JP2016133033A - Pump attachment structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pump attachment structure which avoids that a deflection amount of a chain exceeds an elasticity limit at the removal of a pump.SOLUTION: A large-diameter part 57 whose outside diameter dimension is set larger than an inside diameter dimension of a pump insertion hole 21 of a chain case 2 is arranged at a pump sprocket 5 which is attached to a drive shaft 12 of a high-pressure fuel pump 1. An interval between an end face 58 of the large-diameter part 57 and an opening edge of the pump insertion hole 21 is set shorter than a deflection amount being an elasticity limit in the case that chains 41, 42 are deflected to the chain case 2 side. By this constitution, when withdrawing a pump main body 11 from the pump insertion hole 21, even if the pump sprocket 5 is moved integrally with the high-pressure fuel pump 1, the end face 58 of the large-diameter part 57 abuts on the opening edge of the pump insertion hole 21, and the high-pressure fuel pump 1 can be thereby removed without causing the excess of the deflection amounts of the chains 41, 42 over the elasticity limit.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a pump mounting structure applied to an internal combustion engine.

  Conventionally, as disclosed in Patent Document 1, an internal combustion engine (engine) mounted on a vehicle is provided with a pump (for example, a high-pressure fuel pump) that operates by receiving the rotational force of a crankshaft. An example of a pump mounting structure is shown in FIG. In the mounting structure of the pump 100 shown in FIG. 4, the pump main body 101 is inserted into a pump insertion hole 201 formed in the chain case 200, and the pump 100 is fixed to the chain case 200 by bolting or the like. In this mounting structure, the drive shaft 102 of the pump 100 is located in the chain housing space 400 formed between the chain case 200 and the chain cover 300. Further, by fitting the drive shaft 102 of the pump 100 into the center hole 501 of the pump sprocket 500, the pump sprocket 500 is attached to the drive shaft 102, and the male screw portion 103 formed at the tip portion of the drive shaft 102 is attached. Screw in the nut 600. A flange 601 is formed on the outer peripheral portion of the nut 600, and the pump sprocket 500 is prevented from coming off by contacting the flange 601 with the end surface (the left end surface in FIG. 4) 502 of the pump sprocket 500. Is attached to the drive shaft 102. A timing chain 401 and a pump drive chain 402 are hung on the pump sprocket 500. The timing chain 401 is stretched between a cam sprocket attached to one end of a cam shaft (not shown) and the pump sprocket 500. The pump drive chain 402 is stretched between a crank sprocket attached to one end of a crankshaft (not shown) and the pump sprocket 500.

Japanese Utility Model Publication No. 63-174513

  By the way, when the pump 100 needs to be maintained, it is necessary to remove the pump 100 from the chain case 200. At this time, it is desirable to remove the pump 100 from the chain case 200 with the engine mounted on the vehicle. In this case, it is necessary to extract the pump body 101 from the pump insertion hole 201 of the chain case 200. In this operation, as shown in FIG. 5, the maintenance cover 302 (see FIG. 4) that closes the maintenance opening 301 of the chain cover 300 is removed, and a tool (such as a nut driver) (not shown) is removed from the maintenance opening 301. insert. Then, the tool is fitted to the nut 600 and the nut 600 is rotated. As a result, the nut 600 is removed to the chain cover 300 side (see arrow I in FIG. 5). Thereafter, the bolt 100 that has fixed the pump 100 to the chain case 200 is removed, and the pump 100 is pulled out toward the chain case 200 (see arrow II in FIG. 5).

  However, as described above, the drive shaft 102 of the pump 100 is fitted in the center hole 501 of the pump sprocket 500, and these contact surfaces are in contact with each other at a relatively high pressure. The pump sprocket 500 may be moved to the chain case 200 side integrally with the pump 100. In such a situation, the chains 401 and 402 that are hung on the pump sprocket 500 are largely moved to the chain case 200 side. That is, in the timing chain 401, the upper side is held at the position hung on the cam sprocket, while the lower side is largely moved to the chain case 200 side. Further, in the pump drive chain 402, the lower side is held at the position hung on the crank sprocket, while the upper side is largely moved to the chain case 200 side. In this way, when each chain 401, 402 is bent (bending in the horizontal direction perpendicular to the longitudinal direction of the chains 401, 402), and the amount of bending exceeds the elastic limit of the chains 401, 402, The chains 401 and 402 are plastically deformed and are difficult to reuse.

  The present invention has been made in view of this point, and an object of the present invention is to provide a pump mounting structure that prevents the amount of chain deflection from exceeding the elastic limit when the pump is removed.

  In order to achieve the above object, the solution means of the present invention is such that a pump body is inserted into a pump insertion hole provided in a chain case, and a pump housing is formed in a chain housing space formed between the chain case and the chain cover. It is premised on a pump mounting structure in which a drive shaft is located, a pump sprocket is mounted on the drive shaft, and a chain is hung on the pump sprocket. For this pump mounting structure, the pump sprocket is provided with a large diameter portion whose outer diameter dimension is set larger than the inner diameter dimension of the pump insertion hole, and the end surface of the large diameter portion and the opening of the pump insertion hole The edge is made to face in a direction along the axis of the drive shaft. Then, the distance between the end face of the large-diameter portion of the pump sprocket facing the opening edge of the pump insertion hole is determined by the amount of bending that becomes an elastic limit when the chain is bent toward the chain case side. Also set short.

  Due to this specific matter, when the pump body is pulled out from the pump insertion hole of the chain case when removing the pump, the pump drive shaft and the pump sprocket are relatively movable in the direction along the axis of the drive shaft. And move the pump (withdraw the pump body from the pump insertion hole of the chain case). In this case, even if the pump sprocket moves together with the pump, the outer diameter of the large diameter portion of the pump sprocket is set larger than the inner diameter of the pump insertion hole. The end surface of the diameter portion comes into contact with the opening edge of the pump insertion hole, and the pump sprocket does not move further from the contacted position. The distance between the end surface of the large-diameter portion of the pump sprocket that faces the opening edge of the pump insertion hole is set to be shorter than the amount of bending that becomes the elastic limit when the chain is bent. For this reason, the end surface of the large-diameter portion of the pump sprocket contacts the opening edge of the pump insertion hole before the amount of bending of the chain reaches the elastic limit of the chain, and the pump sprocket is further prevented from moving. That is, the amount of bending of the chain is prevented from reaching the elastic limit of the chain. With the movement of the pump sprocket blocked in this way, the pump body is pulled out from the pump insertion hole and the pump is removed. That is, the pump can be removed without the amount of chain deflection exceeding the elastic limit. As a result, there is no situation where the chain is plastically deformed and cannot be reused.

  In the present invention, the end surface of the large-diameter portion of the pump sprocket and the opening edge of the pump insertion hole face each other, and the distance between them is shorter than the amount of bending that becomes the elastic limit when the chain is bent toward the chain case side. It is set. For this reason, the pump can be removed without the amount of bending of the chain exceeding the elastic limit.

It is sectional drawing which shows the pump attachment structure which concerns on embodiment. It is sectional drawing for demonstrating the jig | tool mounting operation | work at the time of the pump removal operation | work in the pump attachment structure which concerns on embodiment. It is sectional drawing for demonstrating the pump extraction operation | work at the time of the pump removal operation | movement in the pump attachment structure which concerns on embodiment. It is sectional drawing which shows the conventional pump mounting structure. It is sectional drawing for demonstrating the pump removal operation | work in the conventional pump attachment structure.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. This embodiment demonstrates the case where this invention is applied to the attachment structure of the high pressure fuel pump attached to the chain case of the diesel engine for motor vehicles.

−Pump mounting structure−
FIG. 1 is a sectional view showing a pump mounting structure according to the present embodiment. As shown in FIG. 1, in the pump mounting structure according to this embodiment, a pump insertion hole 21 is formed in a chain case 2 integrally formed with a cylinder block, and a high-pressure fuel pump is formed in the pump insertion hole 21. The high pressure fuel pump 1 is supported by the chain case 2 by inserting one pump body 11. The high-pressure fuel pump 1 is fixed to the chain case 2 with bolts B1 and the like. The high-pressure fuel pump 1 boosts the fuel pumped from a fuel tank (not shown) to a predetermined pressure and supplies it to a common rail (not shown), and receives the rotational force of the crankshaft (described later). Actuated by the rotational force of the crankshaft via the pump drive chain 42.

  In this pump mounting structure, the drive shaft 12 of the high-pressure fuel pump 1 is located in the chain housing space 4 formed between the chain case 2 and the chain cover 3.

  A pump sprocket 5 is attached to the drive shaft 12 of the high-pressure fuel pump 1. Specifically, the drive shaft 12 of the high-pressure fuel pump 1 has a tapered portion 13 whose outer diameter dimension gradually decreases from the chain case 2 side to the chain cover 3 side (toward the left side in FIG. 1), and the tapered portion. 13 and a male screw portion 14 formed on the tip side (chain cover 3 side; left side in FIG. 1).

  On the other hand, when the pump sprocket 5 is attached to the drive shaft 12 of the high-pressure fuel pump 1, the pump sprocket 5 is located on the chain case 2 side (the right side in FIG. 1), and teeth for engaging the pump drive chain are formed on the outer periphery. A pump drive chain engaging portion 51 and a timing chain engaging portion 52 located on the chain cover 3 side (left side in FIG. 1) and having timing chain engaging teeth formed on the outer peripheral portion are provided. The inner peripheral surface 55 of the pump drive chain engaging portion 51 is a tapered surface whose inner diameter dimension gradually decreases from the chain case 2 side toward the chain cover 3 side (toward the left side in FIG. 1). The taper angle of the inner peripheral surface (tapered surface) 55 substantially matches the taper angle of the outer peripheral surface of the tapered portion 13 of the drive shaft 12. The timing chain engaging portion 52 has a substantially cylindrical shape, and the inner diameter dimension thereof is set slightly larger than the outer diameter dimension of the male thread portion 14 of the drive shaft 12. Thus, a nut insertion space 54 is formed between the inner peripheral surface of the timing chain engaging portion 52 and the outer peripheral surface of the male screw portion 14.

  Then, the drive shaft 12 of the high-pressure fuel pump 1 is fitted into the center hole of the pump sprocket 5, so that the pump sprocket 5 is attached to the drive shaft 12 and a male screw portion 14 formed at the tip portion of the drive shaft 12. A nut 6 is screwed into the screw. In this state, the entire inner peripheral surface 55 of the pump drive chain engaging portion 51 of the pump sprocket 5 is in contact with the outer peripheral surface of the drive shaft 12 (the outer peripheral surface of the tapered portion 13). A part of the nut 6 is inserted into the nut insertion space 54. A flange 61 is formed on the outer periphery of the nut 6. The outer diameter of the flange 61 is larger than the inner diameter of the timing chain engaging portion 52 of the pump sprocket 5. Therefore, the flange 61 is in contact with the end surface (left end surface in FIG. 1) 56 of the pump sprocket 5 so that the pump sprocket 5 is attached to the drive shaft 12 while being prevented from coming off.

  A timing chain 41 and a pump drive chain 42 are hung on the pump sprocket 5. The timing chain 41 includes a cam sprocket attached to one end of a camshaft (not shown) and a timing chain engaging portion 52 of the pump sprocket 5 (timing chain engaging teeth formed in the timing chain engaging portion 52). It is bridged between. The cam sprocket and the teeth of the timing chain engaging portion 52 are aligned in the direction along the axis of the camshaft (the teeth of the timing chain engaging portion 52 are located directly below the cam sprocket), The timing chain 41 is bridged between the cam sprocket and the teeth of the timing chain engaging portion 52 without bending in the direction along the axis of the camshaft. The pump drive chain 42 includes a crank sprocket attached to one end of a crankshaft (not shown) and a pump drive chain engaging portion 51 of the pump sprocket 5 (for pump drive chain engagement formed in the pump drive chain engaging portion 51). Between the teeth). The positions of the crank sprocket and the teeth of the pump drive chain engaging portion 51 coincide with the positions along the axis of the crankshaft (the crank sprocket is located directly below the teeth of the pump drive chain engaging portion 51. ), The pump drive chain 42 is stretched between the crank sprocket and the teeth of the pump drive chain engaging portion 51 without bending in the direction along the axis of the crankshaft. For this reason, in the operating state of the engine, the rotational force of the crankshaft is transmitted to the pump sprocket 5 via the pump drive chain 42, and the high-pressure fuel pump 1 operates. Further, the rotational force of the pump sprocket 5 is transmitted to the camshaft via the timing chain 41, and the valve system of the engine operates.

  A maintenance opening 31 is formed in the chain cover 3, and a part of the nut 6 (the left end portion in FIG. 1) is located in the maintenance opening 31. The maintenance opening 31 is closed by a maintenance cover 32. Specifically, bolt holes 33 having internal threads formed on the inner surface are formed at a plurality of locations on the opening edge of the maintenance opening 31 in the chain cover 3. On the other hand, bolt insertion holes 34 are formed at positions corresponding to the bolt holes 33 at a plurality of locations on the outer edge of the maintenance cover 32. When the maintenance opening 31 is closed by the maintenance cover 32, the bolt insertion hole 34 of the maintenance cover 32 is aligned with the bolt hole 33 of the chain cover 3, and the bolt B <b> 2 is inserted across these holes 33, 34, The maintenance cover 32 is attached to the chain cover 3 by screwing the bolt B2 into the bolt hole 33 of the chain cover 3.

  As one of the features of the present embodiment, the pump sprocket 5 includes a large-diameter portion 57 whose outer diameter is set larger than the inner diameter of the pump insertion hole 21, and the end surface of the large-diameter portion 57 58 and the end surface 22 of the opening edge of the pump insertion hole 21 face each other in the direction along the axis O of the drive shaft 12.

  Specifically, a large-diameter portion 57 having a flange shape is formed at the end of the outer peripheral surface of the pump drive chain engaging portion 51 of the pump sprocket 5 on the chain case 2 side. The outer diameter dimension of the large diameter portion 57 is set larger than the inner diameter dimension of the pump insertion hole 21. For example, the outer diameter of the large diameter portion 57 is set to be about 5 mm larger than the inner diameter of the pump insertion hole 21. This value is not limited to this and is set as appropriate. For this reason, if a situation occurs in which the pump sprocket 5 moves toward the chain case 2, an end face (the right end face in FIG. 1) of the large-diameter portion 57 of the pump sprocket 5 facing the chain case 2. 58) abuts on the end surface (the left end surface in FIG. 1) 22 of the chain case 2 facing the pump sprocket 5, and the movement of the pump sprocket 5 is prevented.

  Further, as another feature of the present embodiment, the distance between the end surface 58 of the large-diameter portion 57 of the pump sprocket 5 facing the end surface 22 of the opening edge of the pump insertion hole 21 (dimension t in FIG. 1). However, it is set to be shorter than the amount of bending that becomes the elastic limit when the chains 41 and 42 are bent toward the chain case 2 side. Generally, the center distance between the crank sprocket and the pump sprocket 5 is shorter than the center distance between the cam sprocket and the pump sprocket 5. Therefore, when each chain 41, 42 is bent by the same amount toward the chain case 2, the amount of bending per unit length in the longitudinal direction (vertical direction) of each chain 41, 42 is the timing chain. The pump drive chain 42 is larger than 41. Therefore, the distance between the end surface 58 of the large-diameter portion 57 of the pump sprocket 5 facing the end surface 22 of the opening edge of the pump insertion hole 21 is such that the pump drive chain 42 is bent toward the chain case 2 side. In this case, it is set to be shorter than the amount of bending which becomes the elastic limit. For example, when the amount of flexure that is the elastic limit of the pump drive chain 42 toward the chain case 2 is 3 mm, the distance t is set to 2 mm. These values are not limited to this. The interval set in this way is shorter than the amount of bending that becomes the elastic limit when the pump drive chain 42 is bent toward the chain case 2 side, and the timing chain 41 is bent toward the chain case 2 side. In this case, the amount of bending is shorter than the amount of bending that is the elastic limit.

  As a mounting operation of the high-pressure fuel pump 1 for realizing such a pump mounting structure, first, before the chain cover 3 is mounted, the pump insertion hole 21 of the chain case 2 is inserted into the right side (rear side of the engine) in the drawing. ), And the pump body 11 is fixed to the chain case 2 with bolts B1. Thereafter, the pump sprocket 5 is assembled to the drive shaft 12 of the high-pressure fuel pump 1 from the left side (front side of the engine) in the drawing. Then, the nut 6 is screwed into the male threaded portion 14 of the drive shaft 12, and the pump sprocket 5 is attached to the drive shaft 12 while being prevented from coming off. Then, after the pump drive chain 42 is hung on the pump drive chain engaging portion 51 of the pump sprocket 5 and the pump drive chain 42 is hung on the timing chain engaging portion 52, the chain cover 3 is attached.

-Pump removal work-
Next, pump removal work will be described. This pump removing operation is an operation for removing the high-pressure fuel pump 1 from the chain case 2 when it becomes necessary to maintain the high-pressure fuel pump 1. Specifically, this is an operation of extracting the pump body 11 of the high-pressure fuel pump 1 from the pump insertion hole 21 of the chain case 2. This makes it possible to remove the high-pressure fuel pump 1 from the chain case 2 while the engine is mounted on the vehicle. In this pump removal operation, a jig mounting operation and a pump extraction operation are sequentially performed. Each operation will be specifically described below.

  In the jig mounting operation, as shown in FIG. 2, the maintenance cover 32 is removed from the chain cover 3 to open the maintenance opening 31. Then, the jig 7 is inserted from the maintenance opening 31 toward the nut 6.

  The jig 7 includes a mounting plate 71, a nut driver part 72, and an operation part 73.

  The mounting plate 71 is a plate having a diameter larger than that of the maintenance opening 31, and a bolt insertion hole 74 similar to that of the maintenance cover 32 is formed. That is, the bolt insertion hole 74 is formed at a position corresponding to the bolt hole 33 formed in the chain cover 3. When the jig 7 is attached to the chain cover 3, the bolt insertion hole 74 of the attachment plate 71 is aligned with the bolt hole 33 of the chain cover 3, and the bolt B3 is inserted across these holes 33, 74. The bolt B3 is screwed into the bolt hole 33 of the chain cover 3.

  The nut driver part 72 and the operation part 73 are integrally formed and are rotatably supported by the mounting plate 71. Further, the back surface (the left surface in FIG. 2) of the nut driver portion 72 is in contact with the inner surface of the mounting plate 71, whereby the nut driver portion 72 and the operation portion 73 are moved backward with respect to the mounting plate 71 ( The movement to the left in FIG. 2 is impossible. As described above, when the mounting plate 71 is attached to the chain cover 3, the nut driver portion 72 is located in the maintenance opening 31 and is fitted around the outer periphery of the nut 6. As described above, since a part of the nut 6 is located in the maintenance opening 31, the operation of fitting the nut driver portion 72 into the outer periphery of the nut 6 can be performed relatively easily. The operation unit 73 is located outside the attachment plate 71 and can be operated (rotated) by an operator.

  In the pump extraction operation, the operator rotates the operation portion 73 of the jig 7. As a result, the nut driver portion 72 also rotates, and the nut 6 rotates in a direction to come out of the male screw portion 14 of the drive shaft 12, and the nut 6 and the drive shaft 12 move away from each other. Will do. At this time, as described above, the nut driver portion 72 cannot be moved backward (moved to the left in FIG. 2) with respect to the mounting plate 71. A force in a direction opposite to the installation position (right direction in the figure) acts. By this force, the entire high-pressure fuel pump 1 moves in the right direction in the drawing, that is, in the direction in which the pump body 11 comes out of the pump insertion hole 21 of the chain case 2 (see arrow III in FIG. 3). ).

  When the high-pressure fuel pump 1 moves in this way, even if the pump sprocket 5 moves integrally with the high-pressure fuel pump 1 as shown in FIG. The end surface 58 of 57 contacts the end surface 22 of the opening edge of the pump insertion hole 21, and the pump sprocket 5 does not move further from the contacted position. As described above, the distance t between the end surface 58 of the large-diameter portion 57 of the pump sprocket 5 facing and the end surface 22 of the opening edge of the pump insertion hole 21 is such that the chains 41 and 42 are bent toward the chain case 2 side. It is set to be shorter than the amount of bending which becomes the elastic limit in the case of the case. Therefore, the end surface 58 of the large-diameter portion 57 of the pump sprocket 5 contacts the end surface 22 of the opening edge of the pump insertion hole 21 before the amount of deflection of the chains 41 and 42 reaches the elastic limit of the chains 41 and 42. As described above, the pump sprocket 5 is prevented from moving. That is, the amount of bending of the chains 41 and 42 is prevented from reaching the elastic limit of the chains 41 and 42. With the movement of the pump sprocket 5 blocked in this way, the pump body 11 is pulled out from the pump insertion hole 21 and the high-pressure fuel pump 1 is removed. In this way, the high-pressure fuel pump 1 can be removed without the amount of bending of the chains 41 and 42 exceeding the elastic limit. As a result, the situation where the chains 41 and 42 are plastically deformed and cannot be reused is prevented.

  Further, according to the present embodiment, the pump main body 11 is moved in the direction of coming out of the pump insertion hole 21 by the operation force for rotating the operation unit 73. Since the amount of movement of the pump body 11 (the amount of movement in the direction along the axis O of the drive shaft 12) is smaller than the amount of operation by this rotation operation (the amount of rotation of the operation unit 73), a relatively small operation force. Thus, the pump body 11 can be moved.

  Further, according to the shape of the pump sprocket 5 having the shape according to the present embodiment, when the pump sprocket 5 is manufactured by cutting, the large-diameter portion 57 is left in a flange shape when the outer peripheral surface is cut. For this reason, the part (cutting area | region of an outer peripheral part) cut from a rough material (cylindrical rough material) can be decreased, and reduction of processing cost can be aimed at.

-Other embodiments-
In the embodiment described above, the configuration in which the timing chain 41 and the pump drive chain 42 are hung on the pump sprocket 5 attached to the drive shaft 12 of the high-pressure fuel pump 1 has been described. The present invention is not limited to this, and can also be applied to a configuration in which only the pump drive chain 42 is hung on the pump sprocket 5 attached to the drive shaft 12 of the high-pressure fuel pump 1.

  Moreover, the said embodiment demonstrated the case where this invention was applied to the attachment structure of the high pressure fuel pump 1 in the diesel engine for motor vehicles. The present invention is not limited to this, and can be applied to an oil pump or water pump mounting structure as long as the pump is mounted on a chain case in an automobile engine (diesel engine or gasoline engine).

  The present invention can be applied to a mounting structure for a high-pressure fuel pump mounted on an automobile engine.

DESCRIPTION OF SYMBOLS 1 High pressure fuel pump 11 Pump main body 12 Drive shaft 2 Chain case 21 Pump insertion hole 3 Chain cover 4 Chain accommodation space 41 Timing chain 42 Pump drive chain 5 Pump sprocket 57 Large diameter part 58 End surface

Claims (1)

The pump body is inserted into the pump insertion hole provided in the chain case, the drive shaft of the pump is located in the chain housing space formed between the chain case and the chain cover, and the pump sprocket is mounted on this drive shaft. In the pump mounting structure in which a chain is hung on this pump sprocket,
The pump sprocket includes a large-diameter portion whose outer diameter is set larger than the inner diameter of the pump insertion hole, and the end surface of the large-diameter portion and the opening edge of the pump insertion hole are connected to the drive shaft. Facing in the direction along the axis of
The distance between the end surface of the large-diameter portion of the pump sprocket facing the opening edge of the pump insertion hole is shorter than the amount of bending that becomes the elastic limit when the chain is bent toward the chain case. Pump mounting structure characterized by being set.

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