JPH0481055B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is a line pressure control device for an automatic transmission, in particular, a system for controlling the line pressure to an appropriate value for each engine output torque when the manual valve is in the engine braking range. The present invention relates to a device for controlling such that

(Prior art) Automatic transmissions selectively operate various friction elements using line pressure to perform predetermined gear changes, but if the line pressure does not match the engine output torque, the friction elements to be operated may slip. If the line pressure is too low, the power loss may be large, resulting in deterioration of power performance and fuel efficiency.
When the friction element is activated, the excessive engagement capacity may cause a large shift shock (if the line pressure is too high).

Therefore, it is usually manufactured by General Motor Company in the United States.
Normally, the line pressure is adjusted to a value corresponding to the engine output torque using a circuit as shown in FIG. 3, which is used in the THM200-4R automatic transmission. In Fig. 3, 1 is a regulator valve for controlling line pressure, 2 is an oil pump, and 3 is a manual valve. Proportional throttle pressure P _TH
The force from the torque plug 6 that responds to this is received upward in the figure (in the direction of increase in line pressure), and the oil from the oil pump 2 is applied to the line that increases as the engine output torque (throttle opening) increases, as shown in a in Figure 4. It is supplied from circuit 4 to manual valve 3 as pressure P _L.

When the manual valve 3 is in the automatic shift range (D range), the line pressure P _L from the circuit 4 is
Automatic gear shifting is achieved by supplying pressure from corresponding ports to friction elements that are constantly operated, or to shift valves that control gear shifting, and selectively supplying line pressure to other friction elements under the control of these shift valves. The machine can be shifted as required.

By the way, when the manual valve 3 is set to the second speed engine brake range as shown in the figure, the friction element to be operated by the line pressure P _L output from the circuit 4 via the manual valve 3 is a band brake. In some cases, this band brake will grip the brake drum rotating in the trailing direction during engine braking in the relevant range, so if the band brake is operated by the line pressure controlled as described above, In the opening range, the tightening force is insufficient and the band brake inevitably slips.

Therefore, in the range of manual valve 3, pressure (engine brake range pressure) P II is applied to the regulator in a high range, which corresponds to line pressure P _L , which is also the source pressure of throttle pressure P _TH , from circuit 5 that communicates with circuit ₄ . The problem of the band brake slipping is solved by supplying the line pressure to valve 1 in the direction of increasing line pressure, thereby keeping the line pressure P _L at the pressure regulation upper limit value over the entire throttle opening range as shown in b in Figure 4. Ta.

(Problem to be Solved by the Invention) However, in such a conventional line pressure control device, when engine braking is desired and the throttle opening is set to a low opening near fully closed, the manual valve 3 is moved from the D range to the range. When the range is changed, the line pressure P _L is too high, and the band brake that is activated becomes oversized, causing a large shift shock to occur during the shift associated with the range change, which significantly reduces the commercial value of the automatic transmission. It was a loss.

On the other hand, if you try to reduce the line pressure as shown in c in Figure 4 in order to alleviate this shock, the line pressure will not reach this low value over the entire throttle opening range due to the circuit configuration. While driving with the throttle opening increased, the line pressure was too low, causing not only the band brake but also other friction elements to slip.
The automatic transmission becomes almost inoperable.

Therefore, in the end, the actual situation was to set the line pressure of the range as shown in b in FIG. 4, leaving the shock problem associated with range switching unsolved.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems by providing a line pressure control device that can change the engine brake range and line pressure according to the engine output torque.

(Means for Solving the Problems) For this purpose, the line pressure control device of the present invention includes a regulator valve that regulates oil from an oil pump to a line pressure for operating a friction element, and a regulator valve that is separate from this valve. In the manual valve automatic transmission range, the regulator valve receives a force from the torque plug that responds to the torque pressure corresponding to the engine output torque, and adjusts the line pressure so that it increases as the engine output torque increases. When switching the manual valve to the engine brake range, the engine brake range pressure from the manual valve is applied to the regulator valve in the direction of increasing line pressure, and torque is also applied to the torque plug. The automatic transmission is characterized in that the torque plug has a torque pressure acting area larger than an engine braking pressure acting area.

(Function) The torque plug allows the regulator valve to control the line pressure as before in the manual valve's automatic shift range, but the engine brake of the manual valve receives engine braking pressure in addition to torque pressure. In the range,
Since the torque pressure acting area of the torque plug is larger than the engine brake range pressure acting area, the torque plug causes the regulator valve to perform the following line pressure control.

In other words, while the engine output torque is small and the torque pressure is low, the torque plug will not be pushed toward the regulator valve against the engine brake range pressure even by this torque pressure, and the torque plug will not be pushed toward the regulator valve. Do not apply force due to torque pressure to the regulator valve. Therefore, the regulator valve receives only the force from the engine brake range pressure to control the line pressure.

On the other hand, while the engine output torque is large and the torque pressure is high, the torque plug is pushed toward the regulator valve against the engine brake range pressure due to the pressure receiving area difference, and the torque plug uses the force due to the torque pressure to regulate the pressure. Added to the rotor valve. Therefore, the regulator valve also receives the force due to the torque pressure via the torque plug to control the line pressure. For this reason, line pressure is controlled separately between low and high torque pressures, regardless of the engine braking range, and when engine output torque is high and torque pressure is high, engine output torque is low and torque pressure is high. The line pressure is made higher than when it is low, thereby making it possible to control the line pressure to the required value for each engine brake range and even for each engine output torque.

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

FIG. 1 shows an application of the idea of the present invention to the automatic transmission shown in FIG. 3, and the same parts in the figure as in FIG. 3 are designated by the same reference numerals.

In the present invention, the lower end surface 6a in the figure is applied with the torque pressure (throttle pressure) _PTH of the torque plug 6.
is the engine brake range pressure from circuit 5 (
From the upper end surface 6b in the figure where microwave oven pressure) P _II is applied,
The torque plug 6 is configured to have a large pressure receiving area.

In addition, the plug 7 interposed between the regulator valve 1 and the torque plug 6 applies a force corresponding to the engine brake range pressure P _II to the regulator valve 1, and applies the force from the torque plug 6 to the regulator. This is for transmitting the pressure to the rotor valve 1, and determines the engine brake range pressure action area as described below.

In this configuration, when engine braking is desired and the manual valve 3 is switched from the D range to the range with the throttle opening set to TH ₁ or less in FIG. 2, the torque pressure P _TH is low.
Even if the area of the torque plug lower end surface 6a that receives this is larger than the area of the torque plug upper end surface 6b,
Engine brake range pressure P _II from circuit 5 pushes torque plug 6 downward in the figure. Thus, only the force in the direction of increasing the line pressure due to the engine brake range pressure P _II acts on the regulator valve 1 via the plug 7, and the line pressure P _L is increased to the line pressure in the D range as shown in d in Fig. 2. Raise the pressure above the pressure value a.
Here, if the pressure-receiving area of the plug 7 on which the engine brake range pressure P _II acts is made smaller than before, and the line pressure value d is made to correspond to the value shown by c in Fig. 4, the above-mentioned range switching is possible. The accompanying gear change can be performed without the above-mentioned shock, and the above-mentioned problem can be solved.

When running with the power on, leaving the same range and then increasing the throttle opening to TH ₁ or more in Figure 2,
The correspondingly high torque pressure P _TH is due to the size relationship of the pressure receiving areas at both ends of the torque plug 6, and P _TH >
Even if P _II cannot be achieved, the torque plug 6 is pushed upward in the figure, and a force in the same direction is applied to the regulator valve 1 via the plug 7. Thus, the regulator valve 1 controls the line pressure using the torque pressure _PTH , and this line pressure is increased to D as shown by e in FIG.
Change it with the same characteristics as characteristic a in the microwave,
It is possible to prevent the friction element from slipping.

(Effects of the Invention) As described above, the line pressure control device of the present invention has a configuration in which the area of the torque pressure acting surface 6a of the torque plug 6 is larger than the area of the engine brake range pressure acting surface 6b, so that the torque pressure can be set. The line pressure when the torque pressure is less than the set value can be set independently regardless of the line pressure characteristics in other torque pressure regions, and the line pressure when the torque pressure is less than the set value is lower than before to improve the engine braking range. This eliminates the shock problem when switching to the engine brake range, and at the same time, during power-on driving in the engine braking range, the line pressure is increased to a value corresponding to the engine output torque to avoid friction elements slipping. be able to.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the line pressure control device of the present invention, FIG. 2 is a line pressure control characteristic diagram of the same device, FIG. 3 is a circuit diagram showing a conventional line pressure control device, and FIG. The figure is also a line pressure control characteristic diagram. 1...Regulator valve, 2...Oil pump, P _L ...Line pressure, P _TH ...Throttle pressure (torque pressure), P _II ...Range pressure (engine brake range pressure), 3...Manual valve , 4... Line pressure circuit, 5... Engine brake range pressure circuit, 6... Torque plug, 6a... Torque pressure acting end surface, 6b... Engine brake range pressure acting end surface.

Claims (1)

[Claims] 1. A regulator valve that regulates the oil from the oil pump to a line pressure for operating the friction element, and a torque plug separate from this valve. The regulator valve receives the force from the torque plug that responds to the torque pressure corresponding to the engine output torque, and regulates the line pressure so that it increases as the engine output torque increases, and when switching the manual valve to the engine brake range, Applying engine brake range pressure from the manual valve to the regulator valve in a direction to increase line pressure,
An automatic transmission in which the torque pressure is applied to the torque plug in a direction opposite to the torque pressure, wherein the torque pressure action area of the torque plug is larger than the engine brake range pressure action area. line pressure control device.