JP4069422B2 - Pump mounting structure - Google Patents

Description

  The present invention relates to a high-pressure pump mounting structure, and more particularly to an improvement in a high-pressure pump mounting structure that prevents the high-pressure pump from tilting with respect to a camshaft.

  A high-pressure pump for supplying fuel to an internal combustion engine has a lifter that comes into contact with a cam provided on a camshaft that rotates in response to the operation of the internal combustion engine, and the reciprocating motion of the lifter corresponding to the rotation of the cam The fuel is sucked in, and the sucked fuel is increased in pressure to be supplied to the distribution system.

Conventionally, the high-pressure pump is directly attached to a part of the internal combustion engine. For example, Japanese Patent Laid-Open No. 8-14140 discloses a mounting structure for a high-pressure pump configured such that the high-pressure pump is accommodated in an accommodation hole of a head cover of an internal combustion engine (Patent Document 1). According to such a technique, when the accommodation hole of the head cover is formed with high accuracy and the alignment of the camshaft or the cam and the head cover is set correctly, the cam is properly brought into contact with the lifter of the high pressure pump. I was able to.
Japanese Patent Laid-Open No. 8-14140 (paragraph number 0021, FIG. 1, etc.)

  However, in an internal combustion engine that is actually manufactured, even if the machining accuracy of each of the cam journal, cylinder head, head cover, and pump mounting surface is set to be somewhat high, as a result of the accumulated deviation, the pump mounting surface and the camshaft In many cases, the alignment tolerance was large.

  When the alignment tolerance is increased, the high pressure pump is mounted to be inclined with respect to the camshaft, so that the contact surface of the cam and the contact surface of the lifter of the high pressure pump are not parallel to each other. A large surface pressure was generated locally on the surface. For this reason, when alignment tolerance becomes large, the problem that the cam and the lifter are worn out or both of them are seized arises.

  Then, in view of the said subject, this invention aims at providing the attachment structure of the pump for preventing the inclination of a pump.

  In order to achieve the above object, the present invention provides a pump mounting structure for supplying liquid to an internal combustion engine based on the rotational force of a cam that is rotationally driven by a camshaft, and the camshaft journal is sandwiched between the cams. A shaft holding member including at least a pair of shaft bearing portions that rotatably hold the shaft, and a coupling portion that couples the pair of shaft bearing portions, and the coupling portion is integrally formed with the shaft bearing portion. The connecting portion has a pump holding structure, and the shaft holding member has a structure to which a head cover can be attached (for example, attachment by a fastening member such as a bolt), and a liquid is provided in an overlapping region between the shaft holding member and the head cover. A sealing member is disposed to prevent leakage.

  According to the above structure, the shaft bearing portion rotatably holds the camshaft journal on both sides of the cam, while the connecting portion is a one-piece structure integrally formed with the shaft bearing portion. There can be virtually no alignment tolerance of the connecting part with respect to the axis. Since the pump holding structure is provided at the connecting portion and the pump is directly held, there is almost no alignment tolerance between the pump and the camshaft when the pump is held. Since the cam is a member that is concentric with the camshaft and can be mounted with small alignment tolerances, the cam comes into contact correctly with the abutting portion of the pump, such as a pump lifter, and the cam contact surface is not parallel and the pump It is possible to prevent so-called one-sided contact that comes into contact with a part of the plate. And according to the said structure, since the sealing member is provided, it can prevent that a liquid distribute | circulates between a shaft holding member and a head cover, and can prevent what is called an oil leak.

  Here, “liquid” is a fluid medium, for example, fuel in an internal combustion engine.

  Further, the “shaft bearing portion” is not particularly limited as long as a part of the camshaft can be rotatably held without substantial center displacement.

  Further, the “pump holding structure” may be any structure that can maintain the pump in a predetermined position without position variation. For example, the holding structure of the pump may be an opening provided in the connecting portion. This is because the pump can be held without variation in position if the opening is provided with an appropriate diameter.

  According to the above structure, the shaft holding part holds the shaft on at least both sides of the cam, and the connecting part has an integral structure, so there is almost no alignment tolerance of the connecting part with respect to the cam shaft axis. I don't get it. Since the pump holding structure is provided in the connecting portion and the pump is directly held, there is almost no alignment tolerance between the pump and the camshaft when the pump is held. Since the cam is a member that is concentric with the camshaft and can be mounted with small alignment tolerances, the cam comes into contact correctly with the abutting portion of the pump, such as a pump lifter, and the cam contact surface is not parallel and the pump It is possible to prevent so-called one-sided contact that comes into contact with a part of the plate. And since the sealing member is provided, it can prevent that a liquid distribute | circulates between a shaft holding member and a head cover, and can prevent what is called an oil leak.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 3 show a mounting structure of a high-pressure pump according to an embodiment of the present invention. 1 is a cross-sectional view in a plane parallel to the axial direction of the camshaft, and FIG. 2 is a cross-sectional view in the vicinity of the axial center of the high-pressure pump that is perpendicular to the axis of the camshaft FIG. 3 is a cross-sectional view (CC cross-sectional view in FIG. 1) in the vicinity of the camshaft bearing, which is a surface perpendicular to the axis of the camshaft.

  As shown in FIGS. 1-3, the high pressure pump 100 is attached to the cylinder head which is a to-be-attached part via the attachment structure 1 which concerns on this invention. The mounting structure 1 has a shaft holding member 10, holds the high-pressure pump 100 by the shaft holding member 10, and holds the camshaft 71 with the cam 72 interposed therebetween, so that the cam is rotated together with the camshaft 71. 72 is brought into contact with the lifter 3 of the high-pressure pump 100. The shaft holding member 10 functions as a relay alignment structure between the attached portion and the high-pressure pump 100.

  The shaft holding member 10 is formed by casting or forging with a material of a normal structural component, for example, aluminum or another metal alloy.

  Specifically, the shaft holding member 10 is configured by integrally molding a pair of shaft bearing portions 101A and 101B and a connecting portion 102. The shaft bearing portion 101 has a toll structure protruding from the connecting portion 102 in an arm shape toward the camshaft 71, and a bearing surface 103 is provided at the tip thereof so that the journal of the camshaft 71 can slide freely. It is designed to be accommodated.

  As shown in FIGS. 1 and 3, the shaft bearing portions 101A and 101B are combined with the cylinder side bearing portions 11A and 11B formed in the cylinder head to slidably hold the journal of the camshaft 71. ing. In each shaft bearing portion 101A and 101B, a fastening hole 104 is provided at a position perpendicular to the camshaft axis and sandwiching the bearing surface 103, and the shaft bearing portion 101 is connected to the cylinder by a bolt 108 as a fastening member. The camshaft 71 is fastened to the head-side bearing portion 11 in a rotatable state. With such a structure, as shown in FIG. 1, the pair of shaft bearing portions 101 </ b> A and 101 </ b> B slidably holds the journal of the camshaft 71 at two positions sandwiching the cam 72.

  The connecting portion 102 is a portion that connects the pair of shaft bearing portions 101A and 101B, and is integrally formed with the shaft bearing portion. A pump insertion hole 106 is provided in the middle of the connecting portion 102 so that the bracket 2 of the high-pressure pump 100 is inserted and held.

  In FIG. 4, the top view which looked down at the said attachment structure 1 from the upper part is shown. As shown in FIG. 4, in the connecting portion 102, it is preferable that the pump insertion hole 106 be opened at the geometric center portion because the mechanical structural strength can be made uniform. However, the holding position and structure of the high-pressure pump are not limited to this. That is, it is only necessary to provide the high pressure pump 100 with a structure in which the relative position does not easily change so as not to cause an attachment error of the high pressure pump 100 with respect to the cam 72.

  As shown in FIGS. 1, 3, and 4, in the plan view, the coupling portion 102 is provided with the fastening holes 104 for the cylinder head side bearing portion 11 corresponding to the positions of the shaft bearing portions 101 </ b> A and 101 </ b> B. It has been. The connecting portion 102 is provided with a bolt insertion hole 107 for attaching the head cover 70 to the shaft holding member 10 and a bolt insertion hole 109 for attaching the high-pressure pump 100.

  Further, an oil seal 105 is provided on the upper surface of the connecting portion 102 to prevent a liquid such as oil from leaking at a portion where the head cover 70 and the connecting portion 102 overlap. As the oil seal structure, a packing / seal material, which is an elastic member such as rubber or resin, is slid along a groove provided on the upper surface of the connecting portion 102, but other structures may be used. Absent.

  Next, the structure of the high-pressure pump 100 attached by the attachment structure 1 will be briefly described. The high-pressure pump 100 includes a lifter 3 that contacts the cam 72 and reciprocates as the cam rotates, a bracket 2 that slidably accommodates the lifter 3, a plunger 5 that reciprocates as the lifter 3 reciprocates, a plunger And a housing 4 for housing the cylinder 4. When the high-pressure pump 100 is attached to the pump insertion hole 106 of the shaft holding member 10, the shaft holding member 10 is dimensionally adjusted so that the cam 71 comes into contact with the contact surface of the lifter 3 below the bracket 2. ing.

  A portion of the bracket 2 that accommodates the lifter 3 is a lifter guide 23, and a thick portion 24 is provided at the tip thereof. The lifter guide 23 is inserted into the pump insertion hole 106 of the shaft holding member 10. A thick part 31 is formed at the end of the lifter 3, and the thick part 31 and the thick part 24 of the bracket 2 function as a mechanism for preventing the lifter 3 from coming off.

  A retainer 32 is provided in the lifter 3, and the retainer 32 is biased in the cam direction by a spring 33 provided in the cylinder 4. The end of the plunger 5 is gripped at the center of the retainer 32.

  The cylinder 4 is provided with a hole 42 in which the plunger 5 is slidably accommodated, and a pressurizing chamber 41 following the hole 42 is provided in a region where the other end of the plunger 5 reciprocates. A fuel supply path 44 is provided in the upper part of the cylinder 4, and an electromagnetic spill valve 43 is provided at the inlet to the pressurizing chamber 41. The electromagnetic spill valve 43 is opened and closed in response to the reciprocation of the plunger 5. The electromagnetic spill valve 43 opens when the plunger 5 moves in the direction of increasing the volume of the pressurizing chamber 41, and guides fuel into the pressurizing chamber 41. The electromagnetic spill valve 43 is closed when the plunger 5 moves in the direction of decreasing the volume of the pressurizing chamber 41, and the pressurized fuel in the pressurizing chamber 41 passes through the high-pressure fuel passage 61 to the fuel distribution system. It comes to be supplied.

  In the above configuration, the high pressure pump 100 and the shaft holding member 10 are fastened by the bolt 21 through the bolt insertion hole 22 provided in the bracket 2 of the high pressure pump and the bolt insertion hole 109 of the shaft holding member 10. Yes. The head cover 70 and the shaft holding member 10 are fastened with bolts 73 through the bolt insertion holes 74 of the head cover 70 and the bolt insertion holes 107 of the shaft holding member 10.

  In addition, the hole processing of the pump insertion hole 106 is performed as follows. First, the shaft holding member 10 in which the pump insertion hole 106 is not opened is prepared. Then, the bolt 108 is inserted through the shaft holding member 10 fastening hole 104, and the shaft holding member 10 is fastened to the cylinder head side fastening member 11.

  Next, a guide hole for a valve lifter is processed in the cylinder head. At the time of this processing, the pump insertion hole 106 is simultaneously processed together with the guide hole. Since the pump insertion hole 106 is processed in this way, the pump insertion hole 106 can be processed with high accuracy equivalent to the guide hole.

  As described above, according to the mounting structure of the present embodiment, the journal of the camshaft 71 is held by the pair of shaft bearing portions 101A and 101B, while the connecting portion 102 is integrally formed with the pair of shaft bearing portions 101A and 101B. Therefore, there is almost no alignment tolerance of the connecting portion 102 with respect to the axis of the camshaft 71.

  In addition, according to the present embodiment, the pump insertion hole 106 is formed simultaneously with the guide hole for the valve lifter, so that the processing accuracy of the pump insertion hole 106 is as high as that of the guide hole. Since the cam 72 is formed concentrically with the camshaft 71 and attached with a small alignment tolerance, the cam 72 correctly comes into contact with the contact surface with the cam 72 of the lifter 3 of the high-pressure pump 100 in the end. You can prevent hits.

Sectional drawing of the surface parallel to a cam shaft which is the attachment structure of the pump of embodiment. FIG. 2 is a cross-sectional view taken along the line B-B in FIG. 1, illustrating the pump mounting structure of the embodiment. FIG. 2 is a cross-sectional view taken along the line CC of FIG. It is a mounting structure of the pump of an embodiment, and is a top view of connecting parts.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Mounting structure, 10 ... Shaft holding member, 100 ... High pressure pump, 101 ... Shaft bearing part, 102 ... Connection part, 103 ... Shaft bearing surface, 104 ... Fastening hole, 105 ... Oil seal, 106 ... Pump insertion hole, 11 ... Cylinder head side bearing, 110 ... Shaft bearing surface, 2 ... Bracket, 22, 74, 107, 109 ... Bolt insertion hole, 23 ... Lifter guide, 24 ... Thick part, 21, 73, 108 ... Bolt (fastening member) DESCRIPTION OF SYMBOLS 3 ... Lifter, 31 ... Thick part, 32 ... Retainer, 4 ... Cylinder, 41 ... Pressurizing chamber, 42 ... Hole, 43 ... Electromagnetic spill valve, 44 ... Fuel supply path, 5 ... Plunger, 6 ... Housing, 61 ... high pressure fuel passage, 70 ... head cover, 71 ... cam shaft, 72 ... cam

Claims (2)

A pump mounting structure for supplying liquid to an internal combustion engine based on the rotational force of a cam that is rotationally driven by a camshaft,
At least a pair of shaft bearings for rotatably holding the camshaft journal with the cam interposed therebetween;
A shaft holding member comprising: a connecting portion that connects the pair of shaft bearing portions;
The connecting portion is formed integrally with the shaft bearing portion,
The connecting portion includes a holding structure for the pump ,
The shaft holding member has a structure to which a head cover can be attached,
A pump mounting structure , wherein a sealing member for preventing liquid leakage is disposed in an overlapping region between the shaft holding member and the head cover .   The pump mounting structure according to claim 1, wherein the pump holding structure is an opening provided in the connecting portion.

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