JPH09280360A - Automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simplified electronic control automatic transmission in which a shift point can be freely changed while almost all hydraulic circuits of the hydraulic control automatic transmission are being utilized as they are. SOLUTION: The automatic transmission is provided with a regulator valve 11 for outputting a line pressure and a plurality of shift valves 14 to 16 for selectively supplying the line pressure to a frictional element, wherein these shift valves are changed over for making a plurality of shift stages. A predetermined first signal pressure P1 not responding to a degree of opening of a throttle and a vehicle speed is inputted to one end side of each of shift valves 14 to 16 and a second signal pressure P2 is inputted from a solenoid valve 17 to the other end of each of shift valves. An electronic control device 50 determines the shift stage in response to sensing signals of at least a vehicle speed sensor and a throttle opening degree sensor and outputs a control signal to the solenoid valve 17 so that the second signal pressure P2 varying in a stepwise manner in response to the determined shift stage is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic transmission, and more particularly to a simplified electronically controlled automatic transmission.

[0002]

2. Description of the Related Art Generally, a hydraulically controlled automatic transmission has a regulator valve for outputting a line pressure, a governor valve for adjusting the line pressure to a governor pressure according to a vehicle speed, and a line pressure for adjusting a throttle opening. A throttle valve for adjusting the throttle pressure, and a plurality of shift valves to which the governor pressure and the throttle pressure are input in opposite directions and which selectively supplies the hydraulic pressure to the friction element are provided. As described above, the shift valve switches depending on the balance between the governor pressure and the throttle pressure to determine the shift point, and therefore the shift point is uniquely determined by the characteristics of the shift valve.

Currently, in the diversification of characteristics of automatic transmission,
There is a demand for control for changing a shift point according to road conditions, for example, control for delaying an upshift on an uphill or accelerating a downshift for engine braking on a downhill. In order to perform such control, it is unavoidable to use an electronically controlled automatic transmission. However, since the electronically controlled automatic transmission has a completely different hydraulic circuit from the hydraulically controlled automatic transmission, it is necessary to change the entire hydraulic circuit such as the valve body and redesign the circuit exclusively for electronic control. There is a problem of rising costs and increasing man-hours for development.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
As disclosed in JP-A-57949 and JP-A-1-303352, an automatic transmission in which a solenoid valve is used instead of the governor valve to regulate the governor pressure by an electronic control unit so that the shift point can be freely changed. Is proposed. In this case, the hydraulic circuit of the hydraulic control type automatic transmission can be changed to the electronic control type while using the hydraulic circuit almost as it is, so that the cost can be reduced.

However, in the above case, since the throttle pressure is still generated by the throttle valve,
There is a problem that the shift point is restricted by the characteristics of the throttle valve.

SUMMARY OF THE INVENTION An object of the present invention is to provide a simple electronically controlled automatic transmission which can change the shift point freely while using the hydraulic circuit of the hydraulically controlled automatic transmission almost as it is.

[0007]

In order to achieve the above object, the present invention provides a regulator valve for outputting line pressure,
An automatic transmission having a plurality of shift valves for selectively supplying a line pressure to a friction element, and switching the shift valves to a plurality of shift speeds. A predetermined first signal pressure that does not respond to is input to the shift valve, and a second signal pressure is input to the other end of the shift valve from the solenoid valve. The solenoid valve regulates the line pressure by a control signal from the electronic control unit. To generate a second signal pressure, and the electronic control unit determines the shift speed based on at least the detection signals from the vehicle speed sensor and the throttle opening sensor, and the second signal changes stepwise according to the determined shift speed. A control signal is output to the solenoid valve so as to generate pressure.

In the conventional hydraulic control type automatic transmission, the shift valve is switched according to the balance between the governor pressure and the throttle pressure. The shift valve is switched in accordance with the corresponding second signal pressure. This second signal pressure is a hydraulic pressure that changes stepwise in accordance with the shift speed, and is obtained by the solenoid valve adjusting the line pressure. The electronic control unit determines the optimum shift speed based on at least the vehicle speed signal and the throttle signal, and outputs the control signal corresponding to the determined shift speed to the solenoid valve to generate the second signal pressure.

In this way, by applying a predetermined hydraulic pressure from one of the shift valves and applying a stepwise hydraulic pressure corresponding to the shift speed from the other, a simple and simple shift control can be executed. In particular, since fine hydraulic control such as duty control is not required, the control becomes very simple and the accuracy of the solenoid valve is not required. Moreover, the shift point can be freely determined by the control signal output from the electronic control unit, and is not affected by the characteristics of the governor valve or the throttle valve. Further, in the present invention, a plurality of solenoid valves are not required unlike the conventional electronically controlled automatic transmission, and a single solenoid valve is sufficient, so that cost reduction can be achieved.

In the case of the present invention, for example, an existing throttle valve can be used as a valve for generating the first signal pressure. In this case, if the downshift plug is fixed with a pin or the like so that the throttle valve does not move according to the accelerator opening, the first signal pressure is always a constant pressure.

The throttle valve may be used as a pressure regulating valve that responds to an operation from the driver's seat (excluding accelerator operation). In this case, the first operation is performed from the driver's seat.
The signal pressure can be adjusted to a hydraulic pressure that changes in stages. For example,
When the operation mechanism such as the mode switching lever or the mode switch and the throttle valve are interlocked, in the sports mode or the power mode, the first clutch speed is increased in order to increase the clutch engagement speed.
The signal pressure may be adjusted to a high level, and in the normal mode or the economy mode, the first signal pressure may be adjusted to a low level to reduce the clutch engagement shock. As described above, since the shift point can be freely changed depending on the mode, more diverse shift control can be performed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a front view 4 to which the present invention is applied.
1 shows a power transmission mechanism of an automatic transmission having a first speed / reverse speed. This automatic transmission includes a torque converter 1 and
The input shaft 2 through which the engine power is transmitted via the torque converter 1, the three clutches C ₁ , C ₂ , and C ₃ , the two brakes b ₁ and B _2, and the b ₁ brake are engaged and released. Servo piston 3 and Ravigneaux type planetary gear mechanism 4
1, a one-way clutch OWC, an output gear 5, an output shaft 7, and a differential device 8.

Forward sun gear 4a of the planetary gear mechanism 4
The input shaft 2 and are connected by a C ₁ clutch,
The rear sun gear 4b and the input shaft 2 is connected via the C ₂ clutch, is connected via the C ₃ clutch and the carrier 4c and the input shaft 2. The carrier 4c is connected to a fixed member 6 such as a casing through a B ₂ brake and a one-way clutch OWC that allows only the normal rotation (engine rotation direction) of the carrier 4c. The carrier 4c supports two types of planetary gears 4d and 4e, the forward sun gear 4a meshes with a long pinion 4d having a long shaft length, and the rear sun gear 4b meshes with a long pinion 4d via a short pinion 4e having a short shaft length. There is.
The ring gear 4f that meshes with only the long pinion 4d is connected to the output gear 5. The output gear 5 is connected to a differential 8 via an output shaft 7.

The power transmission mechanism includes clutches C ₁ ,
By operating C ₂ , C ₃ , brakes b ₁ , B ₂ and one-way clutch OWC, as shown in Table 1, four forward gears and one reverse gear (only the D range and the R range are shown) are realized. In the following table, ○ indicates the operating state. B ₁ is the working-side oil chamber of the servo piston 3, B ₁ '
Indicates an oil chamber on the release side of the servo piston 3, and when hydraulic pressure is introduced to both oil chambers B ₁ and B ₁ ′ (at the 3rd speed), b
₁ Brake is released.

[0015]

[Table 1]

As described above, only the C ₂ clutch is engaged in the first speed, the C ₂ clutch and the b ₁ brake are engaged in the _second speed, and all the clutches C _{1 to} C ₃ are engaged in the third speed. b _1, B ₂ brake is released, 4
At high speed, the C ₃ clutch and the b ₁ brake are engaged.
When the vehicle is moving backward (R range), the C ₁ clutch and the B ₂ brake are engaged.

The clutches C ₁ , C ₂ , C ₃ and the brakes b ₁ , B ₂ are operated by the hydraulic control device shown in FIG. The hydraulic control device includes an oil pump 10, a regulator valve 11, a manual valve 12, pressure regulating valves 13 and 1-2.
Shift valve 14, 2-3 shift valve 15, 3-4 shift valve 16,
Solenoid valve 17, throttle modulator valve 18, 4-
2 Timing valve 19, 2-4 Timing valve 20, 3-2 Timing valve 21, 4-3 Timing valve 22, Servo control valve 23, B ₁ Brake accumulator 24, C ₂
It includes a clutch accumulator 25, a C ₁ clutch accumulator 26, and the like.

The structure of the hydraulic control device other than the pressure regulating valve 13 and the solenoid valve 17 is described in Japanese Patent Laid-Open No. 4-1315.
Since it is similar to the hydraulic circuit disclosed in Japanese Patent Laid-Open No. 66, JP-A-6-313476, etc., detailed description thereof will be omitted.

The pressure regulating valve 13 uses a throttle valve of a conventional hydraulic control type automatic transmission, and a downshift plug 13a is provided on the right side thereof. In this embodiment, the plug 13a is not interlocked with the accelerator pedal but is interlocked with the mode changeover lever or the mode changeover switch 27 provided in the driver's seat. Therefore, the first signal pressure P ₁ does not respond to the throttle opening, but becomes a hydraulic pressure that changes stepwise according to the movement of the mode switching lever or switch. The first signal pressure P ₁ is input to one end side (left side in FIG. 2) of the shift valves 14, 15 and 16.

The mode switching lever or switch 27
Can switch between multiple modes such as sports mode and power mode with high power performance, and normal mode and economy mode with emphasis on fuel efficiency. In the former mode, the first signal pressure is adjusted higher to increase the clutch engagement speed, and in the latter mode, the first signal pressure is adjusted lower to reduce the clutch engagement shock.

The solenoid valve 17 replaces the conventional governor valve and regulates the line pressure to generate the second signal pressure P ₂ . This signal pressure P ₂ is applied to the shift valves 14, 15, 1
6 is input to the other end side (right side in FIG. 2).

Here, the structure of the solenoid valve 17 will be described with reference to FIG. The solenoid valve 17 is a linear solenoid valve that generates a solenoid pressure proportional to the input current, and is arranged at the position of the governor valve in the hydraulically controlled automatic transmission. Reference numeral 30 is a transmission case, 31 is a recess formed in the transmission case 30 for housing a governor valve, 32 is a coil housed in the recess 31, 33 is a magnetic valve that moves the central portion of the coil 32 in the axial direction. A shaft, 34 is a non-magnetic sleeve fixed to the transmission case 30, and 35 is a non-magnetic valve that moves in the valve sleeve 34 in the axial direction. The valve 35 is pushed up from below by a spring 36, and its upper end is in contact with the valve shaft 33. The lower end of the spring 36 is supported by a spring seat 37.

The sleeve 34 has an input port 34a,
Four ports, that is, an output port 34b, a drain port 34c, and a return port 34d are formed, and the line pressure is input to the input port 34 via the first oil passage 38 of the transmission case 30.
Input to a. The output port 34b is the transmission case 30.
Of the second oil passage 39, and the solenoid pressure (second signal pressure) is output from this port 34b. The drain port 34c communicates with the internal chamber 41 of the transmission case 30 that houses the output shaft 40. Output port 34b
Oil pressure is fed back to the return port 34d through the communication hole 35a formed in the valve 35, and the spring 3
Pressure is adjusted so as to balance with 6.

When the coil 32 is excited, the valve shaft 33 moves downward and pushes the valve 35 downward. As a result, the opening of the port can be adjusted and the solenoid pressure can be adjusted in multiple stages. Since the opening degree of the port is substantially proportional to the current value input to the coil 32, the solenoid pressure also becomes a hydraulic pressure substantially proportional to the current value.

FIG. 4 is an overall view of the control system of the automatic transmission according to the present invention. The solenoid valve 17 is a computer 50
(Electronic control device). Computer 5
Detection signals are input to the 0 from the vehicle speed sensor 51 and the throttle sensor 52. Then, these detection signals and the data stored in the memory of the computer 50 in advance are compared and calculated to determine the optimum shift speed. Then, the computer 50 outputs a control signal (current) corresponding to the determined shift speed to the solenoid valve 17.

FIG. 5 shows the relationship between each shift speed and the solenoid pressure in the D range stored in the memory of the computer 40. The solenoid pressure changes in four steps corresponding to the first to fourth speeds. The solenoid pressure at each shift stage is set to a hydraulic pressure having a certain margin as compared with the balanced hydraulic pressure when the shift valves 14, 15, 16 are switched. Since the solenoid pressure is proportional to the control signal (current) input to the solenoid valve 17, the vertical axis in FIG. 5 can be replaced with a current value.

The solid line in FIG. 5 is the upshift side and the broken line is the downshift side. The solenoid pressure on the downshift side is set slightly lower than the solenoid pressure on the upshift side. In this way, by changing the solenoid pressure between upshift and downshift, hysteresis is given,
It prevents chattering when shifting.

As described above, the shift valves 14, 15, 16
A constant first signal pressure P ₁ (when the mode is not switched) is input to one end side of the
The signal pressure P ₂ is input. Therefore, the shift valve 14,
The positions of 15 and 16 are uniquely determined by the second signal pressure P ₂ . Moreover, since the solenoid pressure is merely a hydraulic pressure that changes in four steps according to the first to fourth speeds, the positions of the shift valves 14, 15 and 16 are clearly determined, and the influence of changes in oil temperature and variations in characteristics. Stable switching operation can be realized. Further, since the solenoid valve 17 does not need to perform fine hydraulic control, it is not necessary to use an expensive valve such as a duty control valve as the solenoid valve 17, and a general inexpensive linear solenoid valve can exert a sufficient function. .

In the above embodiment, the automatic transmission having the forward four-speed shift stage has been described, but it goes without saying that the present invention can be similarly applied to an automatic transmission having other shift stages. In the above embodiment, the pressure regulating valve 13 is operated in a plurality of stages corresponding to the mode switching lever or switch to change the first signal pressure acting on one end of the shift valves 14 to 16. A constant pressure is always set, a mode switching signal is input to the electronic control unit 50, the gear speed is determined by taking the vehicle speed, the throttle opening, and the mode signal into consideration, and the second signal pressure (solenoid pressure) is changed. Good.
In addition to the vehicle speed, the throttle opening, and the mode signal, various signals such as the shift switch, the oil temperature, and the road surface inclination are input to the electronic control unit so that the gear stage can be comprehensively determined. Good.

[0030]

As is apparent from the above description, according to the present invention, one of the shift valves applies a predetermined first signal pressure that does not respond to the throttle opening or the vehicle speed, and the other one of the shift valves responds to the gear position. Second signal pressure (solenoid pressure) that changes in stages
Is applied to change the second signal pressure to switch the shift valve, the shift control is simplified, and stable shift control can be realized. Also, since the solenoid pressure does not require fine hydraulic control such as duty control,
The control is very simple and inexpensive solenoid valves such as linear solenoid valves can be used. Further, since the hydraulic circuit can use the hydraulic circuit of the conventional hydraulic control type automatic transmission almost as it is, the cost can be reduced and the development man-hour can be reduced. Further, since the shift point can be freely determined by the electronic control device, various shift control similar to that of the conventional electronically controlled automatic transmission can be realized.

[Brief description of drawings]

FIG. 1 is a schematic mechanism diagram of an automatic transmission to which the present invention is applied.

FIG. 2 is a hydraulic circuit diagram of the automatic transmission of FIG.

FIG. 3 is a sectional view showing the structure of a solenoid valve.

FIG. 4 is an overall view of a control system of an automatic transmission according to the present invention.

FIG. 5 is a characteristic diagram showing a relationship between each shift speed and a solenoid pressure in a D range.

[Explanation of symbols]

 10 Oil Pump 11 Regulator Valve 12 Manual Valve 13 Pressure Control Valve 14, 15, 16 Shift Valve 17 Solenoid Valve 50 Computer (Electronic Control Unit) 51 Vehicle Speed Sensor 52 Throttle Sensor

Claims (2)

[Claims] 1. An automatic transmission, comprising: a regulator valve for outputting a line pressure; and a plurality of shift valves for selectively supplying the line pressure to a friction element, the shift valve being switched to a plurality of shift stages. A predetermined first signal pressure that does not respond to the throttle opening and the vehicle speed is input to one end of the shift valve, and a second signal pressure is input to the other end of the shift valve from a solenoid valve. Regulates the line pressure by a control signal from the electronic control unit to generate a second signal pressure, and the electronic control unit determines the shift speed based on the detection signals of at least the vehicle speed sensor and the throttle opening sensor. An automatic transmission characterized in that a control signal is output to a solenoid valve so as to generate a second signal pressure that changes stepwise according to the gear position. 2. The automatic transmission according to claim 1, wherein the valve that generates the first signal pressure responds to an operation from a driver's seat and regulates the line pressure to a hydraulic pressure that changes stepwise. An automatic transmission characterized in that