JPH10148175A - Axial plunger pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a pump a variable capacity type so that the discharge capacity at the time of starting can be increased to increase displacement volume only at the time of starting, to improve the starting property of an engine, by making the tilt angle of a cam plate variable without using a special switch valve control device. SOLUTION: Noticing that the tilt angle of a cam plate 23 to a driving spindle 21 is to be variable, and that a supporting member 22 to the cam plate 23, and an energizing member 24 are to be provided as members for making the cam plate 23 variable; the cam plate is fitted so as to make the tilt angle variable to the driving spindle 21, and also a supporting member 22 slidably and fittedly engaging with the driving spindle 21 in an axial direction, and the energizing member 24 for energizing the supporting member 22 so that the tilt angle of the cam plate 23 can be increased, are provided to fill a clearance, constituted of the supporting member 22 and the driving spindle 21, with oil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial plunger pump, and more particularly to an axial plunger pump provided as a high-pressure pump in a direct injection type fuel injection device and other fuel injection devices.

[0002]

2. Description of the Related Art A conventional axial plunger pump will be outlined with reference to FIG. FIG. 4 is a cross-sectional view of the axial plunger pump 1. The axial plunger pump 1 includes a cover 2, a flange 3, and a drive shaft 4.
A swash plate 5, a plurality of plungers 6 (only one is shown in FIG. 4), a barrel 7, a leaf valve 10 having a suction valve 8 and a discharge valve 9, a bellows 11,
Having.

A cover 2 has a suction port 12 for sucking fuel from a fuel tank (not shown) and a fuel injection valve (both not shown) through a common rail (pressure accumulator).
A discharge port 13 for pumping fuel is formed.

The flange 3 rotatably supports the drive shaft 4 via a bearing 14, and forms an oil chamber 15 filled with oil between the flange 3 and the cover 2.

The drive shaft 4 is driven to rotate by an engine (not shown), and a swash plate 5 having a predetermined inclination angle in a direction perpendicular to the axial direction is fixed.

The swash plate 5 has a plurality of plungers 6 in contact with the inclined surface thereof at equal circumferential angular intervals.
Each of the plungers 6 is sequentially reciprocated in the axial direction by the rotational driving of, and fuel (for example, gasoline) is sucked into the pressurizing chamber 16 from the suction port 12 through the suction valve 8.
The liquid is discharged to the discharge port 13 through the discharge valve 9.

In the axial plunger pump 1 having such a configuration, the rotation of the drive shaft 4 is controlled by the plunger 6 via the swash plate 5.
For example, an axial plunger pump 1 provided in an in-cylinder direct injection type fuel injection device for directly injecting fuel such as gasoline into the cylinder of an engine is provided with a pump when the engine is started. At the cranking rotational speed obtained by the motor, the displacement of the pump becomes insufficient, and the fuel pressure becomes unstable when performing a high-pressure start.

[0008] Therefore, it is necessary to set the discharge capacity of the pump for rated operation and to switch the pressure to a low pressure only at the time of starting with a switching valve (not shown) to start the engine. In addition, if the displacement of the pump is set to a large value for high-pressure start, the pump discharge power will be several times the required flow rate during rated operation after the engine is started. There is a problem that the value is far exceeded.

Regarding the axial plunger pump,
JP-A-5-149239, JP-A-6-42431,
JP-A-7-180654 and the like are available.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems. In order to solve the above-mentioned drawbacks, the present invention has an axial displacement type which increases the displacement only at the time of starting. It is an object to provide a plunger pump.

Another object of the present invention is to provide an axial plunger pump which does not use a special switching valve control device for making it a variable displacement type.

Another object of the present invention is to provide an axial plunger pump in which the inclination of the swash plate is made variable so that the discharge capacity at the time of starting can be increased with a simple structure and the startability of the engine can be improved. As an issue.

[0013]

That is, the present invention focuses on making the inclination angle of the swash plate with respect to the drive shaft variable, and providing a swash plate support member and an urging member as members for making the angle variable. An axial having a drive shaft, a swash plate attached to the drive shaft at a predetermined inclination angle, and a plunger that performs reciprocating motion in the axial direction by rotation of the swash plate by the drive shaft to perform a pump action. A plunger pump, wherein the swash plate is attached to the drive shaft so that its inclination angle is variable, and the swash plate is axially slidably fitted to the drive shaft and supports the swash plate. A member, and a biasing member for biasing the support member so that the inclination angle of the swash plate is increased, and a clearance formed by the support member and the drive shaft is filled with oil. Is a axial piston pump, characterized in that the.

By providing a suction valve capable of introducing the oil into the clearance, oil can be quickly introduced into the clearance when the engine is stopped, and the swash plate is returned to a predetermined inclination angle when the engine is stopped. It can be prepared for starting the engine. However, when the common rail is provided with a check valve for maintaining the pressure, the pressure in the common rail is maintained at a predetermined high pressure even after the engine is stopped, so that the swash plate is quickly set to a predetermined inclination angle. Therefore, there is no need to particularly provide the suction valve.

In the axial plunger pump according to the present invention, a support member for supporting the swash plate is fitted to the drive shaft, a clearance formed by the support member and the drive shaft is filled with oil, and the inclination angle of the swash plate is reduced. Since the biasing member for biasing the support member is provided so as to be large, the swash plate is inclined to the maximum inclination angle by the biasing member when the engine is started. That is, since the inclination angle of the swash plate is large, the discharge flow rate per one rotation of the pump is large, and the discharge pressure can be made high by the cell motor, thereby enabling stable high-pressure start. Moreover, since the pump itself is still cold, the viscosity of the oil is still high, the support member fitted to the drive shaft with the above clearance moves relatively slowly, and the inclination angle of the swash plate remains large for a relatively long time. This is effective when the engine is started or when the outside air is at a low temperature and the cranking speed is low. As the engine starts and the temperature of the pump increases, the viscosity of the oil gradually decreases, and the inclination angle decreases.

After the engine is started, the inclination angle becomes small as described above, so that the discharge amount per one rotation of the pump is lower than that at the time of start, and the discharge amount suitable for the rated operation set in advance can be obtained.

Immediately after the engine is stopped or when the temperature of the engine is high, such as when the temperature of the outside air is high, the inclination angle of the swash plate may be largely restored in a short time and the power is sufficiently exhibited because the viscosity of the oil is low. Since the cranking speed of the cell motor by the battery, which is in a possible state, quickly rises and returns to the rotation of the rated operation, there is no problem, and the driving power is rather small.

In this way, the inclination angle of the swash plate can be made variable at the time of starting the engine and at the time of rated operation, so that the discharge capacity for high-pressure start is secured to improve the startability of the engine, The pumping action can also make this accurate.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an axial plunger pump 20 according to an embodiment of the present invention will be described with reference to FIGS. However, the same parts as those in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted. 1 to 3
1 is a sectional view of an essential part of the axial plunger pump 20. FIG. 1 shows a state when the engine is stopped, FIG. 2 shows a state when the engine is started, and FIG. 3 shows a state when the engine is rotating. As shown, the axial plunger pump 20 includes a drive shaft 21 corresponding to the drive shaft 4, a support member 22, a swash plate 23 corresponding to the swash plate 5, and a biasing member 24.
And

The drive shaft 21 has a shaft portion 25 and a flange portion 26. The shaft portion 25 is rotatably held by the bearing 14, and a piston receiving hole 27 is formed at the center thereof.

The support member 22 has a piston portion 28 and a support portion 29. The piston portion 28 is slidably loaded in the piston receiving hole 27, and a second oil chamber 30 is formed in the piston portion 28. The biasing member 24 is accommodated in the second oil chamber 30 to bias the support member 22 toward the swash plate 23. Oil enters the second oil chamber 30 from the oil chamber 15 (first oil chamber) via a clearance 31 between the piston portion 28 and the shaft portion 25 in the piston housing hole 27, and a predetermined amount of oil enters. Oil is filled at a predetermined pressure.

The swash plate 23 includes a flange 26 of the drive shaft 21.
This is supported on a fulcrum part 32 provided at the end of the above in a tiltable manner, and is rotatable by the rotation of the drive shaft 21. The swash plate 23 has a central portion protruding in a semi-spherical shape, which is used as a supported portion 33, and a support portion 29 abuts inward thereof, and is supported by the support member 22 from the side opposite to the plunger 6. ing. Further, the plunger 6 abuts on the end of the swash plate 23, and the rotation of the swash plate 23 causes the plunger 6 to reciprocate in the axial direction, thereby performing a pump action.

The urging member 24 is, for example, a compression spring, and constantly urges the swash plate 23 to the left in the drawing via the support member 22 by the urging force.

In the axial plunger pump 20 having such a structure, when the engine is stopped as shown in FIG. 1, the action force of the plunger 6 receiving the reaction force from the low-pressure pressurizing chamber 16 and the biasing member 24 In a stable state in which the power is balanced, the inclination angle θ1 of the swash plate 23 with respect to the flange portion 26 is in a maximum state. When the engine is started in this state, the pressure in the pressurizing chamber 16 increases, so that the inclination angle becomes θ2 as shown in FIG. 2, and in the rotating state after the start, the inclination angle becomes θ3 as shown in FIG. , Θ3 <θ
2 <θ1.

That is, at the time of starting shown in FIG. 2, the swash plate 23 is rotated by the rotation of the drive shaft 21 to reciprocate the plunger 6, but since the inclination angle of the swash plate 23 is still larger than that of FIG. 6 can be largely driven, and the fuel discharge amount can be increased.

Although the inclination angle of the swash plate 23 decreases from θ1 to θ2 due to the reaction force from the plunger 6, the pump temperature still does not rise so much, the oil temperature is low, the viscosity is high, and the piston By adjusting the clearance 31 in the housing hole 27, the damper effect of the support member 22 (piston portion 28) can be provided, and the swash plate 23 gradually shifts to the inclination angles θ2 and θ3 over a predetermined time. I will do it. Therefore, the discharge pressure required for starting the engine can be maintained for a predetermined time.

As shown in FIG. 3, when the engine is started and enters a normal rotation state, the plunger 6 moves together with the swash plate 23 against the urging force of the urging member 24 and the support member 22.
Is pushed rightward in the figure, and the inclination angle of the swash plate 23 is minimized to θ.
It becomes 3. At this time, the discharge amount per one rotation is the minimum, but since the number of rotations is high, the discharge amount necessary for the rated operation can be secured.

When the engine temperature is high immediately after the engine is stopped or when the temperature of the outside air is high, the inclination angle of the swash plate changes from θ3 to θ1 in a short time because the viscosity of the oil is low.
However, if the engine is restarted immediately after stopping the engine, the inclination angle of the swash plate changes from θ1 to θ3 in a short time. However, since the cranking speed of the cell motor at this time is the rated rotation, there is no shortage in the discharge amount, and the driving power is rather small.

The illustrated axial plunger pump 20 is based on the premise that a check valve (both not shown) for maintaining the pressure in the common rail on the downstream side of the discharge port 13 is used. For example, even if the swash plate is to be started after the engine is completely stopped but before the swash plate returns to the state shown in FIG. 1, while the pressure in the common rail is maintained by the check valve, Even if the inclination angle of 23 is not increased, there is no problem in starting the engine itself.
Therefore, oil is sucked into the second oil chamber 30 through the clearance 31 on the outer periphery without separately providing a valve for sucking oil in the clearance 31.
The swash plate 23 may be gradually returned to the state shown in FIG.

When a check valve for holding the pressure is not provided on the common rail side, as shown by an imaginary line in the partially enlarged portion of FIG.
By providing a suction valve 34 (check valve) at the entrance of the second oil chamber 30 at the boundary portion between the support section 29 and the second oil chamber 30, after the engine stops, the urging force of the urging member 24 promptly causes the oil chamber 15 to remove the oil. Oil can be sucked into the second oil chamber 30 via the suction valve 34, and the swash plate 23 can be returned to the state shown in FIG. 1 via the support member 22 to prepare for the next engine start.

[0031]

As described above, according to the present invention, the swash plate can be tilted, the tilt angle of the swash plate can be changed by the support member and the urging member, and the clearance between the support member and the drive shaft can be further improved. The engine is filled with oil, and the inclination angle of the swash plate is gradually reduced as the engine speed rises.
Engine startability can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a principal part of an axial plunger pump 20 according to an embodiment of the present invention when an engine is stopped.

FIG. 2 is a cross-sectional view of a main part in a state when the engine is started.

FIG. 3 is a cross-sectional view of a main part in a state when the engine is rotating.

FIG. 4 is a cross-sectional view of a conventional axial plunger pump 1.

[Explanation of symbols]

Reference Signs List 1 axial plunger pump (FIG. 4) 2 cover 3 flange 4 drive shaft 5 swash plate 6 plunger 7 barrel 8 suction valve 9 discharge valve 10 leaf valve 11 bellows 12 suction port 13 discharge port 14 bearing 15 oil chamber (first oil chamber) 16 Pressurizing chamber 20 Axial plunger pump (Embodiment, FIG. 1) 21 Drive shaft 22 Support member 23 Swash plate 24 Biasing member (compression spring) 25 Shaft portion of drive shaft 21 26 Flange portion of drive shaft 21 27 Piston Housing hole 28 Piston part of support member 22 29 Support part of support member 22 30 Second oil chamber 31 Clearance between piston part 28 and shaft part 25 32 Support point part 33 Supported part 34 Suction valve (check valve)

Claims (2)

[Claims] 1. A drive shaft, a swash plate attached to the drive shaft at a predetermined inclination angle, and a plunger that reciprocates in the axial direction by the rotation of the swash plate by the drive shaft to perform a pump action. An axial plunger pump, wherein the swash plate is attached to the drive shaft so that its inclination angle is variable, and the swash plate is axially slidably fitted to the drive shaft and supports the swash plate. A support member, and a biasing member for biasing the support member so that the inclination angle of the swash plate increases, and a clearance formed by the support member and the drive shaft is filled with oil. An axial plunger pump characterized in that: 2. The axial plunger pump according to claim 1, wherein a suction valve capable of introducing the oil is provided in the clearance.