JPH0380994B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a line pressure control system for a variable displacement pump that generates line pressure used to control automatic transmissions and the like.

2. Description of the Related Art In general, automatic transmissions regulate hydraulic pressure generated by a variable displacement pump using a regulator valve to which throttle pressure is input, and use this as line pressure. By the way, in the past, the line pressure generated by the regulator valve was fed back and variable as shown in the maintenance manual "Automatic Transaxle" published by Nissan Motor Co., Ltd. (issued in February 1981). Some pumps allow fine adjustment of the discharge volume of a volumetric pump. That is, as shown in FIG.
The discharged liquid is introduced into the pressure regulating chamber 2a of the regulator valve 2, and the throttle pressure is introduced into the lower part of the regulator valve 2 and the discharge liquid is introduced into the upper part of the regulator valve 2 through an orifice. The line pressure is regulated by the fluid pressure discharged from the variable displacement pump 1. and,
The feedback pressure chamber 2b, which communicates with the pressure regulating chamber 2a by the amount of movement of the plunger 3 of the regulator valve 2, is connected to one cylinder chamber 5a of the control cylinder 5 (the upper cylinder chamber in the figure) via the feedback passage 4. The piston 5b of the control cylinder 5 is actuated by the feedback pressure introduced through the feedback passage 4 to finely adjust the discharge amount of the variable displacement pump 1.

By the way, the piston 5b of the control cylinder 5 is formed with a predetermined orifice 6 that communicates the one cylinder chamber 5a with the other cylinder chamber 5c provided on the opposite side of the cylinder chamber 5a with the piston 5b as the boundary. At the same time, a drain port 7 is formed which communicates the other cylinder chamber 5c with the atmospheric pressure side, and the difference in the amount of liquid passing through the predetermined orifice 6 and the drain port 7 causes the other cylinder chamber 5c to be connected to the atmospheric pressure side. Residual pressure is now being generated. In other words, the amount of liquid passing through the pre-drilling orifice 6 is set to be greater than the amount of liquid passing through the drain port 7. and,
By forming the predetermined orifice 6 and the drain port 7 in this way, the variable displacement pump 1
It is designed to perform the two functions of eliminating pulsations that occur in the piston 5b and preventing the pulsations from affecting the operation of the piston 5b, and increasing the line pressure at high vehicle speeds and low throttle openings.

That is, the latter function is set to the highest gear, generally the third gear, which is automatically shifted when the overdrive is released when the gear is set to the overdrive position and the vehicle is running at high speed. In this third gear, for example, the forward clutch (low clutch) is engaged, but the low line pressure at high vehicle speeds and low throttle openings when using overdrive will cause the low clutch to engage when the third gear is set. Even if the clutch is activated, the clutch may not be completely tightened and slippage may occur. Therefore, it is necessary to maintain a reasonably high line pressure even when overdrive is set. Therefore, the previously mentioned pre-drilled orifice 6 and drain port 7
Therefore, residual pressure is generated in the other cylinder chamber 5c, the piston 5b is held at a slightly higher position, and the eccentricity of the cam ring 1a and rotor 1b of the variable displacement pump 1 is increased, thereby increasing the pump discharge amount. This is becoming more and more important.

Problems to be Solved by the Invention However, in the line pressure control system of such a conventional variable displacement pump, the piston 5b
The pre-drive orifice 6 formed in the
From the functional point of view of increasing the line pressure at low throttle openings, it is desirable to increase the diameter of the predetermined orifice 6 and set the residual pressure in the other cylinder chamber 5c high. On the other hand, from the functional point of view of eliminating pulsation, it is more effective to reduce the diameter of the predetermined orifice 6. Therefore, it is not possible to satisfy both of these functions at the same time with one predetermined orifice 6, and as a result, pulsation remains, and when controlling the variable displacement pump 1 with this pulsating element, the pulsating element and the pump If the pulsation of 1 itself resonates, large pulsation will occur in the line pressure. In addition, since the diameter of the pre-orifice 6 cannot be increased, the necessary amount of residual pressure in the other cylinder chamber 5c cannot be obtained, and the line pressure cannot be increased too high at high vehicle speeds and low throttle openings. The point was hot.

Therefore, in the present invention, by separately providing a predetermined orifice for removing pulsation and a predetermined orifice for generating residual pressure, it is possible to simultaneously satisfy two different functions: the function of removing pulsation and the function of increasing residual pressure. The purpose is to provide a line pressure control system for a variable displacement pump.

Means and Action for Solving the Problems In order to achieve the above object, the present invention provides a variable displacement pump, a regulator valve for controlling the line pressure of the variable displacement pump, and a regulator valve for controlling the line pressure of the regulator valve. is introduced into one cylinder chamber via a feedback passage, and a control cylinder that operates a piston with this pressure to control the discharge amount of the variable displacement pump, and the piston of the control cylinder is connected to one cylinder chamber. A first lead orifice that communicates with the other cylinder chamber is formed, and a drain port that communicates the other cylinder chamber with the atmospheric pressure side is formed, and the amount of liquid that passes through the first lead orifice and the drain port is controlled. In the structure in which a residual pressure is generated in the other cylinder chamber with a difference, a second predetermined orifice is formed in the feedback passage to remove line pressure pulsations, and the first The predetermined orifice is used for generating residual pressure, and the second predetermined orifice is used exclusively for removing pulsation.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

That is, FIG. 1 shows a line pressure control system for a variable displacement pump showing one embodiment of the present invention, where 10 is a variable displacement pump, 20 is a regulator valve, and 3 is a variable displacement pump.
0 is the control cylinder.

The variable displacement pump 10 is disposed within a housing portion 41 of a cover 40 housing a torque converter (not shown), and includes a rotor 11 driven by an engine, and a cam ring 12 eccentrically provided around the outer periphery of the rotor 11. There is. A plurality of slits 11a arranged radially are formed in the rotor 11, and a vane 11b protrudes from the outer periphery of the rotor 11 and is slidably fitted into each of the slits 11a. The tips of the vanes 11b are in sliding contact with the inner periphery of the cam cylinder 12, and a space formed between the inner periphery of the cam ring 12 and the outer periphery of the rotor 11 serves as a pump chamber 13.
On the other hand, one end (right end in the figure) of the cam ring 12 is rotatably attached to the cover 40 via a pin 14, and a chest 12a is provided projecting from the other end (left end in the figure) of the cam ring 12. However, due to the compression spring 15 disposed between the chest 12a and the cover 40, the cam ring 12 is rotated upward about the pin 14, that is, the amount of eccentricity between the rotor 11 and the cam ring 12 is controlled. It is biased in the direction of increasing the pump discharge amount. In the portion of the cover 40 facing the inside of the pump chamber 13, there is an inlet port 16 facing perpendicularly to the eccentric direction of the rotor 11 and the cam ring 12.
An outlet port 17 is formed, and the hydraulic fluid sucked up from the reservoir tank 42 as the rotor 11 rotates is transferred to the inlet port 1.
6 into the pump chamber 13, and is discharged from the outlet port 17 through a passage 18.

The regulator valve 20 regulates the pressure of the working fluid in the passage 18 discharged from the variable displacement pump 10, and determines the line pressure of the hydraulic control device of the automatic transmission. The regulator valve 20 has two first and second spools 22 and 23 housed in a sleeve 21, and the first spool 22 at the top in the figure is urged upward by a spring 22a. And the variable displacement pump 10
The hydraulic fluid discharged from the first spool 22 is passed through an orifice 25 into a pressure regulating chamber 24 provided at the bottom of the first spool 22 and a chamber 25 provided at the top of the first spool 22.
It is designed to be introduced via a. Also,
A feedback pressure chamber 26 is provided above the pressure regulating chamber 24, and a feedback pressure chamber 26 is provided adjacent to the pressure regulating chamber 24.
A drain chamber 27 is provided above the control cylinder 6, and the feedback pressure in the feedback pressure chamber 26 is supplied to the control cylinder 30. On the other hand, two independent chambers 28, 28a are formed in the lower part of the second spool 23, and throttle pressures such as pressure modifier pressure and cutback pressure are supplied to these chambers 28, 28a. The throttle pressure, the pump discharge pressure supplied to the chamber 25, and the biasing force of the spring 22a cause the first spool 22 to
The movement position of the line is determined, and line pressure control is performed. The passage 29 communicating with the pressure regulating chamber 24 is a passage for supplying hydraulic fluid to the torque converter, and the other passage 29a is a passage for supplying hydraulic fluid to the lock-up piston.

Further, in the control cylinder 30, a piston 32 is slidably and closely fitted into a cylinder casing 31 attached to the cover 40, and one cylinder chamber 33 is provided in the upper part by the piston 32, and the other cylinder chamber 33 is provided in the lower part. The cylinder chamber 34 is separated from the other cylinder chamber 34. One cylinder chamber 33 is connected to the feedback pressure chamber 2 of the regulator valve 20 via a feedback passage 35.
6, and feedback pressure is supplied into the cylinder chamber 33 of the one side. By the way, the piston 32 is formed with a first predetermined orifice 36 that communicates the one cylinder chamber 33 with the other cylinder chamber 34, and the bottom of the other cylinder chamber 34 is provided with the inside of the cylinder chamber 34 facing the atmosphere. A drain port 37 is formed to open the drain port 37 to return the leaked hydraulic fluid to the reservoir tank.
The amount of working fluid passing through the pre-drilling orifice 36 is set to be large, and residual pressure is generated within the other cylinder chamber 34. Further, the piston 32 is provided with a push rod 38 that is slidably fitted into a fitting hole 40a formed in the cover 40, and the lower end of the push rod 38 is brought into contact with the upper end of the arm portion 12a of the cam ring 12. ing. Therefore, the movement of the piston 32 is transmitted as a rotational movement of the cam ring 12 via the push rod 37, and when the piston 32 is moved downward, the cam ring 12 is rotated downward, and the pump discharge amount is reduced. , on the contrary, when the piston 32 moves upward,
When the cam ring 12 is rotated upward, the pump discharge amount is increased. In this way, the variable displacement pump 10 is operated via the control cylinder 30 by the feedback pressure of the regulator valve 20, which is controlled by the throttle pressure, so that the pump discharge amount according to the operating state can be obtained. It is becoming more and more popular.

In this embodiment, a second pre-read orifice 50 is provided in the feedback passage 35 to open the inside of the passage 35 to the atmosphere.
The hydraulic fluid that has passed through the predetermined orifice 50 is returned to the reservoir tank 42.

With the above-described configuration, in the line pressure control system for the variable displacement pump of this embodiment, the feedback pressure of the regulator valve 20 is equal to or lower than the throttle pressure when the vehicle is running at a high speed and a low throttle opening, for example, when the vehicle is running in the overdrive position. Since the current is low, the first spool 22 moves downward and increases the feedback pressure. Then, the pressure in one cylinder chamber 33 of the control cylinder 30 becomes high, pushing down the piston 32 and rotating the cam ring 12 downward. Therefore, the discharge amount of the variable displacement pump 10 is controlled to decrease. by the way,
At this time, the hydraulic fluid in one cylinder chamber 33 is
The hydraulic fluid in the cylinder chamber 34 is supplied to the other cylinder chamber 34 through the pre-drilled orifice 36 , and the hydraulic fluid in the cylinder chamber 34 is supplied to the reservoir tank 4 through the drain port 37 .
It's starting to go back to 2. At this time, the first
A residual pressure is generated in the other cylinder chamber 34 due to the difference in the amount of liquid passing through the pre-drilled orifice 36 and the drain port 37, and the piston 32 is set slightly above the predetermined position to increase the pump discharge amount. The hydraulic pressure for engaging the low clutch is ensured when the overdrive is switched to the third gear.

By the way, the variable displacement pump 10 is of a vane type, and like a gear type pump, a pulsating component occurs in the discharged liquid. Therefore, when the variable displacement pump 10 is controlled while this pulsation is influenced by the control cylinder 30, the pulsation of the control cylinder 30 and the pulsation of the variable displacement pump 10 interfere, and large pulsations occur in the line pressure. It turns out. However, in this embodiment, since the second predetermined orifice 50 is provided in the feedback passage 35, the pulsation is eliminated by the second predetermined orifice 50, and a smooth feedback pressure is applied to the control cylinder 30. Therefore, the variable displacement pump 10 is not affected by the pulsation of the feedback, and the pulsation component in the line pressure can be significantly reduced, allowing accurate control of each control valve.

In this way, in this embodiment, since the pulsation in the feedback pressure is exclusively removed by the second predetermined orifice 50, the control cylinder 30
The first predetermined orifice 36 provided in the piston 32 can be used exclusively for generating residual pressure. Therefore, in order to approach the target residual pressure, the opening diameter of the first pre-ad orifice 36 is increased to reduce the difference in the amount of hydraulic fluid passing between the first pre-ad orifice 36 and the drain port 37. I've made it bigger. For this reason, piston 3
2 is set at a higher position to increase the pump discharge amount when the vehicle speed is high and the throttle opening is low, so that the low clutch can be reliably engaged when switching to the third gear. Furthermore, since the second pre-drilled orifice 50 is used exclusively for removing pulsation, the diameter of the orifice is made small to efficiently remove pulsation.

Effects of the Invention As explained above, in the line pressure control system of the variable displacement pump of the present invention, the pump pulsation in the feedback pressure is exclusively eliminated by the second pre-read orifice provided in the feedback passage. The first predetermined orifice formed in the piston of the control cylinder can be used exclusively for the residual pressure generated in the other cylinder chamber. Therefore, since the first and second predetermined orifices are used independently for generating residual pressure and removing pulsation, the opening diameter of the first predetermined orifice can be increased in order to obtain high residual pressure. Furthermore, the diameter of the second predetermined orifice can be made small in order to efficiently eliminate pulsation. In this way, by increasing the residual pressure generated in the other cylinder chamber of the control cylinder, the pump discharge amount can be increased at high vehicle speeds and low throttle openings, and the clutch is engaged when downshifting to the low speed side. can be ensured to prevent slipping. In addition, by reducing the diameter of the second pre-dorifice, pulsations are efficiently removed, and the pulsations that occur in the fluid discharged from the variable displacement pump are significantly reduced, resulting in a smooth line pressure and control by each control valve. It has various excellent effects in that it can be performed accurately.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a line pressure control system for a variable displacement pump according to the present invention, and FIG. 2 is a schematic configuration diagram showing a conventional line pressure control system for a variable displacement pump. 10... Variable displacement pump, 20... Regulator valve, 30... Control cylinder, 32
... Piston, 33 ... One cylinder chamber, 34
...The other cylinder chamber, 35...Feedback passage, 36...First pre-read orifice, 37...
...Drain port, 50...Second pre-drilled orifice.

Claims (1)

[Claims] 1. A variable displacement pump, a regulator valve that controls the line pressure of this variable displacement pump, and the line pressure of this regulator valve is taken into one cylinder chamber via a feedback passage, and the piston is actuated by this pressure. and a control cylinder that controls the discharge amount of the variable displacement pump,
Further, a first predetermined orifice is formed in the piston of the control cylinder to communicate one cylinder chamber with the other cylinder chamber, and a drain port is formed in the piston of the control cylinder to communicate the other cylinder chamber with the atmospheric pressure side. 1. In the structure in which residual pressure is generated in the other cylinder chamber due to a difference in the amount of liquid passing through the first orifice and the drain port, a second cylinder is provided in the feedback passage to eliminate line pressure pulsation. A line pressure control system for a variable displacement pump characterized by a predetermined orifice.