JPS6155386A - Control system for line pressure of variable capacity pump - Google Patents

Abstract

PURPOSE:To have a line pressure control system for a variable capacity pump, wherein the two contrary functions to remove pulsation and to raise the residual pressure are provided at the same time, by furnishing a bleeder orifice for removal of pulsation separately from a bleeder orifice fo generation of residual pressure. CONSTITUTION:No.2 bleeder orifice 50 is furnished on the way of a feedback passage 35 leeding from a regulator valve 20. This orifice 50 shall have a comparatively small diameter and be provided with a function to remove pulsation. On the other hand, No.1 bleeder orifice 36 is furnished at the piston 32 in a control cylinder 30. This orifice 36 shall be wider than a drain port 37 and be so formed as to raise the residual pressure in cylinder chamber 34.

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 maintenance instructions issued by Nissan Motor Co., Ltd.
"Automatic Transaxle" (published in February 1982), there is one that feeds back the line pressure generated by the regulator valve and finely adjusts the discharge volume of the variable displacement pump. . That is, as shown in FIG. 2, the discharged liquid from the variable displacement pump is introduced into the pressure regulating chamber ja of the regulator valve, and
The line pressure is regulated by the throttle pressure introduced into the lower part of the regulator valve λ and the discharge liquid pressure of the summer displacement pump introduced into the upper part of the regulator valve λ through an orifice. It has become. The feedback pressure chamber 2 communicates with the n4 pressure chamber Ja according to the amount of movement of the regulator valve -〇 plunger 3.
b is connected to one of the 7-ring chambers ja of the control cylinder j via the feedback passage ψ (the upper cylinder chamber in the figure).
The piston of the control cylinder S is operated by the feedback pressure introduced through the feedback passageway to finely adjust the discharge amount of the variable capacity cylinder.

By the way, the piston 5b of the control cylinder 5
, the one cylinder chamber Ja and this cylinder chamber 5a.
A bleed orifice A is formed that communicates with the other cylinder chamber 5c provided on the opposite side of the piston, and a drain lower is further formed that communicates the other cylinder chamber SC with the atmospheric pressure side. A residual pressure is generated in the other cylinder chamber jc due to the difference in the amount of liquid passing through the bleed orifice 6 and the drain lower. The amount of liquid passing through the bleed orifice 6 is set to be larger than the amount of liquid passing through the pick and drain lower. By forming the bleed orifice 6 and drain lower in this way,
Eliminate pulsation that occurs in variable displacement pump/piston j
b Prevents pulsation from affecting operation, and also allows high vehicle speeds,
It has two functions: increasing line pressure at low throttle openings.

In other words, the latter function is such that when the gear is set to the overdrive position and the gear is running at high speed, when the overdrive is released, the highest gear that is automatically shifted, that is, generally the third gear, is activated.
It is set to gear. In this 8th gear, for example, a four-wheeled clutch (low clutch) is engaged, but the low line pressure when the overdrive is used at high vehicle speeds and low throttle openings causes the low clutch to be engaged when the 8th gear is set. Even if the clutch is actuated, the clutch may not be fully engaged, resulting in a strain. Therefore, it is necessary to maintain a reasonably high line pressure even when overdrive is set. Therefore, residual pressure is generated in the other cylinder chamber jc due to the relationship between the bleed orifice 6 and the drain lower described above, and the piston 5b is held at a slightly higher position to reduce the eccentricity of the cam ring /a and rotor /b of the variable displacement pump. By increasing the size, the pump discharge amount can be increased.

Problems to be Solved by the Invention However, in such a conventional line pressure control system for a variable displacement pump, the bleed orifice 2 formed in the piston jb cannot be used at high vehicle speeds.

From the functional point of view of increasing the line pressure at low throttle opening, it is desirable to increase the diameter of the bleed orifice B and set the residual pressure in the other cylinder chamber sC high. On the other hand, from the functional point of view of eliminating pulsation, it is more effective to reduce the diameter of the bleed orifice B. Therefore, it is not possible to simultaneously satisfy both of these functions with a single bleed orifice, and as a result, pulsation remains, and if the variable displacement pump is controlled using this pulsating element, the pulsating element and the pump itself If the pulsations resonate, large pulsations will occur in the line pressure. Also, since the diameter of the bleed orifice 6 cannot be increased,
There was a problem in that the necessary amount of residual pressure in the other cylinder chamber 5C could not be obtained, and the line pressure could not be increased moderately at high vehicle speeds and low throttle openings.

Therefore, the present invention provides a bleed orifice for removing pulsation,
By providing a bleed orifice for generating residual pressure on the cut side, we provide a line pressure control system for a variable displacement pump that simultaneously satisfies two different functions: pulsation removal function and function of increasing residual pressure. The purpose is to

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 variable displacement pump. A pressure t'' is introduced into one cylinder chamber through a feed puncture passage, and the piston is actuated by this pressure to control the discharge amount of the variable displacement pump. A first bleed orifice is formed that communicates the cylinder chamber with the other cylinder chamber, and a drain port that communicates the other cylinder chamber with the atmospheric pressure side. In the structure in which a residual pressure is generated in the other cylinder chamber due to a difference in the amount of liquid passing therethrough, a second bleed orifice is formed in the feedback passage to eliminate line pressure pulsation.VC
The first bleed orifice is used exclusively for generating remaining balls, and the second bleed orifice is used exclusively for removing pulsation.

Example Embodiments of the present invention will be described in detail below with reference to 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 io is a variable displacement pump, 20 is a regulator valve, and 3o is a control cylinder.

The variable displacement pump 10 is disposed inside a storage part of a cover housing a torque converter (not shown), and includes a rotor driven by an engine, and a cam ring eccentrically provided around the outer circumference of the rotor. 2, the rotor has a plurality of radially arranged slits.
A vane l-//a is formed in each of the sulins l-//a, and a vane l-//a protrudes from the outer periphery of the rotor and is slidably fitted therein. The tips of each of the vanes //b are in sliding contact with the inner periphery of the cam ring 12, and the space formed between the inner periphery of the cam ring 2 and the outer periphery of the rotor 1 becomes a pump chamber 13. ing. On the other hand, one end (the right end in the figure) of the cam ring 12 is rotatably attached to the cover via the bottle, and the arm part / A core a is provided protrudingly, and a compression spring 13 disposed between the arm portion/core a and the cover allows the cam ring/co to rotate in the upward rotation direction about the pin/μ, and to rotate the cam ring/co in the upward rotational direction around the pin/μ. / and cam ring /2 are biased in the direction of increasing the amount of eccentricity between them and increasing the pump discharge amount. The cover portion facing the inside of the pump chamber/3 has an inlet boat/6 facing perpendicularly to the eccentric direction of the rotor// and cam ring/2.
and an outlet bow)/7 are formed, and the working fluid sucked up from the reservoir tank Hiroko as the rotor l/rotates from the inlet bow)/A to the pump chamber lJ.
The liquid is supplied into the vessel and discharged from the outlet boat 17 through a passageway.

The regulator valve 2o is connected to the variable displacement pump IO.
The line pressure of the hydraulic control device of the automatic transmission is determined by regulating the pressure of the hydraulic fluid discharged from the passageway/zone. The regulator valve 2° has two first valves inside the sleeve 2/. Second spool n.

The force is stored, and the first spool at the top in the figure is urged upward by a spring: L2a. The working fluid discharged from the variable displacement pump 10 is introduced into the pressure regulating chamber 2 da provided at the lower part of the first spool n and the chamber J provided at the upper part of the first spool n via the orifice ja. It has become so. Furthermore, a feedback pressure chamber 27 is provided adjacently above the pressure regulating chamber Kohiro, and a drain chamber 27 is further provided above the feedback pressure chamber 2, and the feedback pressure in the feedback chamber 27 is connected to the control cylinder 30. is being supplied to. Meanwhile, two independent chambers 21 + 21 a are formed below the second spool force, and the chambers 21 and 21 a are formed under the second spool force.

Throttle pressure such as pressure modifier pressure and cutback pressure is supplied to 21 &.

The movement position of the first spool 2 is determined by this throttle pressure, the pump discharge pressure supplied to the chamber j, and the urging force of the spring Ua, and line pressure control is performed.

The passage 29a communicating with the pressure regulating chamber J is a hydraulic fluid supply passage to the torque converter, and the other passage 9a is a hydraulic fluid supply passage for the pull-up piston.

Further, in the control cylinder 3o, three pistons are slidably and closely fitted in a cylinder casing 31 attached to the cover, and one cylinder chamber 33 is provided in the upper part by the three pistons, and the other cylinder chamber 33 is provided in the lower part. The cylinder chamber 3 is separated from the other cylinder chamber 3. The one cylinder chamber 33 is communicated with the feedback chamber gK of the regulator valve 3 via the feedback passage 3s, so that feedback pressure is supplied into the one cylinder chamber 33. By the way, a first bleed orifice 36 is formed in the front piston 3.2, which communicates one cylinder chamber 3J with the other cylinder chamber 3, and the bottom of the other cylinder chamber J has a A drain port 37 is formed that is open to the inside of the room S and the atmosphere and returns the leaked hydraulic fluid to the reservoir tank. The amount of working fluid passing through the first bleed orifice 36 is set to be larger than the amount of fluid, so that residual pressure is generated in the other cylinder chamber 3IA. Further, a bushing rod 3t that is slidably fitted into a fitting hole Ua formed in the cover plate is cut out on the piston 3, and the lower end of this bushing rod 31 is connected to the arm part of the cam ring/2. It is attached to the top edge. Therefore, the movement of the piston 3 is transmitted as a rotational movement of the cam ring 2 via the bushing rod j7, and when the piston 3 is moved downward, the cam ring 2 is rotated downward, reducing the pump discharge amount. On the other hand, when the piston 32 moves upward, the cam ring 1 is rotated upward and the pump discharge amount is increased. In this way, the variable displacement pump io is operated via the control cylinder 30 at the foot pressure of the regulator valve 20, which is controlled by the throttle pressure, and the pump discharge amount according to the operating state can be obtained. It looks like this.

Here, in this embodiment, a second bleed orifice sO is provided in the foot nozzle passage Jj to open the inside of the passage 3S to the atmosphere, and the working fluid that has passed through the second bleed orifice 50 is transferred to the lizard nozzle. It is designed to be returned to the tank.

With the above configuration, in the variable displacement pump line pressure control system of this embodiment, the feedback pressure of the regulator valve 20 is controlled at high vehicle speed and low throttle opening, for example at the auto/ζ-dry position. When the vehicle is running, the throttle pressure is low, so the first spool n moves downward to increase the feed/cook pressure. Then the control cylinder.

One of the cylinder chambers 33 of 30 becomes high pressure, and the piston 32
Press down and rotate cam ring/2 downward. Therefore, the discharge amount of the variable displacement pump 10 is controlled to decrease. By the way, at this time, one cylinder chamber 3
The hydraulic fluid in the cylinder chamber 3 is supplied to the other cylinder chamber 3 through the first bleed device 36, and the hydraulic fluid in the cylinder chamber is returned to the reservoir tank B through the drain port 37. It has become. At this time, a residual pressure is generated in the other cylinder chamber S due to the difference in the amount of liquid passing through the first bleed orifice j4 and the flow valve 37, and the piston 32 is set slightly above the predetermined position to increase the pump discharge amount. The variable displacement pump IO is of a vane type, and the variable displacement pump IO is a gear type pump. Similarly, a pulsating component occurs in the discharged liquid. Therefore, if the variable displacement pump 10 is controlled while this pulsation is influenced by the control cylinder 30,
Pulsation of control cylinder 30 and variable displacement pump 10
This will interfere with the pulsation of the line pressure, resulting in large pulsations in the line pressure. However, in this embodiment, since the second bleed orifice 50 is provided in the foot passage JS,
removing the pulsation with the 27° door orifice 50;
A smooth feedback pressure is applied to the control cylinder 30. Therefore, the variable displacement pump 10 is not affected by feedback pulsation, and the pulsation component in the line pressure can be significantly reduced, allowing accurate control of each control pulp.

As described above, in this embodiment, since the pulsation in the feedback pressure is exclusively removed by the second bleed orifice 50, the first bleed orifice J6 provided on the piston 3 of the control/cylinder 30 is used exclusively for generating residual balls. Can be used. Therefore, the first bleed orifice,
The opening diameter of the bleed orifice 36 is increased to increase the difference in the amount of working fluid passing between the first bleed orifice 36 and the drain port J7. For this reason, the piston 3 is set at a higher position to increase the pump discharge amount at high vehicle speeds and low throttle openings, and to ensure that the low clutch is engaged when switching to 3rd gear. There is. Further, since the second bleed orifice 50 is used exclusively for removing pulsation, the diameter of the orifice is made small to efficiently remove pulsation.

As described in the detailed description of the invention, in the line pressure control system for a variable displacement tube of the present invention, the second bleed orifice provided in the feedback passage exclusively eliminates pump pulsation in the feedback pressure. Therefore, the first bleed orifice formed in the piston of the control cylinder can be used exclusively for the residual pressure generated in the other cylinder chamber. Therefore, in this way, the first. Since the second bleed orifice is used independently for generating residual pressure and for removing pulsation, the opening diameter of the first bleed orifice can be increased in order to obtain high residual pressure, and the second bleed orifice
The diameter of the bleed orifice can be reduced 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, ensuring clutch engagement when downshifting to the low speed side. It is possible to prevent this from happening. In addition, by reducing the diameter of the second bleed orifice, pulsation is efficiently removed, and the pulsation that occurs in the fluid discharged from the variable displacement pump is significantly reduced, resulting in smooth line pressure and accurate control by each control pulp. It has various excellent effects.

[Brief explanation of the drawing]

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, 3 units...
Piston, 33... One cylinder chamber 1. Dedication...Other cylinder chamber, 35...Feedback passage, 36
...1st bleed orifice, 37...drain port,
50...Second bleed 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 through a feedback passage, and this pressure drives the piston. a control cylinder that operates to control the discharge amount of the variable displacement pump, and a first bleed orifice that communicates one cylinder chamber with the other cylinder chamber is formed in the piston of the control cylinder, and the Forming a drain port that communicates the other cylinder chamber with the atmospheric pressure side,
In a 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 bleed orifice and the drain port, pulsation of line pressure is eliminated in the feedback passage. A line pressure control system for a variable displacement pump, characterized in that a second bleed orifice is formed.