JPH0159437B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable displacement vane pump, and in particular to a variable displacement vane pump that can be used in an automobile power steering oil pump to reduce the amount of oil discharged when power assistance is not required (for example, during normal driving). , the amount of oil discharged can be increased when power assist is required.

As shown in FIG. 1, a variable displacement vane pump generally includes a drive shaft 1, a rotor 2 attached to the drive shaft 1, a number of vanes 3...3 attached to the rotor 2, and vanes 3... A control cam ring 4 that accommodates the rotor 2 with a rotor 3 attached thereto, a housing 5 that accommodates the control cam ring 4 in a swingable manner in a pump chamber 5a by a pivot 5b, etc.;
A spring member 6 and a stopper member 7, which are provided at opposing portions of the housing 5 and which set the control cam ring 4 at approximately the center of the pump chamber 5a, and a housing 5 opposing portion between the spring member 6 and the stopper member 7. The annular space formed between the outer periphery of the control cam ring 4 and the inner periphery of the pump chamber 5a is divided into a spring member side pressure control chamber and a stopper member side pressure control chamber B in which the discharge chamber 12 opens. It is equipped with 8 orifices.

When the rotor 2 is rotated via the drive shaft 1, the vanes 3...3 attached to the rotor 2 pop out in the centrifugal direction and slide while being pressed against the inner peripheral surface of the control cam ring 4. Due to the change in volume between the vanes 3...3, oil, etc. from the oil tank is introduced into the pump chamber 5a via the suction port 9, suction path 10, suction chamber 11, etc., and the introduced oil, etc. is introduced into the discharge chamber 12. , the discharge passage 13, the orifice 8, the discharge passage 14, the discharge port 15, etc., and as the rotational speed of the drive shaft 1 increases, the presence of the metering orifice 8 causes the spring to be discharged. The pressure in the member-side pressure control chamber A is lower than the pressure in the stopper member-side control chamber B, and this pressure difference causes the control cam ring 4 to swing against the spring force of the spring member 6, causing the rotor 2 to rotate. The amount of eccentricity between the center of rotation and the center of curvature of the inner peripheral surface of the control cam ring 4 is changed to control the amount of oil discharged.

By the way, in the conventional variable displacement vane pump of this type, the orifice 8 is a so-called fixed orifice whose opening degree does not change even when the pressure in the pressure control chamber on the stopper member side changes. The relationship between the oil discharge pressure and the oil discharge amount is as shown in Figures 2 and 3, and is always constant even when driving at high speeds (the shaded area in Figure 2) and when driving straight (the shaded area in Figure 3). The disadvantage was that there was a large amount of oil discharged, which resulted in wasted power consumption.

The present invention has been made with the aim of eliminating the above-mentioned conventional drawbacks, and its gist is that the orifice 8 is a variable orifice whose opening degree is changed depending on the oil discharge pressure.

Next, one embodiment of the present invention will be described based on the drawings from FIG. 4 onwards. In the embodiment shown in the drawings, the orifice 8 is formed by attaching a throttle valve 16 to the housing 5. The throttle valve 16 includes a support piston 16a inserted into a hole 5c provided in the housing 5, and a support piston 16.
a, a piston 16b that is slidably attached, a coil spring 16c that springs the piston 16b and causes the tip of the piston 16b to protrude into the annular space, and one end of the coil spring 16c that is restrained. When the pressure in the stopper member side pressure control chamber B, which is comprised of a cap 16d screwed onto the support piston 16a and in which the discharge chamber 12 opens, increases, the pressure causes the piston 16b to release the coil spring 16c. It is pushed up against the elastic force and increases the opening degree of the orifice 8. In the figure, 17 and 18 indicate that the throttle valve 16 is connected to the hole 5.
A disc spring and a lid body 19 are provided opposite the throttle valve 16, and together with the throttle valve 16, the annular space is transferred to the spring member side pressure control chamber A to the stopper member side pressure. Seal material divided into control room B, 20 and 2
1 is a bearing installed between the drive shaft 1 and the housing 5, 22 is a bearing 2
Oil seal installed between 0 and 21, 2
3 is a cover that constitutes the pump body together with the housing 5; 24 is a bolt that attaches the cover 23 to one side of the housing 5; 25 is a center pin for positioning both; and 26 is a seal between the cover 23 and the housing 5. This is an O-ring.
The spring member 6 includes a bias pin 6a and a coil spring 6b that springs the bias pin 6a.
and a spring retainer 6a that restrains one end of the coil spring 6b, so that the bias pin 6b presses one side of the control cam ring 4. Further, the stopper member 7 is formed by screwing a bolt into the housing 5, and suppresses the other end side of the control cam ring 4 pressed by the spring member 6, and prevents interference between the control cam ring 4 and the rotor 2. It prevents

Since the variable displacement vane pump of the embodiment has the above-described configuration, the opening degree of the orifice 8 is small when the oil discharge pressure is low, and becomes large when the oil discharge pressure is high. Therefore, the relationship between the oil discharge amount and the oil discharge pressure is as shown in FIG. 9.
That is, when the oil discharge pressure is low, the opening degree of the throttle valve 16 that opens with this discharge pressure, that is, the opening degree of the orifice 8, is small, and the amount of oil discharged is also small. As the oil discharge pressure increases, the throttle valve 16, that is, the orifice 8, gradually opens, and the oil discharge amount also increases.When the throttle valve 16 is fully opened, the oil discharge amount becomes approximately constant, and the oil discharge amount increases. When the pressure exceeds a predetermined value, the oil discharge pressure causes the control cam ring 4 to release the coil spring 6b of the spring member 6.
The center of rotation of the rotor 2 and the center of curvature of the inner peripheral surface of the control cam ring 4
As the amount of eccentricity becomes smaller, the amount of oil discharged decreases. Therefore, when the vehicle is traveling straight as shown by the shaded area in Figure 9 (discharge pressure is small because power assist force from the power steering device is not required)
By suppressing the amount of oil discharged in the engine, wasteful consumption of power is suppressed.

In addition, control cam ring 4 and piston 1
By changing the shape of the contact portion with 6b, it is also possible to obtain the characteristics shown by the broken line in FIG. That is, if a projection is provided on the outer circumference of the control cam ring 4 that approaches the piston 16b when the pressure in the pressure control chamber B on the stopper member side becomes high and the control cam ring 4 moves, the piston 16b and the projection can be moved. The opening degree of the orifice 8 formed by the cam ring becomes smaller, the pressure in the stopper member side pressure control chamber B becomes higher, the eccentricity of the control cam ring 4 is reduced, and the discharge amount can be shifted to a characteristic with a smaller amount.

As explained above, the present invention includes a drive shaft 1, a rotor 2 attached to the drive shaft 1, and a control cam ring housing the rotor 2 with a large number of vanes 3...3 attached to the rotor 2. 4, a housing 5 in which the control cam ring 4 is swingably mounted in the pump chamber 5a by a pivot 5b, etc.; Spring member 6 and stopper member 7 set in the center
The annular space provided in the facing part of the housing 5 between the spring member 6 and the stopper member 7 and formed between the outer periphery of the control cam ring 4 and the inner periphery of the pump chamber 5a is used as a spring member side pressure control chamber. The orifice 8 is divided into a pressure control chamber A and a pressure control chamber B on the stopper member side, and the orifice 8 is a variable orifice whose opening degree increases as the oil discharge pressure increases. When used as a steering oil pump, it has the practical effect of reducing power consumption when power assistance is not required.

[Brief explanation of drawings]

Figure 1 is a sectional view of a conventional variable displacement vane pump, Figure 2 is a diagram showing the relationship between the rotation speed and oil discharge amount of a conventional variable displacement vane pump, and Figure 3 is a diagram showing the relationship between the oil discharge pressure and oil discharge amount. Figure 4 and the following diagrams show examples of the present invention, Figure 4 is a sectional view of a variable displacement vane pump when the oil discharge pressure is low, Figure 5 is a sectional view taken along the - line in Figure 4, and Figure 6 is a diagram showing the relationship.
The figure is a cross-sectional view of a variable displacement vane pump when the oil discharge pressure is high, and Figure 7 is the − of Figure 6.
A line sectional view, FIG. 8 is a diagram showing the relationship between the rotation speed and the oil discharge amount, and FIG. 9 is a diagram showing the relationship between the oil discharge pressure and the oil discharge amount. 1...Driveshaft, 2...Rotor, 3...
...Vane, 4...Control cam ring, 5...
...Housing, 5a...Pump chamber, 5b...Pivot, 6...Spring member, 7...Stopper member, 8
... Orifice, A ... Spring member side control room, B ... Stopper member side control room.

Claims (1)

[Claims] 1 Driveshaft 1 and Driveshaft 1
A rotor 2 attached to the rotor 2, a large number of vanes 3...3 attached to the rotor 2, and a vane 3...
A control cam ring 4 that accommodates the rotor 2 with the rotor 3 attached thereto, a housing 5 that houses the control cam ring 4 in a swingable manner by a pivot 5b, etc. in the pump chamber 5a, and a A spring member 6 and a stopper member 7, which set the control cam ring 4 in the substantially central part of the pump chamber 5a, and a control cam ring 4, which is provided in the facing part of the housing 5 between the spring member 6 and the stopper member 7, are provided. The annular space formed between the outer periphery of the cam ring 4 and the inner periphery of the pump chamber 5a is called a spring member side pressure control chamber A and a stopper member side pressure control chamber B.
A variable displacement vane pump characterized in that the orifice 8 is a variable orifice whose opening degree increases with an increase in oil discharge pressure.