JPH11236862A - Inner surface cam type fuel injection pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a burden applied on a spiral stop spot between a governor housing and a pump housing and to suppress fretting corrosion at this part, in an inner surface cam type (VR type) fuel injection pump wherein a plunger is radially slidably arranged at a rotating rotor and by reciprocating the plunger by a cam ring, fuel is distributed and fed with a pressure. SOLUTION: Low pressure fuel introduced from the outside is fed to a feed pump 11 through a lower pressure oil passage on which a governor housing 8 fronts on, and fuel pressurized by the feed pump 11 is fed in a fuel chamber 7 through the governor housing 8. The pressure receiving surface of the governor housing 8 to receive fuel pressulized by the feed pump 8 is limited to an outflow part from the feed pump 11 and a spot fronting on the fuel chamber 7, and a force exerted on the governor housing 8 is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distribution type fuel injection pump for supplying fuel to an engine, and in particular, a plunger is provided in a rotating rotor in a radial direction, and the plunger is reciprocated by a cam ring to form the rotor. The present invention relates to an internal cam type (VR type) fuel injection pump that changes the volume of a pump working chamber.

[0002]

2. Description of the Related Art A VR fuel injection pump of this kind, which was previously filed by the present applicant, is disclosed, for example, in Japanese Patent Application Laid-Open No. 8-6 / 1996.
As shown in Japanese Patent Publication No. 1180, a control sleeve is slidably fitted to a rotor in a fuel chamber, a feed pump is fixedly mounted on a drive shaft connected to the rotor, and a fuel introduced from the outside is fed to the feed shaft. The fuel is pressurized by a pump and supplied to the fuel chamber.

The rotor, control sleeve, feed pump, and the like are housed in a pump housing, and the control sleeve is driven and controlled by a governor housed in the governor housing. As shown in Japanese Patent Application Laid-Open No. 7-150980, this governor housing is a diversion of the one used in a VE type fuel injection pump. A filter is provided on the lower surface, and the governor housing is provided through this filter. Fuel is introduced into the housing.

The governor housing is provided with an overflow valve for discharging surplus fuel to the outside, and the governor shaft projects from the lower surface of the governor housing.
The governor housing is mounted on the upper part of the pump housing to connect the governor shaft to the control sleeve.

The governor housing and the pump housing are screwed together with bolts or the like, and the lower peripheral edge of the governor housing is brought into close contact with the pump housing to form a gap between the governor housing and the pump housing inside the peripheral edge. Fuel pressurized by the feed pump,
The fuel is supplied to the fuel chamber through the gap, and is introduced into the governor housing from the gap through a filter.

[0006]

However, since the governor housing uses a VE type fuel injection pump, the following points are pointed out. That is, according to the above-described configuration, a gap through which the high-pressure fuel pressurized by the feed pump passes is formed between the lower surface of the governor housing and the pump housing. Pressure will be applied over a wide area of the lower surface.

[0007] The pumping pressure of the VR type fuel injection pump (about 800
Kg / cm ² ) is the pumping pressure of the VE type fuel injection pump (about 500
Kg / cm ² ), in the above-described configuration, the force received from below the governor housing by the high-pressure fuel spilling into the fuel chamber each time the pumping is performed (fuel pressure on the downstream side of the feed pump × the governor housing forming the gap) The area of the lower surface) is also large, which places a heavy burden on the spiral stopping portion of the governor housing.

Further, the fuel pressure downstream of the feed pump fluctuates due to the fuel spilling into the fuel chamber at the time of cutoff, and this pressure fluctuation is directly applied to the lower part of the governor housing, and the fretting which has not been observed in the VE type fuel injection pump. There is a concern that corrosion will occur at the spiral stop portion of the governor housing.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inner cam type fuel injection pump in which a load on a spiral stop portion of a governor housing is suppressed, and fretting corrosion at this portion is suppressed.

[0010]

In order to achieve the above object, an internal cam type fuel injection pump according to the present invention comprises a feed pump for pressurizing fuel introduced from the outside, and a rotor capable of rotating only. A cam ring provided around the rotor, a movement defined by the cam ring, a plunger that varies the volume of a pump working chamber formed inside the rotor, and a slidably fitted externally to the rotor, A control sleeve for controlling a communication state between the fuel chamber and the pump operation chamber is housed in a pump housing, and a governor for driving the control sleeve is housed in a governor housing that is separate from the pump housing. Is screwed into the pump housing, and the low-pressure fuel introduced from the outside is supplied to the governor housing. Face through the oil passage is supplied to the feed pump, it is characterized in that the fuel pressurized by the feed pump so as to supply to the fuel chamber through the said governor housing.

Therefore, the low-pressure fuel introduced from the outside is supplied to the feed pump through an oil passage facing the governor housing, and then, after being pressurized by the feed pump, is once guided into the governor housing and is then introduced into the fuel chamber. So that the pressure receiving surface of the governor housing that receives the fuel pressurized by the feed pump can be limited to the outflow portion from the feed pump and the portion facing the fuel chamber. By flowing pressurized fuel between the pump housing and the pump housing, it is possible to avoid the inconvenience of forming a pressure receiving surface over a wide range in the governor housing.

For this reason, the force for urging the governor housing by the fuel pressure on the downstream side of the feed pump can be reduced by the amount by which the pressure receiving area can be made smaller than before, and the force applied to the governor housing due to pressure fluctuation is also reduced. can do.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 4 show an internal cam type distribution type fuel injection pump. In this distribution type fuel injection pump 1, a drive shaft 3 is inserted into a pump housing 2 and one end of the drive shaft 3 is connected to the pump housing 2 And receives driving torque from an engine (not shown), and synchronizes with this engine (at half the engine speed).
It is designed to rotate.

The pump housing 2 includes a housing member 2a for holding a drive shaft 3 and a housing member 2 mounted on the housing member 2a and provided with a delivery valve 4 and the like.
b and a housing member 2 provided on an extension of a rotor 5 to be described later by closing an opening of the housing member 2b.
c.

A rotor support member 6 is fitted in the pump housing 2, and a space surrounded by the rotor support member 6 forms a fuel chamber 7. The fuel chamber 7 communicates with a governor storage chamber 9 defined by a governor housing 8 via a fuel circulation hole 59.

The governor housing 8 is provided with a governor housing member 8 mounted on an upper portion of the housing member 2a.
a, and a governor housing member 8b to which an upper opening of the governor housing member 8a is closed and to which an overflow valve 10 is attached. Assembling of the governor housing member 8a and the housing member 2a is performed by providing stop holes 60 at the four corners of the governor housing member 8a.
This is performed by providing a helical hole at the point a and screwing the bolt into the helical hole via the stop hole 60.

A feed pump 11 fixed to the drive shaft 3 is housed in the pump housing 2.
The fuel supplied into the housing by the feed pump 11 is somewhat pressurized. The fuel passage 12 extends from the outlet of the feed pump 11 to the governor housing 9 through the housing member 2a and the governor housing member 8a.
Is formed, and the fuel pressurized by the feed pump 11 is supplied to the governor storage chamber 9 through the fuel passage 12. The fuel passage 12, the governor storage chamber 9, and the fuel chamber 7 This forms a high-pressure oil passage 50 (shown in fine sand in FIG. 4). A fuel cut valve 13 is provided in the middle of the fuel passage 12 so as to close the fuel passage 12 when the pump is requested to stop.

The fuel passage 12 has a first hole 1 formed in the housing member 2a and opened from the outlet of the feed pump 11 to the contact end face with the governor housing member 8a.
2a and a housing member 2a formed on the governor housing member 8a such that one end thereof is aligned with the first hole 12a.
With the fuel cut valve 1
The second hole 12b opening in the mounting recess 29 for mounting the third hole 12b
One end is opened in the mounting recess 29 so as to be opened and closed by the valve body of the fuel cut valve 13, and the other end is
And a third hole 12c that is open to the outside.

The rotor 5 connected to the drive shaft 3 is rotatably supported by the rotor support member 6. The rotor 5 is rotatably supported in an oil-tight and rotatable manner in an insertion hole 14 formed in the rotor support member 6.
a is engaged with the drive shaft 3 so that only the rotation is allowed as the drive shaft 3 rotates.

A plunger 15 is slidably inserted in the base end portion 5a of the rotor 5 in the radial direction (radial direction). Two (or four) plungers 15 are provided at 180 ° (or 90 °) intervals on the same plane, and the tip of each plunger 15 is located at the center of the base end of the rotor 5. The plunger 15 moves along the inner surface of the cam ring 19 via the shoe 17 and the roller 18.

The cam ring 19 is a ring-shaped member provided concentrically around the rotor 5, and has a cam surface having a number of cam lobes corresponding to the number of cylinders of the engine formed on an inner surface thereof.
When the rotor 5 rotates, the radial direction (radial direction) of the rotor 5
The reciprocation of each plunger 15 is enabled. The volume of the pump working chamber 16 is made variable by the reciprocating motion of the plunger.

That is, a fuel inlet 20 is formed at the side of the pump housing 2, and the fuel flowing into the housing from the fuel inlet 20 is supplied to the space between the cam ring 19 and the governor housing member 8 a or the rotor. Of the feed pump 11 through a low-pressure oil passage 51 (shown in a coarse sand shape in FIG. 4) constituted by a space formed between the cam ring 19 and the shoe 17 and around the connecting portion between the drive shaft 5 and the drive shaft 3. The plunger 15 is guided to the entrance side.
The outward movement is performed by utilizing the pressure difference between the fuel pressure flowing into the pump working chamber 16 and the fuel pressure on the low pressure side flowing outside the shoe 17, and the inward movement is performed. , The cam surface of the cam ring 19. If the cam ring 19 is formed corresponding to four cylinders, cam lobes are formed on the inner surface every 90 degrees, and therefore, two (or four) plungers 15 are formed.
Are simultaneously moved so as to sandwich the pump working chamber 16 and are simultaneously moved away from the center of the cam ring 19.

A spring accommodating chamber 21 is formed at a connection portion between the base end 5a of the rotor 5 and the drive shaft 3, and a spring 22 composed of a compression coil spring is elastically mounted in the spring accommodating chamber 21. Rotor 5
Is constantly biased in a direction away from the drive shaft 3. Also, a shim 23 is provided at the end opposite to the base end 5 a urged by the spring 22, that is, at the tip of the rotor 5.
A snap ring 24 is provided through
2 restricts the movement of the rotor 5 in the direction of the drive shaft in case of breakage.

The rotor 5 has a vertical hole 25 formed in the axial direction thereof and leading to the pump working chamber 16, an inflow / outflow port 26 communicating with the vertical hole 25 and opening on the peripheral surface of the rotor 5,
One end is connected to the vertical hole 25, and the other end is formed with a discharge port 28 that intermittently communicates with a pressure feed passage 27 that communicates with the delivery valve 4.

The inflow / outflow port 26 opens at the surface of the rotor 5 at a position located in the fuel chamber 7, and this opening is covered by a control sleeve 31 slidably fitted to the rotor 5. As shown in FIG. 5, an engagement groove 61 extending in the circumferential direction is formed in an upper portion of the control sleeve 31, and the electric governor 32 housed in the governor housing 8 is formed in the engagement groove 61. The engagement ball 34 provided at the tip of the shaft 33 is engaged. This engagement ball 34 is
When the shaft 33 is rotated by an external signal, the control sleeve 31 moves in the axial direction of the rotor 5.
The control sleeve 31 is provided with a communication portion 35 formed by, for example, a through hole drilled in the radial direction. The communication portion 35 allows the inflow / outflow port 26 to communicate with the fuel chamber 7.

The specific configuration of the inflow / outflow port 26 and the communicating portion 35 of the control sleeve 31 is, for example, as shown in Japanese Patent Application Laid-Open No. 8-61180. And the timing at which the communication between the inflow / outflow port 26 and the communication portion 35 is cut off remains unchanged regardless of the position of the control sleeve 31 in the axial direction.
The timing of the communication between the inflow / outflow port 26 and the communication portion 35 (at the start of cutoff) is advanced as the control sleeve 31 is moved to the left (the base end side of the rotor 5) in the figure.
It is set to be slower as it moves to the right (toward the tip of the rotor 5).

An engagement groove 62 extending in the axial direction is formed in a lower portion of the control sleeve 31, and a locking member 37 fixed to the rod 36 held by the rotor support member 6 is provided in the engagement groove 62. 62. The rod 36 has an arm portion 38 extending in the radial direction engaged with a connecting piece 39 fixed to the cam ring 19, so that the control sleeve 31 rotates in a predetermined relationship when the cam ring 19 rotates. It has become.

The amount of rotation of the cam ring 19 is controlled by a timer device 40.
The timer device 40
Accommodates a timer piston 42 slidably in a cylinder 41 provided in the housing 2.
2 is connected to the cam ring 19 via the lever 43 so as to convert the movement of the timer piston 42 into the rotation of the cam ring 19.

At one end of the timer piston 42, a high-pressure chamber 45 into which high-pressure fuel from the fuel chamber is introduced, and at the other end, a low-pressure chamber 46 communicating with a low-pressure oil passage 51 communicating with the inlet side of the feed pump 11. Each is formed, and in the low pressure chamber 46,
A timer spring 47 is mounted, and the timer piston 42 is constantly biased toward the high-pressure chamber by the timer spring 47. Therefore, the timer piston 42 stops at a position where the spring pressure of the timer spring 47 and the differential pressure between the high-pressure chamber pressure and the low-pressure chamber pressure are balanced, and when the high-pressure chamber pressure increases, the timer piston 42
To the low pressure chamber side against the pressure. As a result, the cam ring 19 is rotated in a direction to advance the injection timing, and the control sleeve 31 connected to the cam ring 19 is also rotated in the same direction, so that the injection timing is advanced. When the high-pressure chamber pressure decreases, the timer piston 47 is moved toward the high-pressure chamber by the spring force of the timer spring 47, and the cam ring 19 is rotated in a direction that retards the injection timing. Is also rotated in the same direction,
The injection timing is delayed.

The pressure in the high-pressure chamber 45 of the timer device 40 is adjusted by a timing control valve (TCV) 48 so as to obtain a required timer advance angle.

The governor housing member 8a constituting the governor housing 8 has a concave groove 53 for mounting a seal member 52 on the lower surface in contact with the housing member 2a. Are divided into That is, the lower surface of the governor housing member 8 a is located above the feed pump 11, and the first pressure receiving surface 54 in which the second hole 12 b is formed, and the low pressure oil formed from the fuel inlet 20 to the feed pump 11. The second and third pressure-receiving surfaces 55 and 56 facing the passage 51 and the second and third pressure-receiving surfaces 55 and 56 facing the fuel chamber 7 are provided with holes 58 through which the shaft 33 of the governor 32 is inserted and the fuel flow holes 59. 4 are formed.

In the above configuration, the fuel introduced from the fuel inlet 20 is supplied to the low-pressure oil in the space formed between the cam ring 19 and the governor housing member 8a and around the connection between the rotor 5 and the drive shaft 3. It reaches the inlet of the feed pump 11 through the path. All of the fuel pressurized by the feed pump is guided to the governor storage space 9 of the governor housing 8 through the fuel passage 12, and the fuel flow holes 5 are formed.
9 to the fuel chamber 7. Excess fuel in the governor housing flows out of the overflow valve 10 to the outside.

When the rotor 5 rotates, the number of inflow / outflow ports 26 corresponding to the number of cylinders sequentially communicates with the communication portion 35 of the control sleeve 31.
The inflow / outflow port 26 of the pump and the communication part 35 of the control sleeve 31 are aligned, and the fuel in the fuel chamber 7 is
6 and moves the plunger 15 in a direction away from the center of the cam ring 19 against the fuel pressure on the low pressure side.

Thereafter, the plunger 15 is moved to the cam ring 19.
As a result, the communication between the inflow / outflow port 26 and the communication portion 35 of the control sleeve 31 is cut off, the discharge port 28 is aligned with one of the pressure feeding passages 27, and the compressed fuel is discharged. The pressure is sent to the delivery valve 4 through the pressure feeding passage 27, and is fed to the injection nozzle through the injection pipe.

When the communication portion 35 of the control sleeve 31 and the next outflow / inflow port 26 communicate with each other again during the pressure feeding step, the compressed fuel flows out to the fuel chamber 7, and the fuel pressure in the injection pipe is reduced at once. And cut off the injection from the injection nozzle. The fuel pumping timing is controlled by the timer device 40, and the injection amount is controlled by the control sleeve 31, so that the above steps are sequentially repeated, so that the required amount of fuel is required for the engine. It continues to be supplied at the timing.

Accordingly, since the high-pressure oil passage 50 from the feed pump 11 to the fuel chamber 7 is formed as described above, the inside of the governor housing 8 is limited only by the fuel passage 12 and the fuel flow hole 59 to the pump housing 2. On the lower surface of the governor housing 8, the fuel pressure of the high-pressure fuel pressurized by the feed pump 11 is applied only to the first and fourth pressure receiving surfaces 54 and 57, and the second and third pressure receiving surfaces are provided. Only the fuel pressure in the low-pressure oil passage 51 is applied to 55 and 56.

As in the prior art, a gap is formed between the governor housing 8 and the pump housing 2 and the fuel pressurized by the feed pump 11 is supplied thereto. Although the fuel pressure of the high-pressure fuel is applied to the lower surface of the governor housing corresponding to the entire pressure-receiving surface, the pressure-receiving surface of the high-pressure fuel can be reduced to half or less by adopting the configuration of the present application. The reduced surface reduces the downward force on the governor housing 8 and the load on the mounting bolt.

Further, the pressure fluctuation occurs on the downstream side of the feed pump 11, that is, in the high-pressure oil passage 50 due to the compressed fuel spilled into the fuel chamber 7 at the time of cutoff. However, as described above, since the pressure receiving surface is small, In addition, the occurrence of fretting corrosion at the contact surface between the governor housing 8 and the pump housing 2 due to the pressure fluctuation, in particular, at the spiral stop portion (around the stop hole 60) can be suppressed.

[0039]

As described above, according to the present invention,
The governor housing containing the governor that drives the control sleeve is screwed into the pump housing containing the feed pump and control sleeve, and low-pressure fuel introduced from the outside is fed to the feed pump through the oil passage facing the governor housing. Since the fuel pressurized by the feed pump is supplied into the pump housing after passing through the governor housing, the pressure receiving surface of the governor housing to which the fuel pressure downstream of the feed pump is applied is smaller than before. Therefore, the force applied to the governor housing can be reduced, and the load on the screw stop portion can be reduced.

Further, the pressure fluctuation generated on the downstream side of the feed pump is directly applied to the governor housing. However, since the pressure receiving surface of the governor housing is made smaller than before, the contact surface between the governor housing and the pump housing, in particular, the spiral stopper Occurrence of fretting corrosion of a portion can be suppressed.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing an inner cam type fuel injection pump according to the present invention.

FIG. 2 is a cross-sectional view of the inner cam type fuel injection pump shown in FIG. 1 cut perpendicular to the axis of the rotor so that a cam ring and a timer device are exposed.

FIG. 3 is a view of a governor housing of the inner cam type fuel injection pump shown in FIG. 1 as viewed from below.

FIG. 4 is an enlarged sectional view showing the vicinity of a contact portion between a governor housing and a pump housing of the inner cam type fuel injection pump shown in FIG. 1; The pressurized high-pressure oil passage is indicated by fine sand.

FIG. 5 is a diagram showing a rotor and a control sleeve, FIG. 5 (a) is a side view thereof, and FIG. 5 (b).
FIG. 6 is a cross-sectional view showing a state cut along the line II in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Distribution type fuel injection pump 5 Rotor 7 Fuel chamber 8 Governor housing 11 Feed pump 15 Plunger 16 Pump working chamber 19 Cam ring 26 Outflow / inlet port 28 Discharge port 31 Control sleeve 32 Governor 50 High pressure oil passage 51 Low pressure oil passage

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takamitsu Kuroda 3-13-26 Yayucho, Higashimatsuyama-shi, Saitama Inside of Zexel Higashimatsuyama Plant

Claims (1)

[Claims] 1. A feed pump for pressurizing fuel introduced from the outside, a rotor allowed to rotate only, a cam ring provided around the rotor, and a movement defined by the cam ring. A plunger formed to vary the volume of a pump working chamber formed therein and a control sleeve slidably fitted to the rotor and controlling a communication state between a fuel chamber and the pump working chamber are housed in a pump housing. The governor that drives the control sleeve is housed in a governor housing that is separate from the pump housing, the governor housing is screwed to the pump housing, and the low-pressure fuel introduced from the outside faces the governor housing. And feeds the fuel pressurized by the feed pump to the feed pump. An inner cam type fuel injection pump, wherein the fuel is supplied to the fuel chamber through the governor housing.