JP2000291503A - Mounting structure for high-pressure fuel pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting structure for a high-pressure fuel pump which is simple in fitting with which it is possible to restrain an increase in emitted sound generated with a drive of the high pressure fuel pump. SOLUTION: A bracket 140 and a high-pressure fuel pump 20 connected thereto are mounted just above a pump drive cam exposed to an overhead of a cylinder head 110. The high-pressure fuel pump 20 connected to the bracket 140 projects through a columnan opening 121 which is formed on an upper surface of a cylinder head cover 120 enveloping the cylinder head 110. A gap between the cylinder head cover 120 and the bracket 140 is sealed with a gasket 132 for the bracket, while a gap between the cylinder head cover 120 and the cylinder head 110 is sealed with a gasket 133 for the cylinder head.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high pressure fuel pump for pressurizing fuel by using, for example, an axial force of an intake and exhaust camshaft and supplying the pressurized fuel to a pressure accumulating pipe of the engine. The present invention relates to a mounting structure for mounting.

[0002]

2. Description of the Related Art For example, a high-pressure fuel pump provided in an in-vehicle engine pressurizes fuel pumped from a fuel tank to a high pressure and sends it to a pressure accumulation pipe such as a delivery pipe or a common rail. The high-pressure fuel stored in the pressure-accumulation pipe in this way is usually injected and supplied to the engine via a fuel injection valve. As a high-pressure fuel pump of this type, for example, a high-pressure fuel pump described in, for example, Japanese Patent Application Laid-Open No. 10-30526 is known.

[0003] The high-pressure fuel pump described in the publication includes a pressurizing cylinder into which fuel is introduced, and a plunger slidably supported in the pressurizing cylinder along the axial direction. The plunger reciprocates in the pressurizing cylinder in conjunction with the rotation of the pump cam provided in the pressurized cylinder, thereby pressurizing and sending out the fuel in the pressurizing cylinder. The high-pressure fuel pump is attached to the engine such that the high-pressure fuel pump is integrally fixed to a cylinder head cover fixed to the cylinder head so as to cover an upper portion of the cylinder head of the engine.

[0004]

In such a high-pressure fuel pump, the plunger reciprocates at a high speed with the operation of the engine. Therefore, in the mounting structure of the above aspect, the reciprocating plunger vibrates and moves. Vibration of the valve system is transmitted to the entire cylinder head cover, and an increase in radiated sound accompanying the vibration is unavoidable.

Conventionally, in order to suppress such transmission of vibration, a method of dividing a part of the cylinder head cover and providing an independent cylinder head cover for mounting a high-pressure fuel pump has been adopted. However,
When the cylinder head cover is divided into a plurality in this way,
The increase in the number of members and the complexity of the structure complicate the mounting process and increase the manufacturing cost. In addition, a new problem arises in that it is necessary to ensure sufficient sealing performance for each of the divided cylinder head covers.

[0006] The present invention has been made in view of such circumstances, and an object of the present invention is to suppress an increase in radiated sound due to driving of a high-pressure fuel pump and to mount the same. An object of the present invention is to provide an easy high pressure fuel pump mounting structure.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, fuel is supplied by being driven by an axial force of at least one of an intake and exhaust camshaft provided on a cylinder head of an engine. A high-pressure fuel pump for pressurizing is attached to the engine, and a bracket for supporting the high-pressure fuel pump is provided on the cylinder head, and a cylinder head cover for covering the cylinder head is provided on the bracket of the high-pressure fuel pump. A mounting portion for the high-pressure fuel pump is separated from a cylinder head cover by providing an oil seal between the periphery of the through-hole and the bracket, whereby the mounting portion is provided. The gist is to make the anti-vibration structure.

[0010] According to the above configuration, vibration generated by driving the high-pressure fuel pump is not transmitted directly to the cylinder head cover. That is, such vibrations are suitably absorbed by the bracket and the oil seal provided between the bracket and the periphery of the through hole. For this reason, the increase in the radiated sound due to the vibration is appropriately absorbed.

According to a second aspect of the present invention, in the mounting structure for the high-pressure fuel pump according to the first aspect, an oil seal provided between the periphery of the through hole and the bracket is provided.
The gist is made of a material or a shape having lower rigidity than an oil seal provided between the cylinder head cover and the cylinder head.

[0010] According to this structure, the oil seal provided between the periphery of the through hole and the bracket is smaller than the oil seal provided between the cylinder head cover and the cylinder head in mounting. Deflection increases. As described above, if the relative amount of deflection of the oil seal provided between the periphery of the through hole and the bracket is set to be large, a slight dimensional error may occur in the formation of the through hole of the cylinder head cover. Even if there is, it is easy to ensure the sealing performance at both the sealing sites.

[0011] The invention described in claim 3 is the invention according to claim 1 or 2.
In the mounting structure for a high-pressure fuel pump described in the above, the bracket is provided so as to protrude above the cylinder head, and the cylinder head cover is configured such that a peripheral portion provided with the through hole has a head side portion of the bracket provided so as to protrude. The point is to have a covering shape.

According to this structure, the inner surface of the cylinder head cover forms a leaning wall so that the peripheral portion of the through hole covers the head side portion of the bracket. This drooping wall makes it difficult for oil scattered from the camshaft in the cylinder head to reach the oil seal provided between the bracket around the through hole of the cylinder head cover and the bracket, without being directly applied to the oil seal. Therefore, a high sealing property can be ensured at the sealing portion, and the durability of the oil seal also increases.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a mounting structure for a high-pressure fuel pump according to the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram schematically showing an entire fuel supply system of, for example, a vehicle-mounted in-line four-cylinder gasoline engine to which a high-pressure fuel pump is attached. This fuel supply system 1
Has a low-pressure pump (feed pump) 10, a high-pressure fuel pump 20, a spill valve 30, a fuel tank 40, a delivery pipe 50, an injector 60, and the like.

Here, the feed pump 10 is a pump that pumps up the fuel in the fuel tank 40 and sends it to the high-pressure fuel pump 20 through a low-pressure oil passage. The high-pressure fuel pump 20 is a pump that pressurizes the fuel fed from the feed pump 10 to a high pressure, and pressure-feeds the high-pressure fuel to the delivery pipe 50 via the high-pressure oil passage 1b. The delivery pipe 50 is a part that accumulates high-pressure fuel pumped from the high-pressure fuel pump 20 therein, and the fuel accumulated in the delivery pipe 50 is supplied to the engine according to the valve opening drive of each injector 60. 100 is injected and supplied.

On the other hand, the high-pressure fuel pump 20 is actually provided in a cylinder head corresponding to the head of the engine 100, and as shown in FIG.
And a plunger 22 reciprocating in the pressurizing cylinder 21
And a pressurizing chamber 23 defined by the inner peripheral wall surface of the pressurizing cylinder 21 and the upper end surface of the plunger 22. The pressurizing chamber 23 communicates with the spill valve 30 via a hole, and also communicates with the high-pressure oil supply passage 1b via a check valve 1c. The high-pressure oil supply passage 1b is provided with a delivery pipe 5
0 is connected. The check valve 1c is connected to the delivery pipe 5
The backflow of fuel from 0 to the pressurizing chamber 23 is regulated. The tappet 24 attached to the lower end of the plunger 22 (the lower end in the figure) is pressed against a pump driving cam 26 provided on the exhaust camshaft 111 e of the engine 100 by the biasing force of a spring 25. The rotation of the pump drive cam 26 with the rotation of the exhaust camshaft causes the plunger 22 to reciprocate in the pressure cylinder 21 to change the volume in the pressure chamber 23.

The fuel that has flowed into the spill valve 30 through the low-pressure oil supply passage 1a is introduced into the pressurizing chamber 23 through the hole when the plunger 22 moves down in the pressurizing cylinder 21.
On the other hand, when the plunger 22 moves upward, the exciting unit 30
The valve body 30b is driven to the closing side based on the energization to a to close the hole, and the fuel in the pressurizing chamber 23 is pressurized to a high pressure.

The high-pressure fuel pressurized in the pressurizing chamber 23 of the high-pressure fuel pump 20 is supplied to the delivery pipe 50 through the high-pressure oil supply passage 1b. FIG. 2 is a perspective view schematically illustrating an appearance of a mounting portion of the high-pressure fuel pump 20 on a head (cylinder head) of the engine 100.

As shown in FIG. 2, in this embodiment, the high-pressure fuel pump 20 is inserted from above a cylinder head cover 120 bolted onto the cylinder head 110 near the longitudinal end of the cylinder head 110. It is attached in the state where it was set.

An axis I is provided inside the cylinder head 110.
An intake camshaft and an exhaust camshaft (not shown) are provided rotatably along the axis E.
Among them, a pump cam is provided near the end of the exhaust camshaft, and the high-pressure fuel pump 20 is driven by the rotation of the pump drive cam 26 as described above (see FIG. 1). ).

On the other hand, as is well known, the intake camshaft and the exhaust camshaft rotate in conjunction with a crankshaft (not shown) of the engine 100 via a timing belt (not shown). Each of the intake camshaft and the exhaust camshaft includes a plurality of valve drive cams (not shown) separate from the pump drive cam 26. Further, an intake valve and an exhaust valve (not shown) provided immediately below each valve driving cam are pressed against each valve driving cam by the urging force of a spring (not shown). An intake valve and an exhaust valve are provided in an intake port (not shown) of each cylinder (not shown) arranged in series along the longitudinal direction of the engine 100.
And an on-off valve for opening and closing an exhaust port (not shown). That is, when both camshafts rotate, the intake valve and the exhaust valve reciprocate according to the shape of each valve drive cam, and open and close the corresponding intake port and exhaust port at appropriate timing.

Next, FIG. 3 is an exploded perspective view showing the mounting portion of the high-pressure fuel pump 20 shown in FIG. 2 above as being disassembled into members such as the high-pressure fuel pump 20, the cylinder head cover 120, and the cylinder head 110. It is.

As shown in FIG. 3, the high-pressure fuel pump 20
Is assembled to the cylinder head 110 via the cylinder head cover 120 and the bracket 140 during that time.

Here, the cylinder head cover 120 is
A resin cover is provided to cover the intake camshaft and the exhaust camshaft (not shown) exposed on the cylinder head 110 and to prevent oil from leaking or scattering outside. The cylinder head cover 120 has an opening 1 through which a pressurizing cylinder 21 which is a portion supported by the bracket 140 of the high-pressure fuel pump 20 is passed.
21 are provided. The opening 121 protrudes in a substantially cylindrical shape from the upper surface of the cylinder head cover 120, and a substantially circular through hole 123 through which the upper step 142 of the bracket 140 to which the high-pressure fuel pump 20 is mounted penetrates is formed on the head upper surface 121 a. Are formed. The cylinder head cover 120 and the cylinder head 110 are bolted together with an annular cylinder head gasket 133 interposed therebetween.

The bracket 140 has a cylindrical shape having upper and lower open ends and both open ends communicating with each other inside. A pedestal for supporting and fixing the high-pressure fuel pump 20 to the cylinder head 110 is provided. As a role. That is, the pressurizing cylinder 21 of the high-pressure fuel pump 20 is fitted from the upper open end, and the cylinder head covers the upper part of the pump drive cam 26 (see FIG. 1 and not shown in FIG. 3) at the lower open end. It is assembled to 110 and fixed appropriately. In addition, this bracket 14
The outer contour of 0 is composed of a substantially cylindrical lower step 141 and a substantially cylindrical upper step 142 having an outer diameter smaller than that of the lower step 141, and a boundary between the upper step 142 and the lower step 141. A flat peripheral portion 141 a is formed above the head of the corresponding lower step 141 along the outer periphery of the upper step 142. The outer diameter of the upper portion 142 is slightly smaller than the inner diameter of the through hole 123 formed in the opening 121 of the cylinder head cover 120.

When mounting the high-pressure fuel pump 20, the components are assembled together along the axis L. That is, the bracket 140 is attached to the cylinder head 1
The head 10 is fixed to a portion (shown by a broken line in FIG. 3) immediately above the pump driving cam 26. An annular bracket gasket 132 as an oil seal is attached to the peripheral portion 141 a of the bracket 140. The bracket gasket 132 is formed so as to have lower rigidity than the cylinder head gasket 133, in other words, to have a larger amount of bending when mounted. When the cylinder head cover 120 is attached to the cylinder head 110, the upper portion 142 of the bracket 140 is connected to the opening 121 of the cylinder head cover 120.
The head upper surface of the bracket 140 and the head upper surface 121a of the opening 121 of the cylinder head cover 120 are substantially coexistent on a plane orthogonal to the axis L while being disposed in the through hole 123 formed in the cylinder head cover 120. At this time, the gasket 132 for the bracket is
And the peripheral portion 141a of the bracket 140.

Here, the bracket gasket 13
As described above, No. 2 is formed to have lower rigidity than the cylinder head gasket 133 provided on the periphery of the cylinder head 110 and the cylinder head cover 120. Therefore, the bracket gasket 132
Has a greater deflection when mounted than the gasket 133 for the cylinder head. Due to this relatively large deflection, the opening 121 of the cylinder head cover 120 is formed.
Even if there is some dimensional error or the like in the formation of the gasket, it is easy to ensure the sealing performance of both gaskets 132 and 133. Further, a portion where relatively strong vibration is transmitted in the vicinity of the high-pressure fuel pump 20 is sealed with a low rigidity gasket 132, and a portion where relatively weak vibration is transmitted and isolated from the high-pressure fuel pump 20 is rigidly connected. The gasket 133 has a high sealing structure, so that the vibration absorption (vibration-proofing) and the sealing performance at both sealing portions are ensured at optimal levels.

Thereafter, the high-pressure fuel pump 20 is fitted into the open end on the bracket 140 via the heat insulator 131. The heat insulator 131 is an annular member formed of a material having a heat insulating property, and has a role of suppressing heat conduction from the engine 100 to the high-pressure fuel pump 20.

With such a structure, the high-pressure fuel pump 2
By attaching 0, the vibration generated by driving the high-pressure fuel pump 20 is not transmitted directly to the cylinder head cover 120, but is suitably absorbed by the bracket 140 and the bracket gasket 132.

FIG. 4 shows such a mounting structure of the high-pressure fuel pump 20 as a partial cross-sectional structure along the line IV-IV in FIG. As shown in FIG. 4, the high-pressure fuel pump 20 uses the bracket 140 mounted on the cylinder head 110 as a pedestal, and the engine 100 is fitted into the open end of the bracket 140 via an annular heat insulator 131. Attached to. Inside the bracket 140, the high-pressure fuel pump 20
Tappet 24 provided at the lower end of pump drive cam 26
It is fixed in a state of being pressed against. The cylinder head cover 120 covers the entire upper part of the head of the cylinder head 110, while the opening 121 formed in the cylinder head cover 120 has a bracket 140 and the high-pressure fuel pump 2.
The connection structure with 0 is penetrated. In addition, in the head upper surface 121a of the opening 121 corresponding to the connection portion between the bracket 140 and the high-pressure fuel pump 20, the head upper surface 121a
The peripheral portion of the through hole 123 formed in the
0, ie, the upper side of the bracket 140, that is, the head 140 of the bracket 140 is covered with the so-called hanging wall 1 on its inner surface.
21b.

On the other hand, as shown by a broken line in FIG. 4, behind the pump driving cam 26, an exhaust cam 112e sharing the same rotation axis (exhaust cam shaft) 111e as the pump driving cam 26 has an exhaust port 114e. Is provided corresponding to the exhaust valve 113e that opens and closes the opening. In addition, the intake camshaft 111i disposed in parallel with the exhaust camshaft 111e has the intake port 114i
Is provided with an intake cam 112i for opening and closing the intake valve 113i provided in the intake cam 112i. In FIG. 4, a portion of the intake cam 112i exposed to the internal space of the cylinder head cover 120 is indicated by a solid line, and another portion accommodated in the cylinder head 110 is indicated by a broken line.

Here, in the engine 100, when the intake camshaft 111i and the exhaust camshaft 111e rotate with the start of operation, the exhaust cam 11
The plunger 22 inside the high-pressure fuel pump 20 reciprocates in conjunction with the operation of 2e. In the internal space of the cylinder head cover 120, the intake and exhaust camshafts 111i, 111i,
Oil for lubrication may also be scattered from the intake cam 111i and the intake / exhaust cams 112i and 112e toward the opening 121 of the cylinder head cover 120. However, in the above-described structure of the present embodiment, the scattered oil is blocked by the hanging wall 121b provided in the opening 121 of the cylinder head cover 120. There is no way to reach 132. That is, the bracket gasket 13
The deterioration due to the oil 2 can be suppressed, and the durability can be increased.

Although the high-pressure fuel pump 20 is attached, the cylinder head cover 120 itself can be basically formed as a single member, so that the production process does not become complicated when attaching them.

As described above, according to the mounting structure of the high-pressure fuel pump of the present embodiment, the following effects can be obtained. (1) The vibration generated by the driving of the high-pressure fuel pump 20 is not directly transmitted to the cylinder head cover 120, and the vibration is not directly transmitted to the cylinder head cover 120.
32 to be suitably absorbed. (2) Since the bracket gasket 132 is formed to have a lower rigidity than the cylinder head gasket 133, it is easy to ensure the sealing performance of both of them, and the gap between the bracket 140 and the cylinder head cover 120 is improved. In addition, vibration absorption (vibration isolation) and sealing in the gap between the cylinder head cover 120 and the cylinder head 110 are ensured at optimal levels. (3) Since deterioration of the bracket gasket 132 due to oil is suitably prevented or suppressed, the durability of the bracket gasket 132 can be enhanced. (4) Since the cylinder head cover 120 can be formed as a single member, the cylinder head cover 1
The production process does not become complicated when the high pressure fuel pump 20 and the high pressure fuel pump 20 are mounted.

The opening 121 of the cylinder head cover in the above embodiment may have any three-dimensional shape such as a polygonal pillar shape or a truncated cone shape, and the outer shape is not limited to a cylindrical shape. . The point is that the peripheral portion of the cylinder head cover 120 where the through hole is provided may have a shape that covers the head side of the bracket 140 that is arranged to protrude from above the cylinder head 110.

In addition, the bracket gasket 132 and the cylinder head gasket 13 in the above embodiment are used.
It is generally preferable to apply a rubber material to 3,
If the bracket gasket 132 is formed to have a lower rigidity than the cylinder head gasket 133, it may be formed from another material having elasticity and heat resistance higher than a predetermined value. The relative rigidity or deflection of both gaskets 132 and 133 can be easily adjusted by changing the relative shape and size of both gaskets 132 and 133 without being limited to the method of selecting the material. further,
As far as the vibration absorbing property accompanying the driving of the high-pressure fuel pump and the sealing property in the gap between the bracket and the cylinder head cover are concerned, the above-mentioned irrespective of the relative rigidity of the material of the bracket gasket 132 and the cylinder head gasket 133 The effects unique to the embodiment are sufficiently exhibited.

In the above-described embodiment, the pump driving cam 26 and the high-pressure fuel pump 20 driven by the pump driving cam 26 are provided near the end of the exhaust cam shaft 111e. It may be provided at any part of the camshaft. It may be provided on the intake camshaft, or the intake camshaft and the exhaust camshaft 11
1e. Further, a plurality of pump driving cams and a high-pressure fuel pump may be provided on one camshaft. Incidentally, even if a plurality of pump driving cams and a high-pressure fuel pump are provided on any of the intake camshaft and the exhaust camshaft, the above-mentioned structure is basically adopted without complicating the structure of dividing the cylinder head cover into a plurality. By applying the same configuration as that of the embodiment, it is possible to obtain an effect excellent in vibration absorption and sealing.

In the above embodiment, the mounting structure of the present invention is applied to the high-pressure fuel pump 20 which pressurizes the fuel by reciprocating movement of the plunger 22 interlocked with rotation of the pump driving cam 26 provided on the exhaust camshaft 111e. I decided that. On the other hand, the mounting structure of the present invention is applied to any type of high-pressure fuel pump mounted in a manner attached to the engine body in order to use the axial force of at least one of the intake camshaft and the exhaust camshaft as a driving force. Can be applied.

In the above embodiment, the cylinder head cover 120 is made of resin, but may be made of metal such as aluminum. In the above-described embodiment, the mounting structure of the high-pressure fuel pump according to the present invention is applied to the in-line four-cylinder engine 100. The present invention can be applied to any engine having the supply system of (1).

[0040]

According to the first aspect of the present invention, the vibration generated by driving the high-pressure fuel pump is not transmitted directly to the cylinder head cover, and the increase in the radiated sound caused by such vibration is preferably absorbed. Will be done.

According to the second aspect of the present invention, the oil seal is provided between the bracket and the periphery of the through hole of the cylinder head cover, and the oil seal is provided between the cylinder head cover and the cylinder head. Easiness can be easily secured.

According to the third aspect of the invention, the oil scattered from the camshaft in the cylinder head does not directly reach the oil seal provided between the bracket around the through hole of the cylinder head cover and the bracket, and reaches the oil seal. It becomes difficult to do. Therefore, a high sealing property can be ensured at the sealing portion, and the durability of the oil seal also increases.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a fuel supply system of an engine to which an embodiment of a mounting structure for a high-pressure fuel pump according to the present invention is applied.

FIG. 2 is an exemplary perspective view schematically showing the appearance of a mounting portion of the high-pressure fuel pump according to the embodiment;

FIG. 3 is an exemplary exploded perspective view showing a mounting portion of the high-pressure fuel pump according to the embodiment;

FIG. 4 is an exemplary sectional view showing a mounting structure of the high-pressure fuel pump according to the embodiment;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel supply system, 1a ... Low pressure oil supply line, 1b ... High pressure oil supply line, 1c ... Check valve, 10 ... Feed pump (low pressure pump), 20 ... High pressure fuel pump, 21 ... Pressurized cylinder, 2
2 plunger, 23 pressurized chamber, 24 tappet, 25
... Spring, 26 ... Pump drive cam, 30 ... Spill valve, 30a ... Exciting part, 30b ... Valve, 40 ... Fuel tank, 50 ... Delivery pipe, 60 ... Injector, 10
0: engine, 110: cylinder head, 111e: exhaust camshaft, 111i: intake camshaft, 112
e: exhaust cam, 112i: intake cam, 113e: exhaust valve, 113i: intake valve, 114e: exhaust port,
114i: intake port, 120: cylinder head cover, 121: opening, 121a: top of head (opening), 1
21b: hanging wall, 123: through hole, 131: heat insulator, 132: gasket for bracket, 133
... gasket for cylinder head, 140 ... bracket,
141: lower part, 141a: peripheral part, 142: upper part.

Claims (3)

[Claims] 1. A high-pressure fuel pump, which is driven by an axial force of at least one of an intake and exhaust camshaft provided on a cylinder head of an engine and pressurizes fuel, is attached to the engine. A bracket for supporting the fuel pump is provided, and a through-hole through which a portion of the high-pressure fuel pump supported by the bracket is provided is provided in a cylinder head cover that covers the cylinder head. An installation structure for a high-pressure pump, wherein an installation portion of the high-pressure fuel pump is separated from a cylinder head cover by providing an oil seal between the bracket and a bracket. 2. The mounting structure for a high-pressure fuel pump according to claim 1, wherein an oil seal provided between the periphery of the through hole and the bracket is provided between the cylinder head cover and the cylinder head. A mounting structure for a high-pressure fuel pump, comprising a material or a shape having lower rigidity than an oil seal. 3. The mounting structure for a high-pressure fuel pump according to claim 1, wherein said bracket is provided so as to protrude above said cylinder head, and said cylinder head cover is provided such that a peripheral portion provided with said through-hole is protruded. A mounting structure for a high-pressure fuel pump, wherein the mounting structure has a shape that covers a head side portion of a provided bracket.