve element 52, a retainer member 53, and a valve spring 54. The valve portion 5 may be provided integrally with the variable displacement oil pump by being built into the housing 1, or may be provided separately and independently from the variable displacement oil pump.

[0042] The valve case 51 is made of a metal material, such as an aluminum alloy, and has a generally cylindrical shape with both ends open in the direction of the central axis Y. The valve case 51 has a valve element accommodating portion 510 therein. The valve element accommodating portion 510 is formed as a stepped through-hole that penetrates the valve case 51 along the direction of the central axis Y of the valve case 51. That is, the valve element accommodating portion 510 has a first valve element sliding contact portion 511 at one end in the direction of the central axis Y, and a second valve element sliding contact portion 512, which has a larger diameter than the first valve element sliding contact portion 511, at the other end in the direction of the central axis Y. The opening of the valve element accommodating portion 510 on the side of the first valve element sliding contact portion 511 is closed by the solenoid unit 6. On the other hand, the opening of the valve element accommodating portion 510 on the side of the second valve element sliding contact portion 512 functions as a drain port Pd that discharges oil from a spring accommodating chamber 55 (described later) and opens to a drain passage Ld. Here, the drain port Pd may not be open to the drain passage Ld but may be directly open to an oil pan (not shown) corresponding to the low-pressure section. The drain port Pd only needs to be connected to the low-pressure section, and may be connected to an oil pan (not shown) corresponding to atmospheric pressure, or may be connected to, for example, the periphery of the intake port 114b, which is under negative pressure. Hereinafter, for the sake of convenience, the valve section 5 will be described by defining the end on the first valve element sliding contact portion 511 side (the right side in FIG. 3) as the first end and the end on the second valve element sliding contact portion 512 side (the left side in FIG. 3) as the second end.

[0043] A first annular groove 513 is formed on the outer periphery of the first valve element sliding contact portion 511 by cutting out the outer periphery of the valve case 51 in the circumferential direction. A plurality of first valve holes 513a are formed in the bottom of the first annular groove 513, communicating the inside and outside of the valve element accommodating portion 510 in the radial direction of the valve case 51, which is perpendicular to the central axis Y. The first valve holes 513a are formed as circular holes that are approximately circular in plan view, and function as supply / discharge ports Pc for supplying / discharging oil (second control oil pressure P2) to / from the second control oil chamber PR2 through the second passage L2.

[0044] Similarly, a second annular groove 514 is formed on the outer circumferential side of the second valve element sliding contact portion 512 by cutting out the outer circumferential surface of the valve case 51 in the circumferential direction. A second valve hole 514a is formed at the bottom of the second annular groove 514, communicating the inside and outside of the valve element accommodating portion 510 in the radial direction of the valve case 51, which is perpendicular to the central axis Y. The second valve hole 514a is formed as a circular hole that is approximately circular in a plan view, and functions as an introduction port Pb that introduces oil (discharge pressure P) from the discharge pressure introduction passage Lb.

[0045] The spool valve element 52 has a stepped cylindrical shape with different outer diameters in the direction of the central axis Y, which is the direction of movement, and is slidably housed in the valve element accommodating portion 510 of the valve case 51. Specifically, the spool valve element 52 has a first land portion 521 that is in sliding contact with the first valve element sliding contact portion 511, and a second land portion 522 that is formed with a larger diameter than the first land portion 521 and is in sliding contact with the second valve element sliding contact portion 512. In addition, an intermediate shaft portion 523 is formed between the first land portion 521 and the second land portion 522 and has a smaller outer diameter than the first land portion 521 and the second land portion 522. In other words, the intermediate shaft portion 523 defines a relay chamber Rc between itself and the valve element accommodating portion 510 in the radial direction of the valve case 51.

[0046] The first land portion 521 and the second land portion 522, which face each other in the direction of the central axis Y in the relay chamber Rc, function as pressure-receiving surfaces that receive the hydraulic pressure introduced from the second valve hole 514a. In this regard, the second land portion 522 has a relatively larger outer diameter than the first land portion 521, and the second pressure-receiving surface Pf2 formed by the second land portion 522 is formed relatively larger than the first pressure-receiving surface Pf1 formed by the first land portion 521. In other words, based on the difference in pressure-receiving area between the first pressure-receiving surface Pf1 and the second pressure-receiving surface Pf2, the hydraulic pressure introduced into the relay chamber Rc from the second valve hole 514a acts on the second pressure-receiving surface Pf2, which is relatively larger than the first pressure-receiving surface Pf1, and presses the spool valve element 52 toward the second end.

[0047] The spool valve element 52 also has a shaft end portion 524, which is located closer to the first end than the first land portion 521 and has a smaller outer diameter than the first land portion 521. The shaft end portion 524 defines a back pressure chamber Rb between the shaft end portion 524 and the valve element accommodating portion 510 in the radial direction of the valve case 51. The back pressure chamber Rb collects oil leaking from the relay chamber Rc through the outer circumferential side of the first land portion 521 (a small gap with the valve element accommodating portion 510). The back pressure chamber Rb communicates with the spring accommodating chamber 55 through a discharge hole 525 formed in a peripheral wall of the first end of the spool valve element 52 facing the back pressure chamber Rb and an internal passage 526 connecting the discharge hole 525 to the spring accommodating chamber 55, which will be described later. That is, the oil collected in the back pressure chamber Rb is guided through the discharge hole 525 and the internal passage 526 to the spring accommodating chamber 55 described below, and is then discharged to an oil pan (not shown) through the drain port Pd and the drain passage Ld.

[0048] The spool valve body 52 also has a spring support portion 527 at its end on the second land portion 522 side facing the retainer member 53, which supports a first end of the valve spring 54 facing the spool valve body 52. ​​The spring support portion 527 is formed by expanding the diameter of the inner circumferential side of the spool valve body 52 in a stepped manner toward the second land portion 522 side, and has a cylindrical spring surrounding portion 527a and a flat spring support surface 527b. As a result, the spring support portion 527 surrounds the outer circumferential side of the first end of the valve spring 54 with the spring surrounding portion 527a, and supports the first end of the valve spring 54 with the spring support surface 527b.

[0049] The retainer member 53 has an annular spring seat 531 that supports the second end of the valve spring 54, and a circular retainer opening 530 that passes through the center of the spring seat 531. That is, the outer peripheral edge of the retainer member 53 is fitted into the open end on the second end side of the valve case 51, and the spring seat 531 supports the second end of the valve spring 54, while the retainer opening 530 communicates between the second valve hole 514a and the drain port Pd.

[0050] The valve spring 54 is a well-known compression coil spring, and is loaded with a predetermined preload (set load W2) into a spring accommodating chamber 55 defined between the spool valve body 52 and the retainer member 53. As a result, the valve spring 54 constantly biases the spool valve body 52 toward the first end side based on the set load W2.

[0051] The solenoid unit 6 includes a cylindrical casing 61, a coil and an armature (not shown) housed inside the casing 61, and a rod 62 fixed to the armature and movable back and forth along the central axis Y together with the armature. An excitation current is applied to the solenoid unit 6 from a control device (not shown) based on the engine operating state detected or calculated from predetermined parameters such as engine oil temperature, water temperature, and engine speed (not shown). The solenoid unit 6 can continuously change the magnitude of the electromagnetic force Fm according to the current value supplied, and is controlled by pulse width modulation (PWM), with the current value being given by a duty ratio.

[0052] (Arm coil spring restriction structure) Fig. 4 is an enlarged view of the main part of Fig. 1, showing an enlarged view of the vicinity of the coil spring SP accommodated in the spring accommodating portion 119 of Fig. 1. Fig. 5 is a cross-sectional view taken along the line AA of Fig. 3.

[0053] 4 and 5, in the area on the outer periphery of pump accommodating portion 110 in first housing 11 and on the outer periphery of first suction port 114, a spring accommodating portion 119 having a generally rectangular recess is formed along the tangential direction of the outer periphery of pump accommodating portion 110 so as to open to joint surface 113 of first housing 11. Arm portion 45 of cam ring 4 accommodated in pump accommodating portion 110 faces spring accommodating portion 119, and coil spring SP that biases cam ring 4 in the eccentric direction is accommodated between arm portion 45 and spring accommodating portion 119 in a state compressed by a predetermined amount and with a predetermined preload (set load W1).

[0054] Spring accommodating portion 119 has a generally rectangular shape in a plan view, and is set to a depth such that center X of coil spring SP is located approximately in the center of the axial width (Z-axis width) of cam ring 4. With this configuration, in this embodiment, as shown in FIG. 5, when coil spring SP is accommodated in spring accommodating portion 119, a predetermined gap C1 is formed between second housing 12 (joint surface of first housing 11) and coil spring SP.

[0055] Spring accommodating portion 119 has one end wall 119a formed on one end side in the X-axis direction that abuts against arm portion 45 of cam ring 4, and another end wall 119b formed on the other end side in the X-axis direction that faces one end wall 119a and abuts against coil spring SP. One end wall 119a abuts against arm portion 45 of cam ring 4 to restrict the maximum eccentricity of cam ring 4. Meanwhile, the other end wall 119b abuts against coil spring SP to support said coil spring SP.

[0056] The spring accommodating portion 119 also has an outer restriction wall 119c, which corresponds to a first restriction wall, that supports the outer portion of the coil spring SP and restricts radially outward displacement of the coil spring SP. On the other hand, the spring accommodating portion 119 also has an inner restriction wall 119d, located on the opposite side of the outer restriction wall 119c across the X-axis, which corresponds to the center of the outer diameter of the coil spring SP, that restricts radially inward displacement of the end of the coil spring SP on the other end wall 119b side. Furthermore, the spring accommodating portion 119 also has a bottom restriction wall 119e, located on the opposite side of the X-axis from the protrusion 46, that corresponds to a third restriction wall that is formed by the bottom wall of the spring accommodating portion 119 and that restricts radially inward displacement of the coil spring SP toward the side opposite the protrusion 46 in the axial direction of the coil spring SP.

[0057] Furthermore, arm portion 45 of cam ring 4 is provided with protrusion 46 at the end on the joining surface 113 side of first housing 11. Protrusion 46 extends in the longitudinal direction (X-axis direction) of coil spring SP from spring contact surface 451, which is the surface that contacts coil spring SP, and overlaps with a portion of the outer periphery of coil spring SP. Protrusion 46 is formed integrally with arm portion 45 and has a prismatic shape with a roughly rectangular cross section. Protrusion 46 is not annular so as to cover the entire periphery of the end portion of coil spring SP on the arm portion 45 side, but is formed so as to overlap only with a partial circumferential region of the end portion of coil spring SP on the arm portion 45 side. Protrusion 46 is provided so as to be spaced apart from coil spring SP arranged inside, and a minute gap C2 is formed between protrusion 46 and the upright coil spring SP.

[0058] Here, the protrusion 46 is preferably provided on the side where the coil spring SP is likely to tilt due to the flow of oil, i.e., downstream of the coil spring SP in the flow of oil introduced from the suction port 114b. In this embodiment, the protrusion 46 is preferably provided at the end of the arm portion 45 on the mating surface 113 side of the first housing 11, which corresponds to the downstream side of the flow of oil introduced from the suction port 114b (see arrow F in FIG. 5). In other words, the protrusion 46 can be provided at any position that can restrict tilt of the coil spring SP, depending on the state in which tilt of the coil spring SP occurs. Furthermore, as described above, when the protrusion 46 is provided at the end of the first housing 11 on the mating surface 113 side, the protrusion 46 is preferably provided at a position that overlaps with the center of the outer diameter (X-axis) of the coil spring SP. Furthermore, although the present embodiment illustrates an example in which a single protrusion 46 is provided, multiple protrusions 46 may be provided as needed, depending on the state in which tilt of the coil spring SP occurs, etc.

[0059] In addition, on the outer peripheral side of cam ring 4, cam ring regulating wall 47 is formed, which has a flat surface shape that is roughly parallel to outer regulating wall 119c of first housing 11 when cam ring 4 is in the maximum eccentric state shown in Figure 4, and corresponds to a second regulating wall that supports the outer portion of coil spring SP and can regulate radial inward positional deviation of coil spring SP.

[0060] (How to assemble a coil spring) FIG. 6 is a diagram illustrating a manufacturing method of a variable displacement oil pump according to this embodiment, in which (a) is a schematic diagram illustrating the coil spring arrangement process, and (b) is a cross-sectional view taken along line BB in FIG. 6(a).

[0061] 6(a), when assembling the coil spring SP, first, the coil spring SP is compressed by a jig 7. This jig 7 is provided with a pair of spring holding portions, each of which is configured to be relatively movable, on a connecting base 70 formed in the shape of a rectangular plate, and includes a first holding portion 71 formed in a bifurcated shape (U-shaped in plan view) via a notch 710, and a flat second holding portion 72 provided in parallel to and facing the first holding portion 71. The coil spring SP is sandwiched between the first holding portion 71 and the second holding portion 72, and the coil spring SP is compressed by narrowing the distance Cx between the first holding portion 71 and the second holding portion 72 to be smaller than the free length of the coil spring SP.

[0062] Next, with cam ring 4 accommodated in pump accommodating portion 110 of first housing 11, coil spring SP compressed by jig 7 is inserted between other end wall 119b of spring accommodating portion 119 and arm portion 45 (see the upper part of FIG. 6(a)). Specifically, as shown in FIGS. 6(a) and 6(b), while holding coil spring SP in a compressed state between first holding portion 71 and second holding portion 72 of jig 7, jig 7 is inserted between other end wall 119b of spring accommodating portion 119 and arm portion 45 from the joint surface 113 side of first housing 11, using notch 710 of jig 7 to avoid protrusion 46 of cam ring 4.

[0063] Thereafter, the coil spring SP, which is sandwiched in a compressed state between the other end wall 119b of the spring accommodating portion 119 and the arm portion 45, and between the first holding portion 71 and the second holding portion 72 of the jig 7, is pushed out in the direction indicated by the arrows by a push-out mechanism (not shown) provided in the jig 7 (see the middle part of FIG. 6(a)). Then, the pushed-out coil spring SP is stretched by a restoring force based on the compression, and one end elastically abuts against the spring abutment surface 451 of the arm portion 45, and the other end elastically abuts against the other end wall 119b of the spring accommodating portion 119, completing the assembly of the coil spring SP (see the lower part of FIG. 6(a)).

[0064] (Explanation of oil pump operation) Next, the operation of the variable displacement oil pump according to this embodiment will be described with reference to Figures 7 and 8. Figure 7 shows the operating state of the variable displacement oil pump in which the amount of eccentricity of cam ring 4 is greatest. Figure 8 shows the operating state of the variable displacement oil pump in which the amount of eccentricity of cam ring 4 is smallest.

[0065] As shown in FIGS. 7 and 8 , in the variable displacement oil pump according to this embodiment, rotation of a crankshaft (not shown) is transmitted to a drive shaft 2 via a chain (not shown), which drives a rotor 31 to rotate in a rotational direction D. As the rotor 31 rotates, oil is drawn up from an oil pan (not shown) via the intake port 114b, the first intake port 114, and the second intake port 124. Simultaneously with this suction action, oil in each pump chamber 30 located in the discharge region is discharged into a discharge passage (not shown) via the first discharge port 115, the second discharge port 125, and the discharge port 115a. The oil discharged into this discharge passage is then pressure-fed via a main gallery to a sliding part (e.g., a crank metal) (not shown), an oil jet device (not shown), a valve timing control device (not shown), and the like, and is also guided to a first passage L1 and a second passage L2 via a discharge pressure introduction passage Lb connected to the main gallery. In addition, a hydraulic sensor (not shown) capable of detecting the discharge pressure P is disposed above the main gallery, and the detection result of this hydraulic sensor is fed back to a control device (not shown).

[0066] Furthermore, as the cam ring 4 swings about the pivot pin 40, the eccentricity Δ (see FIG. 2), which is the difference between the center of rotation Z of the drive shaft 2 and the center O of the pump element housing 41, changes, and the amount of change in volume of the pump chamber 30 (the difference between the maximum volume and the minimum volume) changes. As the eccentricity Δ increases, the amount of change in volume of the pump chamber 30 also increases, while as the eccentricity Δ decreases, the amount of change in volume of the pump chamber 30 also decreases. Furthermore, the eccentricity Δ changes depending on the concentric biasing force based on the internal pressure of the first control oil chamber PR1 (first control oil pressure P1) and the eccentric biasing force based on the set load W1 of the coil spring SP and the internal pressure of the second control oil chamber PR2 (second control oil pressure P2).

[0067] Specifically, from engine start-up until a predetermined engine speed is reached, the first control oil pressure P1 is introduced into the first control oil chamber PR1 via the first passage L1 branched from the discharge pressure introducing passage Lb. In the control valve SV, the discharge pressure P introduced via the second passage L2 branched from the discharge pressure introducing passage Lb acts on the second pressure-receiving surface Pf2 of the spool valve element 82, generating a biasing force (hydraulic pressure Fp2) that is smaller than the set load W2 of the valve spring 54. As a result, as shown in FIG. 7, the spool valve element 82 is maintained in a state where it is most displaced toward the first end, the introduction port Pb and the supply / discharge port Pc are communicated (first state), and the second control oil pressure P2 is introduced into the second control oil chamber PR2. As a result, the resultant force of the hydraulic force Fp2 generated by the second control hydraulic pressure P2 of the second control hydraulic chamber PR2 acting on the second pressure-receiving surface 442 and the set load W1 of the coil spring SP exceeds the hydraulic force Fp1 generated by the first control hydraulic pressure P1 of the first control hydraulic chamber PR1 acting on the first pressure-receiving surface 441, and the cam ring 4 is maintained in the maximum eccentric state.

[0068] When the engine reaches the predetermined rotation speed and discharge pressure P reaches a predetermined engine-required oil pressure, the hydraulic force Po of discharge pressure P becomes greater than the set load W2 of valve spring 54 when the duty ratio of the excitation current supplied to solenoid unit 6 is 0%. As a result, as shown in FIG. 8, spool valve element 52 moves toward the second end, blocking communication between inlet port Pb and supply / discharge port Pc and connecting supply / discharge port Pc and drain port Pd (second state). Oil is discharged from second control oil chamber PR2, and discharge pressure P acts only on first control oil chamber PR1. As a result, hydraulic force Fp1 generated by application of first control oil pressure P1 to first pressure-receiving surface 441 exceeds the set load W1 of coil spring SP. As discharge pressure P increases, the eccentricity Δ of cam ring 4 decreases, resulting in a minimum eccentricity state, and discharge pressure P is maintained at the engine-required oil pressure.

[0069] In other words, in the variable displacement oil pump, the movement of spool valve element 52 toward the second end based on the increase in discharge pressure P described above and the movement of spool valve element 52 toward the first end as spool valve element 52 moves toward the second end and cam ring 4 reaches the minimum eccentricity state are alternately and continuously repeated. In this way, the state in which supply / discharge port Pc communicates with introduction port Pb and the state in which supply / discharge port Pc communicates with drain port Pd are alternately and continuously switched, thereby maintaining discharge pressure P at the required engine oil pressure.

[0070] In the present embodiment, the operating states of the variable displacement oil pump at engine startup and when the discharge pressure P is high are exemplified, but with this variable displacement oil pump, even when the hydraulic force Po of the discharge pressure P is smaller than the set load W2 of the valve spring 54, by adjusting the duty ratio of the excitation current supplied to the solenoid portion 6 of the control valve SV, it is possible to transition to the second state at any timing based on the electromagnetic force Fm of the solenoid portion 6, and the discharge pressure P of the variable displacement oil pump can be controlled in multiple stages.

[0071] (Effects of this embodiment) As described above, in the conventional variable displacement oil pump, the coil spring is fitted onto the outer periphery of the protrusion that protrudes from the spring contact surface of the arm portion of the cam ring. Therefore, when assembling the coil spring, the protrusion must be fitted onto the inner periphery of the coil spring while the compressed coil spring is restored, which makes assembling the coil spring difficult and leaves room for improvement.

[0072] Another possible means for preventing misalignment of the coil spring is to provide a generally cylindrical protrusion or recess that surrounds the outer periphery of the coil spring on the spring contact surface of the arm portion of the cam ring, and fit the coil spring against the inner periphery of this protrusion or recess, thereby supporting the outer periphery of the coil spring with the protrusion or recess, thereby preventing misalignment of the coil spring. However, even in this case, when assembling the coil spring, the compressed coil spring must be restored while fitting it into the inner periphery of the protrusion or recess, which makes assembling the coil spring difficult, as with the method of fitting the coil spring against the outer periphery of the protrusion, and there is room for improvement.

[0073] Here, the difficulty of assembling the coil spring will be specifically explained. When fitting a coil spring onto the outer periphery of a protrusion, or when fitting a coil spring onto the inner periphery of a protrusion or recess, a jig is used to assemble the coil spring in a compressed state in order to apply a preload to the coil spring. This jig sandwiches the coil spring between a pair of opposing retaining parts, and while keeping it compressed, inserts the coil spring together with the pair of retaining parts between the arm portion of the cam ring and the housing (spring accommodating part), and then pushes the coil spring out of the pair of retaining parts to assemble it by forcing it between the arm portion of the cam ring and the housing (spring accommodating part).

[0074] In this case, the coil spring needs to be compressed extra by the thickness of the pair of retaining parts that are inserted together with the coil spring between the arm part of the cam ring and the housing (spring accommodating part). This extra compression increases the restoring force of the coil spring, and when the coil spring is pushed out of the jig, it is released with a greater restoring force, causing the coil spring to abut more strongly against the arm part of the cam ring and the housing (spring accommodating part). As a result, there is a risk that the abutment of the coil spring will damage the arm part of the cam ring and the housing (spring accommodating part).

[0075] Furthermore, because the coil spring is released by being pushed out of the jig, it is difficult to control the posture of the coil spring after being pushed out of the jig. Therefore, it becomes extremely difficult to fit the coil spring onto the outer or inner peripheral side of the protrusion, which is set to have a relatively narrow gap with the coil spring, as described above, and this inevitably leads to a deterioration in the workability of assembling the coil spring. Moreover, because it is difficult to control the posture of the coil spring after being released from the jig, there is a risk that the coil spring will be assembled in a tilted state, resulting in poor assembly of the coil spring.

[0076] As an alternative to fitting the coil spring to the outer periphery of the protrusion, it is possible to form the protrusion as a so-called retainer member separately from the cam ring, and assemble the coil spring with the retainer member fitted to the inner periphery of the coil spring in advance. While this configuration can avoid a decrease in the ease of assembling the coil spring, forming the protrusion as a separate retainer member increases the number of parts in the variable displacement oil pump. As a result, the manufacturing cost and management man-hours for the retainer member, as well as the assembly man-hours, increase, which in turn increases the manufacturing cost of the variable displacement oil pump.

[0077] In contrast, the variable displacement oil pump of this embodiment has a housing 1 (first housing 11) having a pump accommodating section 110, a cam ring 4 movably accommodated inside the pump accommodating section 110, a pump element 3 rotatably accommodated on the inner side of the cam ring 4 and forming a plurality of pump chambers 30 in cooperation with the cam ring 4, a coil spring SP arranged in the pump accommodating section 110 and biasing the cam ring 4 in a direction that increases the eccentricity of the cam ring 4 relative to the rotation axis of the pump element 3, and a protrusion 46 provided on the cam ring 4 and partially formed so as to extend in the longitudinal direction of the coil spring SP from a spring abutment surface 451 against which the coil spring SP abuts and overlap with part of the outer periphery of the coil spring SP.

[0078] In this way, in the variable displacement oil pump according to this embodiment, protrusion 46 is provided on spring contact surface 451 of cam ring 4, which is partially formed so as to overlap with part of the outer periphery of coil spring SP, and this makes it possible to restrict tilting of coil spring SP by protrusion 46. This keeps coil spring SP upright, and makes it possible to apply an appropriate biasing force to cam ring 4 (arm portion 45).

[0079] Furthermore, since the protrusion 46 is partially formed so as to overlap part of the outer periphery of the coil spring SP, when assembling the coil spring SP, it is only necessary to push the coil spring SP inside the protrusion 46, and there is no need to fit the coil spring SP into a protrusion or recess as in the conventional case, so the assembly work of the coil spring SP can be easily performed.

[0080] Furthermore, since the protrusion 46 is partially formed so as to overlap with part of the outer periphery of the coil spring SP, the assembled state of the coil spring SP can be visually confirmed from the outside, compared to when the protrusion 46 is formed in an annular shape that surrounds the outer periphery of the coil spring SP as described above. This makes it possible to easily determine visually whether the assembled state of the coil spring SP is good or bad, which contributes to efficient quality assurance of the oil pump.

[0081] Here, it is also possible to consider a mode in which protrusion 46 is disposed not on cam ring 4 but on the inner surface of second housing 12 that closes spring accommodating portion 119. However, because the inner surface of second housing 12 is finished by machining, if protrusion 46 is provided on the inner surface of second housing 12, it will be necessary to avoid protrusion 46 when machining the inner surface of second housing 12, which is not appropriate because it could lead to a decrease in productivity and an increase in manufacturing costs for the variable displacement oil pump.

[0082] In addition, in the variable displacement oil pump of this embodiment, the housing 1 (first housing 11) has a first regulating wall (outer regulating wall 119c) that regulates the movement of the coil spring SP radially outward, perpendicular to the rotation axis Z of the pump element 3, and the cam ring 4 has a second regulating wall (cam ring regulating wall 47) that regulates the movement of the coil spring SP radially inward, perpendicular to the rotation axis Z of the pump element 3.

[0083] In this manner, in this embodiment, it is possible to restrict positional deviation of the coil spring SP by outer restriction wall 119c, which is a first restriction wall provided in spring accommodating portion 119 of housing 1 (first housing 11), and cam ring restriction wall 47, which is a second restriction wall provided in cam ring 4. This, in cooperation with protrusion 46, makes it possible to effectively suppress tilting of the coil spring SP.

[0084] In addition, in the variable displacement oil pump according to this embodiment, a single protrusion 46 is provided.

[0085] In this manner, in the present embodiment, since a single protrusion 46 is provided, when assembling the coil spring SP, for example, by using a jig 7 in which a first holding portion 71 formed in a bifurcated shape by notch 710 and a flat plate-shaped second holding portion 72 are arranged opposite each other, the coil spring SP can be assembled between cam ring 4 (spring abutment surface 451 of arm portion 45) and housing 1 (other end wall 119b of spring accommodating portion 119 of first housing 11) while compressing and holding the coil spring SP between first holding portion 71 and second holding portion 72, while avoiding protrusion 46 by notch 710. This improves the ease of assembling the coil spring SP.

[0086] Furthermore, since the protrusion 46 is positioned in the middle of the flow of oil guided from the intake port 114b, it can act as a resistance to the flow of oil. Therefore, by providing a single protrusion 46 as in this embodiment, the flow resistance of the oil is reduced compared to when multiple protrusions 46 are provided, and the pressure loss of the pump due to the provision of the protrusion 46 can be reduced.

[0087] Furthermore, in the variable displacement oil pump according to this embodiment, the protrusion 46 is provided at a position that overlaps with the center X of the outer diameter of the coil spring SP.

[0088] In this manner, in this embodiment, the protrusion 46 is provided at a position that overlaps with the center X of the outer diameter of the coil spring SP, so that the protrusion 46 can appropriately and balancedly restrict the tilt of the coil spring SP. In other words, even if the cam ring 4 swings, the protrusion 46 can appropriately restrict the movement of the coil spring SP.

[0089] In addition, in the variable displacement oil pump according to this embodiment, the housing 1 (first housing 11) has a third restriction wall (cam ring restriction wall 47) that restricts movement of the coil spring SP to the radially opposite side of the coil spring SP relative to the protrusion 46.

[0090] In this manner, in this embodiment, cam ring restriction wall 47 is provided as a third restriction wall that restricts movement of coil spring SP on the radially opposite side of coil spring SP from protrusion 46. This makes it possible to sandwich coil spring SP between protrusion 46 and housing 1 (cam ring restriction wall 47 of spring accommodating portion 119 of first housing 11), making it even easier to position coil spring SP.

[0091] In addition, in the variable displacement oil pump of this embodiment, the coil spring SP is arranged in an oil passage connecting the intake port 114b provided in the housing 1 to the pump chamber 30, and the protrusion 46 is arranged downstream of the coil spring SP in the oil passage.

[0092] As described above, in this embodiment, the protrusion 46 is disposed downstream of the coil spring SP in the suction-side oil passage that connects the suction port 114b to the pump chamber 30. This effectively prevents the coil spring SP from tilting due to the flow of oil flowing from the suction port 114b into the pump chamber 30.

[0093] Furthermore, the manufacturing method of the variable displacement oil pump according to this embodiment includes a cam ring placement process of placing a cam ring 4 in the pump accommodating portion 110, and a coil spring placement process of placing a coil spring SP in the pump accommodating portion 110 after the cam ring placement process, in which the coil spring SP is held in a compressed state by a jig 7 having a bifurcated first holding portion 71 having a notch 710 in the middle portion capable of holding one end of the coil spring SP, and a second holding portion 72 capable of holding the other end of the coil spring SP, and the coil spring SP is placed in the pump accommodating portion 110 by inserting the jig 7 between the cam ring 4 and the pump accommodating portion 110 so as to avoid the protrusion 46 by the notch 710 of the first holding portion 71.

[0094] As described above, in this embodiment, the coil spring SP is held in a compressed state by jig 7 having bifurcated first and second holding portions 71 and 72, each having a notch 710 formed therein. The coil spring SP is then inserted between cam ring 4 (spring abutment surface 451 of arm portion 45) and pump accommodating portion 110 (other end wall 119b of spring accommodating portion 119) while avoiding protrusion 46 due to notch 710, thereby assembling the coil spring SP. Therefore, compared to the conventional configuration in which the entire circumference of the coil spring SP is surrounded by a protrusion (or recess), the protrusion 46 can be avoided by notch 710, eliminating the need to overcompress the coil spring to avoid the protrusion 46, as in the conventional configuration. This makes it possible to reduce the compression amount of the coil spring SP by the height of protrusion 46, as shown in FIG. 6 , thereby reducing the repulsive force (restoring force) of the coil spring SP when released from jig 7. As a result, when assembling the coil spring SP, assembly errors of the coil spring SP, such as assembling the coil spring SP in a tilted state due to the large rebound (restoration) of the coil spring SP, are suppressed, thereby ensuring the proper assembly state of the coil spring SP.

[0095] In addition, by reducing the repulsive force (restoring force) of the coil spring SP when releasing the coil spring SP from the jig 7, it is possible to suppress the problem of damaging the seating surface of the coil spring SP (specifically, the spring abutment surface 451 of the arm portion 45 of the cam ring 4 and the other end wall 119b of the spring accommodating portion 119) when assembling the coil spring SP.

[0096] The present invention is not limited to the configurations disclosed in the above embodiments, and can be freely modified according to, for example, the specifications of the engine and valve timing control device of the vehicle in which the variable displacement oil pump is installed.

[0097] In particular, although the above embodiment illustrates an example in which the present invention is applied to a vane-type variable displacement oil pump, the variable displacement oil pump to which the present invention can be applied is not limited to the vane-type, but can also be applied to other types of variable displacement oil pumps, for example, trochoid pumps. Note that when the present invention is applied to a trochoid pump, the outer rotor that constitutes the external gear corresponds to the cam ring.

Claims

1. a housing having a pump housing; a cam ring movably accommodated inside the pump accommodating portion; a pump element rotatably accommodated on an inner peripheral side of the cam ring and cooperating with the cam ring to form a plurality of pump chambers; a coil spring disposed in the pump accommodating portion and biasing the cam ring in a direction that increases the eccentricity of the cam ring relative to the rotation axis of the pump element; a protrusion provided on an arm portion extending toward the outer periphery of the cam ring, the protrusion extending in the longitudinal direction of the coil spring from a spring contact surface that contacts the coil spring and partially formed so as to overlap with a partial circumferential region of the outer periphery of the coil spring; A variable displacement oil pump comprising:

2. 2. The variable displacement oil pump according to claim 1, The housing has a first restriction wall that restricts movement of the coil spring toward the outside in a radial direction perpendicular to the rotation axis of the pump element. A variable displacement oil pump.

3. 2. The variable displacement oil pump according to claim 1, the cam ring has a second restriction wall that restricts movement of the coil spring toward the inside in a radial direction perpendicular to the rotation axis of the pump element. A variable displacement oil pump.

4. 2. The variable displacement oil pump according to claim 1, The protrusion is provided singly. A variable displacement oil pump.

5. 2. The variable displacement oil pump according to claim 1, The protrusion is provided at a position overlapping with the center of the outer diameter of the coil spring. A variable displacement oil pump.

6. 2. The variable displacement oil pump according to claim 1, the housing has a third restriction wall that restricts movement of the coil spring to the radially opposite side of the coil spring relative to the protrusion. A variable displacement oil pump.

7. 2. The variable displacement oil pump according to claim 1, the coil spring is disposed in an oil passage that connects an oil suction port provided in the housing to the pump chamber, The protrusion is disposed downstream of the coil spring in the oil passage. A variable displacement oil pump.

8. A method for manufacturing a variable displacement oil pump according to claim 1, comprising the steps of: a cam ring disposing step of disposing the cam ring in the pump accommodating portion; a coil spring disposing step of disposing the coil spring in the pump accommodating portion after the cam ring disposing step, a step of holding the coil spring in a compressed state using a jig having a bifurcated first holding portion having a notch in the middle portion capable of holding one end of the coil spring and a second holding portion capable of holding the other end of the coil spring, and arranging the coil spring in the pump accommodating portion by inserting the jig between the cam ring and the pump accommodating portion so as to avoid the protrusion by the notch in the first holding portion; A method for manufacturing a variable displacement pump, comprising:

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