JP2002364480A - Fuel supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel supply device capable of preventing damage to a member caused by a foreign matter coming into fuel. SOLUTION: A bolt 61 is screwed with a lead in a same direction with a rotational direction of a cam shaft 20, fastened in predetermined torque, and can connect the cam shaft 20 and an inner rotor 63. When the foreign matter in the fuel is caught between gears of the inner rotor 63 and the outer rotor 64 and abnormal rotational force is generated in the cam shaft 20, the fastening force of the bolt 61 is defeated by the abnormal rotational force and a male screw part 62 of the bolt 61 is loosened from female screw parts 160 and 120, and connection between the cam shaft 20 and the inner rotor 63 is released. Thus, transmission of driving torque to the inner rotor 63 is shut off, and breakage of the inner rotor 63 and the outer rotor 64 can be prevented. Therefore, fuel leakage caused by a broken piece generated by breakage of the member can be prevented and reliability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel supply device, and more particularly to a fuel supply device for an internal combustion engine (hereinafter, the "internal combustion engine" is referred to as an engine).

[0002]

2. Description of the Related Art For example, in a direct injection type engine in which fuel is directly injected into a cylinder, it is necessary to increase the injection pressure in order to atomize the injected fuel. Pumped by a rotary pump such as
The pressure of the fuel is increased by a high-pressure fuel pump, and the fuel is pressure-fed to a fuel injection valve.

Generally, a high-pressure fuel pump has a drive shaft driven by a gear or a belt on a crankshaft of an engine. The drive shaft operates the plunger and feed pump of the high-pressure fuel pump while being driven by the engine. By driving the high-pressure fuel pump with the power of the engine in this way, it is easy to increase the fuel pressure.

In the case of an inner gear type trochoid pump, the feed pump changes the interdental volume between the inner rotor and the outer rotor formed by the trochoid curve, thereby pumping up the fuel in the fuel tank and discharging it to the high-pressure fuel pump. At this time, the feed pressure, which is the discharge pressure from the feed pump, is stabilized within a predetermined range by the pressure regulating valve.

[0005]

However, foreign matter such as abrasion powder of the sliding member may be mixed in the fuel. In the feed pump, there is a possibility that the foreign matter may be caught between the gears of the inner rotor and the outer rotor. is there. If foreign matter is caught between the gears of the inner rotor and the outer rotor, the rotational resistance of the inner rotor and the outer rotor is greatly increased, and the member is damaged because the inner rotor and the outer rotor are forcibly rotated by a drive shaft such as a camshaft. A failure may occur.
Further, there has been a problem that a fragment generated due to damage of the member causes fuel leakage.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a fuel supply device that prevents damage to members due to foreign matters mixed in fuel. Another object of the present invention is to provide a fuel supply device that can easily cut off transmission of drive torque to a driven member when an abnormal rotational force is generated on a drive shaft.

[0007]

According to the fuel supply device of the present invention, the drive torque of the drive shaft is provided at the connection between the drive shaft and the driven member rotated by the drive shaft. An intermittent means is provided for releasing the engagement between the drive shaft and the driven member when the value exceeds a predetermined value set in advance. For this reason, when foreign matter or the like is mixed in the fuel and bites the foreign matter into the driven member, the engagement between the drive shaft and the driven member is released when the rotational resistance of the driven member is greatly increased. Thus, transmission of the driving torque to the driven member can be cut off to prevent the driven member from being damaged. Therefore, it is possible to prevent fuel leakage caused by fragments generated due to damage of the member, and to improve reliability.

According to the fuel supply device of the second aspect of the present invention, the intermittent means is screwed with a lead in the same direction as the rotation direction of the drive shaft to connect the screw member capable of connecting the drive shaft and the driven member. Therefore, when an abnormal rotational force is generated on the drive shaft due to the foreign material or the like in the fuel being caught in the driven member, the tightening force of the screw member is lost to the abnormal rotational force, and the screw member is screwed. And loosen the connection between the drive shaft and the driven member. Therefore, the transmission of the driving torque to the driven member can be cut off with a simple configuration, and the member can be easily prevented from being damaged by a foreign substance or the like mixed in the fuel.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention. One embodiment in which the fuel supply device of the present invention is applied to a fuel injection pump for a diesel engine is shown in FIGS. FIG. 2 is a sectional view of the fuel injection pump 10 shown in FIG.
2 shows the left side surface of which is removed.

As shown in FIG. 1, the pump housing of the fuel injection pump 10 has a housing body 11 and cylinder heads 12 and 13. The housing body 11 is made of aluminum. The cylinder heads 12 and 13 are made of iron, and support a plunger 30 as a movable member in a reciprocating manner. A fuel pressurizing chamber 50 is formed by the inner peripheral surfaces of the cylinder heads 12 and 13, the end surface of the check valve member 36 of the check valve 35, and the end surface of the plunger 30.

The bearing cover 14 is fixed to the housing main body 11 by bolts 29, and accommodates the journal 15 which is a bearing of a camshaft 20 as a drive shaft. The space between the bearing cover 14 and the camshaft 20 is sealed by an oil seal 16.

The camshaft 20 is rotatably accommodated in the housing body 11 and the bearing cover 14. The cam 21 having a circular cross section is eccentric with respect to the camshaft 20 and is formed integrally with the camshaft 20. Plungers 30 are arranged on the opposite sides of the camshaft 20 by 180 degrees in the radial direction. The shoe 18 has a quadrangular outer shape, and the bush 1 is slidable between the shoe 18 and the cam 21 between the shoe 18 and the cam 21.
9 intervenes. Shoe 1 facing plunger 30
8 and the end face of the plunger head 30a are formed in a planar shape and are in contact with each other.

The disc portion 22 is formed integrally with the camshaft 20 forward of the cam 21 in the direction in which the helical gear 23 urges the camshaft 20. The disk portion 22 is formed coaxially with the bearing portion 20 a of the camshaft 20 that is supported by the journal 15, and has a larger diameter than the cam 21. A washer 25 is provided between the disk portion 22 and the bearing cover 14. The end of the bearing cover 14 on the disk portion 22 side and the washer 25 constitute a locking member. Further, the housing body 11 on the side of the cam 21 opposite to the disk portion.
, A washer 26 is provided. Washers 25 and 26 are formed of a material having high hardness and low friction.

The helical gear 23 is attached to one end of the camshaft 20 and rotates together with the camshaft 20. The helical gear 23 receives a driving force from a crankshaft of the engine by a gear train (not shown). The helical gear 23 rotates in the direction of arrow A in FIG. When the helical gear 23 receives a driving force in the direction of arrow A, the camshaft 20 is urged in the direction of arrow B in FIG.

The plunger 30 is reciprocally driven by the cam 21 via the shoe 18 as the camshaft 20 rotates, and pressurizes the fuel sucked into the fuel pressurizing chamber 50 from the fuel inflow passage 51 through the check valve 35. The check valve 35 prevents fuel from flowing back from the fuel pressurizing chamber 50 to the fuel inflow passage 51.

The spring 31 urges the plunger 30 toward the shoe 18. Shoe 18 and plunger 3
Since each contact surface of 0 is formed in a flat shape,
The surface pressure between the shoe 18 and the plunger 30 decreases. Further, as the cam 21 rotates, the shoe 18 revolves without rotating while sliding on the cam 21.

Connecting members 41 and 42 for pipe connection are connected to the cylinder heads 12 and 13, respectively. A fuel discharge passage 52 is formed by the cylinder heads 12 and 13 and the connection members 41 and 42.
A check valve 37 having a check valve member 38 in the middle of the fuel discharge passage 52 is configured. The check valve 37 is connected to the fuel discharge passage 5
2 prevents the fuel from flowing back into the fuel pressurizing chamber 50. The fuel pressurized in each fuel pressurizing chamber 50 is connected to the connecting member 4.
1 and 42 are supplied to a common rail (not shown) via a fuel pipe.

As shown in FIG. 2, an inner gear feed pump 60 as a rotary pump is
Has an inner rotor 63 loosely fitted to the other end and rotated by a key (not shown), and an outer rotor 64 planeted by the inner rotor 63. The feed pump 60 includes an inner rotor 63 and an outer rotor 6.
By the compression / expansion of the gear 4, the fuel sucked from a fuel tank (not shown) via the suction port 65 is pressurized and sent to the discharge port 66. When the fuel pressure in the feed pump 60 becomes equal to or higher than a predetermined pressure, a metering valve (not shown) opens, and excess fuel is returned to the fuel tank. Here, the inner rotor 63 and the outer rotor 64 constitute a driven member.

Inner rotor 63 and outer rotor 64
1 is provided with a front plate 67 having the above-described suction port 65 and discharge port 66. A feed pump cover 6 is provided on the left side surfaces of the inner rotor 63 and the outer rotor 64 shown in FIG.
9 is fixed to the housing main body 11 with the front plate 67 interposed therebetween by bolts or the like (not shown). On the surface of the feed pump cover 69 on the side of the inner rotor 63 and the outer rotor 64, a balance port (not shown) having substantially the same shape as the suction port 65 and the discharge port 66 is formed at a position facing the suction port 65 and the discharge port 66 of the front plate 67. Have been. The balance port is for allowing the fuel pressure generated by the rotation of the inner rotor 63 and the outer rotor 64 to be applied substantially equally to both end surfaces of the inner rotor 63 and the outer rotor 64.

A counterbore 68 is formed on the surface of the inner rotor 63 on the side of the feed pump cover 69, and a female screw 160 into which a male screw 62 of a bolt 61 described later is screwed is formed on the counterbore 68. It is provided so as to penetrate from the 69 side to the other end of the camshaft 20. On the other end side of the camshaft 20, a female screw part 120 to which the male screw part 62 of the bolt 61 is screwed is also provided.
Is provided. The lead directions of the female screw portions 160 and 120 are formed in the same direction as the arrow X direction shown in FIG. 2 which is the rotation direction of the camshaft 20, the inner rotor 63, and the outer rotor 64.

The bolt 61 as a screw member has a male screw portion 62 that is screwed to the above-mentioned female screw portions 160 and 120, and connects the camshaft 20 and the inner rotor 63. Since the bolt 61 is screwed with a lead in the same direction as the rotation direction of the camshaft 20 and the inner rotor 63 and is tightened with a predetermined torque, when an abnormal rotation force is generated in the camshaft 20, the abnormal rotation force is generated. The male screw portion 62 of the bolt 61 loosens from the female screw portions 160 and 120 due to the torque of the bolt 61 losing the rotational force,
The connection between the camshaft 20 and the inner rotor 63 is released. That is, when the driving torque of the camshaft 20 exceeds a predetermined value set in advance, the engagement between the camshaft 20 and the inner rotor 63 is released. When the connection between the camshaft 20 and the inner rotor 63 is released, since the rotational force is not transmitted to the inner rotor 63 and the outer rotor 64, the fuel sucked from the suction port 65 is not pressurized, and the fuel pressurized chamber from the discharge port 66. No fuel is discharged to 50. Therefore, no fuel is supplied from the fuel pressurizing chamber 50 to the common rail, and the engine stops. Here, the male screw part 62 and the female screw parts 160 and 120 constitute an intermittent means.

Further, in this embodiment, knurling or the like is applied to one or both of the end face of the camshaft 20 on the inner rotor 63 side and the wall face of the inner rotor 63 on the camshaft 20 side, so that the friction between the camshaft 20 and the inner rotor 63 is increased. It may be configured to increase the power. By increasing the frictional force between the camshaft 20 and the inner rotor 63, the predetermined torque for releasing the engagement between the camshaft 20 and the inner rotor 63 can be set higher.

Next, the operation of the fuel injection pump 10 having the above configuration will be described. The cam 21 rotates with the rotation of the camshaft 20, and the shoe 18 revolves without rotating with the rotation of the cam 21. As the shoe 18 revolves, the flat contact surfaces formed on the shoe 18 and the plunger 30 slide, whereby the plunger 30 reciprocates.

When the plunger 30 at the top dead center is lowered along with the revolution of the shoe 18, the fuel discharged from the feed pump 60 is adjusted by a metering valve (not shown). The fuel flows into the fuel pressurizing chamber 50 via the valve 35. Plunger 3 reached bottom dead center
When 0 rises again toward top dead center, the check valve 35 closes,
The fuel pressure in the fuel pressurizing chamber 50 increases. Fuel pressurization chamber 50
When the fuel pressure rises above the fuel pressure on the downstream side of the check valve 37, each check valve 37 opens alternately. The fuel supplied from the connecting members 41 and 42 to the common rail through the fuel pipe is compressed by the common rail and maintained at a constant pressure. Then, high-pressure fuel is supplied from the common rail to an injector (not shown) as a fuel injection valve.

In the embodiment of the present invention described above, when foreign matter or the like is mixed in the fuel and is caught between the gears of the inner rotor 63 and the outer rotor 64, the rotational resistance of the inner rotor 63 and the outer rotor 64 is reduced. When the driving torque of the camshaft 20 greatly increases and exceeds a predetermined value set in advance, the engagement between the camshaft 20 and the inner rotor 63 is released. Therefore, transmission of the driving torque to the inner rotor 63 can be cut off to prevent the inner rotor 63 and the outer rotor 64 from being damaged. Therefore, it is possible to prevent fuel leakage caused by fragments generated due to damage of the member, and to improve reliability.

Further, in this embodiment, since the bolt 61 is provided which can be screwed with a lead in the same direction as the rotation direction of the camshaft 20 to connect the camshaft 20 and the inner rotor 63, the inner rotor 63 and the outer rotor 64 are provided. When an extraordinary rotational force is generated in the camshaft 20 due to a foreign matter or the like in the fuel being caught between the gears, the tightening force of the bolt 61 is defeated by the abnormal rotational force, and the male screw portion 62 of the bolt 61 becomes a female screw portion 160. And loose from 120,
The connection between the camshaft 20 and the inner rotor 63 is released. Therefore, the transmission of the driving torque to the inner rotor 63 can be cut off with a simple configuration, and damage to the member due to foreign matters or the like mixed in the fuel can be easily prevented.

In the above embodiment of the present invention, the camshaft 2
Although the bolt 61 is disposed at the connection between the inner rotor 63 and the inner rotor 63, in the present invention, a torque sensor for detecting the driving torque of the camshaft and an on-off clutch for intermittently connecting the camshaft to the inner rotor are provided. When the driving torque of the camshaft detected by the torque sensor exceeds a predetermined value, the engagement between the camshaft and the inner rotor may be released by the on-off clutch.

Further, in this embodiment, an inner gear type trochoid pump is applied to the rotary pump of the present invention, but it goes without saying that a vane type feed pump can be applied in the present invention.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment in which a fuel supply device of the present invention is applied to a fuel injection pump for a diesel engine.

FIG. 2 is a left side view showing a state where a feed pump cover is removed from the fuel injection pump shown in FIG.

[Explanation of symbols]

 Reference Signs List 10 fuel injection pump 11 housing body (housing) 12, 13 cylinder head (housing) 20 camshaft (drive shaft) 21 cam 30 plunger (movable member) 50 fuel pressurizing chamber 60 feed pump (rotary pump) 61 bolt (screw) 62) External thread (driven member) 64 Outer rotor (driven member) 68 Counterbore part 69 Feed pump cover 120 Female thread (interrupting means) 160 Female thread (interrupting means)

Claims (2)

[Claims] 1. A drive shaft, a cam that rotates together with the drive shaft, a movable member that presses fuel sucked into a fuel pressurization chamber by reciprocating with the rotation of the cam, and that is rotated by the drive shaft. A rotary pump for sucking and pressurizing fuel in a fuel tank by rotation of the driven member, and discharging the fuel into the fuel pressurizing chamber. A shaft and a connecting portion of the driven member are provided,
A fuel supply device, comprising: intermittent means for releasing the engagement between the drive shaft and the driven member when the drive torque of the drive shaft exceeds a predetermined value set in advance. 2. The apparatus according to claim 1, wherein the connecting / disconnecting means includes a screw member which is screwed with a lead in the same direction as the rotation direction of the drive shaft, and is capable of connecting the drive shaft and the driven member. The fuel supply device as described in the above.