JPH0570030B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a control device for an automatic transmission.

(b) Conventional technology As a conventional automatic transmission control device,
-There is one shown in Publication No. 101152. The automatic transmission control device shown therein is configured to control four forward speeds by switching four shift valves using one solenoid valve. That is, the solenoid valve is capable of outputting four levels of oil pressure, and the shift valve is configured to be switched depending on the magnitude relationship between the oil pressure output from the solenoid valve and a spring that applies a pushing force to the spool of the shift valve. The switching characteristics of each shift valve are different from each other. This makes it possible to switch four shift valves using one solenoid valve.

(c) Problems to be Solved by the Invention However, the conventional automatic transmission control device as described above has a problem in that the switching accuracy of the shift valve varies. That is, the solenoid valve performs duty ratio control using a constant pilot pressure regulated by the pilot pressure valve, and outputs four levels of hydraulic pressure. However, if the pilot pressure itself, which is regulated by the pilot pressure valve, fluctuates, the duty pressure, which is controlled by the duty ratio, will also fluctuate, and as a result, the switching point of the shift valve, which is switching controlled, will also fluctuate. become. The pilot pressure valve is a valve that regulates a constant pressure, but the pressure regulation value fluctuates due to changes in flow rate, etc., and the value of the pilot pressure also varies due to variations in the setting force of the spring of the pilot pressure valve. Here, the accuracy of the switching valve becomes a problem due to changes in the spring load due to the stroke of the switching valve and variations in the set load. The spool of the switching valve normally requires a stroke of 5 to 6 mm to switch the oil path. Therefore, a change in spring force (stroke x spring constant) occurs before and after the stroke. Furthermore, it is necessary to allow a certain percentage of variation in the set load, and the larger the set load, the greater the variation. Therefore, when setting the duty pressure, it is necessary to take the above-mentioned changes and variations in the load into consideration. When multiple switching valves are controlled by stepped duty pressures output by a single solenoid valve, the difference in each duty pressure will be affected by the above-mentioned load changes and variations in the pilot pressure valve and switching valve. It is necessary to set the settings so that they are sufficiently safe. That is,
In addition to increasing the pilot pressure, it is also necessary to increase the duty pressure that the solenoid can output. Increasing the pilot pressure increases oil pressure loss, and the solenoid that can output high oil pressure becomes larger. The present invention aims to solve such problems.

(d) Means for Solving the Problems The present invention solves the above problems by causing duty pressure and pilot pressure to act against each other on the spool of the switching valve. That is,
The automatic transmission control device according to the present invention includes a plurality of switching valves 10, 26, 40 each switching between two positions, a pilot pressure valve 48 capable of outputting a constant pilot pressure to a pilot pressure oil path 50, operates according to a given duty ratio signal,
one solenoid valve 56 that can adjust the oil pressure of the duty pressure oil path 20 connected to the pilot pressure oil path 50 via the orifice 52 to a state lower than the pilot pressure; each switching valve 10, 26,40 spool 1
2, 28, and 42 are large pressure-receiving area portions 12a that apply opposing forces when hydraulic pressure is applied;
28a, 42a and small pressure receiving area portions 12b, 28
The duty pressure oil passage 20 is connected to the port 22, 34, 46 that applies hydraulic pressure to the large pressure receiving area portion 12a, 28a, 42a of each switching valve 10, 26, 40, A pilot pressure oil passage 50 is connected to the ports 23, 35, 47 that apply hydraulic pressure to the small pressure receiving area portions 12b, 28b, 42b of the valves 10, 26, 40, and the large pressure receiving area portions of each switching valve 10, 26, 40. 12a, 28a, 42a and small pressure receiving area portion 12b,
28b and 42b are different in pressure receiving area ratio, and the solenoid valve 56 is different from the switching valves 10 and 2.
6 and 40 in a stepwise manner to control the oil pressure of the duty pressure oil passage 20.

(E) Function The duty pressure adjusted by the solenoid valve acts on the large pressure receiving area of the switching valve spool, and the pilot pressure adjusted by the pilot pressure valve acts on the small pressure receiving area. .
The switching valve is switched depending on the magnitude relationship between duty pressure and pilot pressure. Solenoid valve is
The pilot pressure supplied through the orifice is used as a hydraulic pressure source, and this pressure is reduced according to the duty ratio to become the duty pressure. Therefore, when the pilot pressure fluctuates, the duty pressure also fluctuates accordingly, and a counterforce corresponding only to the duty ratio acts on the switching valve. That is, even if the pilot pressure fluctuates, the switching point of the switching valve remains as set and will not fluctuate.

The switching valve may not be provided with a spring, and may be switched based only on the magnitude relationship between the pilot pressure and the duty pressure. In this case, fluctuation factors such as spring load changes and variations are eliminated, and a decrease in switching accuracy is prevented. Further, a spring may be provided to stabilize the position of the spool when no hydraulic pressure is applied, but in this case, the load of the spring is set to the minimum necessary value. As a result, the influence of changes and variations in the spring load becomes very small and has almost no effect on switching accuracy.

(F) Embodiments Hereinafter, embodiments of the present invention will be described based on FIGS. 1 to 3 of the accompanying drawings.

FIG. 2 shows a schematic diagram of the power transmission mechanism of an automatic transmission with three forward speeds and one reverse speed. This power transmission mechanism includes an input shaft I that transmits rotational force from an engine output shaft E via a torque converter T/C, an output shaft O that transmits driving force to a final drive device,
It has a first planetary gear set G1, a second planetary gear set G2, a high and reverse latch H&R/C, a forward clutch F/C, a band brake B, a low and reverse brake L&R/B, and a one-way clutch OWC. ing. 1st planetary gear set G1
are sun gear S1, internal gear R1,
A carrier PC1 supports a pinion gear P1 that meshes with both gears S1 and R1 at the same time, and a planetary gear set G2 includes a sun gear S2.
, internal gear R2, and both gears S2 and R
2 and a carrier PO2 that supports a pinion gear P2 that meshes with the pinion gear P2 at the same time. Each component is connected as shown. The above power transmission mechanism is a high and reverse clutch H&R/C,
By operating forward clutch F/C, band brake B, and rolled reverse brake L&R/B (one-way clutch OWC) in various combinations, each element S1, S2, R1, R2 of planetary gear sets G1 and G2 is , PC1, and PC2), thereby making it possible to obtain three forward speeds and one reverse speed by varying the rotational speed of the output shaft 0 relative to the rotational speed of the input shaft I.

FIG. 1 shows only the parts of the hydraulic circuit that are directly related to the present invention. The 1-2 shift valve 10 includes a spool 12 having a large pressure receiving area portion 12a and a small pressure receiving area portion 12b. The large pressure receiving area 12a has a larger pressure receiving area than the small pressure receiving area 12b. Further, the large pressure receiving area portion 12a and the small pressure receiving area portion 12b are arranged so as to apply opposing forces to the spool 12 when hydraulic pressure is applied. Spool 1
2 communicates the oil passage 16 and the oil passage 18 at the lower half position in the figure, and drains the oil passage 18 at the upper half position in the figure. The position of the spool 12 is determined from the duty pressure oil passage 20 through the port 22 to the large pressure receiving area portion 1.
2a and the small pressure receiving area portion 12 from the pilot pressure oil passage 50 through the port 23.
It is determined by the balance with the hydraulic force acting on b. Line pressure is always supplied to the oil passage 16 from the manual valve 24 during forward movement. Note that the oil passage 16 is also connected to the forward clutch F/C.

The 2-3 shift valve 26 has a large pressure receiving area 28
a and a spool 28 having a small pressure receiving area portion 28b.
It is made up of. The large pressure receiving area portion 28a has a larger pressure receiving area than the small pressure receiving area portion 28b. Further, the large pressure receiving area portion 28a and the small pressure receiving area portion 28b are arranged so as to apply opposing forces to the spool 28 when hydraulic pressure is applied. Note that the pressure receiving area of the large pressure receiving area portion 28a of this 2-3 shift valve 26 is the same as the large pressure receiving area portion 12a of the 1-2 shift valve 10;
The pressure receiving area of the small pressure receiving area portion 28b of the 2-3 shift valve 26 is made smaller than the pressure receiving area of the small pressure receiving area portion 12b of the 1-2 shift valve 10. The spool 28 connects the oil passage 18 and the oil passage 32 in the upper half position in the figure, and connects the oil passage 32 in the lower half position in the figure.
drain. The position of the spool 28 is determined by the hydraulic force acting on the large pressure receiving area portion 28a from the duty pressure oil passage 20 via the port 34, and the hydraulic force acting on the small pressure receiving area portion 28b from the pilot pressure oil passage 50 via the port 35. It is determined by the balance between the forces caused by Oil passage 18 is band brake B
Connected to servo apply chamber S/A for fastening. An oil passage 32 in which an orifice 31 is provided is connected to a high and reverse clutch H&R/C. Further, the oil passage 32 is connected to an oil passage 38 by a check valve 36. Check valve 36
is arranged in a direction that allows oil to flow from the oil path 32 side to the oil path 38 side, but does not allow oil to flow in the opposite direction.

The 3-2 timing valve 40 includes a spool 42 having a large pressure receiving area portion 42a and a small pressure receiving area portion 42b. Large pressure receiving area 42a
has a larger pressure receiving area than the small pressure receiving area portion 42bb. Further, the large pressure receiving area 42a of the 3-2 timing valve 40 has the same pressure receiving area as the large pressure receiving area 12a of the 1-2 shift valve 10 and the large pressure receiving area 28a of the 2-3 shift valve 26. ing. The pressure receiving area of the small pressure receiving area portion 42b of the 3-2 timing valve 40 is smaller than the pressure receiving area of the small pressure receiving area portion 28b of the 2-3 shift valve 26. The large pressure receiving area portion 42a and the small pressure receiving area portion 42b are arranged so as to apply opposing forces to the spool 42 when hydraulic pressure is applied. The spool 42 communicates the oil passage 32 and the oil passage 38 in the lower half position in the figure, and blocks the oil passage 38 and the oil passage 32 in the upper half position in the figure. The position of the spool 42 is such that it is connected to the large pressure receiving area portion 42 from the duty pressure oil passage 20 through the port 46.
The force due to the hydraulic pressure acting on a and the small pressure receiving area portion 42b from the pilot pressure oil passage 50 through the port 47.
It is determined by the balance with the hydraulic force acting on the The oil passage 38 is connected to a servo release chamber S/R for releasing the band brake B. Note that since the pressure receiving area of the servo release chamber S/R is larger than the pressure receiving area of the servo apply chamber S/A, the band brake B is always released when hydraulic pressure acts on the servo release chamber S/R.

The aforementioned duty pressure oil passage 20 is connected via an orifice 52 to a pilot pressure oil passage 50 to which a constant pressure is always supplied from a pilot pressure valve 48. The duty pressure oil passage 20 has an opening 54.
A solenoid valve 56 that can open and close this opening 54 is provided. The duty ratio of the solenoid valve 56 is controlled by a signal from an electronic control device 58. Thereby, the oil pressure in the duty pressure oil passage 20 can be adjusted to a predetermined oil pressure commanded by the electronic control device 58.

Electrical signals from a vehicle speed sensor 60, a throttle opening sensor 62, etc. are input to the electronic control device 58, and based on these, the electronic control device 58 adjusts the oil pressure of the duty pressure oil passage 20 to P ₁ , P ₂ ,
Outputs signals for adjustment in four stages, P ₃ and P ₄ .
Note that the magnitude of the hydraulic pressure is set as P ₄ > P ₃ > P ₂ > P ₁ . On the other hand, the relationship between the large pressure receiving area portion 12a and the small pressure receiving area portion 12b of the spool 12 of the 1-2 shift valve 10 is that when the oil pressure of the port 22 is below P _A , the force due to the pilot pressure acting on the small pressure receiving area portion 12b. is set to be larger, resulting in the state shown in the lower half of the figure, and conversely, when the oil pressure of the port 22 becomes greater than P _A , it is set to be in the state shown in the upper half of the figure. Similarly, 2-3 shift valve 26
Also, when the oil pressure of the port 34 is less than or equal to P _B , the state is shown in the lower half of the figure, and when it becomes greater than P _B , the state is shown in the upper half of the figure. Also, regarding the 3-2 timing valve 40, when the hydraulic pressure acting on the port 46 is less than or equal to P _C , it will be in the state shown in the lower half of the diagram, and when it is greater than P _C , it will be in the state shown in the upper half of the diagram. It's like this. The magnitude of these oil pressures is set so that P _A > P _B > P _C. Furthermore, the relationship between the hydraulic pressures of P ₁ , P ₂ , P ₃ and P ₄ and P _A , P _B and P _C is as follows: P ₄ > P _A > P ₃ > P _B > P ₂ > P _C >P ₁ . This relationship is illustrated in FIG. 3.

By setting the hydraulic characteristics as described above,
Shift control and 3-2 shift timing adjustment can be performed.

First, regarding gear shifting, the duty pressure oil passage 20
When the oil pressure reaches P ₄ , the 1-2 shift valve 10
Both the and 2-3 shift valves 26 are in the state shown in the upper half of the figure, and only the forward clutch F/C is engaged, resulting in the first speed state. Next, when the oil pressure of the duty pressure oil passage 20 is set to P ₂ or P ₁ , the 1-2 shift valve 10 becomes the state shown in the lower half of the figure, and the 2
-3 shift valve 26 is also in the lower half state. Therefore, in addition to the forward clutch F/C, hydraulic pressure is supplied to the servo apply chamber S/A, and the band brake B is engaged, so that the automatic transmission enters the second speed state. Next, when the oil pressure of the duty pressure oil passage 20 is set to _P3 , the 1-2 shift valve 10 is in the lower half of the figure, while the 2-3 shift valve 26 is in the upper half of the figure. As a result, hydraulic pressure is supplied to the high and reverse clutch H&R/C and the servo release chamber S//R, resulting in the third speed state.
Since the check valve 36 is provided, the oil pressure in the oil passage 32 is supplied to the servo release chamber S/R regardless of the state of the 3-2 timing valve 40.

Further, the 3-2 timing valve 40 operates as follows. That is, the position of the 3-2 timing valve 40 is switched when the oil pressure of the duty pressure oil passage 20 is _P2 and _P1 . That is, when the oil pressure is _P2 , the 3-2 timing valve 40 is in the upper half state, and the oil passage 38 is in a blocked state, and on the other hand, when the oil pressure is _P1 , the oil passage 32 and the oil passage 38 are communicated with each other. Utilizing this, for example, the timing of the 3-2 shift can be adjusted as follows. That is, the oil pressure of the duty pressure oil passage 20 is set to P ₃ (i.e., 3rd speed).
When switching from to P ₂ , the 2-3 shift valve 26
switches to the second speed state (ie, switches from the upper half state to the lower half state), while the 3-2 timing valve 40 remains in the upper half position. Therefore, the high and reverse clutch H&
Although the R/C hydraulic pressure begins to be discharged, the hydraulic pressure in the servo release chamber S/R is not discharged. After this state is maintained for a predetermined time, the oil pressure in the duty pressure oil passage 20 is switched from _P2 to _P1 . As a result, the 2-3 shift valve 26 remains in the lower half position and does not switch.
3-2 The timing valve 40 switches from the upper half state to the lower half state, and the oil passage 38 and the oil passage 32 communicate with each other. As a result, the hydraulic pressure in the servo release chamber S/R also begins to be discharged. In this way, by delaying the discharge of the hydraulic pressure from the servo release chamber S/R by a predetermined period of time compared to the discharge of the hydraulic pressure from the high and reverse clutch H&R/C, the automatic transmission can be temporarily brought into a neutral state. The engine rotational speed is increased, and then the engine is brought into the second speed state. As a result, a neutral state is inserted between the 3rd and 2nd gear shifts, and the speed change can be performed by reducing the difference in rotational speed between the engine side and the automatic transmission side, thereby reducing the shift shock. As mentioned above, the neutral time inserted during the 3-2 shift is controlled by the electronic control unit 58 according to the driving conditions, and is always appropriately controlled according to the vehicle speed and throttle opening conditions.

During the above-mentioned operation, the 1-2 shift valve 1
The 0, 2-3 shift valve 26 and the 3-2 timing valve 40 always switch at the set switching point. That is, if the pilot pressure adjusted by the pilot pressure valve 48 becomes higher than the set value for some reason, the solenoid valve 56 uses this high oil pressure to adjust the oil pressure, so the duty pressure is adjusted accordingly. The duty pressure of the oil passage 20 will also increase. For this reason, 1
-2 shift valve 10, 2-3 shift valve 26
And the oil pressure acting on the large pressure receiving area portions 12a, 28a, and 42a of the 3-2 timing valve 40 becomes higher than the set value. However, the force opposing the hydraulic force acting on the large pressure receiving area portions 12a, 28a and 42a is
and 42b, this pilot pressure is also high. Therefore, even if the pressure regulation value of the pilot pressure valve 48 changes, the switching points of the 1-2 shift valve 10, 2-3 shift valve 26, and 3-2 timing valve 40 are not affected, and the duty ratio remains unchanged. Determined only by This allows each valve to be switched as set.

In addition, in this embodiment, the 1-2 shift valve 1
The 0, 2-3 shift valve 26 and the 3-2 timing valve 40 are switched only by the hydraulic pressure acting on the large pressure receiving area portions 12a, 28a, and 42a and the small pressure receiving area portions 12b, 28b, and 42b. , 28 and 42, the cost can be reduced compared to the case where springs are provided, and there is no influence from variations in the springs.

Note that it is of course possible to provide a spring that applies a relatively small pushing force to each spool of the 1-2 shift valve 10, 2-3 shift valve 26, and 3-2 timing valve 40. When such a spring is provided, there is an advantage that the spool always moves to the predetermined position when the hydraulic pressure stops acting.

(g) Effects of the Invention As explained above, according to the present invention, the pilot pressure regulated by the pilot pressure valve and the duty pressure obtained by controlling the duty ratio of the pilot pressure are made to oppose each other in the switching valve. Since this is made to work, switching control of the switching valve can be performed based on the duty ratio regardless of variations in pilot pressure, and switching accuracy is improved.
As a result, the pilot pressure can be set low, reducing oil pressure loss, and since the pilot pressure is low, the solenoid can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a schematic diagram of an automatic transmission, and FIG. 3 is a diagram showing hydraulic characteristics. 10...1-2 shift valve, 12...spool,
12a...Large pressure receiving area part, 12b...Small pressure receiving area part,
20...Duty pressure oil path, 22...Port, 23...
Port, 26...2-3 shift valve, 28...Spool, 28a...Large pressure receiving area part, 28b...Small pressure receiving area part, 40...3-2 timing valve, 42...Spool, 42a...Large pressure receiving area part, 42b...Small Pressure receiving area section, 46, 47...Port, 48...Pilot pressure valve, 50...Pilot oil passage, 52...Orifice, 56...Solenoid valve.

Claims (1)

[Claims] 1. A plurality of switching valves 10, 26, 40 each switching between two positions, a pilot pressure valve 48 capable of outputting a constant pilot pressure to a pilot pressure oil passage 50, and a given duty ratio. Operates according to signals,
one solenoid valve 56 that can adjust the oil pressure of the duty pressure oil path 20 connected to the pilot pressure oil path 50 via the orifice 52 to a state lower than the pilot pressure; each switching valve 10, 26,40 spool 1
2, 28, and 42 are large pressure-receiving area portions 12a that apply opposing forces when hydraulic pressure is applied;
28a, 42a and small pressure receiving area portions 12b, 28
The duty pressure oil passage 20 is connected to the port 22, 34, 46 that applies hydraulic pressure to the large pressure receiving area portion 12a, 28a, 42a of each switching valve 10, 26, 40, A pilot pressure oil passage 50 is connected to the ports 23, 35, 47 that apply hydraulic pressure to the small pressure receiving area portions 12b, 28b, 42b of the valves 10, 26, 40, and the large pressure receiving area portions of each switching valve 10, 26, 40. parts 12a, 28a, 42a and small pressure receiving area part 12
The solenoid valve 56 has a different pressure receiving area ratio from the switching valves 10 and 2.
6. A control device for an automatic transmission configured to control the oil pressure of a duty pressure oil passage 20 so as to change the hydraulic pressure of the duty pressure oil passage 20 in stages.