JP4154560B2 - Assembly method of fuel injection pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for assembling a fuel injection pump, and more particularly to a method for assembling a fuel injection pump having a cam ring on the outer periphery of a cam.
[0002]
[Prior art]
Conventionally, a cam ring that is assembled eccentrically with respect to the drive shaft is provided on the outer periphery of the cam, and the cam ring revolves with the rotation of the drive shaft to reciprocate the plungers arranged at equiangular intervals in the circumferential direction of the drive shaft. A fuel injection pump that pressurizes fuel with a plunger is known.
[0003]
In such a fuel injection pump assembly process, the camshaft is rotated by the housing by aligning the center axis of the cam ring with the center axis of the cam and aligning the center axis of the bearing of the housing with the center axis of the camshaft. The cam and the cam ring are accommodated in the housing while freely bearing. In addition, when a sliding member such as a washer for preventing wear of the housing is provided at a sliding contact portion between the housing and the cam, the cam ring, etc., the cam ring and the camshaft are mounted on the housing with the sliding member positioned with respect to the housing. Assemble.
[0004]
[Problems to be solved by the invention]
However, since the cam ring, washer, etc. can float in the internal space of the housing until they are positioned in contact with the cam stored in the housing, the cam shaft is positioned with respect to the housing, and the cam ring, washer, etc. are cam and housing. It is difficult to position with respect to. For this reason, assembly of a fuel injection pump provided with a cam ring requires a large number of assembly steps using a jig having a complicated positioning mechanism, which increases the manufacturing cost of this type of fuel injection pump. It has become.
[0005]
An object of the present invention is to provide a method for assembling a fuel injection pump that simplifies the assembling process and shortens the time required for assembling.
Another object of the present invention is to provide a method for assembling a fuel injection pump in which a floating member can be easily positioned.
[0006]
[Means for Solving the Problems]
According to the assembly method of the fuel injection pump according to claim 1, the first housing and the cam ring are assembled in the first step, the second housing and the camshaft are assembled in the second step, and the second and subsequent steps are performed. One housing and cam ring are assembled, and the second housing and cam shaft are assembled. Thereby, since a 1st process and a 2nd process can be advanced in parallel, the time which an assembly | attachment of a fuel injection pump requires can be shortened. By inserting the other end portion of the camshaft into the second bearing portion of the second housing and holding the end portion of the camshaft protruding from the second housing, the second housing can be locked by the cam. Therefore, the assembly of the first housing and the cam ring is moved relative to the assembly of the second housing and the camshaft to position the central axes of the first housing, the second housing and the camshaft. be able to. Since the second housing and the camshaft can be held together by holding the camshaft, the assembly process can be simplified. When the end of the camshaft projecting from the second housing is held and one end of the camshaft is inserted into the first bearing portion of the first housing, the cam is placed on the camring unless the center axes of the cam and camring are aligned. There is no contact between the cam ring and the cam. Therefore, in the fourth step, the end of the camshaft protruding from the second housing is held and the camshaft is rotated so that the center axes of the cam and the cam ring are aligned. The recess of the housing can be closed.
[0007]
According to the method for assembling the fuel injection pump according to claim 2, the end of the camshaft protruding from the second housing is held, and the second housing and the annular sliding member are locked by the cam. Positioning can be performed by moving the second housing, the camshaft, and the annular sliding member in an integrated state relative to the one housing and the cam ring. According to the method for assembling the fuel injection pump according to claim 2, since the second housing, the camshaft, and the annular sliding member can be integrally held by holding the camshaft, the annular sliding that is a floating member Positioning of the member becomes easy.
[0008]
In the second step, the third step, and the fourth step, the end of the camshaft protruding from the second housing is held by a jig as in the fuel injection pump assembly method according to claim 3. It is desirable to do.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example showing an embodiment of the present invention will be described with reference to FIGS. First, a fuel injection pump assembled by an assembling method according to an embodiment of the present invention will be described with reference to FIG.
[0010]
The fuel injection pump 10 installed in the jig 50 is a radial pump for a diesel engine in which a plurality of plungers (not shown) are arranged at equal intervals on the outer periphery of the drive shaft. The fuel discharged from the fuel injection pump 10 is supplied from a common rail (not shown) to the injector.
[0011]
The camshaft 20 includes a first shaft portion 24 and a second shaft portion 22 that are coaxial with each other, and a cam 23 having a circular contour that is eccentric with respect to the first shaft portion 24 and the second shaft portion 22. The second shaft portion 22, the first shaft portion 24, and the cam 23 are integrally formed. The second shaft portion 22 protrudes from the second housing 30, and an annular constricted recess 21 is formed in the protruding portion. The first shaft portion 24 is rotatably supported by the first housing 40, and the second shaft portion 22 is rotatably supported by the second housing 30. A bush 45 serving as a first bearing portion is fixed to the first housing 40 by press-fitting at a portion in sliding contact with the first shaft portion 24. A bush 31 as a second bearing portion is fixed to the second housing 30 by press-fitting at a portion in sliding contact with the second shaft portion 22.
[0012]
A cam ring 25 is in sliding contact with the outer periphery of the cam 23. A bushing 26 is fixed to the cam ring 25 by press-fitting at a portion in sliding contact with the cam 23. A tappet (not shown) that reciprocates together with a plunger (not shown) housed in a cylinder (not shown) is in contact with the outer wall of the cam ring 25. The plunger constitutes a movable member described in claims, pressurizes the fuel sucked into a fuel chamber (not shown), and sends it to a common rail (not shown). As the camshaft 20 rotates, the cam ring 25 revolves around the central axes of the shaft portions 22 and 24 to reciprocate the tappet and plunger.
[0013]
The first housing 40 is formed with a recess 44 for accommodating the cam 23 and the cam ring 25. The concave portion 44 forms a space having a shape in which three columns having different diameters are stacked. The small diameter portion of the recess 44 forms a cylindrical space in which the cam ring 25 revolves. The second housing 30 is fitted to the middle diameter portion and the large diameter portion of the recess 44. The diameter of the small diameter portion of the recess 44 is set so that a minute gap is formed between the outer wall of the cam ring 25 and the inner wall of the first housing 40 when the cam ring 25 revolves. The recess 44 is closed by fixing the second housing 30 to the first housing 40. Washers 34 and 42 as annular sliding members are provided between the end surfaces on both axial sides of the cam 23 and the first housing 40 and the second housing 30. Washers 34 and 42 are provided to prevent the first housing 40 and the second housing 30 from being worn by sliding contact with the cam 23. Both ends of the pins 32 and 33 are inserted into the washer 34 and the second housing 30 to prevent the washer 34 from rotating relative to the second housing 30. Both ends of the pins 41 and 43 are inserted into the washer 42 and the first housing 40 to prevent the washer 42 from rotating with respect to the first housing 40.
Hereinafter, a method for assembling the fuel injection pump 10 will be described.
[0014]
(First step)
In the first step, as shown in FIG. 1, the first housing 40 is installed on the jig 50 so that the recess 44 opens vertically upward, and the cam ring 25 is stored in the recess 44 of the first housing 40. The jig 50 is for preventing the first shaft portion 24 of the camshaft 20 from being supported in a third process or a fourth process described later. The pins 41 and 43 are inserted into the first housing 40 until the cam ring 25 is housed in the recess 44, the positioning holes are aligned with the pins 41 and 43, and the washer 42 is dropped into the recess 44. It is not necessary to fix the washer 42 to the first housing 40. This is because after the second housing 30 is fixed to the first housing 40, the cam ring 25 restricts the movement of the washer 42 in the camshaft axial direction.
[0015]
(Second step)
In the second step, as shown in FIG. 2, the second shaft portion 22 of the camshaft 20 is fitted to the bush 31 with the second housing 30 dropped into the concave portion 64 of the jig 60 with the joint surface with the first housing 40 facing upward. And the end of the second shaft portion 22 is protruded from the second housing 30. The axial length L of the small diameter cylindrical portion of the jig 60 is set longer than the length of the second shaft portion 22 protruding from the second housing 30. The pins 32 and 33 are inserted into the second housing 30 until the second shaft portion 22 is inserted into the bush 31, the positioning holes are aligned with the pins 32 and 33, and the washer 34 is temporarily assembled to the second housing 30. deep. It is not necessary to fix the washer 34 to the second housing 30. This is because after the second housing 30 is fixed to the first housing 40, the cam ring 25 restricts the movement of the washer 34 in the camshaft axial direction. Further, during assembly, the washer 34 is clamped by the cam 23 and the second housing 30 by locking the camshaft 20 to the jig 60. The jig 60 is provided with a plate 62 for locking the concave portion 21 of the second shaft portion 22. The plate 62 has a hole portion 63 into which the tip of the second shaft portion 22 is inserted, and is provided on the jig 60 so as to reciprocate in a direction perpendicular to the central axis of the second shaft portion 22. The spring 61 urges the plate 62 to the left in FIG. The set load of the spring 61 is set so that the camshaft 20 can be rotated by rotating the jig 60. Since the state in which the inner peripheral wall of the plate 62 is fitted in the recess 21 is maintained by the urging force of the spring 61, once the plate 62 and the recess 21 are fitted, the jig 61 is compressed unless the force that compresses the spring 61 acts on the plate 62. The second housing 30 and the camshaft 20 are not detached from the 60. Since the inner diameter of the washer 34 is smaller than the longest distance from the central axis of the second shaft portion 22 to the contour of the cam 23, when the camshaft 20 and the second housing 30 are locked to the jig 60, the end surface of the cam 23 is The movement of the washer 34 in the axial direction of the camshaft is restricted by contacting the washer 34. Accordingly, at this time, the washer 34 does not rotate by being removed from the pins 32 and 33. Such an integrated relationship among the jig 60, the second housing 30, the camshaft 20, and the washer 34 is maintained even if the state shown in FIG.
[0016]
(Third process)
In the third step, the first shaft portion 24 of the camshaft 20 that is locked to the jig 60 together with the second housing 30 is inserted into the bush 45 of the first housing 40 as shown in FIG. At this time, unless the center axis C of the cam 23 that is eccentric with respect to the center axis D of the camshaft 20 coincides with the center axis B of the cam ring 25, the cam 23 and the cam ring 25 collide in the axial direction. The cam 23 cannot be inserted into the cam ring 25.
[0017]
(Fourth process)
In the fourth step, the camshaft 20 is rotated together with the jig 60 so that the center axis C of the cam 23 and the center axis B of the cam ring 25 coincide with each other as shown in FIG. At this time, when the camshaft 20 is rotated while applying a force to the camshaft 20 in a direction in which the camshaft 20 is inserted deeper into the bush 45, the center axis C of the cam 23 and the center axis B of the cam ring 25 coincide with each other. The cam 23 can be inserted into the cam ring 25, and the second housing 30 can be fitted into the first housing 40 and the recess 44 can be closed with the second housing 30 by being inserted deeper. When the section of the fitting portion between the first housing 40 and the second housing 30 is not circular as in the present embodiment, the cam 23 is aligned when the center axis C of the cam 23 and the center axis B of the cam ring 25 coincide. Is inserted into the cam ring 25, and then the second housing 30 is rotated with respect to the first housing 40 so that the cross-sectional shapes of the fitting portions of the first housing 40 and the second housing 30 overlap with each other. The two housings 30 may be fitted. After the fourth step, the spring 61 is compressed and the jig 60 is removed from the camshaft 20.
[0018]
According to the method for assembling the fuel injection pump 10 described above, the end of the camshaft 20 protruding from the second housing 30 is held by the jig 60, whereby the second housing 30 and the washer 34 are engaged with the jig 60 by the cam 23. Stop. Therefore, the first housing 40, the cam ring 25 and the second housing 30, the camshaft 20, and the washer 34 are moved together to move the first housing 40 and the second housing. 30 and the central axis of the camshaft 20 can be made to coincide. By holding the camshaft 20 with the jig 60, the second housing 30, the camshaft 20, and the washer 34 can be held together, so that the jig used in the assembly process can be simplified and the number of processes can be reduced. Furthermore, the cam shaft 20 is rotated by the jig 60 so that the center axis C of the cam 23 and the center axis B of the cam ring 25 coincide with each other, and the cam 23 can be easily inserted into the cam ring 25.
[0019]
In the embodiment described above, the method of assembling the fuel injection pump 10 including the washers 34 and 42 has been described. However, even in the fuel injection pump 10 that does not include the washers 34 and 42, the first step and the second step. By combining the temporarily assembled component assemblies after the third step, the first step and the second step can be performed in parallel, so that the time required for assembly can be shortened.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first step of a method for assembling a fuel injection pump according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a second step of the method of assembling the fuel injection pump according to one embodiment of the present invention.
FIG. 3 is a cross-sectional view showing a third step of the method of assembling the fuel injection pump according to one embodiment of the present invention.
FIG. 4 is a cross-sectional view showing a fourth step of the method of assembling the fuel injection pump according to one embodiment of the present invention.
FIG. 5 is a cross-sectional view showing a fuel injection pump assembled according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Fuel injection pump 20 Cam shaft 22 2nd shaft part 23 Cam 24 1st shaft part 25 Cam ring 31 Bush (2nd bearing part)
30 Second housing 32, 33, 41, 43 Pin 34 Washer (annular sliding member)
40 First housing 44 Recess 45 Bush (first bearing)
50, 60 jigs

Claims (3)

A camshaft having a cam that rotates together with a drive shaft; a cam ring that is slidably assembled with respect to the cam on the outer periphery of the cam, and that reciprocally drives a movable member that pressurizes fuel as the cam rotates; A first housing having a recess for housing the cam ring and a first bearing portion for rotatably supporting one end portion of the cam shaft; and a second bearing portion for rotatably supporting the other end portion of the cam shaft. And a method of assembling a fuel injection pump comprising a second housing that closes the recess,
A first step of storing the cam ring in the recess of the first housing;
A second step of inserting the other end portion of the camshaft into the second bearing portion of the second housing and projecting the end portion of the camshaft from the second housing;
While holding the end of the camshaft protruding from the second housing and locking the second housing with the cam, the first bearing portion of the first housing has a depth to which the cam contacts the cam ring. A third step of inserting one end of the camshaft;
A fourth step of holding the end of the camshaft protruding from the second housing and inserting the cam into the cam ring while rotating the camshaft, and closing the recess with the second housing;
A method for assembling a fuel injection pump, comprising: In the second step, the other end of the camshaft is inserted into the annular sliding member, and the annular sliding member is assembled between the second housing and the cam,
The said 3rd process WHEREIN: The edge part of the said cam shaft which protrudes from said 2nd housing is hold | maintained, and the said 2nd housing and the said annular sliding member are latched by the said cam. Assembly method of fuel injection pump. 3. The fuel injection pump according to claim 1, wherein in the second step, the third step, and the fourth step, an end portion of the camshaft protruding from the second housing is held by a jig. Assembly method.

Images