JP2015124650A - Tappet device and fuel supply pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resolve unbalance in slide resistance and reduce labor hours in component processing and assembly.SOLUTION: A tappet device (6) converts rotational motion of a shaft (5) having a cam (52) into a reciprocating linear motion and transmits the motion to a plunger (7) forming a part of a compression chamber (83) of a fuel supply pump (100) and includes: a roller (61) which is disposed contacting with an outer peripheral surface of the cam (52); a shoe (62) which rotatably holds the roller (61) and causes the plunger (7) to linearly reciprocate along an axis direction in conjunction with movement of the roller (61) resulting from rotation of the cam (52); and a rotation prevention part (64) which prevents the roller (61) from rotating around an axis of the plunger (7) relative to the cam (52). The rotation prevention part (64) causes the cam (52) and the roller (61) to engage with each other and causes the roller (61) and the shoe (62) to engage with each other.

Description

  The present invention relates to a tappet device and a fuel supply pump including the tappet device.

2. Description of the Related Art A fuel injection device that is provided in a diesel engine or the like and uses a common rail to efficiently inject fuel at a high pressure is known.
Such a fuel injection device is configured such that the plunger reciprocates linearly by the rotation of the camshaft, and the fuel in the pressurized chamber is sent to the injector by the reciprocating linear motion of the plunger. Here, a tappet device is provided between the cam of the camshaft and the plunger to convert the rotational movement of the cam into the reciprocating linear movement of the plunger.

The tappet device accommodates a roller arranged in contact with the outer peripheral surface of the cam, a tappet (shoe), and a tappet (shoe) that holds the roller and moves the plunger back and forth linearly along the axial direction according to the operation of the roller. Housing.
Here, although the cam and the roller are always in contact with each other, a tappet device having a roller rotation prevention mechanism is known in order to prevent the roller from rotating around the axis of the plunger for some reason.
Specifically, the tappet (shoe) is provided with a protrusion, a guide groove is formed in the inner wall of the housing, and the protrusion is fitted into the guide groove to prevent the tappet (shoe) from rotating. A tappet device that can prevent rotation of a roller held by the roller is known (for example, see Patent Document 1).

JP 2009-236033 A

  However, in the conventional tappet device, the sliding resistance is unbalanced between the portion where the protrusion and the guide groove are provided and the other portion, and in some cases, the tappet (shoe) is not attached to the inner wall of the housing. There is a risk of causing contact with one piece or uneven wear associated therewith. In addition, providing a protrusion on the tappet (shoe) and forming a guide groove in the housing complicate the shape of each part, and as a result, the labor and cost of processing these parts increase. It also increases the time and effort of assembly.

  Accordingly, the present invention has been made in view of the above problems, and a tappet device that can eliminate the imbalance of sliding resistance even when a rotation prevention mechanism is provided, and can reduce the work of parts processing and assembly, and the tappet device. It aims at providing a fuel supply pump provided with a tappet device.

  In order to solve the above-mentioned problem, the present invention is a tappet device that converts the rotational motion of a shaft having a cam into a reciprocating linear motion and transmits it to a plunger that forms a part of a pressurizing chamber of a fuel supply pump. A roller disposed in contact with the outer peripheral surface of the cam, and a shoe that holds the roller rotatably, and moves the plunger in a reciprocating linear motion along an axial direction in accordance with the operation of the roller accompanying the rotation of the cam. An anti-rotation mechanism for preventing rotation of the roller around the axis of the plunger with respect to the cam, wherein the anti-rotation mechanism engages the cam and the roller.

  As one aspect of the present invention, it is preferable that the rotation prevention mechanism includes a convex portion formed on one of the roller and the cam and a concave portion formed on the other and engaged with the convex portion.

  As one aspect of the present invention, the rotation prevention mechanism includes a locking member provided on a contact surface of the roller with the cam, and a cam groove formed in a portion of the cam facing the locking member. Are preferably provided.

  As one aspect of the present invention, it is preferable that the locking member is provided at a position deviated in the axial direction of the roller from the axial line of the plunger.

  As one aspect of the present invention, the locking member is preferably formed in an annular shape along the outer peripheral surface of the roller.

  As one aspect of the present invention, the locking member is preferably formed in an annular shape with a part cut out along the outer peripheral surface of the roller.

  As one aspect of the present invention, it is preferable that the roller and the locking member are integrally formed.

  As one aspect of the present invention, it is preferable that a plurality of the locking members are provided.

  As one aspect of the present invention, the locking member preferably has elasticity.

  In addition, the present invention is a fuel supply pump, characterized by including the tappet device.

  According to the present invention, even if a rotation prevention mechanism is provided in the tappet device, it is possible to eliminate the imbalance of sliding resistance and to reduce the labor of processing and assembling parts.

It is the perspective view of the fuel supply pump which carried out the cross sectional view. It is the perspective view of the tappet apparatus which looked at a part in cross section. It is the schematic seen from the axial direction of the roller explaining the structure of a rotation prevention mechanism. It is the schematic seen from the side surface direction of a roller explaining the composition of a rotation prevention mechanism. It is a perspective view which shows the other form of the latching member provided in the roller. It is the schematic seen from the side surface direction of the roller explaining the structure of the rotation prevention mechanism using the roller of FIG. It is the schematic seen from the side surface direction of the roller explaining the structure of the rotation prevention mechanism which provided the some locking member. It is the schematic seen from the side surface direction of a roller explaining other composition of a rotation prevention mechanism.

  Preferred embodiments of the present invention will be described with reference to the drawings. In addition, embodiment shown below is an illustration and can take various embodiment in the scope of the present invention.

<Fuel supply pump>
FIG. 1 is a perspective view of a part of the fuel supply pump 100 in a cross-sectional view.
The fuel supply pump 100 pressurizes fuel supplied from a fuel tank (not shown) into a pressurizing chamber by movement of a plunger and sends the fuel to a common rail through a fuel discharge valve. The fuel supply pump 100 shown in FIG. 1 has a single plunger. However, in the present invention, it is not necessary to limit the number of plungers, and a plurality of pressure chambers and a plurality of plungers are arranged in parallel. It may be a so-called row type pump arranged.
The fuel supply pump 100 includes a feed pump 1 that pumps fuel from a fuel tank, a pump main body 2 that pressurizes fuel sent from the feed pump 1 and sends high-pressure fuel to a common rail, and a pressurizing chamber And a metering valve (not shown) for adjusting the flow rate of the fuel sent to the fuel cell.

(Feed pump and metering valve)
As shown in FIG. 1, the feed pump 1 pumps up fuel stored in a fuel tank and sends it to a metering valve. The feed pump 1 is a gear pump having a drive gear 1b connected to the end of the camshaft 5 via a coupling 1a and a driven gear 1c that meshes with the drive gear 1b. When the feed pump 1 is driven, fuel is sucked up from the fuel tank and sent to the metering valve.
The metering valve adjusts the amount of fuel when the fuel sent from the feed pump 1 is sent to the fuel pressurizing chamber 83 of the pump body 2. By providing the metering valve, the fuel amount can be adjusted according to the combustion pressure of the internal combustion engine and sent to the fuel pressurizing chamber 83.

(Pump body)
As shown in FIG. 1, the pump body 2 includes a housing 3, a bearing 4, a camshaft 5, a tappet device 6, a plunger 7, a cylinder head 8, a spring 9, and a fuel intake valve 10. The fuel discharge valve 11 is provided.

(housing)
The housing 3 accommodates each mechanism such as the camshaft 5, the tappet device 6, and the plunger 7. The housing 3 is formed with a first accommodation space 31 that accommodates the bearing portion 4 and the camshaft 5, and a second accommodation space 32 that accommodates the tappet device 6 and the cylinder head 8.
The first accommodation space 31 is a space formed so as to extend in the axial direction of the camshaft 5. The first accommodation space 31 is formed so as to penetrate from one surface of the housing 3 to one surface facing this surface.
The second accommodation space 32 is formed in a cylindrical shape extending in the axial direction of the plunger 7. The first accommodation space 31 and the second accommodation space 32 are formed so that their extending directions are substantially orthogonal to each other, and one of the second accommodation spaces 32 communicates with the first accommodation space 31. The other is penetrating toward a different surface from the first accommodating space 31.

(Bearing part)
The bearing portion 4 supports the shaft portion 51 of the camshaft 5 in a rotatable manner. The bearing portion 4 is accommodated on one side of the first accommodation space 31.

(Camshaft)
The camshaft 5 is for causing the plunger 7 to reciprocate linearly via the tappet device 6 as it rotates. The camshaft 5 is rotatably supported by the bearing portion 4.
The camshaft 5 includes a shaft portion 51 that rotates about an axis, and a cam portion 52 provided on the shaft portion 51.
The shaft portion 51 is formed in a substantially cylindrical shape and is connected to a crankshaft of the engine via a gear. Thereby, the shaft part 51 rotates by driving of the engine.
The cam portion 52 has one or a plurality of cam peaks, is fixed to the shaft portion 51, and rotates around the axis of the shaft portion 51 as the shaft portion 51 rotates.
The camshaft 5 is disposed in the first housing space 31 so that the cam portion 52 is positioned below the second housing space 32.

(Tappet device)
FIG. 2 is a perspective view showing a part of the tappet device 6 in cross-section.
As shown in FIGS. 1 and 2, the tappet device 6 converts the rotational motion of the cam portion 52 into the reciprocating linear motion of the plunger 7. The tappet device 6 is interposed between the plunger 7 and the cam portion 52 and is disposed in the second accommodation space 32.
The tappet device 6 includes a roller 61, a shoe 62, a body 63, and a rotation prevention mechanism 64.

The roller 61 is formed in a substantially cylindrical shape, and is arranged so that the outer peripheral surface thereof is in contact with the outer peripheral surface of the cam portion 52. The roller 61 is disposed such that its own axial direction is substantially parallel to the axial direction of the camshaft 5. The roller 61 is pushed by the cam portion 52 by the rotation of the camshaft 5 and operates to follow the cam portion 52. As a result, the roller 61 reciprocates linearly along the axial direction of the plunger 7 due to the vertical component of the paper surface of FIG.
The roller 61 is formed with a groove 61a for fitting a ring 64a constituting the rotation preventing mechanism 64. The groove 61 a is for positioning the ring 64 a on the outer peripheral surface of the roller 61, and is formed so as to extend along the circumferential direction of the roller 61. The groove 61a is formed to such a depth that the ring 64a protrudes from the outer peripheral surface of the roller 61 in a state where the ring 64a is fitted.

The shoe 62 holds the roller 61 so as to be rotatable about its axis, is press-fitted into the body 63, and is disposed near the lower end of the body 63. Here, since the shoe 62 is press-fitted into the body 63, the position is fixed in the body 63, and the shoe 62 and the body 63 can be slid together in the housing 3. . The shoe 62 is formed in a substantially cylindrical shape, and a concave portion 62a for accommodating the roller 61 is formed on one surface (the lower surface side in the paper surface of FIG. 2). The plunger 7 is pressed against the other surface of the shoe 62 (the upper surface side in the paper surface of FIG. 2).
Thus, since the shoe 62 holds the roller 61, the shoe 62 performs a reciprocating linear motion along the axial direction of the plunger 7 as well as a reciprocating linear motion along the axial direction of the plunger 7 of the roller 61.

The body 63 is formed in a substantially cylindrical shape and is disposed in the second accommodation space 32. The body 63 has a shoe 62 fixed to the inner peripheral surface thereof, and is slidable in the second housing space 32 together with the shoe 62. In other words, the shoe 62 and the body 63 can reciprocate along the axial direction of the plunger 7.
In addition to the shoe 62, a plunger 7 and a spring 9 are inserted into the body 63.

FIG. 3 is a schematic view showing the configuration of the rotation prevention mechanism 64 as viewed from the axial direction of the roller 61, and FIG. 4 is a schematic view showing the configuration of the rotation prevention mechanism 64 as viewed from the side of the roller 61. is there.
As shown in FIGS. 1 to 4, the rotation prevention mechanism 64 prevents the roller 61 from rotating around the axis of the plunger 7 with respect to the cam portion 52. The rotation prevention mechanism 64 engages the cam portion 52 and the roller 61. Here, since the roller 61 is held by the shoe 62, the cam portion 52, the roller 61, and the shoe 62 are connected by engagement, so that the roller 61 and the shoe 62 rotate with respect to the cam portion 52. It is supposed not to.

  The rotation prevention mechanism 64 is provided on the outer peripheral surface of the roller 61 and is formed at a portion of the cam portion 52 facing the ring 64a as a locking member disposed on the contact surface with the cam portion 52 and the ring 64a. And a cam groove 64c.

The ring 64 a is formed in a substantially C shape in a side view with a part of the annular member cut out, and is disposed in the groove 61 a of the roller 61. The ring 64 a is formed so as to cover at least half of the circumferential length of the roller 61. The ring 64a is formed so that it can be fitted from the peripheral surface side of the roller 61 by being partly cut out, and is easier to assemble than an annular member without a cutout. . The ring 64a is partly cut away in order to facilitate assembly, but the roller 61 is always engaged with the cam portion 52 regardless of the state of the roller 61. Therefore, an annular ring without a notch may be used. The ring 64a may be formed of metal, or may be formed of an elastic material such as rubber or a resin having excellent corrosion resistance such as PTFE.
The ring 64 a is provided at a position shifted from the center of the axial length of the roller 61 toward the end of the roller 61. In other words, the ring 64a is provided at a position off the axis of the plunger 7. Here, the ring 64a is provided at a position deviated from the axis of the plunger 7. However, if the mechanism prevents the rotation of the roller 61, the position where the ring 64a is provided can be freely set. However, since a relatively large force acts on the axis of the plunger 7 in the roller 61 as compared with other places, it is preferable to remove this position and provide the ring 64a.
The cam groove 64 c is formed on the contact surface of the cam portion 52 with the roller 61. The cam groove 64 c is formed in an annular shape on the contact surface of the cam portion 52. The cam groove 64c is formed to be deeper than the protruding amount of the ring 64a from the outer peripheral surface of the roller 61.
A shoe groove 64 b is formed at a portion of the shoe 62 facing the ring 64 a as a relief groove for avoiding a collision between the ring 64 a provided on the roller 61 and the shoe 62. The shoe groove 64 b is formed on the lower surface of the shoe 62. The shoe groove 64b is formed to be deeper than the protruding amount of the ring 64a from the outer peripheral surface of the roller 61.

  By configuring the rotation prevention mechanism 64 as described above, the cam portion 52 and the roller 61 are engaged via the ring 64a. That is, the rotation prevention mechanism 64 includes a ring 64a that is a convex portion and a cam groove 64c that is a concave portion.

(Plunger)
The plunger 7 constitutes a part of the fuel pressurizing chamber 83 in the cylinder head 8 and is slidably held in a space 82 formed in the cylinder head 8. This space 82 is open above and to the side of the cylinder head 8. The plunger 7 reciprocates linearly with the reciprocating linear motion of the shoe 62 and the body 63 within the housing 3, and applies high pressure to the fuel in the fuel pressurizing chamber 83. The upper end portion of the plunger 7 constitutes a part of the wall surface of the fuel pressurizing chamber 83, and the lower end portion thereof is locked to the spring seat 91. The plunger 7 is pulled down toward the shoe 62 by the spring seat 91.

(cylinder head)
A part of the cylinder head 8 is accommodated in the second accommodating space 32 of the housing 3, and the plunger 7 is inserted into a space 82 formed in the accommodated portion 81. The plunger 7 is slidable along the axial direction in the space 82. This space 82 forms a fuel pressurizing chamber 83 for applying high pressure to the fuel together with the plunger 7 and the fuel intake valve 10.
The fuel pressurization chamber 83 can efficiently pressurize the fuel taken in via the fuel intake valve 10 by the plunger 7 reciprocating linearly moving at a high speed. The fuel pressurized by the reciprocating linear motion of the plunger 7 is sent to the common rail via the fuel discharge valve 11.

(spring)
The spring 9 biases the plunger 7 downward by a biasing force generated from its own elasticity. The spring 9 is disposed in the second accommodation space 32 of the housing 3, one end abuts on the cylinder head 8, and the other end is connected to the spring seat 91.

(Fuel intake valve)
The fuel intake valve 10 is a valve for supplying the fuel sent through the metering valve to the fuel pressurizing chamber 83, and is disposed in the vicinity of the upper opening in the space 82 of the cylinder head 8. The fuel intake valve 10 includes a holder portion 10a, a valve body 10b, a valve piston 10c, and a spring 10d. The valve piston 10c is slidably inserted into the valve body 10b and is urged by a spring 10d in a direction to close the valve. The valve piston 10c has a flange portion 10e at the lower end, and the valve piston 10c moves against the urging force of the spring 10d, thereby creating a gap between the flange portion 10e and the valve body 10b. The fuel can flow into the fuel pressurizing chamber 83.

(Fuel discharge valve)
The fuel discharge valve 11 is a valve for sending high-pressure fuel to the common rail, and is disposed in the vicinity of the side opening in the space 82 of the cylinder head 8. The fuel discharge valve 11 includes a ball valve 11a and a spring 11b. The ball valve 11a is urged in the valve closing direction by a spring 11b. When the plunger 7 is pushed up by the movement of the cam portion 52 and the shoe 62 and the pressure inside the fuel pressurizing chamber 83 becomes high, the pressure of the fuel is increased. Thus, the ball valve 11a is moved against the urging force of the spring 11b. As a result, the fuel discharge valve 11 is opened and fuel can be sent to the common rail.

<Function of rotation prevention mechanism>
According to the rotation prevention mechanism 64 of the tappet device 6 as described above, when the roller 61 tries to rotate around the axis of the plunger 7 for some reason, the ring 64a provided on the roller 61 also rotates around the axis of the plunger 7 together with the roller 61. Try to rotate to. However, since the ring 64a is fitted in the cam groove 64c of the cam portion 52, the rotation of the roller 61 is prevented. Further, since the shoe 62 holds the roller 61, the rotation of the shoe 62 is prevented together with the roller 61. Since the ring 64 a is also fitted in the groove 61 a of the roller 61, the ring 64 a is neither displaced nor detached from the roller 61.
Here, since the rotation prevention mechanism 64 is provided below the shoe 62, it does not affect the reciprocating motion (sliding) of the shoe 62 in the housing 3, and compared with the conventional rotation prevention mechanism. As a result, the sliding resistance does not cause an imbalance, and the shoe 62 and the body 63 do not come into contact with the inner wall of the housing 3 or cause uneven wear. In addition, since the shape of the shoe 62 and the body 63 is not changed, the mechanism of the rotation prevention mechanism 64 can be simplified, increasing the labor and cost of processing the component parts and increasing the labor of assembly. There is nothing.

<Others>
The present invention is not limited to the above embodiment.
FIG. 5 is a perspective view of the roller 611 in which the roller 61 and the ring 64a are integrally formed, and FIG. 6 is a schematic view illustrating the configuration of the rotation prevention mechanism 641 using the roller 611 as viewed from the side of the roller 611. FIG. As shown in FIGS. 5 and 6, the roller 61 and the ring 64a in FIGS. 1 to 4 may be integrally formed.
Specifically, a diameter-expanded portion 611a having a diameter larger than that of the other portion is formed at a position shifted toward one end side from the position at the center of the axial length of the roller 611. The enlarged diameter portion 611a protrudes radially outward from the outer peripheral surface of the roller 611, and is formed in an annular shape along the circumferential direction of the outer surface of the roller 611. That is, the enlarged diameter portion 611a functions as a locking member. Note that a part of the enlarged diameter portion 611a may be cut away.
By adopting such a configuration, it is not necessary to prepare two parts such as the roller 61 and the ring 64a as shown in FIGS. 1 to 4, and the number of parts can be reduced. Further, since the enlarged diameter portion 611a is integrally formed with the roller 611, the number of steps for fitting the ring 64a into the roller 61 during assembly can be reduced, and the assembly can be simplified. .

FIG. 7 is a schematic view illustrating the configuration of the rotation prevention mechanism 64 provided with a plurality of rings 64a, as viewed from the side of the roller 612. As shown in FIG. 7, a plurality of rotation prevention mechanisms 64 shown in FIGS. 1 to 4 may be provided.
Specifically, a plurality of grooves 61a are formed in the roller 612, and the rings 64a are fitted and attached to these grooves 61a. A plurality of cam grooves 64c corresponding to the respective rings 64a are formed in the cam portion 522, and the respective rings 64a are fitted into the cam grooves 64c. A plurality of shoe grooves 64b corresponding to the respective rings 64a are formed in the shoe 622, and the respective rings 64a are fitted into shoe grooves 64b serving as escape grooves for preventing the ring 64a and the shoes 622 from colliding with each other.
By adopting such a configuration, the effect of preventing the rotation of the roller 612 relative to the cam portion 522 can be further enhanced. As shown in FIG. 7, in the case where two rings 64a are provided, the ring 64a may be provided at a position that is equidistant from the central position of the roller 612 in the axial direction length (position through which the axis of the plunger 7 passes).

FIG. 8 is a schematic view illustrating another configuration of the rotation preventing mechanism as viewed from the side of the roller. In the above embodiment, in the engaging portion between the roller 61 and the cam portion 52, the roller 61 side is a convex portion (ring 64a) and the cam portion 52 side is a concave portion (cam groove 64c). The configuration may be reversed.
Specifically, an annular groove 613 a along the circumferential direction of the roller 613 is formed at a position shifted to one end side from the position at the center of the axial length of the roller 613. In addition, an annular protrusion 523a along the circumferential direction of the cam portion 523 is formed in the cam portion 523 at a position facing the groove 613a of the roller 613.
By adopting such a configuration, the groove 613a of the roller 613 and the protrusion 523a of the cam portion 523 are engaged with each other, so that the rotation prevention mechanism 643 of the roller 613 is configured.
That is, any engagement mechanism may be employed as long as the roller 61 and the cam portion 52 are engaged with each other.
Other modifications can be made as appropriate without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Feed pump 2 Pump main body 3 Housing 4 Bearing part 5 Cam shaft 52 Cam 6 Tappet apparatus 61 Roller 61a Groove 611a A diameter-expanded part (locking member, convex part)
62 Shoe 63 Body 64 Anti-rotation mechanism 64a Ring (locking member, convex part)
64b shoe groove 64c cam groove (concave)
7 Plunger 8 Cylinder head 83 Fuel pressurizing chamber (pressurizing chamber)
9 Spring 10 Fuel intake valve 11 Fuel discharge valve 100 Fuel supply pump

Claims (10)

A tappet device that converts rotational motion of a shaft having a cam into reciprocating linear motion and transmits it to a plunger that forms part of a pressurizing chamber of a fuel supply pump,
A roller disposed in contact with the outer peripheral surface of the cam;
A shoe that rotatably holds the roller and reciprocates linearly along the axial direction of the plunger in accordance with the operation of the roller accompanying the rotation of the cam;
An anti-rotation mechanism for preventing rotation of the roller around the axis of the plunger with respect to the cam;
The tappet device, wherein the rotation preventing mechanism engages the cam and the roller. The rotation prevention mechanism is
The tappet device according to claim 1, further comprising: a convex portion formed on one of the roller and the cam; and a concave portion formed on the other and engaging with the convex portion. The rotation prevention mechanism is
A locking member provided on a contact surface of the roller with the cam;
A cam groove formed in a portion of the cam facing the locking member;
The tappet device according to claim 1, further comprising:   4. The tappet device according to claim 3, wherein the locking member is provided at a position deviated in the axial direction of the roller from the axial line of the plunger. 5.   The tappet device according to claim 3 or 4, wherein the locking member is formed in an annular shape along an outer peripheral surface of the roller.   5. The tappet device according to claim 3, wherein the locking member is formed in an annular shape in which a part is cut out along an outer peripheral surface of the roller.   The tappet device according to claim 3 or 4, wherein the roller and the locking member are integrally formed.   The tappet device according to any one of claims 3 to 7, wherein a plurality of the locking members are provided.   The tappet device according to any one of claims 3 to 8, wherein the locking member has elasticity.   A fuel supply pump comprising the tappet device according to any one of claims 1 to 9.

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