JPH0554575B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for controlling the line pressure of an automatic transmission to an appropriate value for each temperature.

(Prior art) Automatic transmissions use the line pressure obtained by regulating oil from an oil pump using a regulator valve as base pressure, and use this to selectively operate various friction elements to automatically select a predetermined gear. do. Therefore,
The friction element to be operated must have a fastening force that matches the output torque of the engine (represented by engine throttle opening, for example); otherwise, if the fastening force is insufficient, the friction element will generate sliding power. This causes losses and early wear of the friction elements, and when the fastening force is excessive, the selection shock and shift shock that occur as the friction elements are fastened become larger. For this reason, the line pressure, which influences the engagement force of the friction element, must be changed step by step to match the engine output torque.To meet this requirement, regulator valves are usually manufactured using the "Automatic Transformer" published by Nissan Motor Co., Ltd. Axle RN4FO2A type, RL4F02
It is common to configure it as described in the "Mold Maintenance Manual" (A261C06), and change the line pressure of the automatic converter according to the engine throttle opening.

(Problems to be Solved by the Invention) The viscosity of the oil described above varies depending on the temperature, and the viscosity increases at low temperatures, which increases flow resistance. In this case, the oil flow rate slows down and the selected range changes from neutral (N) to forward travel (D).
This may cause a delay in the operation of a friction element that should be activated when switching to the range or reverse travel (R) range, or a delay in the operation of a friction element that should be activated from a non-operating state when changing gears while driving.

The former operation delay makes it difficult to start and irritates the driver, while the latter operation delay causes a gear shift shock due to engine racing, which is undesirable in any case.

However, in the conventional line pressure control device,
It was not possible to correct the line pressure for changes in oil temperature, and the above problem was unavoidable.

(Means for Solving the Problems) In view of the above-mentioned points, the present invention proposes a device capable of controlling line pressure such that the line pressure at low temperatures is made higher than usual to eliminate the problem regarding the above-mentioned operation delay. It is equipped with a regulator valve that adjusts the pressure of oil from the oil pump to generate line pressure, receives this line pressure on a pressure receiving surface facing the spring, and adjusts the line pressure to an appropriate value. In the automatic transmission that performs gear shifting operation using the line pressure, the pressure regulating mechanism generates pressure according to the oil temperature between the choke yoke and the orifice by sequentially passing the line pressure toward the pressure receiving surface to the drain port via the choke yoke and the orifice. The present invention is characterized in that a switching valve is provided which responds to the regulated pressure and directs the line pressure to the pressure receiving surface while the pressure is high, and directs the pressure to the pressure receiving surface while the pressure is low.

(Function) In this configuration, the line pressure sequentially passes through the yoke and orifice forming the pressure regulating mechanism and communicates with the drain port, thereby causing a pressure drop and generating a pressure lower than the line pressure between the yoke and the orifice. The higher the temperature of the oil and the lower the viscosity of the oil, the higher this pressure becomes due to viscous resistance, and eventually the pressure becomes proportional to the oil temperature. The switching valve responds to this pressure by feeding back the line pressure to the pressure receiving surface of the regulator valve while the pressure is high, and feeding back the lower pressure to the pressure receiving surface in place of the line pressure while the pressure is low. Therefore, when the above pressure is high and the oil temperature is high, the feedback oil pressure is the same as before, so the regulator valve performs the same line pressure control as before, but when the above pressure is low and the oil temperature is low,
Since the feedback oil pressure is lower than before, the regulator valve can increase the line pressure more than before, and the problems of start delay and shift shock at low oil temperatures can be solved.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

The drawing shows an embodiment of the line pressure control device of the present invention.
1 in the diagram is an oil pump that is constantly driven by the engine.
Reference numeral 2 indicates a regulator valve, and reference numeral 3 indicates a switching valve provided in the present invention.

The oil pump 1 discharges oil into a line pressure circuit 4, and the regulator valve 2 includes a spool 2b elastically supported at the left half position in the figure by a spring 2a. Regardless of the stroke position, the spool 2b directs the oil from the oil pump 1, which is led to the circuit 5 connected to the line pressure circuit 4, through the circuit 6 to various lubricating parts of the torque converter and automatic transmission. The circuit 5 is cut off from the drain port 2c at the left half position in the figure to generate line pressure P _L in the circuit 4.

This line pressure is directed through a circuit 7 to a switching valve 3, which includes a spool 3b elastically supported in the left half position in the figure by a spring 3a. Circuit 8 connected to circuit 7 regardless of the stroke position of spool 3b
This circuit sequentially incorporates a choke 9 and an orifice 10 having different circuit resistances in the middle, and the end farthest from the switching valve 3 serves as a drain port 8a. The yoke 9 and the orifice 10 constitute a pressure regulating mechanism. Then, a circuit 11 connects between the yoke 9 and the orifice 10 to the switching valve 3, and a circuit 12 extending from the switching valve is communicated with the chamber 3c of the switching valve 3. Pressure receiving surface 2d provided to oppose 2a
make them go to The switching valve 3 allows the circuit 12 to communicate with the circuit 11 when the spool 3b is in the left half position in the figure, and transfers the feedback pressure P _F toward the pressure receiving surface 2d in the circuit 12 to the pressure between the cheese yoke 9 and the orifice 10, which will be described later. P _S , and when the spool 3b is in the right half position in the figure, the circuit 12 is connected to the circuit 7, and the feedback pressure P _F is set to the line pressure P _L.

Further, on the spool 2b of the regulator valve 2, a throttle pressure _PTH corresponding to the engine throttle opening (engine output torque) is applied from the circuit 13 to the lower end surface of the spool 2b in the drawing in cooperation with the spring 2a. Thus, the spool 2b is at a position where the upward force in the figure due to the spring 2a, the upward force in the figure due to the throttle pressure _PTH , and the downward force exerted in the figure by the feedback pressure P _F acting on the pressure receiving surface 2d are balanced. When the spool 2b strokes, the circuit 5 is cut off from the drain port 2c between the left half position in the figure and the right half position in the figure to increase the line pressure P _L , and when the spool 2b further descends from the right half position in the figure, the circuit 5 through the drain port 2c to lower the line pressure P _L.

The operation of the above embodiment will be explained next. Under normal conditions, spool 2b is located in the left half position in the figure, and spool 3b
It is also located in the left half of the figure. Here, when the oil pump 1 is driven by starting the engine, oil is discharged into the circuit 4, and the regulator valve 2 has the spool 2b in the left half position in the figure.
Line pressure P _L is generated in circuit 4 by cutting off circuit 5 from drain port 2c. This line pressure goes to the drain port 8a via the circuits 7 and 8, the yoke 9 and the orifice 10, and due to the difference in circuit resistance between the yoke 9 and the orifice 10, a pressure P _S lower than the line pressure P _L is applied between them. generate. This pressure P _S becomes an oil temperature proportional pressure that increases as the oil temperature rises because the viscous resistance becomes smaller and the pressure drop due to the chain yoke 9 becomes lower as the oil temperature rises.

When the oil temperature is low and the pressure P _S is low, this pressure is output to the circuit 12 because the spool 3b is initially in the left half position in the figure and connects the circuit 12 to the circuit 11. reach. By the way, since the pressure P _S is now low, the spool 3b cannot be pushed against the spring 3a, so it maintains the left half position in the figure, and the feedback pressure P _F in the circuit 12 is set to the same low value as the pressure P _S. Make it. Feedback pressure P _F is pressure receiving surface 2d
acts on the spool 2b and presses it downward in the figure, but since the feedback P _F is low, the spool 2b
The upward force in the figure from the spring 2a and the throttle pressure _PTH strengthens the tendency of the circuit 5 to be cut off from the drain port 2c, thereby increasing the line pressure _PL accordingly. With this increase in line pressure, the pressure P _S and therefore the feedback pressure P _F are also increased, and when the feedback pressure P _F reaches a certain value, the spool 2b is further lowered from the right half position in the figure. At this time, the circuit 5 begins to communicate with the drain port 2c, and the line pressure P _L is maintained at the value at this time. Therefore, while the oil temperature is low, since the feedback pressure P _F is lower than the line pressure P _L , the line pressure P _L is kept high, and the engagement of the friction element that is operated thereby is made slightly less than when the oil temperature is low. This also eliminates the problems of start delay and shift shock when the oil temperature is low.

After that, when the oil temperature rises, the pressure P _S rises, as is clear from the above. This pressure increase also increases the feedback pressure P _F , and the regulator valve 2 is able to reduce the line pressure P _L to match the increase in oil temperature, which prevents the line pressure from being kept unnecessarily high and causing the select shock and This can prevent the shift shock from becoming larger.

During this time, as the feedback pressure P _F increases, the spool 3b rises as shown in the figure, but when the oil temperature reaches a predetermined value and the pressure P _S reaches the specified value, the same value of the feedback pressure P _F increases as shown in the figure.
is the right half position in the figure. At this time, the circuit 12 is connected to the circuit 7, and the feedback pressure P _F is changed to the line pressure P _L
As a result, the regulator valve 2 can perform the same line pressure control as the conventional one without any trouble. and line pressure
The feedback pressure P _F that has reached the same value as P _L is
At step c, the spool 3b is held at the right half position in the figure, and this normal control is maintained thereafter.

Note that the pressure regulating mechanism may be a temperature compensation valve using a bilevel or the like.

(Effects of the Invention) Thus, as described above, the line pressure control device of the present invention is provided with the switching valve 3 to lower the feedback pressure P _F when the oil temperature is low to increase the line pressure P L, and to increase the line pressure P _L when the oil temperature is high. Since the configuration is such that the line pressure P _L is lowered to the normal value by increasing the pressure P _F , the line pressure P _L
can be changed to an appropriate value for each oil temperature, thus eliminating problems such as a delay in starting or a shift shock caused by the large viscous resistance of the oil at low oil temperatures.

[Brief explanation of the drawing]

The drawing is a circuit diagram of the line pressure control device of the present invention. 1...Oil pump, 2...Regulator valve,
2a...Spring, 2b...Spool, 2d...Pressure receiving surface, 3
...Switching valve, 3a...Spring, 3b...Spool, 3c...
Chamber, 4... line pressure circuit, 7... line pressure feedback circuit, 8... drain circuit, 8a... drain port, 9... choke (pressure regulating mechanism), 10... orifice (pressure regulating mechanism), 11... pressure circuit, 12... Feedback pressure circuit, 13... Throttle pressure circuit.

Claims (1)

[Claims] 1. A regulator valve is provided which regulates the pressure of oil from the oil pump to generate line pressure, receives this line pressure on a pressure receiving surface facing a spring, and adjusts the line pressure to an appropriate value, In an automatic transmission that performs gear shifting operation using line pressure, a pressure regulating mechanism that creates pressure according to oil temperature between the choke yoke and the orifice by sequentially passing the line pressure toward the pressure receiving surface to the drain port via the choke yoke and the orifice; An automatic transmission characterized by being provided with a switching valve that responds to the regulated pressure and directs the line pressure to the pressure receiving surface while the pressure is high, and directs the pressure to the pressure receiving surface while the pressure is low. line pressure control device.