supply pump

Abstract

The cam ring (501) of the supply pump rotates without rotating around the cam shaft. The tappet (40) reciprocates in a direction perpendicular to the cam shaft in response to the rotation of the cam ring (501), so that the tappet (40) slides along the cam ring sliding surface (53). The plunger (30) reciprocates together with the tappet (40) to pressurize and deliver fuel. The cam ring sliding surface (53) is shaped in a convex shape having a non-circular curved profile line. The height of the inside of the cam ring sliding surface (53) is higher than the height of the periphery of the cam ring sliding surface (53). Specifically, an ellipsoidal surface portion (531) is formed at the cam ring sliding surface (53), and the axial direction of the major axis of the ellipsoidal surface portion (531) is set to coincide with the direction perpendicular to the sliding direction of the cam ring sliding surface (53).

Description

Technical Field

[0001] This disclosure relates to a supply pump. Background Technology

[0002] In a previously proposed supply pump, fluid is pressurized and delivered by reciprocating the tappet and plunger in response to the rotation of the cam ring.

[0003] For example, in JP2009-138596A, in order to limit the jamming of the sliding part between the tappet and the cam ring, a recess is provided on the tappet sliding surface. This recess does not contact the cam ring sliding surface, thereby dispersing the contact surface pressure of the tappet sliding surface and achieving uniform contact surface pressure.

[0004] Typically, a fuel supply pump delivers fuel as a fluid to an internal combustion engine. In recent years, there has been a growing need to increase the injection pressure of the fuel injected into internal combustion engines to reduce fuel consumption and comply with emissions regulations. Furthermore, robust fuel performance, particularly improved anti-seize properties, is required in colder regions and emerging economies. Summary of the Invention

[0005] This disclosure is based on the above viewpoints, and the purpose of this disclosure is to provide a supply pump with further improved anti-seize performance.

[0006] This disclosure includes a supply pump according to the first through fourth aspects. What is common to all four aspects is that the supply pump includes a camshaft, a cam, a cam ring, a tappet, and a plunger. The cam is eccentric to the camshaft and configured to rotate integrally with the camshaft. The cam ring is configured to rotate about the camshaft without rotating while sliding along the outer periphery of the cam.

[0007] The tappet is configured to reciprocate in a direction perpendicular to the camshaft in response to the rotation of the cam ring, thereby sliding the tappet along the cam ring sliding surface, which is the outer circumferential surface of the cam ring extending in a direction parallel to the camshaft. The plunger is configured to reciprocate together with the tappet to pressurize and deliver fluid. The tappet has a tappet recess formed on the tappet sliding surface, which is opposite to the cam ring sliding surface, and the tappet recess does not contact the cam ring sliding surface.

[0008] In the first aspect of the supply pump, the cam ring sliding surface is convex, and the contour of the convex shape is a non-circular closed curve, and the height of the inner side of the cam ring sliding surface is higher than the height of the periphery of the cam ring sliding surface. Here, it should be noted that the contour line is also called a contour line, which is a line with constant height, that is, a convex line connecting points of equal height (or elevation).

[0009] Preferably, an ellipsoidal portion is formed at the sliding surface of the cam ring, such that the axial direction of the major axis of the ellipsoidal portion coincides with one of the sliding direction and the direction perpendicular to the sliding direction of the cam ring sliding surface, and the axial direction of the minor axis of the ellipsoidal portion coincides with the other of the sliding direction and the direction perpendicular to the sliding direction.

[0010] When the operating pressure of the supply pump increases, the thrust of the tappet on the sliding surface of the cam ring increases, resulting in increased contact surface pressure between the tappet and the sliding surface of the cam ring. Therefore, the risk of jamming between the tappet and the sliding surface of the cam ring increases. Therefore, in the first aspect of this disclosure, the convex profile of the cam ring sliding surface is set as a closed curve, such as an ellipse, instead of a circle, thereby avoiding the concentration of contact surface pressure in the central portion of the cam ring sliding surface, resulting in a wider contact surface pressure distribution. This reduces the maximum contact surface pressure and improves anti-jamming properties.

[0011] Furthermore, it is preferable that the vertex of the ellipsoidal portion is eccentrically displaced from the center of the cam ring sliding surface. In a structure where the plunger axis (i.e., the sliding center of the tappet) is eccentrically displaced from the center of the camshaft, this eccentric displacement of the vertex of the ellipsoidal portion from the center of the cam ring sliding surface is effective in terms of oil film formation and contact surface pressure dispersion.

[0012] In the supply pump of the second aspect, the tappet has an elastically deformable portion that allows the tappet to elastically deform, thereby increasing the contact area between the tappet sliding surface and the cam ring sliding surface when a load is applied to the tappet toward the cam ring. For example, the tappet has an annular groove that serves as the elastically deformable portion and is formed on the upper surface of the tappet, which is the surface of the tappet opposite to the tappet sliding surface.

[0013] By providing an elastically deformable portion at the tappet, the advantage of dispersing contact surface pressure when a load is applied to the tappet can be obtained. When the depth of the tappet recess is small, it is difficult to achieve machining accuracy. According to a second aspect of this disclosure, even when the depth of the tappet recess is large, tappet deformation can be absorbed. Therefore, machinability is improved.

[0014] In the third aspect of the supply pump, the cam ring has a stress relaxation groove formed on the non-sliding surface of the cam ring. The non-sliding surface of the cam ring extends in a direction parallel to the cam shaft and perpendicular to the sliding surface of the cam ring. The stress relaxation groove extends in an axial direction through the plunger and is configured to relax the transmission of stress applied axially to the plunger.

[0015] When the reciprocating motion of the tappet is reversed, the contact surface pressure at the edge of the cam ring sliding surface increases, making the edge prone to deformation and bulging. In view of the above, according to the third aspect of this disclosure, a stress relaxation groove is formed at the non-sliding surface of the cam ring. Therefore, by allowing deformation of the edge when a load is applied, the stress generated by the contact surface pressure can be dispersed. Furthermore, if the cam ring is used in a twin-cylinder pump with a relatively small lift, there is a problem of non-sliding surface bulging and sliding surface depression when the bushing is press-fitted into the cam ring. Therefore, in particular, the contact surface pressure increases when the tappet passes over the edge. Therefore, the effect of the third aspect of this disclosure is advantageous.

[0016] In the supply pump of the fourth aspect, the cam ring has a cooling recess formed in at least one of two opposite ends of the cam ring sliding surface, the two opposite ends being opposite to each other in the sliding direction of the cam ring sliding surface. The cooling recess is configured to receive fluid and cool the cam ring sliding surface.

[0017] As one of the jamming mechanisms between the cam ring and the tappet, there exists a mode in which heat is captured and stored in the sliding surface of the cam ring, causing the temperature to rise to near the melting point of the substrate, thus resulting in jamming. In the prior art, this is achieved by eccentrically moving the sliding center of the tappet (plunger axis) and the center of the cam shaft relative to each other, causing the tappet to overlap with the sliding surface of the cam ring, thereby supplying a cooler fluid to the inner side of the sliding surface. According to the fourth aspect of this disclosure, fluid supply to the inner side of the sliding surface can be facilitated, thereby limiting the temperature rise. Therefore, anti-jamming properties are improved.

[0018] Preferably, the cooling recess is formed on one side of the cam ring sliding surface, centered along the sliding direction, which is also the side to which the tappet slides during the piston's movement toward the camshaft (i.e., during non-delivery periods). Conversely, the cooling recess is not formed on the other side of the cam ring sliding surface, centered along the sliding direction, which is also the side to which the tappet slides when the piston moves away from the camshaft (i.e., during delivery periods). Therefore, the degradation of oil film formation can be limited within the range of high loads applied during delivery. Attached Figure Description

[0019] The accompanying drawings described herein are for illustrative purposes only, for the purposes of selecting embodiments and not all possible implementations, and are not intended to limit the scope of this disclosure.

[0020] Figure 1 This is a cross-sectional view of the supply pump common to embodiments of this disclosure.

[0021] Figure 2 It is along Figure 1 The cross-sectional view taken from line II-II in the diagram.

[0022] Figure 3A This is a left-side view of the cam ring of the first embodiment in Group A.

[0023] Figure 3B yes Figure 3A The front view of the cam ring is shown.

[0024] Figure 4A This is a plan view of the cam ring of the first embodiment in Group A.

[0025] Figure 4B It is shown Figure 4A A schematic diagram showing the contact surface pressure range of the cam ring.

[0026] Figure 5A This is a plan view of the cam ring of the comparative example in group A.

[0027] Figure 5B It is shown Figure 5A A schematic diagram showing the contact surface pressure range of the cam ring.

[0028] Figure 6 It is a diagram used to describe the relationship between the projected heights of the ellipsoidal portion.

[0029] Figure 7A This is a plan view of the cam ring of the second embodiment in Group A.

[0030] Figure 7B yes Figure 7A The front view of the cam ring is shown.

[0031] Figure 8 This is a plan view of the cam ring in the third embodiment of Group A.

[0032] Figure 9 This is a diagram showing the initial state of the tappet in the embodiment of Group B.

[0033] Figure 10 This is a schematic diagram showing the tappet of the embodiment B during the fuel delivery time (elastic deformation state).

[0034] Figure 11 This is a diagram showing the tappet of the comparative example in group B in its initial state.

[0035] Figure 12A This is a diagram showing the contact surface pressure distribution of the tappet in the embodiment of Group B.

[0036] Figure 12B This is a diagram showing the contact surface pressure distribution of the tappet in the comparative example of group B.

[0037] Figure 13A This is a left-side view of the cam ring in the first embodiment of Group C.

[0038] Figure 13B yes Figure 13A The front view of the cam ring is shown.

[0039] Figure 14 This is a plan view of the cam ring in the first embodiment of Group C.

[0040] Figure 15A This is a plan view of the cam ring of the comparative example in group C, showing the deformation of the cam ring.

[0041] Figure 15B yes Figure 15A The front view of the cam ring is shown.

[0042] Figure 16A This is a plan view of the cam ring in the second embodiment of Group C.

[0043] Figure 16B yes Figure 16A The front view of the cam ring is shown.

[0044] Figure 17A This is a left-side view of the cam ring in the first embodiment of Group D.

[0045] Figure 17B yes Figure 17A The front view of the cam ring is shown.

[0046] Figure 18A This is a plan view of the cam ring of the first embodiment in Group D.

[0047] Figure 18B A plan view showing the sliding range of the tappet in the first embodiment of group D.

[0048] Figure 19 It is a diagram describing the operating stroke of the supply pump.

[0049] Figure 20A This is a plan view of the cam ring in the second embodiment of Group D.

[0050] Figure 20B yes Figure 20A The front view of the cam ring is shown. Detailed Implementation

[0051] Hereinafter, several embodiments of the supply pump according to the present disclosure will be described with reference to the accompanying drawings. In the embodiments, substantially the same structures are indicated by the same reference numerals, and redundant descriptions thereof will be omitted. The following embodiments are divided into four groups A to D, which offer different solutions to the common objective of “improving anti-jamming performance.” Each group contains one to three embodiments. The embodiments in each group may be collectively referred to as “this embodiment.”

[0052] (Supply pump)

[0053] First, refer to Figure 1 and Figure 2This section will describe the overall structure of the common supply pumps for each group. The overall structure of the supply pumps is substantially the same as that disclosed in JP2009-138596A. The names of each component of the supply pump are essentially the corresponding names from JP2009-138596A. Furthermore, for some reference numerals, the reference numerals used in JP2009-138596A are incorporated. In each embodiment, reference numeral 50 is used as a reference numeral for the cam ring. The supply pumps are used in the accumulator fuel injection system of a diesel engine to supply high-pressure fuel to the common rail.

[0054] The housing of the supply pump 100 includes a housing body 11 and a pair of cylinder heads 12. A cam chamber 13 is formed in the housing body 11, through which fuel is supplied from the supply pump. The two opposite ends of the cam chamber 13 are closed by the cylinder heads 12. The cam chamber 13 receives a cam 17 and a cam ring 50.

[0055] The camshaft 14 is rotatably supported by the housing body 11 via journal 15 and rotated by a diesel engine (not shown). An oil seal 16 seals between the camshaft 14 and the housing body 11. A cam 17 with a circular cross-section is located at the axial midpoint of the camshaft 14, such that the cam 17 is eccentric to the camshaft 14 and rotates integrally with it. Figure 2 In the diagram, the direction of rotation of cam 17 is indicated by an arc-shaped arrow. Furthermore, the center of camshaft 14 is indicated by the camshaft center Ca.

[0056] A cam ring 50, rotating about a camshaft 14, is fitted to the outer periphery of a cam 17. The cam ring 50 includes a cam ring body 51 and a bushing 52. The cam ring body 51 is made of an iron-based metal. The bushing 52 is formed into a cylindrical tube and is made of metal (e.g., copper, aluminum, iron-based metal) or resin. The outer contour of the cam ring body 51 is formed into a quadrangular prism shape, and a circular through-hole extends through the cam ring body 51. The bushing 52 is press-fitted into the through-hole of the cam ring body 51 and is slidable along the outer periphery of the cam 17. Figure 1 and Figure 2 Each of the upper and lower outer surfaces of the cam ring 50 shown forms a cam ring sliding surface 53, which extends in a direction parallel to the cam shaft 14. Furthermore, Figure 2 Each of the left and right outer surfaces of the cam ring 50 shown extends in a direction parallel to the cam shaft 14 and forms a non-sliding surface 54 of the cam ring perpendicular to the sliding surface 53 of the cam ring.

[0057] exist Figure 1 and Figure 2In this cam ring 50, a set of plungers 30 and tappets 40 made of iron-based metal are provided on each of the upper and lower sides. Each plunger 30 is inserted into a cylinder formed in the corresponding cylinder head 12 and configured to reciprocate within the cylinder. Each tappet 40, shaped as a disc, is received in the cam chamber 13 and positioned such that the tappet sliding surface 43 of the tappet 40 is opposite to the corresponding cam ring sliding surface 53. (See Figure 3.) Figure 9 As shown in Figures 13 and 17, each embodiment of the push rod 40 has a push rod recess 41 formed at the push rod sliding surface 43 and does not contact the cam ring sliding surface 53.

[0058] A corresponding spring 21 installed in the cam chamber 13 pushes the tappet 40 against the cam ring 50, thereby limiting the rotation of the cam ring 50. When the cam 17 rotates, the cam ring 50 rotates around the cam shaft 14 without rotating, while the cam ring 50 slides along the outer circumference of the cam 17. When the tappet sliding surface 43 of the tappet 40 slides along the cam ring sliding surface 53, the tappet 40 and the plunger 30 reciprocate in a direction perpendicular to the cam shaft 14 in response to the rotation of the cam ring 50.

[0059] The plunger 30 and the tappet 40 are arranged coaxially. The axis of the plunger 30 and the tappet 40 is called the plunger axis Zp. Furthermore, in... Figure 2 In the cross-section shown, the straight line extending through the camshaft center Ca and parallel to the axis Zp of each plunger will be referred to as the center reference line Za. The cam ring 50 moves left and right relative to the center reference line Za in response to the rotation of the camshaft 14. In this embodiment, located at... Figure 2 The upper plunger axis Zp is eccentrically displaced to the right from the center reference line Za, while the one located at... Figure 2 The other plunger axis Zp on the lower side is eccentrically displaced to the left from the center reference line Za. That is, located at... Figure 2 The upper plunger axis Zp and located Figure 2 The other plunger axis Zp on the lower side is eccentrically displaced from the center reference line Za towards the front of the rotation direction of the camshaft 14. The eccentricity of each plunger axis Zp relative to the center reference line Za is represented by d1.

[0060] Inside each cylinder head 12, a fuel pressurization chamber 22 is formed on the side of the plunger 30 opposite to the tappet 40, to which fuel is supplied from the feed pump 25. Furthermore, an inlet check valve 23 and an outlet check valve 24 are installed inside each cylinder head 12. The inlet check valve 23 allows fuel to flow only from the feed pump 25 to the fuel pressurization chamber 22. The outlet check valve 24 allows fuel to flow only from the fuel pressurization chamber 22 to the common rail (not shown).

[0061] One end of the camshaft 14 is connected to an internal gear-type feed pump 25. The feed pump 25 is rotatably housed inside the pump cover 26. When the camshaft 14 rotates, the feed pump 25 pressurizes the fuel drawn from the fuel tank and discharges the pressurized fuel. The fuel discharged from the feed pump 25 is supplied to the fuel pressurization chamber 22 through a fuel passage (not shown) and an inlet check valve 23. A metering valve installed in the middle of the fuel passage regulates the amount of fuel supplied to the fuel pressurization chamber 22 based on the engine's operating status.

[0062] A connecting passage 261 formed at the pump cover 26 guides fuel discharged from the feed pump 25 to one end face of the camshaft 14. An axial lubricating oil passage 141 and a radial lubricating oil passage 142 are formed in the camshaft 14. The axial lubricating oil passage 141 opens at said one end face of the camshaft 14 and communicates with the connecting passage 261. The radial lubricating oil passage 142 communicates between the axial lubricating oil passage 141 and the outer peripheral surface of the cam 17. A portion of the fuel discharged from the feed pump 25 is supplied to the cam chamber 13 through these paths.

[0063] Next, the operation of the supply pump 100 will be described. When the camshaft 14 rotates, the feed pump 25 draws fuel from the fuel tank, pressurizes the drawn fuel, and discharges it. Furthermore, the cam 17 rotates in response to the rotation of the camshaft 14, and the cam ring 50 rotates in response to the rotation of the cam 17 but does not rotate. Each tappet 40 and its corresponding plunger 30 reciprocates in response to the rotation of the cam ring 50.

[0064] When the plunger 30, located at top dead center, moves towards bottom dead center, fuel discharged from the feed pump 25 flows into the fuel pressurization chamber 22 through the inlet check valve 23. When the plunger 30, having reached bottom dead center, moves towards top dead center again, the inlet check valve 23 closes. This causes the fuel pressure in the fuel pressurization chamber 22 to increase. When the fuel pressure in the fuel pressurization chamber 22 increases, the outlet check valve 24 opens. This allows high-pressure fuel to be supplied to the common rail. As described above, the plunger 30 reciprocates together with the pushrod 40 to pressurize and deliver fuel.

[0065] Conversely, a portion of the fuel discharged from the feed pump 25 is guided through the connecting passage 261, the axial lubricating oil passage 141, and the radial lubricating oil passage 142 to the gap between the cam 17 and the bushing 52 of the cam ring 50, and then flows into the cam chamber 13. In this way, the sliding portion between the cam 17 and the bushing 52 is lubricated, and the cam ring sliding surface 53 and the tappet sliding surface 43 are also lubricated.

[0066] Next, the detailed structure and operation of the cam ring 50 and tappet 40 in the supply pump 100 of each embodiment will be described in turn. In the accompanying drawings of the following embodiments, only details are shown. Figure 1 and Figure 2The upper side shows the tappet 40 and plunger 30, while the details are omitted. Figure 1 and Figure 2 The lower side shows the tappet 40 and plunger 30. In each embodiment of Groups A, C, and D, the reference numeral for the cam ring has a third digit corresponding to that embodiment after "50". In the Group B embodiments, the reference numeral for the tappet is set to "404".

[0067] In the following text, from Figure 2 The external view of the cam ring 50 observed from the direction of observation is called the front view, and from... Figure 1 The external view of the cam ring 50 observed from the observation direction is called the left-side view. Furthermore, the view of the cam ring sliding surface 53 observed from the plunger 30 side is called the plan view. In addition, the left-right direction in the plan view and the front view is defined as the X direction. The up-down direction in the plan view is defined as the Y direction, and the up-down direction in the front view is defined as the Z direction. Xr represents the center line extending along the X direction through the center of the cam ring 50, which is essentially a rectangular parallelepiped. Yr represents the center line extending along the Y direction through the center of the cam ring 50, and Zr represents the center line extending along the Z direction through the center of the cam ring 50.

[0068] exist Figure 3B , Figure 7B , Figure 13B and Figure 17B In each of the front views shown, the cam ring 50 is represented by a solid line, while the tappet 40, plunger 30, and cylinder head 12 are represented by dashed lines (double-dotted lines). The cam ring sliding surface 53 is opposite to the tappet sliding surface 43 and slides in response to the rotation of the camshaft 14. Depending on the rotational position of the camshaft 14, the Z-direction centerline Zr of the cam ring 50 may coincide with or be displaced from the center reference line Za. Each front view shows the state where the Z-direction centerline Zr of the cam ring 50 coincides with the center reference line Za.

[0069] (Group A)

[0070] Group A's supply pump will refer to Figures 3A to 8 The following description is provided. In the supply pump of group A, the cam ring sliding surface 53 is shaped as a convex shape, such that the height of the inner side of the cam ring sliding surface 53 is higher than the height of the periphery of the cam ring sliding surface 53. Each contour line of the convex shape is a non-circular closed curve (see example...). Figure 4A (The outline shown). Here, in addition to elliptical closed curves, non-circular closed curves also include oblong closed curves, oval closed curves, gourd-shaped closed curves, etc. In the plan view of each embodiment in Group A, the convexity of the cam ring sliding surface 53 is represented by the outline. The height of the convexity is actually a tiny height on the order of μm. However, in Figure 3A , Figure 3B and Figure 7BIn this figure, the height is exaggerated. Furthermore, the illustration and description of the convex shape on the cam ring sliding surface 53 on the lower side of the figure are omitted.

[0071] (First embodiment of Group A)

[0072] Reference Figures 3A to 4B The cam ring 501 of the first embodiment is described. Figure 3B In the front view, the curved arrows indicate the rotation of the camshaft 14, and the double arrows in the left-right direction indicate the sliding of the cam ring 501. Additionally, the double arrows in the up-down direction indicate the reciprocating motion of the plunger 30. The X-direction corresponds to the sliding direction of the cam ring sliding surface 53. The Y-direction corresponds to the direction perpendicular to the sliding direction of the cam ring sliding surface 53.

[0073] The cam ring sliding surface 53 has an ellipsoidal portion 531. The height of the inner side of the ellipsoidal portion 531 is higher than the height of the periphery of the ellipsoidal portion 531. In the ellipsoidal portion 531 of the first embodiment, the axial direction of the major axis of the ellipsoidal portion 531 is set to coincide with the direction perpendicular to the sliding direction (Y direction), and the axial direction of the minor axis of the ellipsoidal portion 531 is set to coincide with the sliding direction (X direction). Furthermore, the vertex of the ellipsoidal portion 531 is represented by Pv.

[0074] Figure 5A A plan view of a comparative example cam ring 509 with a spherical surface portion 539 is shown. Furthermore, Figure 4B The contact surface pressure range is shown when the tappet 40 contacts the sliding surface 53 of the cam ring in the first embodiment. Figure 5B The range of contact surface pressure when the tappet 40 contacts the sliding surface 53 of the cam ring in the comparative example is shown. The range where the contact surface pressure Ps is equal to or greater than the threshold PsH is represented by an ellipse in the first embodiment and by a circle in the comparative example. When the contact surface pressure threshold PsH is set to be equal in both the first embodiment and the comparative example, the size of the elliptical region in the first embodiment is larger than the size of the circular region in the comparative example. In other words, the maximum contact surface pressure in the first embodiment is less than the maximum contact surface pressure in the comparative example. When the convexity of the cam ring sliding surface 53 is set to an ellipsoid, the size of the range where the contact surface pressure Ps is equal to or greater than the threshold PsH can be increased, thereby reducing the maximum contact surface pressure. Therefore, anti-jamming performance is improved.

[0075] refer to Figure 6 This will describe the relationship between the projected height of the ellipsoidal portion 531. Figure 6 The left side corresponds to Figure 3A , Figure 6 The right side corresponds to Figure 3B However, in Figure 6 In, with Figure 3A and Figure 3BIn comparison, for descriptive purposes, the projected height is further exaggerated. The width of the cam ring 501 as viewed from the front is denoted by Wx, and the depth of the cam ring 501 as viewed from the left is denoted by Dy. Furthermore, the height of the reference surface near the convex shape of the cam ring sliding surface 53 is denoted by H0.

[0076] Figure 6 The front view of the cam ring 501 shown on the right represents the projected height (first projected height) Hx of the vertex Pv of the ellipsoidal portion 531. This projected height is measured along a cross-section of the ellipsoidal portion 531 extending in the sliding direction (X direction) through the vertex Pv and parallel to the plunger axis Zp, from the positions of the two opposite endpoints Px0 of the ellipsoidal surface of the ellipsoidal portion 531 to the vertex Pv. In the front view, the elliptical arc of the ellipsoidal portion 531 intersects the reference plane within a width Wx, such that the two opposite endpoints Px0 of the ellipsoidal surface in the X direction exist on the reference plane. Therefore, the projected height Hx of the cam ring sliding surface 53 along the plane extending in the sliding direction (X direction) is the height measured from the reference plane to the vertex Pv.

[0077] Figure 6 The side view of the cam ring 501 shown on the left represents the projected height (second projected height) Hy of the vertex Pv of the ellipsoidal portion 531. This projected height is measured along a cross section of the ellipsoidal portion 531 extending through the vertex Pv in a direction perpendicular to the sliding direction (Y direction) and parallel to the plunger axis Zp, from the positions of the two opposite endpoints Py0 of the ellipsoidal surface of the ellipsoidal portion 531 to the vertex Pv. In the side view, the elliptical arc of the ellipsoidal portion 531 does not intersect the reference surface within the depth Dy. Therefore, the intersection point of the extension of the front surface 51F of the cam ring 501 with the elliptical arc and the intersection point of the extension of the rear surface 51R of the cam ring 501 with the elliptical arc are the two opposite endpoints Py0 of the ellipsoid. That is, the two opposite endpoints Py0 of the ellipsoid in the Y direction are located at a height H0 above the reference surface.

[0078] In summary, the projected height Hx of the cam ring sliding surface 53 along the plane extending in the sliding direction (X direction) is higher than the projected height Hy of the cam ring sliding surface 53 along the plane extending in the direction perpendicular to the sliding direction (Y direction). Furthermore, the radius of curvature Rx of the ellipsoidal surface of the cam ring sliding surface 53 along the plane in the sliding direction (X direction) is smaller than the radius of curvature Ry of the ellipsoidal surface of the cam ring sliding surface 53 along the plane perpendicular to the sliding direction (Y direction).

[0079] (advantage)

[0080] When the operating pressure of the supply pump 100 increases, the thrust of the tappet 40 on the cam ring sliding surface 53 increases, resulting in increased contact surface pressure. Therefore, the risk of jamming between the tappet 40 and the cam ring sliding surface 53 increases. Therefore, in the embodiment of Group A, each line of the convex profile of the cam ring sliding surface 53 is set as a non-circular closed curve, such as an ellipse, thereby avoiding the concentration of contact surface pressure in the central portion of the cam ring sliding surface 53, resulting in a wide contact surface pressure distribution. This reduces the maximum contact surface pressure and improves anti-jamming properties.

[0081] Specifically, the convexity of the cam ring sliding surface 53 is formed by an ellipsoidal portion 531. Specifically, in the ellipsoidal portion 531 of the first embodiment, the axial direction of the major axis of the ellipsoidal portion 531 is set to coincide with the direction perpendicular to the sliding direction (Y direction) of the cam ring sliding surface 53. Therefore, compared to the case where the axial direction of the major axis of the ellipsoidal portion 531 is set to coincide with the sliding direction (X direction) of the cam ring sliding surface 53, the ellipsoidal portion 531 can be manufactured more easily.

[0082] (Second embodiment of Group A)

[0083] Reference Figure 7A and Figure 7B The second embodiment of the cam ring 502 is described. In the second embodiment, the vertex Pv of the ellipsoidal portion 532 is eccentrically displaced from the center of the cam ring sliding surface 53. The eccentricity d2 of the vertex Pv from the center of the cam ring sliding surface 53 is equal to the eccentricity d1 between the plunger axis Zp and the center reference line Za extending through the camshaft center Ca. By eccentrically displacing the vertex Pv of the ellipsoidal portion 532 from the center of the cam ring sliding surface 53 according to the eccentricity d1 of the plunger axis Zp relative to the camshaft center Ca, it is effective in terms of oil film formation and contact surface pressure dispersion.

[0084] (Third embodiment of Group A)

[0085] Reference Figure 8 The cam ring 503 of the third embodiment is described. The third embodiment differs from the first embodiment in the axial directions of the major and minor axes of the ellipsoidal portion 533. In the ellipsoidal portion 533 of the third embodiment, the axial direction of the major axis of the ellipsoidal portion 533 is set to coincide with the sliding direction (X direction) of the cam ring sliding surface 53, and the axial direction of the minor axis of the ellipsoidal portion 533 is set to coincide with the direction perpendicular to the sliding direction (Y direction). Even with this configuration, as in the first embodiment, compared to the spherical portion 539 of the comparative example, the anti-jamming property is improved by expanding the range in which the contact surface pressure is equal to or greater than a predetermined contact surface pressure.

[0086] (Other embodiments of Group A)

[0087] The convexity of the cam ring sliding surface 53 is not limited to an ellipsoidal shape, wherein the axial direction of the major axis is set to coincide with one of the sliding direction (X direction) and the direction perpendicular to the sliding direction (Y direction), and the axial direction of the minor axis is set to coincide with the other of the sliding direction (X direction) and the direction perpendicular to the sliding direction (Y direction). For example, the convexity of the cam ring sliding surface 53 can be an ellipsoidal shape, wherein the axial direction of the major axis is set to coincide with the axial direction of the axis inclined to the X direction. Furthermore, the convexity of the cam ring sliding surface 53 can be any suitable form, wherein each profile is a closed curve other than a circle, and the range of contact surface pressure equal to or greater than a predetermined value is greater than... Figure 5A and Figure 5B The scope of comparative examples. Here, in addition to elliptical closed curves, non-circular closed curves also include oblong closed curves, oval closed curves, gourd-shaped closed curves, etc.

[0088] (Group B)

[0089] Reference Figures 9 to 12B Describe the supply pump of group B. In the supply pump of group B, the tappet 404 has an elastically deformable portion that allows the tappet 404 to elastically deform, thereby increasing the contact area between the tappet sliding surface 43 and the cam ring sliding surface 53 when a load is applied to the tappet 404 toward the cam ring 50.

[0090] (First embodiment of Group B)

[0091] Figure 9 The pushrod 404 of the Group B embodiment is shown in its initial state. Figure 10 The push rod 404 during pressurization and fuel delivery is shown (hereinafter referred to as fuel delivery time). The push rod 404 has an annular groove 46 that serves as an elastically deformable portion and is formed at the upper surface 44 of the push rod, which is the surface of the push rod 404 opposite to the push rod sliding surface 43. Figure 1 and Figure 2 As shown, a portion of the upper surface 44 of the tappet adjacent to the outer peripheral edge of the upper surface 44 serves as a spring seat 45 for the spring 21. An annular groove 46 is located inside the spring seat 45.

[0092] As described above, the tappet 404 has a tappet recess 41 formed at the tappet sliding surface 43 and does not contact the cam ring sliding surface 53. Here, "does not contact the cam ring sliding surface 53" refers to the positional relationship of the tappet 404 in its initial state before a load is applied. Furthermore, it is assumed that the cam ring 50 used with the tappet 404 has a cam ring sliding surface 53, the central portion of which is convex, such as an ellipsoid or a sphere, as in the embodiments of Group A or the comparative examples of Group A.

[0093] The annular groove 46 is located inside the "closed curve Tc," which is formed by multiple contact points connecting the outer periphery of the tappet recess 41 and the cam ring sliding surface 53 when the tappet 404 is in an elastically deformed state. Ideally, the closed curve Tc becomes circular if each of the convexities of the tappet recess 41 and the cam ring sliding surface 53 is a sphere. For example, if one or both of the convexities of the tappet recess 41 and the cam ring sliding surface 53 are ellipsoids, the closed curve Tc may become an ellipse or other types of closed curves.

[0094] exist Figure 10 In the diagram, the square arrow at plunger 30 indicates the load caused by fuel pressure during fuel delivery. Due to this load, tappet 404 deforms from near the annular groove 46, as... Figure 10 The square arrow at point (*1) indicates this. Then, as... Figure 10 As shown in the middle (*2), the outer peripheral edge and periphery of the tappet recess 41 contact the cam ring sliding surface 53, thereby receiving the load over a large range. Therefore, the pressure at the edge contact surface is reduced. Furthermore, when the convexity of the tappet recess 41 and the cam ring sliding surface 53 are respectively formed as spherical surfaces with approximately equal radii, the advantages of enhanced wedge effect and promotion of oil film formation can be obtained.

[0095] Figure 11 A comparative example tappet 40 is shown. The comparative example tappet 40 does not have the annular groove 46 serving as an elastically deformable portion, and the upper surface 44 of the tappet 40 is flat. As in the embodiment of Group B, a tappet recess 41 is formed at the tappet sliding surface 43. Even when a load is applied to the tappet 40 towards the cam ring 50 during fuel delivery, the comparative example tappet 40 is not easily deformed.

[0096] Reference Figure 12A and Figure 12B The contact surface pressure distribution of this embodiment is compared with that of the comparative example. For example... Figure 10 middle, Figure 12A and Figure 12B The square arrows at each plunger 30 indicate the load caused by fuel pressure during fuel delivery. Because the deformation in the tappet 40 of the comparative example is small, the contact surface pressure is concentrated in the central portion. Therefore, in the comparative example, the depth Th of the tappet recess 41 in the initial state needs to be set small. In contrast, the tappet 404 of this embodiment can elastically deform due to the annular groove 46. Therefore, the contact surface pressure can be dispersed. Therefore, the depth Th of the tappet recess 41 in the initial state can be set large.

[0097] (advantage)

[0098] By providing an annular groove 46 at the tappet 404, the advantage of dispersing contact surface pressure when a load is applied to the tappet 404 can be obtained. When the depth of the tappet recess 41 is set small (e.g., about 1 μm), it is difficult to achieve machining accuracy. According to this embodiment of Group B, even when the depth of the tappet recess 41 is set large, deformation of the tappet 404 can be absorbed. Therefore, machinability is improved.

[0099] Furthermore, the annular groove 46 is located inside the "closed curve Tc," which is formed by multiple contact points connecting the outer periphery of the tappet recess 41 and the cam ring sliding surface 53 when the tappet 404 is in an elastically deformed state. Therefore, when a load is applied to the tappet 404 towards the cam ring 50, the tappet 404 undergoes elastic deformation, causing the tappet sliding surface 43 and the cam ring sliding surface 53 to come into contact with each other at a position inside the closed curve Tc. Thus, the effect of elastic deformation can be reliably obtained.

[0100] (Other embodiments of Group B)

[0101] The elastically deformable portion is not limited to the annular groove 46. Specifically, the elastically deformable portion needs to be only the portion that enables the elastic deformation of the tappet 404 in a way that increases the contact area between the tappet sliding surface 43 and the cam ring sliding surface 53. Furthermore, the elastically deformable portion is not limited to an annular groove that extends continuously in the circumferential direction. For example, the elastically deformable portion can be a plurality of recesses that are discontinuous in the circumferential direction.

[0102] (Group C)

[0103] Reference Figures 13A to 16B The supply pump of group C is described. In the supply pump of group C, cam rings 505 and 506 have stress relaxation grooves 555 and 556 formed at the non-sliding surface 54 of the cam rings 505 and 506. The non-sliding surface 54 of the cam rings extends in a direction parallel to the camshaft 14 and perpendicular to the sliding surface 53 of the cam rings.

[0104] Each stress relaxation groove 555, 556 extends in a direction intersecting the axial direction of the plunger axis Zp, and relaxes the stress transmitted in the axial direction of the plunger axis Zp. In the description of Group C, the cam ring sliding surface 53 is abbreviated as "sliding surface 53", and the cam ring non-sliding surface 54 is abbreviated as "non-sliding surface 54".

[0105] (First embodiment of Group C)

[0106] Figures 13A to 14 This refers to the cam ring 505 of the first embodiment in group C. In... Figure 13BIn the front view, the curved arrows indicate the rotation of the camshaft 14, and the double arrows in the left-right direction indicate the sliding of the cam ring 505. Additionally, the double arrows in the up-down direction indicate the reciprocating motion of the plunger 30.

[0107] The cam ring 505 has four stress relaxation grooves 555 disposed at four locations, including the upper and lower portions of the left and right non-sliding surfaces 54 and 54 of the cam ring 505. Each stress relaxation groove 555 extends in a direction parallel to the cam shaft 14, i.e., in an axial direction perpendicular to the plunger axis Zp. In the first embodiment, each stress relaxation groove 555 is uniformly formed along its entire extent in a direction perpendicular to the sliding direction (Y direction), making it easy to machine the stress relaxation grooves 555.

[0108] (advantage)

[0109] Reference Figure 15A and Figure 15B The comparative example cam ring 509 has a drawback: it lacks stress relaxation grooves. In the plan view, the four corners of the cam ring sliding surface 53, located on two opposite sides in the sliding direction (X direction) and two opposite sides in the direction perpendicular to the sliding direction (Y direction), are referred to as the four edge portions. When the reciprocating motion of the tappet 40 reverses, the contact surface pressure of each edge portion increases, thus the edge portions tend to deform and bulge.

[0110] Furthermore, the margin from the outer periphery of bushing 52 to the sliding surface 53 of the cam ring in the height direction (Z direction) is defined as margin Mz, and the margin from the outer periphery of bushing 52 to the non-sliding surface 54 of the cam ring in the sliding direction (X direction) is defined as margin Mx. When the margin Mz in the height direction is greater than the margin Mx in the sliding direction, the non-sliding surface 54 tends to deform significantly. For example, in the case of a cam ring used in a twin-cylinder pump with a relatively small lift, there is a concern that the non-sliding surface 54 will bulge and the sliding surface 53 will be recessed when the bushing 52 is press-fitted into the cam ring. Therefore, in particular, there is a concern that the contact surface pressure will increase when the tappet 40 crosses the edge portion.

[0111] In view of the above points, in the embodiment of group C, the stress relaxation groove 555 is formed at the non-sliding surface 54 of the cam ring. Therefore, by allowing deformation of the edge portion when a load is applied to it, the stress generated by the contact surface pressure can be dispersed. This is particularly effective for cam rings with relatively small lift in twin-cylinder pumps.

[0112] (Second embodiment of Group C)

[0113] Figure 16A and 16BThe second embodiment of the cam ring 506 represents Group C. In this second embodiment, stress relaxation grooves 556 are formed at four locations corresponding to the four opposite edge portions of the cam ring sliding surface 53, located on two opposite sides in the sliding direction (X direction) and two opposite sides in the direction perpendicular to the sliding direction (Y direction). Specifically, stress relaxation grooves 556 are formed at a total of eight locations, including four locations on the cam ring 506 axially upward on the plunger axis Zp and four locations on the cam ring 506 axially downward on the plunger axis Zp. By forming each stress relaxation groove 556 at a location corresponding to an edge portion that is prone to deformation under load, the reduction in strength of the entire cam ring 506 can be limited.

[0114] (Other embodiments of Group C)

[0115] The extension direction of each stress relaxation groove is not limited to a direction perpendicular to the axial direction of the plunger axis Zp. Specifically, the extension direction of each stress relaxation groove can be an intersecting direction that intersects the axial direction of the plunger axis Zp, and this intersecting direction can include a direction inclined relative to the axial direction of the plunger axis Zp. The advantage is that it disperses the contact surface pressure of the tappet 40, except when the groove is formed parallel to the axial direction of the plunger axis Zp.

[0116] In the front view of the cam ring, the stress relaxation groove does not necessarily need to be symmetrical with respect to the X-direction centerline Xr and the Z-direction centerline Zr of the cam ring. For example, the stress relaxation groove can be arranged such that the stress relaxation groove is offset downward at the non-slip surface 54 on the left side, while the stress relaxation groove is offset upward at the non-slip surface 54 on the right side. Even in this configuration, the stress relaxation groove is formed at positions corresponding to the edge portions of the four locations.

[0117] (Group D)

[0118] Reference Figures 17A to 20B The supply pump of group D is described. In the supply pump of group D, cam rings 507, 508 have cooling recesses 577, 578 in at least one of two opposite ends of each cam ring sliding surface 53, the two opposite ends being opposite to each other in the sliding direction of the cam ring sliding surface 53. Fuel flows into the cooling recesses 577, 578 to cool the cam ring sliding surface 53. In the embodiment of group D, the fluid is described as fuel.

[0119] (First embodiment of Group D)

[0120] Figures 17A to 18B This refers to the cam ring 507 of the first embodiment in group D. In... Figure 17B In the front view, the curved arrows indicate the rotation of the camshaft 14, and the double arrows pointing left and right indicate the sliding of the cam ring 507. Additionally, the double arrows pointing up and down indicate the reciprocating motion of the plunger 30. Figure 18A and Figure 18B In this context, it is assumed that the cam ring sliding surface 53 has an ellipsoidal portion 531 similar to that in the first embodiment of Group A.

[0121] exist Figure 17B In the cam ring 507, a cooling recess 577 is provided at the left end of the sliding surface 53 in the sliding direction. The cooling recess 577 of the sliding surface 53 exists on one side and the other side of the center line Xr in the X direction, such that the cooling recess 577 is V-shaped and is formed in the central portion of the sliding surface 53, which is centered in the direction perpendicular to the sliding direction (Y direction).

[0122] exist Figure 18B In the diagram, the sliding range of the tappet 40 is indicated by a dashed shaded line. In the first embodiment, the cooling recess 577 is formed only within a contact range Ty in the direction perpendicular to the sliding direction (Y direction) of the cam ring sliding surface 53, within which the tappet 40 contacts the cam ring sliding surface 53.

[0123] Figure 19 The operating strokes of the supply pump 100 are represented as I-IV. The plunger 30 moves upward from bottom dead center I away from the camshaft 14 to top dead center III to pressurize and deliver fuel. After top dead center III, the plunger 30 moves downward and approaches the camshaft 14. This period corresponds to the fuel intake time, i.e., the "non-delivery time".

[0124] exist Figure 18A and Figure 18B In this embodiment, the left side of the center of the cam ring sliding surface 53 in the sliding direction (X direction) corresponds to the side where the tappet 40 slides towards the camshaft 14 during the movement of the plunger 30 toward the camshaft 14 (i.e., during non-delivery time). Furthermore, the right side of the center of the cam ring sliding surface 53 in the sliding direction (X direction) corresponds to the side where the tappet 40 slides towards the camshaft 14 during the movement of the plunger 30 away from the camshaft 14 (i.e., during delivery time). The cooling recess 577 of the first embodiment is formed on the side where the tappet 40 slides towards the camshaft 14 during non-delivery time, but not on the other side where the tappet 40 slides towards the camshaft 14 during delivery.

[0125] (advantage)

[0126] As one of the jamming mechanisms between the cam ring 507 and the tappet 40, there exists a mode in which heat is captured and stored in the sliding surface 53 of the cam ring, causing the temperature to rise to near the melting point of the substrate, thus resulting in jamming. In the prior art, to address this, the tappet 40 overlaps with the sliding surface 53 of the cam ring by eccentrically displacing the sliding center (plunger axis Zp) of the tappet 40 and the center Ca of the camshaft 14 relative to each other, thereby supplying fuel with a low temperature to the inner side of the sliding surface. According to the embodiment of Group D, fuel supply to the inner side of the sliding surface can be facilitated, thereby limiting the temperature rise. Therefore, anti-jamming properties are improved.

[0127] However, when the size of the cooling recess 577 becomes larger than required, the contact area between the tappet 40 and the cam ring sliding surface 53 decreases, which is detrimental in terms of reduced contact surface pressure and oil film formation. Therefore, by locally providing the cooling recess 577, the contact area between the tappet 40 and the cam ring sliding surface 53 can be maintained at its maximum level. Furthermore, by forming the cooling recess 577 only on the side of the tappet 40 that slides towards it during non-delivery periods, the deterioration of oil film formation can be limited within the range of high loads applied during delivery.

[0128] (Second embodiment of Group D)

[0129] Figure 20A and 20B This refers to the cam ring 508 of the second embodiment in group D. In... Figure 20A In this embodiment, it is assumed that the cam ring sliding surface 53 has an ellipsoidal portion 531 similar to that in the first embodiment of Group A. In the second embodiment, the cooling recess 578 is formed by an inclined surface that extends along the entire range of the cam ring sliding surface 53 in a direction perpendicular to the sliding direction (Y direction). With this configuration, the amount of fuel flowing into the cooling recess 578 is increased, thereby improving cooling performance. Furthermore, the cooling recess 578 is easier to machine than in the first embodiment.

[0130] (Other embodiments of Group D)

[0131] From the perspective of the cooling performance of the cam ring sliding surface 53, cooling recesses can be formed in two opposite ends of the cam ring sliding surface 53 in opposite directions. Preferably, the optimal size and optimal location of the cooling recesses are determined from the perspective of ensuring the area of ​​the cam ring sliding surface 53 receiving the load of the tappet 40 and the cooling performance.

[0132] (Other embodiments common to groups A through D)

[0133] The fluid delivered by the supply pump plunger is not limited to fuel or a mixture of fuel and lubricating oil; it can also be lubricating oil without fuel.

[0134] The embodiments in groups A to D are not limited to those implemented independently, and two or more groups of embodiments can be combined and implemented.

[0135] As described above, this disclosure is not limited to the above embodiments and can be implemented in various forms without departing from the scope of this disclosure.

Claims

1. Supply pump, including: Camshaft, which is configured to rotate; A cam that is eccentric to the camshaft and is configured to rotate integrally with the camshaft; A cam ring is configured to slide along the outer periphery of the cam while rotating around the camshaft without rotating. A tappet is configured to reciprocate in a direction perpendicular to the camshaft in response to rotation of the cam ring, such that the tappet slides along a cam ring sliding surface, which is the outer peripheral surface of the cam ring extending in a direction parallel to the camshaft. as well as A plunger, configured to reciprocate with the pushrod to pressurize and deliver fluid, wherein: The tappet has a tappet recess formed on a tappet sliding surface opposite to the sliding surface of the cam ring, wherein the tappet recess does not contact the sliding surface of the cam ring; and The cam ring sliding surface is convex, and the outline of the convex shape is a non-circular closed curve. The height of the inner side of the cam ring sliding surface is higher than the height of the periphery of the cam ring sliding surface. An ellipsoidal portion is formed at the sliding surface of the cam ring, such that the axial direction of the major axis of the ellipsoidal portion is set to coincide with one of the sliding direction of the cam ring sliding surface and a direction perpendicular to the sliding direction, and the axial direction of the minor axis of the ellipsoidal portion is set to coincide with the other of the sliding direction and the direction perpendicular to the sliding direction. as well as The projected height of the vertex of the ellipsoidal portion, measured from the positions of the two opposite endpoints of the ellipsoidal surface of the ellipsoidal portion to the vertex in a cross section extending through the vertex and parallel to the axis of the plunger, is higher along the plane extending in the sliding direction of the cam ring sliding surface than along the plane extending in the direction perpendicular to the sliding direction.

2. The supply pump according to claim 1, wherein the axial direction of the major axis of the ellipsoidal portion is configured to coincide with the direction of the sliding direction perpendicular to the sliding surface of the cam ring.

3. The supply pump according to claim 1 or 2, wherein the vertex of the ellipsoidal portion is eccentrically displaced from the center of the cam ring sliding surface.

4. The supply pump according to claim 3, wherein the eccentricity of the vertex of the ellipsoidal portion from the center of the ellipsoidal portion in the sliding direction of the cam ring sliding surface is equal to the eccentricity between the axis of the plunger and the center of the cam shaft.

5. Supply pump, including: Camshaft, which is configured to rotate; A cam that is eccentric to the camshaft and is configured to rotate integrally with the camshaft; A cam ring is configured to slide along the outer periphery of the cam while rotating around the camshaft without rotating. A tappet is configured to reciprocate in a direction perpendicular to the camshaft in response to rotation of the cam ring, such that the tappet slides along a cam ring sliding surface, which is the outer peripheral surface of the cam ring extending in a direction parallel to the camshaft. as well as A plunger, configured to reciprocate with the pushrod to pressurize and deliver fluid, wherein: The push rod has: A tappet recess formed on a tappet sliding surface opposite to the cam ring sliding surface, wherein the tappet recess does not contact the cam ring sliding surface; and The elastically deformable portion allows the tappet to elastically deform, thereby increasing the contact area between the tappet sliding surface and the cam ring sliding surface when a load is applied to the tappet toward the cam ring; and The push rod has an annular groove as the elastically deformable portion, and the annular groove is formed on the upper surface of the push rod, which is the surface of the push rod opposite to the sliding surface of the push rod.

6. The supply pump according to claim 5, wherein the annular groove is located inside a closed curve, the closed curve being formed by a plurality of contact points connecting the peripheral edge of the tappet recess and the sliding surface of the cam ring in the elastically deformed state of the tappet.

7. Supply pump, including: Camshaft, which is configured to rotate; A cam that is eccentric to the camshaft and is configured to rotate integrally with the camshaft; A cam ring is configured to slide along the outer periphery of the cam while rotating around the camshaft without rotating. A tappet is configured to reciprocate in a direction perpendicular to the camshaft in response to rotation of the cam ring, such that the tappet slides along a cam ring sliding surface, which is the outer peripheral surface of the cam ring extending in a direction parallel to the camshaft. as well as A plunger, configured to reciprocate with the pushrod to pressurize and deliver fluid, wherein: The tappet has a tappet recess formed on a tappet sliding surface opposite to the sliding surface of the cam ring, wherein the tappet recess does not contact the sliding surface of the cam ring; and The cam ring has a stress relaxation groove formed on the non-sliding surface of the cam ring, the non-sliding surface of the cam ring extending in a direction parallel to the cam shaft and perpendicular to the sliding surface of the cam ring, wherein the stress relaxation groove extends in a direction intersecting the axial direction of the plunger, and the stress relaxation groove is configured to relax the transmission of stress applied in the axial direction of the plunger.

8. The supply pump according to claim 7, wherein, The stress relaxation groove is one of a plurality of stress relaxation grooves formed at multiple locations, the multiple locations corresponding to four edge portions of the cam ring sliding surface, the four edge portions being located on two opposite sides in the sliding direction of the cam ring sliding surface and on two opposite sides in a direction perpendicular to the sliding direction.

9. Supply pump, including: Camshaft, which is configured to rotate; A cam that is eccentric to the camshaft and is configured to rotate integrally with the camshaft; A cam ring is configured to slide along the outer periphery of the cam while rotating around the camshaft without rotating. A tappet is configured to reciprocate in a direction perpendicular to the camshaft in response to rotation of the cam ring, such that the tappet slides along a cam ring sliding surface, which is the outer peripheral surface of the cam ring extending in a direction parallel to the camshaft. as well as A plunger, configured to reciprocate with the pushrod to pressurize and deliver fluid, wherein: The tappet has a tappet recess formed on a tappet sliding surface opposite to the sliding surface of the cam ring, wherein the tappet recess does not contact the sliding surface of the cam ring; and The cam ring has a cooling recess formed in at least one of two opposite ends of the cam ring sliding surface in the sliding direction of the cam ring sliding surface, wherein the cooling recess is configured to receive fluid to cool the cam ring sliding surface.

10. The supply pump of claim 9, wherein the cooling recess is located on one side of the cam ring sliding surface centered in the sliding direction, the side being the side toward which the tappet slides along the cam ring sliding surface when the plunger moves toward the camshaft.

11. The supply pump according to claim 9 or 10, wherein the cooling recess is formed only inside the contact area of ​​the sliding surface of the cam ring that contacts the pushrod, and the contact area extends in a direction perpendicular to the sliding direction of the sliding surface of the cam ring.

12. The supply pump according to claim 9 or 10, wherein the cooling recess is formed by an inclined surface of the cam ring sliding surface, the inclined surface extending along the entire range of the cam ring sliding surface in a direction perpendicular to the sliding direction.

Images