JP2636489B2 - Hydraulic control device for automatic transmission - Google Patents

Description

The present invention relates to a hydraulic control device for an automatic transmission.

(B) Conventional technology A conventional hydraulic control device for an automatic transmission is disclosed in, for example, JP-A-59-159452. The four-speed automatic transmission shown here has clutches that are engaged at first, second, and third speeds. An accumulator for mitigating a change in the oil pressure is provided in an oil passage that supplies the oil pressure of the clutch.

(C) Problems to be Solved by the Invention However, the conventional hydraulic control apparatus for an automatic transmission as described above includes the engagement of the clutch at the time of ND selection and the engagement of the clutch at the time of 4-3 shift. There is a problem that the effect of the accumulator cannot be set to be appropriate for both. That is, since the clutch is engaged at the first speed, the second speed, and the third speed as described above, the clutch is switched from the disengaged state to the engaged state when the ND select is performed, and the 4-3 shift is performed. Similarly, when the operation is performed, the state is switched from the released state to the engaged state. However, there is a great difference between the torque capacity of the clutch required at the first speed and the torque capacity required at the third speed. For the same input torque, the first speed is about 3 times faster than the third speed.
In view of the fact that the torque capacity is required to be doubled, and that the torque converter has a torque increasing function at the first speed, a torque capacity that is six times or more is required. On the other hand, since the accumulator performs the same operation at the time of the ND selection and at the time of the 4-3 shift, if the appropriate engagement state is set at the time of the ND selection, the torque capacity becomes large at the time of the 4-3 shift. Too long, and a large shift shock occurs. An object of the present invention is to solve such a problem.

(D) Means for Solving the Problems The present invention solves the above problems by switching the hydraulic pressure acting on the back pressure chamber of the accumulator according to the shift speed. That is, the present invention has a hydraulic friction engagement element (clutch C ₃ ) which is engaged at two or more shift speeds, and the required torque capacity of this hydraulic friction engagement element differs between two or more shift speeds. It is premised that a hydraulic control device for a transmission is provided with an accumulator (90) capable of relaxing a change in hydraulic pressure of the hydraulic friction engagement element, and acts on a back pressure chamber (116) of the accumulator. A back pressure switching valve (91) capable of switching the hydraulic pressure to be applied is provided, and the back pressure switching valve outputs a hydraulic pressure which is output at any one of the two or more shift speeds and which is not output at the other shift speeds. A switching operation is performed as pilot pressure, and a plurality of oil passages to which hydraulic pressures of different hydraulic values are guided are selectively switched. A back pressure switching valve is configured to switch hydraulic pressures having different hydraulic values between one switching position and the other switching position. Pressure chamber It is configured to act. In addition, the code | symbol in a parenthesis shows the corresponding member of the Example mentioned later.

(E) Operation The back pressure switching valve switches the hydraulic pressure at a predetermined gear position as the pilot pressure. This oil pressure is output at the fourth speed, for example, and is not output at the first speed. in this case,
The switching position of the back pressure switching valve changes between the fourth speed and the first speed. A high oil pressure is applied to the back pressure chamber of the accumulator at the first speed switching position, and a low oil pressure is applied to the back pressure chamber at the fourth speed switching position. By doing so, the substantially constant hydraulic pressure obtained during the piston stroke of the accumulator in the first speed is higher than the substantially constant hydraulic pressure obtained in the fourth speed. Therefore, the torque capacity at the time of engagement of the hydraulic friction engagement element is appropriately set at the first speed and the fourth speed, respectively.

(F) Embodiment FIG. 2 shows the automatic transmission as a skeleton diagram. This automatic transmission includes a fluid transmission mechanism 10, a main transmission mechanism 12, and a subtransmission mechanism 14.
And a differential mechanism 16. The fluid transmission mechanism 10 is constituted by a torque converter with a lock-up mechanism 11, and is arranged with a first axis 18 coaxial with a crankshaft (not shown) of the engine as a rotation axis. The torque from the engine is input to the fluid transmission mechanism 10, and the output from the fluid transmission mechanism 10 is input to the main transmission mechanism 12 via the shaft 20. Like the fluid transmission mechanism 10, the main transmission mechanism 12, which is arranged with the first axis 18 as the rotation axis, is a first planetary gear set G
₁ (which consists of a sun gear S ₁ , an internal gear R ₁ and a carrier PC ₁ supporting a pinion gear P ₁ meshing simultaneously with both gears S ₁ and R ₁ ), a second planetary gear set G ₂ (this is sun gear S ₂ and internal gear R ₂
And a carrier PC ₂ which supports both gears S ₂ and R ₂ pinion gear P ₂ meshing simultaneously), the first clutch C _1, second clutch C _2, the third clutch C _3, the first brake
B ₁ , a second brake B _2, and a first one-way clutch OWC _{1. The} rotational force input from the shaft 20 is shifted to a forward fourth speed and a reverse first speed including an overdrive speed as described later. It can be output to the shaft 22. That is, the clutch
C ₁ , C ₂ and C ₃ , brake B ₁ (first one-way clutch OW
By operating C ₁ ) and B ₂ in various combinations,
You can change the rotating state of each element of the planetary gear set G ₁ and G _2, whereby it is possible to change various rotational speed of the shaft 22 relative to the rotational speed of the shaft 20.

The main transmission mechanism output gear 24 is provided on the shaft 22 so as to rotate integrally therewith.
Meshes with an auxiliary transmission mechanism input gear 28 which is arranged with a second axis 26 parallel to the first axis 18 as a rotation axis. The main transmission mechanism output gear 24 and the auxiliary transmission mechanism input gear 28 are gears having the same number of teeth (note that it is of course possible to change the gear ratio as desired). The auxiliary transmission mechanism input gear 28 is connected to the auxiliary transmission mechanism 14. The auxiliary transmission mechanism 14 has a third planetary gear set G ₃ , a fourth clutch C ₄ , a third brake B _3, and a second one-way clutch OWC ₂ . The third planetary gear set G ₃ are, the sun gear S _3, the internal gear R _3, and a double gear S ₃ and R ₃ simultaneously meshing pinion gears P ₃ the supporting carrier PC ₃ Prefecture. The internal gear R ₃ is connected so as to rotate integrally with the auxiliary transmission input gear 28, and the carrier PC ₃ is connected to the second axis 2.
It is connected so as to rotate integrally with a shaft 32 arranged with 6 as a central axis. The fourth clutch C ₄ is a carrier
It is possible to control the connection and disconnection between PC ₃ and Sun Gear S ₃ ,
The third brake B ₃ can be fixed to the stationary part as needed sun gear S _3. 2nd one-way clutch OWC ₂
They are arranged in parallel with the third brake B _3. The shaft 32 is provided with a final pinion gear 34 so as to rotate integrally with the shaft 32. The final pinion gear 34 meshes with the final gear 36. This final gear 36
, A differential mechanism 16 is integrally provided.

The torque input from the engine to this automatic transmission is
Fluid transmission mechanism 10, shaft 20, main transmission mechanism 12, shaft 22, main transmission mechanism output gear 24, auxiliary transmission mechanism input gear 28, auxiliary transmission mechanism 14,
The shaft 32, the final pinion gear 34, the final gear 36, and the differential mechanism 16 are transmitted in the above order. In the meantime, the automatic transmission can perform a forward five-speed reverse and a first reverse gear. That is, each clutch, brake, etc.
By operating in a combination as shown in the figure, five forward speeds and one reverse speed can be obtained. Note that in FIG.
Mark indicates that the clutch and brake are engaged,
In the case of a one-way clutch, it indicates a load state. Α ₁ , α ₂ and α ₃ are internal gears, respectively.
The ratio of the number of teeth of the sun gears S ₁ , S ₂ and S _{3 to} the number of teeth of R ₁ , R ₂ and R ₃ , and the gear ratio is the ratio of the number of teeth of the shaft 20 to the number of rotations of the shaft 32.
Is the ratio of the rotation speeds of More specifically described each gear in the gear position of the fourth and fifth speed, the fourth clutch C ₄ are fastening and third brake B ₃ of the subtransmission mechanism 14 is released. As a result, the auxiliary transmission mechanism 14 is in a directly connected state, that is, a state of a gear ratio of 1, and the rotation of the auxiliary transmission mechanism input gear 28 is transmitted to the shaft 32 as it is. On the other hand, in the case of the first to third speeds and in the case of reverse travel, the following operation is performed. That is, the subtransmission mechanism 14 is in a state where the fourth clutch C ₄ is released and the third brake B ₃ (or the second one-way clutch OWC ₂₎ has concluded. In this state the axis
32 rotates in a state where the speed is reduced with respect to the auxiliary transmission mechanism input gear 28. For example, if the gear ratio of the internal gear R ₃ and the sun gear S ₃ and 0.45, the gear ratio of the subtransmission mechanism 14 becomes 1.45. Therefore, in this case, the ratio of the rotation speed of the shaft 32 to the shaft 20 is obtained by multiplying the rotation speed ratio of the main transmission mechanism 12 by 1.45. As a result, the combination of the main transmission mechanism 12 and the sub transmission mechanism 14 can provide the gear ratio as shown in FIG.

FIG. 4 shows a hydraulic circuit of a hydraulic control device for controlling the power transmission mechanism.

This hydraulic control device is a pressure regulator valve
50, manual valve 52, pilot valve 54, torque converter supply pressure valve 56, pressure modifier valve 58, lock-up control valve 60, lock-up auxiliary valve 61, reduction control valve 6
2, 1-2 shift valve 64, 2-3 shift valve 66, 3
-4 shift valve 68, 4-5 shift valve 70, OD timing valve 72, accumulation shift valve 74, forward clutch timing valve 76, 1st speed fixed range pressure reducing valve 78, accumulator control valve 80, 1-2 accumulator valve 82, OD Accumulator 84, direct clutch accumulator 86, modifier accumulator 88, accumulator 90, back pressure switching valve 91, servo release accumulator 92, shift solenoid 93, shift solenoid 94, shift solenoid 95, timing solenoid 96, line pressure solenoid 97 and lockup Each of these valves and the like are connected to each other as shown in FIG.
The torque converter 12 (where an apply chamber T / A and a release chamber T / R of the lock-up clutch 11 are formed), clutches C ₁ , C ₂ , C ₃ and C ₄ , a brake B ₁ ,
B ₂ and B ₃ (The brake B ₂ has an apply chamber S / A, a release chamber S / R and an OD apply chamber OD / A)
Are connected as shown. With such a configuration, the clutch and the brake operate as shown in the above table according to the vehicle speed and the throttle opening of the engine, but a detailed description of those valves not directly related to the present invention is omitted. I do. Parts related to the present invention will be described later with reference to FIG.

FIG. 5 shows a control unit 300 for controlling the operation of the solenoids 93, 94, 95, 96, 97 and 98. The control unit 300 includes an input interface 311, a reference pulse generator 312, a CPU (central processing unit) 313, a ROM (read only memory) 314, and a RAM (random access memory) 31.
5 and an output interface 316, which are connected by an address bus 319 and a data bus 320. The control unit 300 includes an engine speed sensor 301, a vehicle speed sensor 302, a throttle opening sensor 303, a select position switch 304, a kick down switch 305, an idle switch 306, a full throttle switch 307, an oil temperature sensor 308, a turbine speed. Signals from the sensor 309, the overdrive switch 310, and the like are input. On the other hand, solenoids 93, 94, 95, 9
Signals are output at 6, 97 and 98.

The following description will be made based on FIG. 1 which shows only portions directly related to the present invention. The line pressure solenoid 97 adjusts the duty pressure according to the duty ratio signal given from the control unit 300, and causes the duty pressure to act on the accumulator control valve 80 and the pressure modifier valve 58. The accumulator control valve 80 adjusts the accumulator control pressure in accordance with the duty pressure and outputs it to the oil passage 102.
Note that the duty ratio given to the line pressure solenoid 97 basically corresponds to the throttle opening. The pressure modifier valve 58 also adjusts the modifier pressure in accordance with the given duty pressure, and outputs this to the pressure regulator valve 50. The pressure regulator valve 50 adjusts the line pressure according to the modifier pressure from the pressure modifier valve 58, and outputs this to the manual valve 52. The manual valve 52 outputs a line pressure to the oil passage 104 in the case of the D range. The line pressure output to the oil passage 104 has a characteristic as shown in FIG. 6 with respect to the duty ratio signal given to the solenoid 97, while the accumulator control pressure output to the oil passage 102 is Similarly, the duty ratio signal has characteristics as shown in FIG. That is, the accumulator control pressure is similar to the line pressure in that it changes according to the duty ratio, but the value is lower than the line pressure.
The back pressure switching valve 91 has a spool 106 and a spring 108, and according to a hydraulic pressure acting on a port 110, an oil passage 102
Switching position connecting the oil passage 112 and the oil passage 112, and the oil passage 104 and the oil passage 112
Can be switched to a switching position for connecting. The port 110, oil passage 114 for supplying the hydraulic pressure is connected to the clutch C _2. That is, the hydraulic pressure does not act on the port 110 at the first speed and the second speed, but at the third speed, the fourth speed, and the fifth speed. The oil passage 112 is connected to the back pressure chamber 116 of the accumulator 90. Piston 118 and spring
The working pressure chamber 122 of the accumulator 90 consisting of 120 is connected to a fluid passage 124 for supplying hydraulic pressure to the clutch C _3.

Next, the operation of this embodiment will be described. When the ND selection is performed, the clutch C ₃
Is supplied with hydraulic pressure. At this time, the accumulator 90 performs a hydraulic pressure rising relief operation. That is, the piston 118 of the accumulator 90 is moving to the side that compresses the spring 120 by the hydraulic pressure acting on the back pressure chamber 116. The back pressure chamber 116 is supplied with hydraulic pressure from a back pressure switching valve 91 through an oil passage 112.
It is located at a position where 4 and the oil passage 112 are connected. That is, N-
At the time D select not to act hydraulic pressure to the port 110 for the clutch C ₂ hydraulic pressure is not supplied, the back pressure switching valve 9
Numeral 1 connects the oil passage 104 and the oil passage 112. Therefore,
The line pressure from the oil passage 104 acts on the back pressure chamber 116 of the accumulator 90. Therefore, the hydraulic pressure in the operating pressure chamber 122 of the accumulator 90 is equal to the hydraulic pressure (the operating pressure chamber 1) corresponding to the line pressure.
The pressure rises rapidly up to a value lower than the line pressure by an area ratio between the pressure chamber 22 and the back pressure chamber 116), and then gradually rises during the stroke of the spring 120. Clutch C ₃ is engaged by the gradually rises to go hydraulic.
Therefore, the clutch C ₃ will be fastened by a relatively high pressure.

Then, when the shift from the fifth speed to fourth speed is performed, so that the hydraulic pressure is supplied from the oil line 124 to the clutch C ₃ at the same released state. Also in this case, the effect of accumulator 90 to reduce the hydraulic pressure rise can be obtained. However, since the same hydraulic clutch C ₃ to port 110 of the back pressure switching valve 91 acts in this case, it switched to the side spool 106 back pressure switching valve 91 to compress the spring 108, the oil passage 102 and the oil passage 112 are connected. Therefore, the oil pressure of the oil passage 102 (that is, the oil pressure lower than the line pressure obtained by the accumulator control valve 80) acts on the back pressure chamber 116 of the accumulator 90. Therefore, the working pressure chamber 122 of the accumulator 90
The hydraulic pressure rises relatively quickly to a value corresponding to the hydraulic pressure acting on the back pressure chamber 116 (similarly, a hydraulic pressure smaller by the area ratio between the working pressure chamber 122 and the back pressure chamber 116), and then the stroke of the piston 118 It gradually rises accordingly. While clutch C ₃ is engaged by the oil pressure the gradually increasing, the hydraulic pressure has become lower than the case of the N-D select. Thus, the torque capacity of the clutch C ₃ at the time of shifting from the fifth speed to fourth speed is smaller. Since the required torque capacity at the fourth speed clutch C ₃ (and at the third speed) becomes significantly smaller than the required torque capacity at the first speed, 5-4 and during a shift when the N-D Selector so that the clutch C ₃ is engaged in with hydraulic pressure corresponding to the required torque capacity, respectively. Thus, it is possible to reduce a shift shock when shifting from the fifth speed to the fourth speed.

(G) Effect of the Invention As described above, according to the present invention, the back pressure of the accumulator is changed in accordance with the gear positions having different required torque capacities. Thus, the shift shock can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a hydraulic circuit according to an embodiment of the present invention, FIG. 2 is a skeleton diagram of an automatic transmission, FIG. 3 is a diagram showing a combination of elements operating at each shift speed, and FIG. FIG. 5 is a diagram illustrating the control unit, and FIG. 6 is a diagram illustrating characteristics of hydraulic pressure. C ₃ …… Clutch (hydraulic friction fastening element), 90 …… Accumulator, 91 …… Back pressure switching valve, 116 …… Back pressure chamber.

Claims (2)

(57) [Claims] 1. A hydraulic control device for an automatic transmission, comprising: a hydraulic friction engagement element which is engaged at two or more shift speeds, wherein a required torque capacity of the hydraulic friction engagement element is different at two or more shift speeds. A hydraulic pressure control device for an automatic transmission provided with an accumulator capable of mitigating a change in hydraulic pressure of the hydraulic friction engagement element, wherein a back pressure switchable for switching a hydraulic pressure acting on a back pressure chamber of the accumulator A valve is provided, and the back pressure switching valve performs a switching operation by using, as a pilot pressure, a hydraulic pressure that is output at any one of the two or more shift speeds and that is not output at the other shift speeds, and has different hydraulic pressure values. A plurality of oil passages to which the hydraulic pressure is guided are selectively switched, and the hydraulic pressure applied to the back pressure chamber of the accumulator is switched between one switching position and the other switching position. A hydraulic control device for an automatic transmission. The hydraulic pressure supplied at one switching position of the back pressure switching valve is a line pressure, and the hydraulic pressure supplied at the other switching position is a hydraulic pressure adjusted by a solenoid so as to correspond to an engine load. The hydraulic control device for an automatic transmission according to claim 1.