Patent Application
20110158835
1. Field of the Invention
The invention relates to a roller lifter that contacts through a roller a cam reciprocating a member for pumping a liquid in a liquid pump such as a high-pressure fuel pump configuring a fuel supply system of an automobile engine, a method of producing the roller lifter and a liquid pump.
2. Description of the Related Art
Roller lifters (roller tappets) that contact a member for pumping a liquid with a reciprocating cam through a roller have conventionally been used as lifters (also referred to as tappets) provided in liquid pumps such as high-pressure fuel pumps composing fuel supply systems of automobile engines, for example. More specifically, this type of liquid pump as described above is provided with a member for pumping a liquid in the form of a plunger and a cam that causes the plunger to reciprocate by rotating. The plunger is urged in the direction of reciprocation that faces the cam by an elastic member such as a coil spring. Namely, liquid pumps provided with a roller lifter are composed in the form of plunger drive pumps that pump a liquid by causing a plunger, which is urged toward a cam that rotates centering about a prescribed axis of rotation, to reciprocate by rotation of the cam. In this configuration, the roller lifter is interposed between the plunger and the cam.
In addition to supporting one end of the plunger, the roller lifter contacts the cam while urged toward the cam by an elastic member for urging the plunger. In other words, the plunger is urged in the direction facing the cam mediated by the roller lifter together with receiving rotation of the cam. Thus, the roller lifter reciprocates together with the plunger accompanying rotation of the cam. The roller lifter is mediated by a rotating body in the form of a roller during contact with the cam.
The roller in the roller lifter is in a state in which the mutual outer peripheral surface thereof contacts the cam while being supported so that the direction of the axis of rotation is the same as that of (parallel to) the cam. While in this state, the roller moves in the direction of reciprocating motion of the plunger mediated by the roller lifter, namely in the direction opposing the urging force applied by an elastic member of the plunger, and in the opposite direction thereof (direction in which urged by the elastic member). Here, the roller in contact with the cam rotates by frictional force and so forth in response to rotation of the cam.
This type of roller lifter has a portion that holds the roller that contacts the cam, and a portion that forms guide surfaces that guide reciprocating motion of the roller lifter by contacting a prescribed sliding surface formed by a member, for example, that houses the plunger. According to this type of roller lifter, frictional force accompanying cam rotation at contacting portions of the roller lifter and the cam is absorbed by rotation of the roller, thereby reducing wear of the contacting portions.
An example of a technology relating to a roller lifter is disclosed in Japanese Patent Application Publication No. 9-125915 (JP-A-9-125915). JP-A-9-125915 discloses a configuration containing a hollow body made of a pressed sheet metal material, and a block housed in the body having a cylindrical bearing surface that houses a roller. In this configuration, the body configures a portion that forms guide surfaces, and the block configures a portion that holds the roller.
In JP-A-9-125915, the portion that forms the guide surfaces and the portion that holds the roller in the roller lifter are composed by different members. In other words, the roller lifter of JP-A-9-125915 has a structure in which a plurality of members containing the body and the block are assembled. Consequently, the number of constituent parts and the number of production steps increase, thereby resulting in increased costs.
In addition, some typical conventional roller lifters are produced by cold forging. More specifically, after forming a rod-shaped (cylindrical) material by cold forging, the material is formed into a prescribed shape by machining. In other words, portions having a prescribed shape in the roller lifter, such as the portion that holds the roller, the portion that forms the guide surfaces, and the portion that supports the plunger, are formed by machining a material formed by cold forging.
In this manner, according to a roller lifter produced by cold forging, although the number of constituent parts is less than the previously described configuration of JP-A-9-125915, numerous machining steps are required after cold forging. Namely, since there are limitations on the shapes that can be formed by cold forging, it is difficult to form portions having a prescribed shape such as the portion that holds the roller by cold forging alone. Thus, since cold forging only enables parts to be formed to a shape that is far removed from a final target shape (finished product shape), cold forging requires numerous machining steps. Consequently, the number of production steps increases resulting in increased costs.
In addition, it is difficult to realize both lightweight and reduced costs in the case of a roller lifter produced by cold forging. Namely, since there are limitations on the shapes that can be formed by cold forging as previously described, a relatively large surplus portion (surplus material) remains in the material after forming, and that surplus material serves to impair weight reduction of the finished product. Although this surplus material can be removed by increasing the number of machining steps, an increase in the number of machining steps results an increased costs.
On the other hand, there are cases in which a rotation stopper in the form of a portion having a shape for preventing rotation of the roller lifter is provided in the roller lifter for preventing rotation of a roller lifter in which the direction of reciprocating motion of the roller lifter is the direction of the axis of rotation. In other words, the rotation stopper is a portion having a shape for preventing relative rotation of the roller lifter with respect to a member in which a reciprocating roller lifter is enclosed. The rotation stopper is provided from the viewpoint of maintaining urging of the roller to contact the cam and preventing uneven wear at contacting portions of the roller and cam.
It is difficult to form such a rotation stopper by cold forging since there are limitations on the shapes that can be formed by cold forging as previously described. Therefore, there are cases in which it is necessary to provide a separate member from the material formed by cold forging in order to provide a rotation stopper in the roller lifter. In such cases, both production steps and costs increase due to the need for machining steps for fabricating the separate member and forming a portion having a shape corresponding to the separate member (such as a hole) in the material after forming.
With the foregoing in view, the invention provides a roller lifter that allows portions having a prescribed shape, such as a portion that holds a roller, to be formed from an integral material by press forming or other sheet metal forming, and which together with being able to considerably reduce both the number of production steps and cost, enables a compact and lightweight structure to be easily realized, a method of producing the roller lifter, and a liquid pump provided with the roller lifter.
Therefore, according to one aspect of the invention, a roller lifter is provided having a roller that is rotatably supported and a body that supports the roller, wherein the body has: a base portion in the form of a flat plate; a roller holding portion in the form of a pair of opposing plate-shaped portions that are formed by bending towards one of plate surfaces of the base portion, the roller holding portion being configured to hold the roller between the plate-shaped portions; and a guide portion in the form of a plate-shaped portion formed by bending towards the other one of the plate surfaces of the base portion and also formed by curving so that the plate-shaped portion follows a cylindrical surface shape in which a direction perpendicular to the plate surface of the base portion is the axial direction of the cylinder, the guide portion being configured to form a guide surface in a shape that follows the cylindrical surface shape.
In addition, in the above-mentioned roller lifter, the body is preferably also provided with a rotation stopper in the form of a plate-shaped portion that is movably enclosed in a guide member having a surface of contact with the guide surfaces and protrudes from the body towards the outside of the cylindrical surface shape in the radial direction, the rotation stopper being configured to prevent relative rotation, with respect to the guide member, of the body having the axial direction of the cylinder as the direction of the axis of rotation, by engaging with the guide member.
In addition, in the above-mentioned roller lifter, the rotation stopper is provided in the form of a portion that is formed by bending at an end portion at least either in a direction of one of the plate surfaces or the other one of the plate surfaces in a plate-shaped portion that constitutes the guide portion.
In addition, in the above-mentioned roller lifter, the rotation stopper is also preferably provided in the form of an extending portion extending from the base portion.
In addition, in the above-mentioned roller lifter, the plate-shaped portion that configures the guide portion has end portions that mutually make contact in the circumferential direction with respect to the cylindrical surface shape.
In addition, the plate-shaped portion that configures the guide portion also preferably has a gap between end portions in the circumferential direction with respect to the cylindrical surface shape.
In addition, in the above-mentioned roller lifter, the guide portion is a portion that is elongated from the plate-shaped portion that configures the guide portion in the direction toward one of the plate surfaces, the guide portion further having an extending portion that causes the guide surface to extend in the direction of one of the plate surfaces.
In addition, in the above-mentioned roller lifter, if the length of the extending portions is roughly equal to the width of the plate-shaped portion, inclination of the orientation of the roller lifter during reciprocating motion of the roller lifter is inhibited, thereby making this preferable.
According to a different aspect of the invention, in a method of producing a roller lifter having a roller that is rotatably supported, a method of producing a roller lifter is provided that includes: a material preparation step of preparing a material in the form of a flat plate having a first portion that configures a base portion in the form of a flat plate, a second portion which is in the form of a pair of portions that protrude from the first portion in mutually opposite directions, and which configures a roller holding portion that holds the roller therebetween in an opposed state, and a third portion which is in the form of a portion that protrudes from the first portion in at least a direction that intersects the protruding direction of the second portion, and which configures a guide portion that forms a guide surface of a shape that follows a cylindrical surface shape in which a direction perpendicular to the plate surfaces of the base portion is the axial direction of the cylinder; a first forming step of forming the roller holding portion by bending the second portion towards one of the plate surfaces of the material with respect to the first portion; and a second forming step of forming the guide portion by bending the third portion towards the other one of the plate surfaces of the material with respect to the first portion and curving so that the guide portion follows the cylindrical surface shape.
In addition, in the above-mentioned method of producing a roller lifter,
the second forming step preferably further forms a protruding portion that protrudes towards the outside of the cylindrical surface shape in the radial direction in order to function as a rotation stopper for preventing relative rotation, with respect to the guide portion, of the body having the axial direction of the cylinder as the direction of the axis of rotation, by engaging with the guide member.
In addition, in the above-mentioned method of producing a roller lifter, if the first forming step and the second forming step are all carried out by press forming, the number of production steps and costs can be reduced, thereby making this preferable.
In addition, in the above-mentioned method of producing a roller lifter, the body of the roller lifter is preferably formed from an integrated plate-shaped material having the first portion, the second portion and the third portions.
In addition, a liquid pump is provided having the above-mentioned roller lifter or a roller lifter produced according to the above-mentioned method of producing a roller lifter, and the liquid pump is further provided with a plunger that pumps a liquid by reciprocating motion; a cam that reciprocates the plunger by rotating; and an elastic member that urges the plunger in a direction of the reciprocating motion toward the cam, wherein the roller lifter supports the plunger by means of the base portion, and contacts the cam through the roller in a state of being urged in the direction toward the cam by the elastic member.
The invention demonstrates the following effects. Namely, according to the invention, with respect to a roller lifter provided with a rotatably supported roller, since portions having a prescribed shape, such as a portion that holds the roller, can be formed by sheet metal forming such as press forming from an integral material, the number of production steps and costs can be reduced considerably and a compact and lightweight structure can be realized easily.
The features, advantages, and technical and industrial significance of this invention will be described in the following detailed description of example embodiments of the invention with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:
The invention attempts to form a body having a portion of a prescribed shape such as a portion that supports a roller in a roller lifter by sheet metal forming such as press forming by contriving the sheet-like shape of a flat sheet-shaped material capable of being press formed. The following provides an explanation of embodiments of the invention. Furthermore, in the embodiments explained below, explanations are provided for the case of the roller lifter as claimed in the invention being applied to a high-pressure fuel pump composing a fuel supply system of an automobile engine.
First, an explanation is provided of a high-pressure fuel pump 1 as claimed in a first embodiment using
Fuel inside the fuel tank 2 is suctioned up by a feed pump 7 and delivered towards the low-pressure fuel path 5. The feed pump 7 is provided in a state of being connected to the low-pressure fuel path 5 within the fuel tank 2. A check valve 8 is provided in the high-pressure fuel path 6 for preventing backflow of fuel delivered from the high-pressure fuel pump 1. Fuel that has been pumped from the high-pressure fuel pump 1 to the delivery pipe 3 through the high-pressure fuel path 6 is injected accompanying drive control of the injector 4 and then supplied in prescribed aliquots to the combustion chamber of each cylinder of an engine.
A relief path 10 is connected to the delivery pipe 3 via a relief valve 9. The relief path 10 communicates with the fuel tank 2. The relief valve 9 is a pressure control valve that controls pressure by allowing a portion of the fuel to escape when the fuel pressure has become equal to or greater than a set pressure. Thus, when the fuel in the delivery pipe 3 reaches a set pressure, the relief valve 9 is opened and a portion of the fuel inside the delivery pipe 3 passes through the relief path 10 and is returned to the fuel tank 2. A fuel supply device is configured in an automobile engine by employing a configuration that contains the high-pressure fuel pump 1 in this manner.
The high-pressure fuel pump 1 is provided with a plunger 11, a cam 12, a coil spring 13 and a roller lifter 20. The plunger 11 pumps liquid in the form of fuel by reciprocating. The plunger 11 is provided inserted in a cylinder 14 possessed by the high-pressure fuel pump 1 while able to reciprocate. The cylinder 14 is a portion that is formed in the form of an opening in a body 15 that composes the body portion of the high-pressure fuel pump 1.
A pressurizing chamber 16 is formed within the body 15. The pressurizing chamber 16 is formed by the inner wall surfaces of the body 15 that form a spatial portion that communicates with the cylinder 14, and the end surface and the like on one end of the plunger 11. The pressuring chamber 16 communicates with the low-pressure fuel path 5 via an intake port 15a formed in the body 15, and communicates with the high-pressure fuel path 6 via a delivery port 15b similarly formed in the body 15.
A solenoid spill valve 17 is provided in the intake port 15a. Namely, when the solenoid spill valve 17 is open, the low-pressure fuel path 5 and the pressurizing chamber 16 communicate and fuel that has passed through the low-pressure fuel path 5 is introduced into the pressurizing chamber 16 through the solenoid spill valve 17. On the other hand, when the solenoid spill valve 17 is closed, the low-pressure fuel path 5 and the pressurizing chamber 16 are isolated, and introduction of fuel into the pressurizing chamber 16 is interrupted.
The solenoid spill valve 17 has a solenoid coil 17a, a valve body 17b and a coil spring 17c, and the solenoid spill valve 17 is switched between open and closed based on whether or not power is supplied thereto. More specifically, when power is not supplied to the solenoid coil 17a, the valve body 17b is moved away from the intake port 15a (seat portion formed in the opening thereof) by urging force of the coil spring 17c, or in other words, the solenoid spill valve 17 is open. On the other hand, when power is supplied to the solenoid coil 17a, the valve body 17b blocks the intake port 15a (covers the seat portion thereof) in opposition to the urging force of the coil spring 17c, or in other words, the solenoid spill valve 17 is closed.
As a result of the solenoid spill valve 17 being closed at the timing at which the reciprocating plunger 11 moves toward the pressuring chamber 16 (upper side in
The cam 12 causes the plunger 11 to reciprocate by rotating. The cam 12 is formed on a camshaft 12a rotatably supported at a prescribed position. Thus, the cam 12 integrally rotates with the camshaft 12a, having a common location for the center of the axis of rotation therewith, accompanying rotation of the camshaft 12a. The cam 12 has two cam noses 12b separated by an angle of 180° about the center of the axis of rotation of the camshaft 12a. The plunger 11 reciprocates (see arrow A2) due to rotation of the cam 12 (see arrow A1) accompanying rotation of the camshaft 12a.
The coil spring 13 functions as an elastic member for urging the plunger 11 in the reciprocating direction that faces the cam 12 (to be referred to as the “cam direction”). The coil spring 13 is provided so that the central axis thereof coincides with the axial center of the plunger 11. One end of the coil spring 13 is supported by the body 15 via a spring seat 13a.
The roller lifter 20 is interposed between the plunger 11 and the cam 12. The roller lifter 20 supports one end of the plunger 11 and contacts the cam 12 while in the state of being urged in the cam direction by the coil spring 13 for urging the plunger 11. Consequently, the other end of the coil spring 13, of which one end is supported by the body 15 as previously described, is supported by the roller lifter 20 as a result of being mediated directly by the roller lifter 20 or by another member such as a seat member.
In other words, as a result of being mediated by the roller lifter 20, the plunger 11 receives rotation of the cam 12 together with being urged in the cam direction. Thus, the roller lifter 20 reciprocates with the plunger 11 accompanying rotation of the cam 12. The roller lifter 20 is mediated by a rotating body in the form of a roller 21 during contact with the cam 12. Consequently, the roller lifter 20 is provided with the rotatably supported roller 21 and a body 30 that supports the roller 21.
In the roller lifter 20, the roller 21 is in a state in which the outer peripheral surface thereof is in contact with the outer peripheral surface of the cam 12 when supported such that the direction of the axis of rotation is the same as (parallel to) that of the cam 12. While in this state, plunger 11 mediated by the roller lifter 20 reciprocates accompanying rotation of the cam 12, or in other words, moves in the direction in opposition to the urging force applied by the coil spring 13 of the plunger 11 (upward direction in
Movement (reciprocating motion) of the roller lifter 20 is guided by a lifter guide 18. The lifter guide 18 is a cylindrical member in which the roller lifter 20 is installed, and of which one end is supported while fixed to the body 15. Thus, the roller lifter 20 reciprocates within the lifter guide 18 mediated by the body 30 while in contact with an inner peripheral surface 18a of the lifter guide 18.
As has been described above, in a high-pressure fuel pump 1 as claimed in the first embodiment, the roller lifter 20 provided with the roller 21 and the body 30 is present between the plunger 11 and the cam 12. The following provides a detailed explanation of the configuration of the roller lifter 20.
As was previously described, the roller lifter 20 is provided with the roller 21 and the body 30. The body 30 is a member configured by bending an integral flat plate-shaped material. As shown in
The base portion 31 is a flat plate-shaped portion. The base portion 31 serves as a portion that is contacted by one end of the plunger 11 in the state in which the roller lifter 20 is interposed between the plunger 11 and the cam 12. More specifically, in the base portion 31, one plate surface (upper surface in
The roller holding portion 32 consists of a pair of opposing plate-shaped portions formed by bending one of the plate surfaces (plate surface opposite from the plunger contact surface 31a) of the base portion 31. Thus, the roller holding portion 32 has a pair of opposing plate-shaped portions in the form a pair of supporting plates 32a. The supporting plates 32a are portions that extend downward from a pair of opposing side edges of the roughly rectangular shaped base portion 31 as previously described in a direction roughly perpendicular to the plate surface of the base portion 31. In other words, the pair of supporting plates 32a is opposed roughly in parallel. In the first embodiment, the supporting plates 32a have a roughly rectangular shape in which the corners of the distal end (lower side) thereof are beveled.
The roller holding portion 32 holds the roller 21 between the pair of supporting plates 32a. Namely, the roller holding portion 32 rotatably supports the roller 21 in a state in which the roller 21 is clamped by the two opposing supporting plates 32a. Thus, in the roller holding portion 32, the opposing direction of the supporting plates 32a (vertical direction in
The roller 21 has a cylindrical external shape as previously described, and the outer peripheral surface thereof is the surface that contacts the cam 12 (to be referred to as the “cam contact surface 21a”). The roller 21 has a shaft supporting portion 22 that has the rotating shaft of the roller 21, and a portion that composes the outer peripheral portion of the roller 21 and forms the cam contact surface 21a in the form of an outer peripheral portion 23. In other words, the roller 21 is held in a state of being supported between the shaft supporting portion 22 and the supporting plates 32a in the roller holding portion 32. Here, the supporting holes 32b possessed by the supporting plates 32a are used to support the shaft supporting portion 22.
In the roller 21, a roller bearing is suitably composed by the shaft supporting portion 22 and the outer peripheral portion 23. Namely, in the case a roller bearing is composed by the shaft supporting portion 22 and the outer peripheral portion 23, although not shown in the drawings, a plurality of rolling bodies are contained while allowing to roll freely between the shaft supporting portion 22 and the outer peripheral portion 23. More specifically, in the case where a plurality of spheres are contained as rolling bodies, a roller bearing is composed in the form of a ball bearing and a plurality of needle-shaped bodies are contained as rolling bodies, the roller bearing is composed in the form of a needle bearing. However, there are no particular limitations on the configuration of the roller 21. The configuration of the roller 21 may also be, for example, a configuration in which an integral member is rotatably axially supported in the roller holding portion 32 (configuration in which the shaft supporting portion 22 and the outer peripheral portion 23 rotate integrally).
The guide portion 33 is a plate-shaped portion that is formed by bending the other plate surface of the base portion 31 (plate surface opposite from the one of the plate surfaces previously described, namely the plunger contact surface 31a), and curving so as to follow a cylindrical surface shape in which the direction perpendicular to the plate surface of the base portion 31 is the axial direction of the cylinder. The guide portion 33 has curved plate-shaped portions in the form of curved portions 33a. The curved portions 33a are portions that extend upward while having coupling portions 33b interposed between the curved portions 33a and the base portion 31. In other words, the coupling portions 33b are portions that connect the curved portions 33a with the base portion 31, and are curved portions of the guide portion 33 with respect to the base portion 31.
In the first embodiment, the guide portion 33 has a pair of curved portions 33a. This pair of curved portions 33a is opposed in a direction that intersects the direction in which the supporting plates 32a that compose the roller holding portion 32 are opposed. In other words, the pair of curved portions 33a extend upward mediated by the coupling portions 33b from another opposing pair of side edges other than the pair of opposing side edges from which the supporting plates 32a extend in the roughly rectangular base portion 31.
The cylindrical surface shape that is followed when the curved portions 33a composing the guide portion 33 are curved has a direction perpendicular to the plate surface of the base portion 31, namely the vertical direction, as the axial direction of the cylinder. In addition, the cylindrical surface shape followed by the curved portions 33a is such that the position of the cylinder axis (central axis) is roughly the center position of the base portion 31. Namely, the cylindrical surface shape followed by the curved portions 33a is represented by a circle C2 indicated with a double dot broken line having for the center point thereof a point C1 located roughly in the center of the base portion 31 in the overhead view (planar view) of the roller lifter 20 shown in
In the first embodiment, the pair of opposing curved portions 33a are formed to have a mutually linearly symmetrical shape in the view along the direction of the axis of rotation of the roller 21 shown in
The guide portion 33 forms guide surfaces 34 of a shape that follows the cylindrical surface shape. The guide surfaces 34 are formed by the outer peripheral surfaces of the curved portions 33a that compose the guide portion 33. Namely, plate-shaped portions that follow the cylindrical surface shape as previously described in the form of the outer peripheral surfaces of the curved portions 33a partially have the shape of a cylindrical surface. Therefore, the outer peripheral surfaces of the curved portions 33a serve as the guide surfaces 34 formed by the guide portion 33.
In the overhead view shown in
The guide surfaces 34 contact the inner peripheral surface 18a of the lifter guide 18 in the state in which the roller lifter 20 is contained within the lifter guide 18 (see
The roller lifter 20, provided with the configuration described above, supports the plunger 11 from one end with the base portion 31 having the plunger contact surface 31a between the plunger 11 and the cam 12, and contacts the cam 12 mediated by the roller 21 having the cam contact surface 21a while being urged in the direction of the cam by the coil spring 13. The roller lifter 20 reciprocates (slides) within the lifter guide 18 in the state in which the guide surfaces 34 are in contact with the inner peripheral surface 18a of the lifter guide 18 accompanying rotation of the cam 12. The plunger 11 then reciprocates accompanying this reciprocating motion.
In addition, a rotation stopper is provided for the roller lifter 20 of the first embodiment. The rotation stopper employs a configuration for preventing rotation relative to the lifter guide 18 of the roller lifter 20 having the direction of reciprocating motion of the roller lifter 20 (vertical direction) as the direction of the axis of rotation (to be referred to as “relative rotation”). An example of a configuration employed for the rotation stopper in the first embodiment is described below.
As shown in
More specifically, as shown in the overhead view of
Consequently, as shown in the overhead of
The rotation stopper bar 24 is provided in a state of being inserted into an insertion hole 18b formed in the lifter guide 18. The insertion hole 18b is formed corresponding to the direction of the rotation stopper bar 24 relative to the roller lifter 20 in the state of being contained in the lifter guide 18. Thus, as shown in the overhead view of
In this manner, the relative rotation of the roller lifter 20 is restricted by the rotation stopper bar 24 provided with respect to the lifter guide 18. More specifically, relative rotation of the roller lifter 20 is restricted since outside corners (outside of the cylindrical surface shape) formed on the ends of the pair of curved portions 33a in the portion of the gap C3 present between the ends of the both curved portions 33a make contact with the rotation stopper bar 24.
Continuing, an explanation is provided of a method of producing the roller lifter 20. The production method as claimed in the first embodiment is a method of producing the roller lifter 20 provided with a rotatably supported roller 21 that includes a step for preparing a flat plate-shaped material (to be referred to as a “material preparation step”), a step for forming the roller holding portion 32 (to be referred to as a “first forming step”) and a step for forming the guide portion 33 (to be referred to as a “second forming step”).
In the material preparation step, as shown in
The first portion 41 composes the flat plate-shaped base portion 31. Thus, the first portion 41 is a portion that fauns the central portion of the plate-shaped material 40 over a range corresponding to the roughly rectangular base portion 31. The plate surface on one side of the first portion 41 (front side in
The second portion 42 consists of a pair of portions that protrude from the first portion 41 in mutually opposite directions. More specifically, as shown in
The projections 42a are portions corresponding to the supporting plates 32a that compose the roller holding portion 32 in the body 30 of the roller lifter 20. Thus, the projections 42a have a roughly rectangular shape in which corners on the ends in the protruding direction from the first portion 41 are beveled. Furthermore, a through hole 42b corresponding to the supporting hole 32b used to support the roller 21 is formed in each projection 42a.
The second portion 42 in the form of the pair of projections 42a composes the roller holding portion 32 that holds the roller 21 mutually there between in an opposed state. Namely, the pair of projections 42a are made to be in a mutually opposed state by bending to the back side with respect to the first portion 41. The roller 21 is then rotatably supported between the opposing projections 42a.
The third portions 43 are portions that protrude in a direction that intersects the protruding direction of the second portion 42 from the first portion 41. More specifically, as shown in
In the first embodiment, the plate-shaped material 40 has the third portions 43 extending in the directions of both sides (in mutually opposing directions) in the direction that intersects the direction that the second portion 42 protrudes from the first portion 41. Namely, the direction in which the second portion 42 protrudes from the first portion 41 is the horizontal direction in
The strip-like portions 43a are portions corresponding to the curved portions 33a composing the guide portion 33 in the body 30 of the roller lifter 20, while the connecting portions 43b are portions corresponding to the coupling portions 33b also composing the guide portion 33. Thus, the strip-like portions 43a have a shape such that the distal ends of the connecting portions 43b protruding from the first portion 41 protrude by approximately the same length in the direction perpendicular to the protruding direction of the connecting portions 43b (horizontal direction in
The third portions 43 compose the guide portion 33 that forms the guide surfaces 34 having a shape that follows the cylindrical surface shape having for the direction of the axis of the cylinder thereof the direction perpendicular to the plate surface of the base portion 31. Namely, since the pair of T-shaped portions composed of the strip-like portions 43a and the connecting portions 43b are bent towards the opposite side (front side) from the projections 42a in the form of the second portion 42 with respect to the first portion 41, bent portions in the form of the coupling portions 33b are formed by the connecting portions 43b. In addition, the curved portions 33a are formed by curving the strip-like portions 43a into an arcuate shape. The guide surfaces 34 are then formed by the outer peripheral surfaces of the curved portions 33a, or in other words, the back sides of the strip-like portions 43a.
In the first forming step, the roller holding portion 32 is formed by the second portion 42 being bent towards one of the plate surfaces (back side) of the plate-shaped material 40 with respect to the first portion 41. Namely, in this step, the second portion 42 in the form of the pair of projections 42a is bent towards the back side with respect to the first portion 41. Here, since the pair of projections 42a are portions that form the supporting plates 32a of the roller holding portion 32, they are bent until they are oriented in a roughly parallel opposing state.
The through holes 42b possessed by the projections 42a are used as the supporting holes 32b for supporting the roller 21, and the roller 21 is held between the projections 42a in an opposed state. In this manner, the roller holding portion 32 is formed by bending the second portion 42 in the form of the projections 42a. Bending of the second portion 42 for forming the roller holding portion 32 in this manner is carried out by sheet metal forming such as press forming.
In the second forming step, the guide portion 33 is formed by bending the third portions 43 towards other plate surface of the plate-shaped material 40 (opposite side (front side) of the side to which the second portion 42 is bent) with respect to the first portion 41 and curving so as to follow the cylindrical surface shape. Namely, the third portions 43 composed of the strip-like portions 43a and the connecting portions 43b are bent towards the front side with respect to the first portion 41 from the portion of the connecting portions 43b. In addition, in this step, the strip-like portions 43a of the third portions 43 are curved so as to have an arcuate shape. Here, since the pair of strip-like portions 43a are portions that form the curved portions 33a of the guide member 33, they are curved so as to follow a common cylindrical surface shape.
In this manner, the guide portion 33 that forms the guide surfaces 34 is formed by bending the third portions 43 from the portions of the connecting portions 43b and curving the strip-like portions 43a. Bending and curving of the third portions 43 for forming the guide portion 33 in this manner are carried out by sheet metal forming such as press forming.
As has been described above, the roller lifter 20 of the first embodiment is produced by a production method that includes the material preparation step, the first forming step and the second forming step. Furthermore, there are no particular limitations on the chronological order in which the first forming step and the second forming step are carried out. In other words, the first forming step and the second forming step may be carried out with either step carried out first or they may be carried out simultaneously.
In addition in the first embodiment, in plate-shaped material 40 although the third portions 43 in the form of portions composed of the strip-like portions 43a and the connecting portions 43b protrude in the directions of both sides from the first portion 41 (vertical direction on both sides in
Namely, as shown in
According to the roller lifter 20 and the production method of the roller lifter 20 as described above, portions having a prescribed shape such as the roller holding portion 32 of the roller lifter 20 provided with a rotatably supported roller 21 can be formed by sheet metal forming such as press forming from an integral material in the form of the plate-shaped material 40, thereby making it possible to considerably produce the number of production steps and costs while also easily realizing a compact and lightweight structure.
Namely, in the roller lifter 20 of the first embodiment, portions having a prescribed shape such as the roller holding portion 32 and the guide portion 33 are formed by forming the integral plate-shaped material 40 by sheet metal forming such as press forming for the portion of the body 30 that supports the roller 21. In other words, the body 30 is formed to nearly a final target shape (finished product shape) by sheet metal forming such as press forming only. Consequently, the number of machining steps can be reduced considerably thereby resulting in an accompanying significant reduction in costs.
In addition, since the body 30 is formed by sheet metal forming from the integral plate-shaped material 40, there is less likelihood of surplus material remaining on the body 30, thereby making it possible to achieve a compact structure and light weight. Consequently, the roller lifter 20 can easily be made compact and lightweight.
The following provides an explanation of effects brought about by the roller lifter 20 of the first embodiment in comparison with the related art.
More specifically, as shown in
Consequently, when producing the roller lifter 120, numerous machining steps are required to form portions having a prescribed shape such as the roller holding portion 132 required in the body 130. Namely, since there limitations on the shapes that can be formed by cold forging, cold forging only enables parts to be formed to a shape that is far removed from a final target shape (finished product shape), and numerous machining steps are required after cold forging.
In addition, in the roller lifter 120 as claimed in this example, a rotation stopper pin 125 is used as a rotation stopper in the form of a separate member from the members that compose the body 130. The rotation stopper pin 125 forms a projecting portion in the guide surface 134 by being press-fit into the guide surface 134 of the body 130. The projecting portion formed by this rotation stopper pin 125 fits into a groove and the like formed in the inner peripheral surface of a member in which the roller lifter 120 is contained (refer to the above-mentioned lifter guide 18). In other words, the roller lifter 120 is subjected to an action that stops rotation by the projecting portion formed by the rotation stopper pin 125 that engages from the inside with the member in which the roller lifter 120 is contained.
According to this rotation stopper, it is necessary to produce the rotation stopper pin 125 as a separate member from the members that compose the body 130 as well as a machining step for forming a portion having a shape (such as press-fitting hole) that corresponds to the rotation stopper pin 125 in the body 130.
In this manner, in the related art as demonstrated by the roller lifter 120 claimed in this example, since numerous machining steps are required, the number of production steps increase resulting in an accompanying increase in costs. With respect to this point, according to the roller lifter 20 of the first embodiment, since portions having a prescribed shape such as the roller holding portion 32 in the body 30 are formed by sheet metal forming such as press forming, and since machining of the body 30 (such as drilling) is not required for composing a rotation stopper, additional machining following sheet metal forming is not required. Consequently, both the number of production steps and costs can be reduced considerably.
The following provides an explanation of other embodiments of the roller lifter 20. Furthermore, in each of the embodiments explained below, the same reference numerals are used for the sake of convenience to indicate those portions that are in common with the portions of the first embodiment, and explanations thereof are omitted.
The following provides an explanation of a second embodiment of the roller lifter 20. In the roller lifter 20 of the second embodiment, a rotation stopper 35 is provided in the body 30 as shown in
Namely, as shown in
In addition, the rotation stopper 35 prevents rotation relative to the lifter guide 18 of the body 30 (the previously described relative rotation), having for the direction of the axis of rotation thereof the coaxial direction with respect to the guide member 33 (direction perpendicular to the plate surface of the base portion 31 (vertical direction)), by engaging with the lifter guide 18. Here, the lifter guide 18 functions as a guide member having a contact surface with the guide surfaces 34 in the form of the inner peripheral surface 18a. In other words, the body 30 is movably contained within the lifter guide 18.
More specifically, as shown in
In the roller lifter 20 of the second embodiment, the rotation stopper 35 is provided in the form of a portion that is formed by bending at the end in the direction of the other plate surface (upward direction) in the plate-shaped portion that composes the guide portion 33. Namely, the rotation stopper 35 in the form of the upper protruding piece 36 is provided as a portion that is formed by bending at the upper edge that is the upper end of one of the curved portions 33a serving as plate-shaped portions that compose the guide portion 33. Furthermore, in the second embodiment, although the rotation stopper 35 is provided at one location in the body 30, it may also be provided at a plurality of locations. In the case a plurality of the rotation stoppers 35 are provided, the plurality of rotation stoppers 35 are provided at prescribed intervals in the circumferential direction of the body 30.
In the second embodiment, with respect to the production method of the roller lifter 20, the plate-shaped material 40 prepared in the material preparation step has a portion that forms the rotation stopper 35. More specifically, as shown in
The protruding piece 46 is provided on the strip-like portion 43a of one of the third portions 43 (upper side in
In the second forming step as previously described, the upper protruding piece 36 is formed in the form of the rotation stopper 35 in the body 30 by curving one of the strip-like pieces 43a, which forms the one of the curved portions 33a of the guide member 33, together with bending the protruding piece 46 to the outside in the radial direction. Bending of the protruding piece 46 to form the rotation stopper 35 in this manner is carried out in the second forming step by sheet metal forming such as press forming for forming the guide portion 33. In other words, the step for forming the rotation stopper 35 is included in the second forming step. However, the step for forming the rotation stopper 35 may also be a separate step from the first forming step for forming the plate-shaped material 40 and the second forming step.
According to the roller lifter 20 and the production method of the roller lifter 20 of the second embodiment, the number of production steps and costs can be further reduced. Namely, since a rotation stopper can be integrally formed, a separate member such as the rotation stopper pin 24 (see
Moreover, processing for composing the rotation stopper can be easily carried out with greater accuracy in comparison with the case of the first embodiment. In other words, in the second embodiment, processing for forming the groove 18c with respect to the upper protruding piece 36 can be carried out with comparatively greater accuracy than processing for forming the insertion hole 18b for the rotation stopper bar 24 in the case of the first embodiment.
The following provides an explanation of a third embodiment of the roller lifter 20. As shown in
The lower protruding piece 37 is formed by cutting out a portion of the body 30 extending from the base portion 31 to one of the curved portions 33a through one of the coupling portions 33b of the guide member 33 (base of the guide portion 33 with respect to the base portion 31) together with bending to the outside in the radial direction. In other words, the rotation stopper 35 in the form of the lower protruding piece 37 is provided in the form of a portion that is cut out from the base of the guide portion 33 relative to the base portion 31 and then bent to the outside in the radial direction. Thus, a notch 37a is present in a portion extending from the base portion 31 to one of the curved portions 33a through one of the coupling portions 33b in the form of a portion where the lower protruding piece 37 has been cut out.
The lower protruding piece 37 is formed in the form of a portion in which the base side thereof is connected to the portion of one of the curved portions 33a in the body 30. In the third embodiment, the lower protruding piece 37 has a shape such that the distal end thereof becomes wider as shown in the drawings. However, there are no particular limitations on the shape of the lower protruding piece 37 provided it allows the strength of the body 30 to be secured in the roller lifter 20 at the base portion 31 and the guide portion 33 in the state in which the lower protruding piece 37 is formed (state in which the notch 37a is present). The lower protruding piece 37 formed in this manner is fit into the groove 18c of the lifter guide 18 (see
As shown in
According to the roller lifter 20 of the third embodiment, the rotation stopper 35 can be provided without increasing the length of the body 30 in the vertical direction in comparison with the second embodiment. In other words, since the rotation stopper 35 in the third embodiment is positioned at an intermediate portion of the body 30 in the vertical direction (portion between the upper end of the body 30 (lower end of the guide portion 33) and the lower end of the body 30 (lower end of the roller holding portion 32)), there is no effect on the length of the body 30 in the vertical direction. In other words, the length of the body 30 in the vertical direction can be shortened by an amount resulting from the absence of the upper protruding piece 36 on the upper end of the body 30 as in the second embodiment.
Since the length of the body 30 in the vertical direction can be shortened, the entire roller lifter 20 can be reduced in size. As a result, the size of the high-pressure fuel pump 1 can also be reduced, making it possible to lower the installation height of the high-pressure fuel pump 1 in an engine. In addition, since the rotation stopper 35 does not affect the length of the body 30 in the vertical direction, the length in the vertical direction of the guide surfaces 34 formed by the guide portion 33 in the body 30 can conversely can easily be increased. The guideability of the roller lifter 20 by the guide surfaces 34 is improved by increasing the length in the vertical direction of the guide surfaces 34.
Furthermore, the upper protruding piece 36 of the second embodiment may also be provided for the rotation stopper 35 in addition to the lower protruding piece 37. In other words, in the case of providing a plurality of rotation stoppers 35 as previously described, together with providing the upper protruding piece 36 at the upper end of one of the curved portions 33a of the guide portion 33, the lower protruding piece 37 may be provided at the lower end of the same curved portion 33a. In other words, the rotation stopper 35 is provided in the form of a portion formed by at least bending at the end in the direction of one of the plate surfaces (lower direction) and the direction of the other plate surface (upper direction) in one of the plate-shaped portions (curved portions 33a) that compose the guide portion 33.
The following provides an explanation of a fourth embodiment of the roller lifter 20. As shown in
The extending piece 38 is formed in the form of a portion in which a portion of one of the curved portions 33a and the coupling portions 33b is cut out from the guide portion 33. In other words, the rotation stopper 35 in the form of the extending piece 38 is provided in the form of a portion that is cut out at a portion of one of the curved portions 33a and coupling portions 33b together with being bent to the outside in the radial direction. Thus, a notch 38a is present in the portion of one of the curved portions 33a and coupling portions 33b in the form of a portion where the extending piece 38 has been cut out.
The extending piece 38 is formed in the form of a portion in which the base side (side opposite from the distal end protruding to the outside in the radial direction) is connected to the portion of the base portion 31 in the body 30. In the fourth embodiment, the extending piece 38 has a shape such that the distal end thereof becomes wider as shown in the drawings. However, there are no particular limitations on the shape of the extending piece 38 provided it allows the strength of the body 30 to be secured in the roller lifter 20 at the guide portion 33 in the state in which the extending piece 38 is formed (state in which the notch 38a is present). The extending piece 38 formed in this manner is fit into the groove 18c of the lifter guide 18 (see
As shown in
The same effects as the third embodiment are obtained by the roller lifter 20 of the fourth embodiment. Furthermore, although the rotation stopper 35 is provided in the form of the extending piece 38 as a portion that extends from the base portion 31 by cutting out a portion of one of the third portions 43 that compose the guide portion 33, the rotation member is not limited thereto. In other words, the rotation stopper 35 may also be provided by cutting out a portion of the second portion 42 that composes the roller holding portion 32.
The following provides an explanation of a fifth embodiment of the roller lifter 20. As shown in
Thus, in the roller lifter 20 of the fifth embodiment, in comparison with the roller lifter 20 of the first embodiment, for example, the portion of the gap C3 (see
In addition, the contacting portions 33c between the opposing curved portions 33a are provided by extending each curved portion 33a to both sides in the circumferential direction by roughly the same length each, and are present at positions opposing the opposing direction of the pair of supporting plates 32a (direction of the axis of rotation of the roller 21) (see
As shown in
Furthermore, in the fifth embodiment, although the extending portions 43c are provided on both sides in the lengthwise direction of the strip-like portions 43a for each of the pair of strip-like portions 43a, the extending portions 43c are not limited thereto. In other words, the extending portions 43c may be provided only on one side in the lengthwise direction of the strip-like portions 43a, or may be provided only on one of the strip-like portions 43a among the pair of strip-like portions 43a.
In addition, although the ends of the curved portions 33a are in contact over the entire vertical direction at the contacting portions 33c in the fifth embodiment (the extending portions 43c are formed by extending the entire strip-like portions 43a in the direction of width (vertical direction in
According to the roller lifter 20 of the fifth embodiment, rigidity of the guide portion 33 is enhanced since the pair of curved portions 33a that compose the guide portion 33 are mutually supported through the contacting portions 33c. Processability of the body 30 (such as grindability of grinding carried out in the form of finishing on the guide surfaces 34) is improved by enhancing the rigidity of the guide portion 33. In addition, the withstand load of the body 30 is improved as a result of enhancing the rigidity of the guide portion 33. More specifically, withstand load is improved with respect to, for example, a load like that of the guide surfaces 34 being pressed against the inner peripheral surface 18a of the lifter guide 18 that is received by the body 30 through the roller 21 accompanying rotation of the cam 12.
The following provides an explanation of a sixth embodiment of the roller lifter 20. As shown in
The extending portions 39 are plate-shaped portions that are formed by protruding downward from the curved portions 33a serving as plate-shaped portions that compose the guide portion 33. The outer surfaces of the extending portions 39 serve as surfaces that form portions of the guide surfaces 34. In other words, the extending portions 39 form surface portions connecting to the outer peripheral surfaces of the curved portions 33a that form the guide surfaces 34, and extend the guide surfaces 34 downward. The extending portions 39 are respectively provided on both ends in the circumferential direction on each of the pair of curved portions 33a. Thus, the extending portions 39 are portions that form the above-mentioned gap C3 (see
The curved portions 39 are provided at locations that do not interfere with the roller holding portion 32 or the roller 21 by protruding downward from the curved portions 33a. As shown, for example, in the drawings of the sixth embodiment, the extending portions 39 have a length roughly equal to the width of the curved portions 33a (length in the vertical direction). In other words, the extending portions 39 of the sixth embodiment partially extend by roughly twice the width of the guide surfaces 34 (length in the vertical direction) downward, and this partially extends the width of the curved portions 33a downward by roughly twice that width.
As shown in
Furthermore, in the sixth embodiment, although the end protruding pieces 49 that form the extending portions 39 in the body 30 are provided on both sides in the lengthwise direction of the strip-like portions 43a for each of the pair of strip-like portions 43a, the end protruding pieces 49 are not limited thereto. In other words, the extending portions 39 may be provided only on one side in the circumferential direction in each curved portion 33a or may be provided only on one of the pair of curved portions 33a. In this case, in the plate-shaped material 40, the end protruding pieces 49 are provided only on one side in the lengthwise direction in the strip-like portions 43a or are provided only on one of the pair of strip-like portions 43a.
According to the roller lifter 20 of the sixth embodiment, the guide surfaces 34 can be lengthened in the vertical direction without increasing the length in the vertical direction of the body 30. As a result, since the guiding length of the roller lifter 20 by the guide surfaces 34 (contact surfaces of the guide surfaces 34 with the inner peripheral surface 18a of the lifter guide 18) is increased, the orientation of the roller lifter 20 that reciprocates within the lifter guide 18 is inhibited from inclining (so-called cocking) and becomes stable within the range of the clearance.
Namely, as shown in
Each portion provided in the roller lifter 20 of each embodiment as explained thus far can be suitably combined in a single roller lifter 20. The following provides an example of such a combination in the form of a seventh embodiment of the roller lifter 20. As shown in
Namely, the roller lifter 20 of the seventh embodiment has the rotation stopper 35 in the form of an extending piece 38 in the same manner as the fourth embodiment. In addition, the roller lifter 20 of the seventh embodiment has the extending portions 39 explained in the sixth embodiment. Moreover, in the roller lifter 20 of the seventh embodiment, contacting portions 33c are provided in a state in which ends of the pair of opposing curved portions 33a are in contact in the same manner as in the fifth embodiment. Here, in the roller lifter 20 of the seventh embodiment, the contacting portions 33c are provided as a result of contact between those portions including the extending portions 39 as the ends of the curved portions 33a.
Thus, although not shown in the drawings, the plate-shaped material 40 of the seventh embodiment has a portion corresponding to the stamped out piece 48 (see
Although each of the above-mentioned embodiments of the invention has been explained by using the high-pressure fuel pump 1 (see
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-227648 | Sep 2008 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IB2009/006704 | 9/2/2009 | WO | 00 | 12/28/2010 |
