JP3888408B2 - Fuel injection pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection pump for an internal combustion engine (hereinafter referred to as an “internal combustion engine”).
[0002]
[Prior art]
Conventionally, a pump that pressurizes fluid sucked into a pressurizing chamber by a movable member that receives a driving force from a driving member such as a cam and reciprocates in an axial direction is known.
In the case of a pump in which the cam slides directly with the movable member and reciprocates the movable member, the contact area between the cam and the movable member is small and the surface pressure is high. There is a risk that the sliding portion between the cam and the movable member will burn.
[0003]
In view of this, for example, in a fuel injection pump disclosed in Japanese Patent Application Laid-Open No. 6-249133, a shoe that can come into contact with a movable member and a flat surface is interposed between a cam and a movable member, and a contact point between the shoe and the movable member is interposed. The structure which can reduce the surface pressure in is adopted.
[0004]
[Problems to be solved by the invention]
However, in the fuel injection pump disclosed in Japanese Patent Laid-Open No. 6-249133, when the number of cylinders of the pump is plural, a rotational force is generated by frictional force between adjacent shoes provided in adjacent cylinders. The shoe may rotate or swing due to the rotational force. If the shoe rotates or swings, the shoe may incline and contact the movable member at a portion other than a predetermined contact surface that contacts the movable member. There is.
[0005]
The present invention has been made to solve such a problem, and an object of the present invention is to provide a fuel injection pump capable of preventing the shoe from rotating or swinging and preventing the movable member from being damaged. To do.
[0006]
[Means for Solving the Problems]
According to the fuel injection pump of the first aspect of the present invention, the contact pressure that reduces the contact pressure between the plurality of adjacent shoes that are in plane contact with the plurality of movable members and that transmits the driving force of the cam to the movable member. A reduction means is provided. For this reason, by reducing the frictional force generated between the adjacent shoes provided in the adjacent cylinders by the contact pressure reducing means, the shoes are prevented from rotating or swinging, and the shoes are inclined to be movable members. It is possible to prevent the shoe and the movable member from coming into contact with each other at a part other than the predetermined contact surface that is in contact with the movable member.
[0007]
Furthermore, according to the fuel injection pump of the first aspect of the present invention, since the contact pressure reducing means is a washer portion that can rotate relative to the shoe, the washer portion rotates due to a frictional force generated between adjacent shoes. , It is possible to prevent the rotational force from being transmitted to the adjacent shoes. Therefore, it is possible to prevent the shoe from rotating or swinging with a simple configuration and to easily prevent the movable member from being damaged.
[0008]
According to the fuel injection pump according to claim 2 of the present invention, the contact pressure reducing means is provided on the opposite end faces of the adjacent shoes, so that it is possible to reliably prevent the rotational force from being transmitted to the adjacent shoes. it can. Therefore, the shoe can be reliably prevented from rotating or swinging, and the movable member can be reliably prevented from being damaged.
[0009]
According to the fuel injection pump of claim 3 of the present invention, the contact pressure reducing means is provided on one of the opposing end faces of the shoes adjacent to each other, thereby preventing the rotational force from being transmitted to the adjacent shoes with a simple configuration. can do. Therefore, it is possible to easily prevent the shoe from rotating or swinging, and to prevent the movable member from being damaged.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a plurality of examples showing embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
1 to 3 show a first embodiment in which the present invention is applied to a fuel injection pump of a diesel engine.
[0011]
First, the fuel supply system of the first embodiment is shown in FIG. As shown in FIG. 2, the fuel injection pump 1 is a two-cylinder fuel injection pump, and the drive shaft 11 is rotatably supported by the pump housing 10 via an oil seal 14 and a journal 15. The two cams 21 and 22 are formed integrally with the drive shaft 11 and their rotational phases are shifted by 180 °.
[0012]
The inner gear type feed pump 20 has an outer gear 23 and an inner gear 24. As the inner gear 24 rotates together with the drive shaft 11, the fuel is sucked from the fuel tank 45 through the fuel passage 50, the sucked fuel is pressurized, and the fuel is sent from the fuel passage 56 to the fuel chamber 16. The fuel chamber 16 communicates with the return passage 57 via the throttle 60. When the fuel pressure in the fuel chamber 16 becomes equal to or higher than a predetermined pressure, the regulating valve 66 is opened, and surplus fuel in the fuel chamber 16 is returned to the inlet of the feed pump 20.
[0013]
The metering valve 40 is an electromagnetic valve for metering the amount of fuel sucked into the fuel pressurizing chamber 54 from the fuel chamber 16 through the fuel suction passage 53 and the check valve 64 according to the engine operating state. The valve member 46 is biased toward the valve seat 44 by a spring 47, that is, in a valve closing direction. When energization of the solenoid 43 is turned on, the valve member 46 is attracted in the direction away from the valve seat 44 against the biasing force of the spring 47, that is, in the valve opening direction. By controlling the control current value supplied to the solenoid 43, the opening area of the valve portion formed by the valve member 46 and the valve seat 44 is controlled, and the amount of fuel sucked into the fuel pressurizing chamber 54 is adjusted.
[0014]
The double plungers 61 and 62 are reciprocally driven by the cams 21 and 22 through the shoes 31 and 32 and the tappets 51 and 52 as the drive shaft 11 rotates, and suck the fuel into the fuel pressurizing chamber 54. Pressurize inhaled fuel. The pressurized fuel is supplied from the fuel passage 55 to the common rail 46 through the check valve 63. The common rail 46 accumulates the pressure-fluctuated fuel supplied from the fuel injection pump 1 and holds it at a constant pressure. High pressure fuel is supplied from the common rail 46 to an injector (not shown).
[0015]
As shown in FIG. 1, the cylindrical shoes 31 and 32 adjacent to each other have bushes 41 and 42 press-fitted to the inner periphery, and are slidably fitted to the outer periphery of the cams 21 and 22. On the outer peripheral wall of the shoes 31, 32 on the plunger 61, 62 side, contact surfaces 31a, 32a that come into contact with and slide against the tappets 51, 52 are formed in a flat shape.
[0016]
The plungers 61 and 62 are supported in cylinders 91 and 92 formed in the pump housing 10 so as to be reciprocally movable. The tappets 51 and 52 are fitted to the plungers 61 and 62. The springs 81 and 82 urge the plungers 61 and 62 and the tappets 51 and 52 toward the shoes 31 and 32. The sliding surfaces 51a and 52a of the tappets 51 and 52 are pressed against the contact surfaces 31a and 32a of the shoes 31 and 32 by the biasing force of the springs 81 and 82, and slide on the contact surfaces 31a and 32a. The holding members 101 and 102 prevent the tappets 51 and 52 from dropping from the plungers 61 and 62. Here, the plungers 61 and 62 and the tappets 51 and 52 constitute a movable member.
[0017]
Since the contact surfaces 31a and 32a of the shoes 31 and 32 and the sliding surfaces 51a and 52a of the tappets 51 and 52 are formed in a flat shape, the surface pressure between the shoes 31 and 32 and the tappets 51 and 52 decreases. For this reason, as the cams 21 and 22 rotate, the shoes 31 and 32 revolve without rotating while sliding with the cams 21 and 22 via the bushes 41 and 42.
[0018]
A washer 111 is provided between the pump housing 10 and one end face 31 a of the shoe 31 so as to be rotatable relative to the shoe 31. A washer 112 is provided between the pump housing 10 and the other end face 32 b of the shoe 32 so as to be rotatable relative to the shoe 32. Further, a washer 71 as a washer portion is provided on the other end surface 31 b of the shoe 31 so as to be rotatable relative to the shoe 31, and a washer 72 as a washer portion is provided on the shoe 32 on one end surface 32 a of the shoe 32. It is provided so as to be capable of relative rotation. Here, the other end face 31b of the shoe 31 and one end face 32a of the shoe 32 constitute opposite end faces of the adjacent shoes 31 and 32.
[0019]
As shown in FIG. 3, the washer 71 has a cylindrical shape and includes a flange portion 71a and a cylindrical portion 71b. The washer 71 is made of metal or ceramic, and the surface of the metal is treated with a lubricant called lubrite. 3 shows the washer 71 as a representative, the washer 72 shown in FIG. 1 has the same configuration as the washer 71 shown in FIG.
[0020]
As shown in FIG. 1, one end surface 31 a of the shoe 31 is in contact with the washer 111, and the other end surface 31 b of the shoe 31 is in contact with the flange portion 71 a of the washer 71. One end surface 32 a of the shoe 32 is in contact with the flange portion 72 a of the washer 72, and the other end surface 32 b of the shoe 32 is in contact with the washer 112. Since the surface of the washers 111 and 112 is coated with lubricant or molybdenum disulfide in the same manner as the washers 71 and 72, the washers 111 and 112 and the washers 71 and 72 are accompanied by the revolving motion of the shoes 31 and 32. Can be rotated. In particular, the washers 71 and 72 can rotate without transmitting a rotational force to the adjacent shoes 32 and 31 with the revolving motion of the shoes 31 and 32.
[0021]
A step portion 31 c is formed on the inner periphery of the shoe 31 on the other end surface 31 b side, and the step portion 31 c is in contact with the cylindrical portion 71 b of the washer 71. Further, a stepped portion 32 c is formed on the inner periphery of the shoe 32 on the one end surface 32 a side, and the stepped portion 32 c is in contact with the cylindrical portion 72 b of the washer 72. For this reason, it is possible to prevent the washers 71 and 72 from coming into contact with the bushes 41 and 42 and to prevent the bushes 41 and 42 from being deformed.
[0022]
Next, the operation of the fuel injection pump 1 having the above configuration will be described.
(1) The cams 21 and 22 rotate as the drive shaft 11 rotates, and the shoes 31 and 32 revolve without rotating as the cams 21 and 22 rotate. As the shoes 31 and 32 revolve, the tappets 51 and 52 and the plungers 61 and 62 reciprocate.
[0023]
(2) When the plungers 61 and 62 at the top dead center are lowered with the revolution of the shoes 31 and 32, the pressure in the fuel pressurizing chamber 54 is lowered, and the fuel flows into the fuel pressurizing chamber 54 from the check valve 64. To do. When the plungers 61 and 62 that have reached the bottom dead center rise again toward the top dead center, the check valve 64 is closed and the fuel pressure in the fuel pressurizing chamber 54 rises. When the fuel pressure in the fuel pressurizing chamber 54 rises higher than the fuel pressure in the fuel passage 55, the check valve 63 is opened and high pressure fuel is supplied from the fuel passage 55 to the common rail 46.
[0024]
In the above (1) and (2), the contact pressure between the shoe 31 and the shoe 32 that is a force that hinders the revolving motion of the shoes 31 and 32 is transmitted to the washers 71 and 72 as a frictional force. The washers 71 and 72 rotate relative to the shoes 31 and 32 by the frictional force, and the rotational force is not transmitted to the adjacent shoes 32 and 31. That is, the washers 71 and 72 can reduce the contact pressure between the adjacent shoes 31 and 32.
[0025]
In the first embodiment, the washer 71 is provided on the other end surface 31b of the shoe 31, and the washer 72 is provided on the one end surface 32a of the shoe 32. Therefore, the friction force generated between the adjacent shoes 31 and 32 is It is possible to prevent the washers 71 and 72 from rotating relative to the shoes 31 and 32 and transmitting the rotational force to the adjacent shoes 32 and 31. Therefore, the shoes 31 and 32 are reliably prevented from rotating or swinging with a simple configuration, and the shoes 31 and 32 are inclined so that the outer peripheral surfaces of the shoes 31 and 32 other than the contact surfaces 31a and 32a are the tappet 51, 52 can be prevented from coming into contact with the sliding surfaces 51a and 52a. Therefore, it is possible to easily and surely prevent the plungers 61 and 62 from being damaged due to the occurrence of an eccentric load.
[0026]
(Second embodiment)
A fuel injection pump according to a second embodiment of the present invention is shown in FIG. The same components as those in the first embodiment are denoted by the same reference numerals.
As shown in FIG. 4, a washer 171 as a washer portion is provided on the other end surface 31 b of the shoe 31 so as to be rotatable relative to the shoe 31. The other end surface 31 b of the shoe 31 and one end surface 32 a of the shoe 32 are in contact with the flange portion 171 a of the washer 171. That is, the washer 171 is provided on one of the opposing end surfaces 31b, 32a of the adjacent shoes 31, 32.
[0027]
As shown in FIG. 5, the washer 171 has a cylindrical shape and is made of a composite material of a flange portion 171a and a cylindrical portion 171b. The flange portion 171a and the cylindrical portion 171b are made of metal or ceramic, and the surface of the metal is treated with a lubricant called rubrite.
[0028]
The other end surface 31 b of the shoe 31 and one end surface 32 a of the shoe 32 are in contact with the flange portion 171 a of the washer 171. For this reason, the washer 171 can rotate without transmitting a rotational force to the adjacent shoes 32 and 31 with the revolving motion of the shoes 31 and 32.
[0029]
A step portion 31 c is formed on the inner periphery of the shoe 31 on the other end surface 31 b side, and the step portion 31 c is in contact with the cylindrical portion 171 b of the washer 171. For this reason, it is possible to prevent the washer 171 from coming into contact with the bush 41 and to prevent the bush 41 from being deformed.
[0030]
In the second embodiment, since the washer 171 is provided on the other end surface 31b of the shoe 31, the washer 171 rotates relative to the shoe 31 by the frictional force generated between the adjacent shoes 31 and 32, and is adjacent to the shoe 31. It is possible to prevent the rotational force from being transmitted to the shoes 32 and 31. Therefore, the shoes 31 and 32 are prevented from rotating or swinging with a simple configuration, and the shoes 31 and 32 are inclined so that the outer peripheral surfaces of the shoes 31 and 32 other than the contact surfaces 31a and 32a are the tappets 51 and 52. Contact with the sliding surfaces 51a and 52a can be prevented. Therefore, it is possible to easily prevent the plungers 61 and 62 from being damaged due to the occurrence of an offset load on the plungers 61 and 62.
[0031]
In the first and second embodiments, the fuel injection pump in which the shoes 31, 32 and the tappets 51, 52 slide as the shoes 31, 32 revolve as the cams 21, 22 rotate is described. The structure of the present invention may be applied to a fuel injection pump in which a plane contact is made without sliding between the tappet and the tappet.
[0032]
(Third embodiment)
A fuel injection pump according to a third embodiment of the present invention is shown in FIG. Components that are substantially the same as those in the first embodiment are denoted by the same reference numerals.
As shown in FIG. 6, the two plungers 161 and 162 are supported in cylinders 91 and 92 formed in the pump housing 10 so as to be reciprocally movable. The sliding surfaces 161a and 162a of the plungers 161 and 162 are pressed against the contact surfaces 31a and 32a of the shoes 31 and 32 by the biasing force of the springs 81 and 82, and slide on the contact surfaces 31a and 32a. The plungers 161 and 162 are reciprocally driven by the cams 21 and 22 through the shoes 31 and 32 as the drive shaft 11 rotates. Here, the plungers 161 and 162 constitute a movable member.
[0033]
Contact surfaces 31a and 32a that come into contact with and slide on the sliding surfaces 161a and 162a of the plungers 161 and 162 are formed in a flat shape on the outer peripheral walls of the shoes 31 and 32 on the plungers 161 and 162 side. Since the contact surfaces 31a and 32a of the shoes 31 and 32 and the sliding surfaces 161a and 162a of the plungers 161 and 162 are formed in a planar shape, the surface pressure between the shoes 31 and 32 and the plungers 161 and 162 decreases. For this reason, as the cams 21 and 22 rotate, the shoes 31 and 32 revolve without rotating while sliding with the cams 21 and 22 via the bushes 41 and 42.
[0034]
In the third embodiment, the washer 71 is provided on the other end surface 31b of the shoe 31, and the washer 72 is provided on the one end surface 32a of the shoe 32. Therefore, the friction force generated between the adjacent shoes 31 and 32 is It is possible to prevent the washers 71 and 72 from rotating relative to the shoes 31 and 32 and transmitting the rotational force to the adjacent shoes 32 and 31. Therefore, the shoes 31 and 32 are reliably prevented from rotating or swinging with a simple configuration, and the shoes 31 and 32 are inclined so that the outer peripheral surfaces of the shoes 31 and 32 other than the contact surfaces 31a and 32a are the tappet 51, 52 can be prevented from coming into contact with the sliding surfaces 51a and 52a. Therefore, it is possible to easily and surely prevent the plungers 61 and 62 from being damaged due to the occurrence of an eccentric load.
[0035]
In the third embodiment, the fuel injection pump in which the shoes 31, 32 and the plungers 161, 162 slide as the shoes 31, 32 revolve as the cams 21, 22 rotate is described. The configuration of the present invention may be applied to a fuel injection pump that makes a flat contact without sliding.
[0036]
In the above-described embodiments of the present invention, a two-cylinder fuel injection pump has been described. Of course, the configuration of the present invention can be applied to a three-cylinder or more fuel injection pump.
[Brief description of the drawings]
FIG. 1 shows a fuel injection pump according to a first embodiment of the present invention and is an enlarged view of a main part of FIG.
FIG. 2 is a schematic cross-sectional view showing a fuel supply system using a fuel injection pump according to a first embodiment of the present invention.
FIG. 3 is a perspective view showing a washer according to a first embodiment of the present invention.
FIG. 4 is a schematic sectional view showing a fuel injection pump according to a second embodiment of the present invention.
FIG. 5 is a sectional view showing a washer according to a second embodiment of the present invention.
FIG. 6 is a schematic sectional view showing a fuel injection pump according to a third embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fuel injection pump 10 Pump housing 11 Drive shaft 21, 22 Cam 31, 32 Shoe 31a, 31b, 32a, 32b End surface 41, 42 Bush 51, 52 Tappet (movable member)
61, 62 Plunger (movable member)
71, 72 Washer (washer part)
81, 82 Spring 161, 162 Plunger (movable member)
171 Washer (washer)

Claims (3)

A cam that rotates with the drive shaft;
A plurality of shoes slidably assembled with the cam on an outer periphery of the cam;
A plurality of movable members that contact the shoe at a flat surface and pressurize the fuel by reciprocating;
A contact pressure reducing means provided on an end face of the shoe, configured by a washer portion rotatable relative to the shoe, for reducing a contact pressure between the adjacent shoes;
A fuel injection pump comprising: The contact pressure reducing means, a fuel injection pump of claim 1, wherein Rukoto provided at both end surfaces facing the shoe adjacent to each other. The contact pressure reducing means, according to claim 1 Symbol mounting the fuel injection pump, characterized in that provided on one of opposite end faces of the shoe adjacent to each other.

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