JP2003184688A - Fuel pump device of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the entire length of a cylinder head of an engine and heighten supporting rigidity of a high-pressure fuel pump in a high-pressure fuel pump device of a cylinder injection engine. <P>SOLUTION: An extension part 12A of an exhaust camshaft 12 extends to the outside of a cylinder head 10. The extension part 12A is cantilevered by a journal supporting part 26 projecting from a rear end wall 27 of the cylinder head 10. A high pressure fuel pump 35 is attached to the cylinder head 10 via a pump thermocase 29, and a plunger part 40 is driven by a cam 25 of the extension part 12A. Because the high pressure fuel pump 35 is made to approach to the rear end wall 27 by projecting the journal supporting part 26, the projection of the extension part 12A can be shortened and the extension part 12A can be cantilevered, so as to shorten the entire length of the cylinder head part. The pump thermocase 29 is integrated with the thermocase, and coupled to the cylinder head 10 together with the thermocase, so as to heighten supporting rigidity of the high pressure fuel pump 35. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine fuel pump system for supplying fuel to an injector of a fuel injection system.

[0002]

2. Description of the Related Art In a gasoline engine mounted on an automobile or the like, an injection nozzle of a fuel injector is arranged in a combustion chamber, and a fuel-air mixture is produced by directly injecting fuel into air introduced into a cylinder from an intake port. In-cylinder injection type engines are known which are designed to burn. In-cylinder injection type engines are capable of performing stratified combustion and can increase the degree of freedom in combustion control such as operation control based on the fuel injection amount, so they are attracting attention as an internal combustion engine that is advantageous for improving practical fuel efficiency and exhaust gas purification. Has been done.

A cylinder injection engine is provided with a high-pressure fuel pump for supplying high-pressure fuel to a fuel injector, and this high-pressure fuel pump is generally driven by a camshaft of the engine.

An example of a high-pressure fuel pump device in a conventional cylinder injection type engine will be described with reference to FIG. As shown in FIG. 6, a cylinder head 1 of a conventional in-cylinder injection engine is provided with an intake camshaft 2 and an exhaust camshaft 3, and one end of the exhaust camshaft 3 is extended to form an extension portion 4. The extension 4 is provided with a cam 5. High-pressure fuel pump 6 (plunger pump)
Is arranged at the rear of the cylinder head 1, and its plunger 7 is engaged with the cam 5. Then, the rotation of the exhaust cam shaft 3 causes the plunger 5 to reciprocate by the cam 5 to pressurize the fuel supplied from the fuel tank (not shown) and send it to the fuel injector (not shown).

[0005]

The conventional high-pressure fuel pump device described above has the following problems. Since the high-pressure fuel pump 6 has a high discharge pressure and a large pump driving force, the reaction force acting on the cam 5 is large. Therefore, the journal support portions 8, 8 are provided on both sides of the extension portion 4 of the exhaust camshaft 3.
9 is provided to increase the support rigidity of the extension portion 4, but this causes a problem that the total length of the cylinder head 1 becomes long, the number of parts and weight increase, and the number of assembling steps also increases. Furthermore, it is necessary to increase the support rigidity of the high-pressure fuel pump 6, which causes an increase in weight.

The present invention has been made in view of the above points, and is capable of shortening the overall length of the cylinder head portion, and reducing the number of parts, weight and assembly man-hours. The purpose is to provide a device.

[0007]

In order to solve the above-mentioned problems, a fuel pump device for an engine according to the invention of claim 1 is a journal for supporting a camshaft on an extension part of an end part of the camshaft. And a cam for driving the fuel pump, and the journal part is cantilevered by a journal support part formed so as to project outward from the end wall of the cylinder head. A housing member for accommodating the cam and a case member having a mounting portion for the fuel pump which is orthogonal to the housing member are joined together,
The fuel pump is attached so as to be close to the cylinder head end wall via the case member. With this configuration, the journal support portion is projected from the end wall of the cylinder head, and the fuel pump is arranged close to the end wall of the cylinder head. It becomes shorter and cantilever support becomes possible. According to another aspect of the present invention, there is provided a fuel pump device for an engine, wherein a journal portion for supporting the cam shaft and a cam for driving the fuel pump are provided in an extension portion extending one end portion of the cam shaft, and the journal portion is a cylinder. A cantilevered support is provided by a journal support formed so as to project outward from the end wall of the head, and a housing part accommodating the cam and a fuel pump orthogonal to the housing are mounted on the outside of the journal support part. Connecting a case member having a portion, the case member integrally includes a passage portion connected to the cooling water passage of the cylinder head,
The fuel pump may be coupled to the cylinder head via the case member. With this configuration, the support rigidity of the fuel pump is increased. Also,
A fuel pump device for an engine according to a third aspect of the invention is characterized in that, in the configuration of the second aspect, the passage member is a thermo case that accommodates a thermostat. With this configuration, the fuel pump can be supported by the thermo case.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below with reference to the drawings. As shown in FIGS. 1 to 3, the in-cylinder injection engine according to the present embodiment has a 4-valve D
This is an in-line three-cylinder engine of the OHC (double overhead camshaft) type, and the cylinder head 10 is provided with two camshafts, an intake camshaft 11 and an exhaust camshaft 12. The intake camshaft 11 and the exhaust camshaft 12 are rotatably supported by the cylinder head 10 by journal support portions 13 and 14, respectively.

Cam sprockets 15 and 16 are attached to one ends of the intake and exhaust cam shafts 11 and 12, respectively. A variable valve timing mechanism 17 is provided on the cam sprocket 15 of the intake cam shaft 11. A cam chain 18 is wound between the cam sprockets 15 and 16 and a crank sprocket (not shown) attached to the crankshaft of the engine, and the crankshaft causes the intake and exhaust cams to pass through the cam chain 18. Drive the shafts 11 and 12 to move the intake and exhaust camshafts 11,
The cams 19 and 20 formed in 12 open and close the intake and exhaust valves 21 and 22 (only the tappet part can be seen in the drawing) at a predetermined timing.

At this time, the opening / closing timing of the intake valve 21 can be controlled by adjusting the hydraulic pressure supplied to the variable valve timing mechanism 17 according to the operating state of the engine. A detection rotor 23 is attached to the other end of the intake camshaft 11, and a rotation angle sensor 24 attached to the cylinder head 10 detects the rotation angle of the intake camshaft 11.

The other end of the exhaust camshaft 12 is extended to form an extension portion 12A. The extension portion 12A is inserted into the journal support portion 26 at the end of the cylinder head 10 and is extended to the outside. ing. A cam 25 that drives a high-pressure fuel pump (described later) is formed in the extension portion 12A. The endmost journal support portion 26 projects outward from a rear end wall 27 (end wall) of the cylinder head 10 that is arranged close to the end of the intake camshaft 11. The cylinder head 10 has a cylindrical cooling water passage 28 protruding below and adjacent to the lowermost journal support portion 26.

A pump / thermocase 29 (case member) is a gasket in the journal support portion 26 and the cooling water passage 28.
It is attached by bolts 31 and 32 through 30. The pump / thermocase 29 is formed by integrally forming a pump case portion 33 coupled to the journal support portion 26 and a substantially cylindrical thermocase portion 34 (passage member) coupled to the cooling water passage 28. A high-pressure fuel pump 35 is connected to the pump case portion 33 by a bolt 36, and the thermocase portion 34
A thermostat (not shown) is housed in the (thermocase), and the thermocap 37 is fastened together with the bolt 32.

Further, the pump case portion 33 is connected to the journal support portion 26, and the extension portion 12 of the exhaust camshaft 12 is joined.
It is formed by a substantially bottomed cylindrical housing portion 38 that accommodates A, and a substantially cylindrical pump mounting portion 39 that is orthogonal to the housing portion 38. Then, the high-pressure fuel pump 35 is attached to the pump attachment flange 43 formed at the end of the pump attachment portion 39, and the tappet 41 of the plunger portion 40 of the high-pressure fuel pump 35 is accommodated in the housing portion 38 by the cam of the extension portion 12A. 25 is engaged. As shown in FIG. 3, the pump mounting portion 39 is such that the high-pressure fuel pump 35 side is slightly downward when the pump / thermocase 29 is mounted on the cylinder head 10.
It is arranged to be slightly inclined with respect to the horizontal direction.

In FIGS. 4 and 5, reference numeral 42 is a journal support mounting flange, 44 is a cylinder head mounting surface, 45 is a thermocap mounting surface, 46 is a heater union, and 47 is a water temperature sensor mounting boss. 1 to 3, reference numeral 48 is an intake port, 49 is an exhaust port, 50 is a spark plug, and 51 is a timing cover.

The high-pressure fuel pump 35 is a general one used in a cylinder injection type engine, and is supplied from a fuel tank by a feed pump by reciprocating a plunger (not shown) in the cylinder. Fuel inlet
High-pressure fuel is supplied to the fuel injector by suction from 52 and discharge from the discharge port 53. A regulator (not shown) is built in, the discharge pressure is adjusted, and excess pressure is returned from the return port 54 to the fuel tank side. The fuel leaked from the gap between the cylinder and the plunger is returned to the tank side from the drain port 55. The pump part and the drive part by the cam 25 are separated by a metal bellows or the like (not shown) to prevent the fuel and the lubricating oil from being mixed with each other. In addition, a damper means (not shown) is provided in the fuel passage in order to prevent pulsation due to pumping.

The high-pressure fuel pump 35 is close to the rear of the rear end wall 27 of the cylinder head 10, the upper portion thereof does not project upward from the cylinder head cover 56, and the side of the cylinder head 10 on the intake port 48 side. The pump mounting flange 43 of the pump / thermocase 29 is arranged so that it does not protrude from the
Mounted on.

The operation of this embodiment having the above-described structure will be described below. The rotation of the exhaust camshaft 12 causes the cam 25 of the extension 12A to reciprocate the plunger of the high-pressure fuel pump 35 to suck the fuel sent from the fuel tank side from the suction port 52 and discharge it from the discharge port 53 to generate high pressure. Supply fuel to the fuel injector.

Since the high-pressure fuel pump 35 is driven by the exhaust camshaft 12, the load on the intake camshaft 11 does not increase, and the variable valve timing mechanism is used.
17 does not deteriorate the responsiveness. By slightly inclining the pump mounting portion 39 of the pump / thermo case 29 downward with respect to the horizontal direction, the lubricating oil can be supplied from the cylinder head 10 side to the cam 25 and the tappet 41. It is not necessary to provide an oil supply means such as an oil jet.

A journal support portion 26 for supporting the extension portion 12A of the exhaust camshaft 12 is attached to a rear end wall 27 of the cylinder head 10.
Since the protrusion length of the extension 12A is shortened and the support rigidity is increased by projecting the extension 12A, the journal support 26 of the extension 12A can support the cantilever. As a result, the total length of the cylinder head portion can be shortened, and in comparison with the conventional example in which both sides of the extension portion of the camshaft are supported,
It is possible to reduce the number of parts, the weight and the number of assembling steps.

By integrally forming the pump case portion 33 and the thermo case portion 34, the supporting rigidity of the high-pressure fuel pump 35 can be increased. Also, since the high pressure fuel pump 35 is attached to the cylinder head 10 via the pump / thermo case 29, the high pressure fuel pump 35 can be installed at a mounting position according to the engine specifications simply by replacing the pump / therm case 29. It can be changed easily.

The high pressure fuel pump 35 includes an exhaust camshaft 12
It is arranged in the space between the extension 12A of the cylinder head 10 and the rear end wall 27 of the cylinder head 10, and does not protrude from the side portion of the cylinder head 10 on the intake port 48 side and the upper portion of the cylinder head cover 56, thus downsizing the engine. be able to. Further, by disposing the high-pressure fuel pump 35 close to the intake camshaft 11 side, the fuel pipe to the fuel injector can be shortened.

In the above embodiment, the case where the present invention is applied to a high-pressure fuel pump device for a cylinder injection type engine has been described as an example, but the present invention is not limited to this, and a plunger type by a cam shaft is used. The present invention can be similarly applied to the fuel pump device of another type of engine as long as it drives the above fuel pump.

[0023]

As described in detail above, according to the fuel pump apparatus for an engine according to the invention of claim 1, the journal support portion is projected from the end wall of the cylinder head, and the fuel pump is attached to the cylinder head. Since the camshaft is arranged close to the end wall, the extension length of the camshaft is short and cantilever support is possible. As a result, the total length of the cylinder head portion can be shortened, and the number of parts, the weight, and the number of assembling steps can be reduced as compared with the conventional example in which both sides of the extension portion are supported. According to the engine fuel pump device of the invention of claim 2, since the case member is integrally provided with the passage portion connected to the cooling water passage of the cylinder head, the support rigidity of the fuel pump can be increased. . According to the engine fuel pump device of the invention of claim 3, the fuel pump can be supported by the thermo case.

[Brief description of drawings]

FIG. 1 is a plan view of a cylinder head portion of an engine according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of a fuel pump device for an engine according to an embodiment of the present invention.

FIG. 3 is an enlarged view showing a side surface of the apparatus shown in FIG. 1 with a part thereof cut away.

FIG. 4 is a front view of a pump / thermocase of the apparatus shown in FIG.

5 is a side view of the pump / thermocase shown in FIG. 4. FIG.

FIG. 6 is a plan view of a cylinder head portion showing a conventional engine fuel pump device.

[Explanation of symbols]

10 cylinder head 12 Exhaust camshaft (camshaft) 12A extension 25 cams 26 Journal Support Department 27 Rear end wall (end wall) 28 Cooling water passage 29 Pumps and thermo cases (case members) 34 Thermo case part (passage part, thermo case)

Claims (3)

[Claims] 1. A journal part for supporting the camshaft and a cam for driving a fuel pump are provided in an extension part extending from one end part of the camshaft, and the journal part is outward from an end wall of a cylinder head. Cantilevered by a projecting journal support part, and a case member having a housing part accommodating the cam and a fuel pump mounting part orthogonal to the housing part is coupled to the outside of the journal support part, A fuel pump device for an engine, wherein the fuel pump is mounted so as to be close to an end wall of the cylinder head via the case member. 2. A journal portion for supporting the cam shaft and a cam for driving a fuel pump are provided in an extension portion of the cam shaft, the extension portion extending from one end portion of the cam shaft, and the journal portion extends outward from an end wall of the cylinder head. A cantilevered support is formed by a projecting journal support part, and a case member having a housing part accommodating the cam and a fuel pump mounting part orthogonal to the housing part is coupled to the outside of the journal support part. The fuel pump device for an engine, wherein the case member integrally includes a passage portion connected to a cooling water passage of the cylinder head, and the fuel pump is coupled to the cylinder head via the case member. 3. The fuel pump apparatus for an engine according to claim 2, wherein the passage portion is a thermo case that accommodates a thermostat.