JPH0570027B2 - - Google Patents

Description

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

(b) Prior Art A conventional speed change control device for an automatic transmission is disclosed in Japanese Patent Application Laid-open No. 101152/1983. The shift control device for the automatic transmission 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 switching characteristics of the shift valves are set so that one shift valve is switched for each step change in the oil pressure. This makes it possible to switch four shift valves using one solenoid valve.

(c) Problems to be Solved by the Invention However, although the conventional shift control device for an automatic transmission as described above is capable of controlling switching between gears using one solenoid valve, friction during gear shifting is A separate solenoid valve is required to reduce shift shock by adjusting the timing of hydraulic pressure supply to elements (clutches, brakes, etc.) or hydraulic discharge from friction elements (hereinafter referred to as "shift timing"). That is, in addition to the solenoid valve for shifting, a solenoid valve for adjusting the shift timing is required. For this reason, not only the size of the transmission control device has increased, but also the price has increased.
Moreover, the hydraulic circuit becomes complicated.

Note that it is conceivable that the solenoid valve for switching the shift valve also be used for switching the timing valve, but in this case, the following problems arise. In other words, there is a possibility that the variation in switching timing of the timing valve becomes large. The timing valve is switched by moving the spool against the force of a spring by the force of a switching signal pressure from a solenoid valve. Although there is a certain degree of variation in the spring load, even if there is variation at the same ratio, the greater the set load, the greater the value of the variation load. Therefore, the timing at which the timing valve actually switches varies widely. When switching a large number of valves using switching signal pressure from one solenoid valve, the problem is how to ensure this accuracy. The present invention aims to solve such problems.

(d) Means for Solving the Problems The present invention solves the above problems by setting the switching signal pressure at which the timing valve switches to a smaller value than that of the shift valve. That is,
The shift control device for an automatic transmission according to the present invention is based on the assumption that two or more shift valves are used to control the shift of three forward gears or more, and includes a first solenoid valve 76 that outputs solenoid pressure; , a first position and a second position corresponding to the two gears, respectively, depending on the magnitude relationship between the force exerted by the first shift spring 30 and the solenoid pressure opposed thereto.
The first position is reached when the force exerted by the first shift valve 26 and the second shift spring 14 is greater than the opposing force due to the switching signal pressure, and the magnitude relationship between the two forces is as follows. The second shift valve 10 is in the second position in the opposite case, and the first position is in the case where the force exerted by the timing spring 44 is greater than the force due to the switching signal pressure, and the second shift valve 10 is in the second position when the magnitude relationship between the two forces is reversed. a timing valve 40 that is in a second position and thereby adjusts the timing of hydraulic pressure supply to or discharge from the friction element whose operating state is switched by the first shift valve 26; and a switching signal in response to an applied electric signal. A second solenoid valve 56 that outputs pressure, and an electronic control device 58 that provides electrical signals to the first solenoid valve 76 and the second solenoid valve 56.
The electronic control device 58 has the second solenoid valve 5
As the switching signal pressure according to 6, it is possible to output an electric signal that adjusts at least three levels of oil pressure: a first oil pressure P1, a second oil pressure P2 higher than this, and a third oil pressure P3 higher than this, and the second shift The relationship between the spring 14, the timing spring 44, and the switching signal pressure is such that when the first hydraulic pressure is output, the second shift valve 10 is in the first position, the timing valve 40 is in the first position, and the second hydraulic pressure is output. When the second shift valve 10 is in the first position, the timing valve 40 is in the second position, and when the third hydraulic pressure is output, the second shift valve 10 is in the second position, and the timing valve 40 is in the second position. It is set to be in position.

The second shift valve serves as a 1-2 shift valve 10 that controls shifting between the first speed and the second speed.
It can be set so that the first speed is the second speed and the second position is the first speed.

(e) Operation When the solenoid valve is activated by an electric signal from the electronic control device and the state is switched from outputting the first hydraulic pressure to outputting the second hydraulic pressure, the second shift valve is shifted to the first position. while the timing valve switches from the first position to the second position. Next, when the third hydraulic pressure is output, the second shift valve is also switched to the second position. That is, the timing valve is switched in the region where the switching signal pressure is lowest. A low switching signal pressure means that the setting force of the timing spring is small, and when this setting force is small, the variation value is also small, and as a result, the fluctuation in the signal pressure for switching the timing valve becomes small. Furthermore, the fact that the setting force of the timing spring is small means that the time it takes for the spool to stroke and actually switch is short, and in addition to reducing the above-mentioned variations, the timing can be switched with high precision. Note that shift valves have relatively larger variations than timing valves, and even if the start of gear changes changes for a short time, it is not noticeable to the driver, but if the timing valve fluctuates, it can cause a large shock. However, timing valves require more precise switching. Therefore, the timing valve is set to the more accurate side.

(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 to which rotational force from an engine output shaft E is transmitted via a torque converter T/C, an output shaft O to transmit driving force to a final drive device, a first planetary gear set G 1 , a first planetary gear set G 1 , and a first planetary gear set G ₁ . It has two planetary gear sets _G2 , a high and reverse clutch 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. 1st planetary gear set G ₁
is sun gear S ₁ , internal gear R ₁ , and pinion gear P ₁ that meshes with both gears S ₁ and R ₁ at the same time.
It consists of a carrier PC that supports ₁ and
Further, the planetary gear set _G2 is composed of a sun gear _S2 , an internal gear _R2 , and a carrier _PC2 that supports a pinion gear _P2 that meshes with both gears _S2 and _R2 at the same time. Each component is connected as shown. The above power transmission mechanism includes a high and reverse clutch H&R/C, a forward clutch F/C, a band brake B, and a low and reverse brake L&R/B (one-way clutch).
OWC) in various combinations, each element _{S 1 ,} S _{2 ,} R ₁ ,
The rotational states of R ₂ , PC ₁ and PC ₂ can be changed, thereby varying the rotational speed of the output shaft O relative to the rotational speed of the input shaft I, resulting in three forward speeds, one backward speed, and one backward speed.
You can get speed.

FIG. 1 shows only the parts of the hydraulic circuit that are directly related to the present invention. The 1-2 shift valve 10 is composed of a spool 12 and a spring 14, and the spool 12 communicates the oil passage 16 and the oil passage 18 at the lower half position in the figure, and communicates the oil passage 18 with the oil passage 18 at the upper half position in the figure. drain. The position of the spool 12 is determined by the balance between the hydraulic force acting on the port 22 from the oil passage 20 and the force exerted by the spring 14. Line pressure is always supplied to the oil passage 16 from the manual valve 24 during forward movement. In addition, the oil passage 16 is a forward clutch F/C.
connected with.

The 2-3 shift valve 26 is composed of a spool 28 and a spring 30, and the spool 2
8 connects the oil passage 18 and the oil passage 32 at the upper half position in the figure, and drains the oil passage 32 at the lower half position in the figure. The state of the spool 28 is determined by the oil pressure acting on the port 34 from the oil passage 70. The oil passage 18 is connected to a servo apply chamber S/A for engaging the band brake B. 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. The check valve 36 connects the oil passage 3 from the oil passage 32 side.
It is arranged in a direction that allows oil to flow toward the 8 side, but does not allow oil to flow in the opposite direction.

3-2 timing valve 40 is connected to spool 42
and a spring 44, and when the spool 42 is in the lower half position in the figure, it is connected to the oil passage 32 and the oil passage 3.
8, and in the upper half position in the figure, the oil passage 38
and the oil passage 32 are cut off. The position of the spool 42 is determined by the hydraulic pressure acting on the port 46 from the oil passage 20. 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 oil passage 20 is connected via an orifice 52 to an oil passage 50 to which a constant pressure is always supplied from a pilot pressure valve 48. The oil passage 20 is provided with an opening 54, and a second solenoid valve 56 that can open and close this opening 54 is provided. The second solenoid valve 56 is the electronic control device 5
The duty ratio is controlled by the signal from 8.
Thereby, the oil pressure in the oil passage 20 can be adjusted to a predetermined oil pressure commanded by the electronic control device 58.

The aforementioned oil passage 70 is connected via an orifice 72 to an oil passage 50 to which a constant pressure is always supplied from the pilot pressure valve 48. The oil passage 70 is provided with an opening 74, and a first solenoid valve 76 that can open and close this opening 74 is provided. The first solenoid valve 76 is the electronic control device 5
It is turned on and off by the signal from 8. The first solenoid valve 76 has an opening 74 when it is on.
is open and closed when off. This allows the oil pressure in the oil passage 70 to be turned on and off.

Electrical signals from a vehicle speed sensor 60, a throttle opening sensor 62, etc. are input to the electronic control device 58, and the electronic control device 58 adjusts the oil pressure in the oil passage 20 to P ₁ , P ₂ , and P ₃ based on these signals. Outputs signals for adjustment in three stages. Note that the magnitude of the hydraulic pressure is set as P ₃ > P ₂ > P ₁ . On the other hand, the 1-2 shift valve 10 is set so that when the oil pressure of the port 22 is less than P _A , it will be in the state shown in the lower half of the figure, and when it is greater than P _A , it will be in the state shown in the upper half of the figure. . In addition, the 3-2 timing valve 40 will be in the state shown in the lower half of the figure when the hydraulic pressure acting on the port 46 is less than P _B , and will be in the state shown in the upper half of the figure when it becomes greater than P _B. It is set as.
The magnitude of these oil pressures is set so that P _A > P _B. Further, the relationship between the hydraulic pressures of P ₁ , P ₂ and P ₃ and P _A and P _B is such that P ₃ >P _A >P ₂ >P _B >P ₁ . To illustrate this relationship, the third
It will look like the figure.

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

First, regarding gear shifting, the oil pressure in the oil passage 20 is P ₃
At this point, the 1-2 shift valve 10 is in the state shown in the upper half of the figure, and regardless of the position of the 2-3 shift valve 26, only the forward clutch F/C is engaged, resulting in the first speed state. Next, when the oil pressure in the oil passage 20 is set to P ₂ or P ₁ , the 1-2 shift valve 1
0 is the state in the upper half of the figure. On the other hand, the 2-3 shift valve 26 is in the lower half state when the first solenoid valve 76 is on. Therefore, in addition to the forward clutch F/C, hydraulic pressure is also supplied to the servo apply chamber S/A, and the band brake B
is engaged, and the automatic transmission enters the second speed state. Next, when the first solenoid valve 76 is turned off,
The 2-3 shift valve 26 is in the upper half state in the figure. As a result, the high and reverse clutch H
Hydraulic pressure is supplied to &R/C and 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. In other words, the oil pressure in the oil passage 20 is _P2 .
At _P1 , the position of the 3-2 timing valve 40 is switched. That is, at oil pressure P ₂ , the 3-2 timing valve 40 is in the upper half state, and the oil path 3
8 is in a shut-off state, and conversely, when the oil pressure is P ₁ , the oil passage 32 is closed.
and the oil passage 38 communicate with each other. Utilizing this, for example, the timing of the 3-2 shift can be adjusted as follows. That is, even after the 3-2 shift is commanded, the first solenoid valve 76 is switched from OFF to ON, and the 2-3 shift valve 26 is switched from the 3rd speed state to the 2nd speed state, the oil pressure in the oil passage 20 is not maintained. _P2
If the state is maintained, the 3-2 timing valve 40 is maintained at the upper half position. Therefore,
Although the hydraulic pressure of the high and reverse clutch H&R/C begins to be discharged, the servo release chamber S/R
hydraulic pressure is not discharged. After this state is maintained for a predetermined time, the oil pressure in the oil passage 20 is switched from _P2 to _P1 .
Thereby, the 3-2 timing valve 40 is switched from the upper half state to the lower half state, and the oil passage 38 and the oil passage 32 are communicated 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 the neutral state, and during this period 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 difference in rotational speeds between the engine side and the automatic transmission side can be reduced and the gears can be shifted, 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. Note that the electronic control device 5
8. Even if the second solenoid valve 56 or the like fails and the oil pressure in the oil passage 20 becomes 0, the second speed is maintained and the vehicle can run safely.

Note that the switching of the first solenoid valve 76 from off to on and the switching of the second solenoid valve 56 from hydraulic pressure P ₂ to P ₁ can be controlled completely independently. Therefore, for example, the 3-2 timing valve 40 may be switched prior to switching the 2-3 shift valve 26.
In addition, by setting the oil pressure to P ₂ for a short period of time from the start of 1-2 gear shifting, and then switching to oil pressure P ₁ ,
It is also possible to temporarily delay the release of the hydraulic pressure in the servo release chambers S/R to obtain a cushioning effect. Further, in the above-described embodiment, the 3-2 timing valve 40 was used as the timing valve, but the timing can be similarly adjusted not only for downshifts but also for upshifts using the present invention. Further, the present invention can be applied to a timing valve that switches between an oil passage that passes through an orifice and an oil passage that does not pass through an orifice.

(g) Effects of the Invention As explained above, according to the present invention, the timing valve is switched at the lowest point of the switching signal pressure, so the timing valve can be switched with high precision, resulting in good gear shifting. performance can be ensured.

[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 of the embodiment. 10...1-2 shift valve, 26...2-3 shift valve, 40...3-2 timing valve, 56
...Solenoid valve, 58...Electronic control device.

Claims (1)

[Claims] 1. A shift control device for an automatic transmission that performs shift control of three or more forward gears using two or more shift valves, comprising: a first solenoid valve 76 that outputs solenoid pressure; and a first shift spring. 30 and the solenoid pressure opposing the force, the first position and the second position corresponding to the two gear stages are selected.
The first position is reached when the force exerted by the first shift valve 26 and the second shift spring 14 is greater than the opposing force due to the switching signal pressure, and the magnitude relationship between the two forces is as follows. The second shift valve 10 is in the second position in the opposite case, and the first position is in the case where the force exerted by the timing spring 44 is greater than the force due to the switching signal pressure, and the magnitude relationship between the two forces is reversed. a timing valve 40 that is in a second position and thereby adjusts the timing of hydraulic pressure supply to or discharge from the friction element whose operating state is switched by the first shift valve 26; A second solenoid valve 56 that outputs a switching signal pressure, and an electronic control device 58 that provides an electric signal to the first solenoid valve 76 and the second solenoid valve 56.
The electronic control device 58 has the second solenoid valve 5
As the switching signal pressure according to 6, it is possible to output an electric signal that adjusts at least three levels of oil pressure: a first oil pressure P1, a second oil pressure P2 higher than this, and a third oil pressure P3 higher than this, and the second shift The relationship between the spring 14, the timing spring 44, and the switching signal pressure is such that when the first hydraulic pressure is output, the second shift valve 10 is in the first position, the timing valve 40 is in the first position, and the second hydraulic pressure is output. When the second shift valve 10 is in the first position, the timing valve 40 is in the second position, and when the third hydraulic pressure is output, the second shift valve 10 is in the second position, and the timing valve 40 is in the second position. Shift control device of an automatic transmission that is set to the position. 2 The second shift valve is a 1-2 shift valve 10 that controls speed change between the first speed and the second speed, and is set so that the second speed is in the first position and the first speed is in the second position. 2. The speed change control device for an automatic transmission according to claim 1, wherein the speed change control device is set to .