JPH1122820A - Control device for automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make setting of the shift range of an automatic transmission without causing shortage of the torque capacity of a friction engagement element and without generating a down-shift to the shift range which enables engine brake resulting from failure. SOLUTION: A control device for an automatic transmission is equipped with a condition meet judging means (Step 4) which judges that the predetermined conditions are met and a pattern setting means (Steps 5 and 6) which includes solenoid valves for setting the shift range enabling engine brake on the lower speed side than the given shift range and establishes different combination of on-off state of at least two solenoid valves for the on-off combination of the solenoid valve for setting the shift range in case judgement is passed that the given conditions are met.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling an automatic transmission for a vehicle, and more particularly to a control device for setting a gear by controlling on / off of a solenoid valve.

[0002]

2. Description of the Related Art In an automatic transmission for a vehicle, a hydraulic pressure is appropriately supplied to and discharged from a frictional engagement device such as a clutch or a brake to control the engagement or disengagement of the frictional engagement device. The transmission path of the reaching torque is changed, that is, the gear ratio is changed. The control of hydraulic pressure for engaging or disengaging the friction engagement device has recently been performed.
This is being done using solenoid valves. That is, a solenoid valve that outputs a signal pressure that is controlled to be turned on and off is connected to each of a plurality of shift valves that change an oil path for the friction engagement device, and is further provided for setting an engine brake state. By providing other solenoid valves and turning on or off these solenoid valves as appropriate,
A predetermined forward gear is set, and the engine brake is applied at any gear. Therefore, in this type of automatic transmission, the shift speed is uniquely determined by the combination of ON and OFF of these solenoid valves.

On the other hand, in an automatic transmission that executes shift control using a solenoid valve, a situation in which an intended shift speed cannot be set or an unintended shift is caused by an electrical failure or a mechanical failure of the solenoid valve. May be performed. Therefore, for example, Japanese Patent Application Laid-Open
In the invention described in Japanese Patent Application Publication No. 0210, the solenoid valve for turning on the solenoid valve for applying the engine brake at the lower gear is set for the combination of on / off of the solenoid valve for setting the predetermined gear. The combination of OFF is a combination in which the ON / OFF states of the two solenoid valves are different.

That is, it is unlikely that two solenoid valves fail simultaneously. Therefore, in the above-mentioned automatic transmission, the occurrence of a downshift to a gear position where the engine brake works can be prevented beforehand due to the failure of the solenoid valve.

[0005]

By the way, in an automatic transmission for a vehicle, in addition to a shift by engagement / disengagement of a friction engagement device, various controls such as control of a hydraulic pressure during a shift and control of a hydraulic pressure according to a shift pattern are provided. Controls the hydraulic pressure. Further, in order to reduce the size and weight of the control device, there is a case where the control is not performed by an independent control system but is performed by diverting to another control system.

Therefore, as in the above-described conventional automatic transmission, from the viewpoint of fail-safe, the engine brake is activated at a combination of ON / OFF of a solenoid valve for setting a predetermined shift speed and a shift speed lower than that. If control is performed such that the on / off combination of the solenoid valves is different from the on / off state of the two solenoid valves, inconvenience may occur when setting one of the gears. For example, two types of combinations of ON / OFF of a solenoid valve for setting a predetermined shift speed are possible, and according to one of the combinations, ON / OFF of a solenoid valve for applying an engine brake at a low speed shift speed is used.
Two solenoid valves are turned on / off for the combination of off
Although the off state can be made different, in the combination, the engagement pressure of the friction engagement device that sets the predetermined shift speed is controlled to a low pressure, and as a result, the torque capacity of the friction engagement device is reduced. Could be short.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an excessive engine brake is effective due to a failure of a solenoid valve, or a torque capacity of a friction engagement device for setting a shift speed is insufficient. An object of the present invention is to provide a control device for an automatic transmission that can prevent such a situation as before.

[0008]

In order to achieve the above-mentioned object, according to the first aspect of the present invention, a plurality of shift speeds are set according to a combination of ON / OFF of a plurality of solenoid valves. And at least two solenoids for the combination of on / off of a solenoid valve for effecting engine braking at a speed lower than the speed. In an automatic transmission control device that can be a combination in which the ON / OFF state of a valve is different,
A condition satisfaction judging means for judging that a predetermined condition is satisfied, and turning on / off a solenoid valve for setting the gear position when the condition satisfaction is judged by the condition satisfaction judging means. Pattern setting in which the on / off state of at least two solenoid valves is different from the on / off combination of solenoid valves for effecting engine braking at a speed lower than the shift speed Means.

Therefore, according to the control device of the present invention,
When a preset condition such as a vehicle speed or an output shaft rotation speed is equal to or higher than a preset reference value is satisfied, a low-speed gear position is set as a combination of ON / OFF of a solenoid valve for setting the gear position. In this case, a combination in which the on / off states of at least two solenoid valves are different from the on / off combination for applying the engine brake is adopted. Therefore, in setting the gear stage,
Even if one of the solenoid valves fails, it is possible to prevent a shift to a state where the engine brake is effective at a lower shift speed. If the condition is not satisfied, the speed change is performed by a combination in which the ON / OFF state of one solenoid valve is different from the ON / OFF combination of the solenoid valve that sets the lower gear position where the engine brake works. The gear is set, but by adopting a condition that does not hinder the shift to the state where the engine brake is effective at the lower gear, the special discomfort due to the failure of the solenoid valve can be avoided. it can.

[0010]

Next, the present invention will be described more specifically with reference to the drawings. First, a schematic configuration of an example of an automatic transmission targeted by the control device of the present invention will be described. FIG.
1 shows an automatic transmission 10 described in Japanese Patent Application Laid-Open No. H8-159263, in which the mechanical parts are a sub-transmission mechanism D of a front type overdrive configuration and a forward connection 4 of a simple connection 3 planetary gear train configuration. It has a five-speed configuration in which a first-speed main transmission mechanism M is combined with a first reverse speed, and this mechanism is connected to a torque converter T with a lock-up clutch L.

The auxiliary transmission mechanism D includes a one-way clutch (OWC) F-0 and a multi-plate clutch C-0 parallel to the sun gear S0, the carrier C0 and the ring gear R0.
And a multi-disc brake B-0 in series therewith. On the other hand, the main transmission mechanism M includes three gear units P1 in a simple connection in which respective transmission elements including sun gears S1 to S3, carriers C1 to C3, and ring gears R1 to R3 are appropriately connected.
, P3 to P3, and the multiple disc clutches C-1, C-2, the band brake B-1, the multiple disc brakes B-2 to B-4, and the one-way clutch (OWC) in relation to the speed change elements of the respective gear units P1 to P3. ) F-1 and F-2 are provided. In the drawing, reference numeral SN1 denotes a C0 sensor for detecting the rotation of the drum of the clutch C-0, and SN2 denotes a C2 sensor for detecting the rotation of the drum of the clutch C-2. Although not shown, each clutch and brake has a hydraulic servo composed of a piston-cylinder mechanism for engaging and disengaging the friction members.

As shown in FIG. 6, the automatic transmission 10 has a mechanism having the above-described structure, a hydraulic control device 20 for controlling the torque converter and the lock-up clutch, and a hydraulic source incorporated in the mechanism. An oil pump (not shown) is provided. In the on-vehicle state, the automatic transmission 10 is connected to the engine E, and the hydraulic control device 20 of the automatic transmission 10 includes the solenoid valves SL1 to SL4 and the linear solenoid valves S incorporated therein.
The automatic transmission control computer 30 is connected to the automatic transmission control computer 30 via the LN, SLT, and SLU.
Are connected to various sensors 40 and an engine control computer 50 disposed in various parts of the vehicle including the engine E and the automatic transmission 10.

In this automatic transmission 10, the output torque of the engine E shown in FIG. 6 is transmitted to the input shaft N of the auxiliary transmission mechanism D via the torque converter T shown in FIG. Under the control of the hydraulic control device 20, the torque of the input shaft N engages the clutch C-0 to directly connect the sub transmission mechanism D, and engages the clutch C-1 of the main transmission mechanism M. When all of the other frictional engagement elements are released, the input is input to the gear unit P3, the reverse rotation of the ring gear R3 is prevented by the one-way clutch F-2, and the carrier C3 is released.
Is output to the output shaft U as the first speed rotation.

Next, the second speed is achieved when the subtransmission mechanism D is directly connected and the clutch C-1 and the brake B-3 are engaged. At this time, the torque input to the gear unit P2 is: The carrier C1 of the gear unit P1 is output as a reaction force element to the carrier C2 of the gear unit P2 and the ring gear R1 of the gear unit P1 directly connected thereto, and is output to the output shaft U as the second speed rotation.

Similarly, the third speed is achieved by directly engaging the subtransmission mechanism D, engaging the clutch C-1 and the brake B-2, and releasing the other frictional engagement elements. At this time, the torque input to the ring gear R2 of the gear unit P2 is output as the third speed rotation from the output shaft U via the carrier C2 using the sun gear S2 as a reaction force element.

Further, the fourth speed is likewise set by the auxiliary transmission mechanism D
Is directly connected and the clutch C-1 and the clutch C-2 are engaged together. At this time, since the gear unit P2 is directly connected to the ring gear R2 and the sun gear S2, the input torque is output as it is. In the fifth speed, the main speed change mechanism M is in the same state as the above-described fourth speed, and in response to this, the clutch C-0 of the sub speed change mechanism D is released and the brake B-0 is engaged. The sun gear S0 is fixed so that the auxiliary transmission mechanism D
At a high speed.

In the reverse gear, the sub-transmission mechanism D is brought into the above state, and the clutch C-2 and the brake B-
4 is achieved. At this time, the torque input to the sun gear S2 of the gear unit P2 is output as reverse rotation of the carriers C2 and C3 of the gear units P2 and P3 using the ring gear R3 as a reaction force element.

The relationship between the engagement and disengagement of each friction engagement element and the one-way clutch at each of the above-mentioned shift speeds is shown in FIG. In the figure, the meanings of symbols such as Δ and X are as described in the remarks column of FIG.

The brake B in the above automatic transmission 10
The circuit shown in FIG. 2 is provided as a hydraulic circuit for controlling −2 and B-3. Specifically, brake B-
3, a hydraulic servo 28 for controlling engagement / disengagement of the brake B-3, an oil passage 201 connected to the hydraulic servo 28 for supplying / discharging oil pressure to / from the hydraulic servo 28, and an oil passage 201
And a linear solenoid valve SLU for applying a signal pressure to the B-3 control valve 25.

The oil passage 201 is provided with a first oil passage 201d for supplying a hydraulic pressure to the B-3 control valve 25 and a B-3
It has second oil passages 201e and 201f for supplying oil pressure from the control valve 25 to the hydraulic servo. The B-3 control valve 25 includes a valve body 250,
An input port 254 connected to the first oil passage 201d;
An output port 255 connected to the second oil passage 201e;
A discharge port 257 connected to the discharge oil passage EX.

As shown in FIG.
Is a first pressure receiving surface A1 in which the feedback pressure of the second oil passage 201e is applied in a direction that allows the output port 255 and the discharge port 257 to communicate with each other, and a signal pressure (PSLU) to the output port 255 and the discharge port 257. And a signal pressure (PSLU) that is larger in diameter than the second pressure receiving surface A2 and is applied in a direction that allows the output port 255 and the input port 254 to communicate with each other. And a third pressure receiving surface A3. The linear solenoid valve SLU constantly applies a signal pressure (PSLU) to the third pressure receiving surface A3 and selectively applies a signal pressure (PSLU) to the second pressure receiving surface A2.

B-3 Valve body 25 of control valve 25
Reference numeral 0 denotes a spool 251 having a first pressure receiving surface A1, and a plunger 253 having second and third pressure receiving surfaces A2 and A3 coaxially disposed on the spool 251. The spring 258 is disposed between the spool 251 and the plunger 253.

In FIG. 2, a brake B-3 is a frictional engagement element for achieving the second speed of the automatic transmission 10. When releasing the brake B-3 to achieve the third speed, the brake B-3 is activated. B-2 is engaged. The second pressure receiving surface A2
A B-2 release valve 24 is provided as a switching valve for switching between application and cutoff of the signal pressure (PSLU) to and from the B-
The 2 release valve 24 applies a signal pressure (PSLU) to the second pressure receiving surface A2 at least at the time of shifting from the second speed to the third speed, and after the shift is completed, a signal pressure (PSL) to the second pressure receiving surface A2.
SLU) is configured to block.

The brake B-2 to be engaged when the brake B-3 is released is a hydraulic servo 2 for controlling the engagement and release.
9 and the valve body 250 of the B-3 control valve 25
Has a fourth pressure receiving surface A4 for applying an engagement pressure to the hydraulic servo 29 in a direction in which the output port 255 and the discharge port 257 are communicated with each other.

The circuit parts directly involved in the hydraulic pressure and supply / discharge of the hydraulic servos 28 and 29 for engaging and releasing the friction material of the brake B-3 and the brake B-2, including the above-described elements, include -2 shift valve 21, 2-3 shift valve 2
2, 3-4 shift valve 23, B-2 release valve 2
4, B-3 control valve 25, relay valve 26
And a B-2 accumulator 27 are provided,
These are solenoid valves SL1 to SL4 shown in FIG. 5 for switching each shift valve, a linear solenoid valve SLU for lock-up, a B-2 accumulator 27, a linear solenoid valve SLN for an accumulator control valve for controlling its back pressure, and an engine load. Linear solenoid valve SLT that outputs a corresponding control signal
And so on. The supply of the hydraulic pressure for adjusting the B-3 brake hydraulic pressure to the B-3 control valve 25 is performed via the 1-2 shift valve 21. Further, a relay valve 26 controlled by the hydraulic pressure from the brake B-2 is provided between the B-3 control valve 25 and the brake B-3.

Further, the connection relationship between the valves and the oil passages will be described in detail. A D range pressure oil passage 201 connected to a manual valve (not shown) branches via a 1-2 shift valve 21, and one oil passage 201a is The oil passage 201h is connected to the relay valve 26 via the 2-3 shift valve 22, and is connected to the oil passage 201f of the brake B-3 via the relay valve 26. The other branch 2
01b is a 3-4 shift valve 23, an oil passage 201c, B
The control valve 25 is connected to the input port 254 of the B-3 control valve 25 via the -2 release valve 24 and the oil passage 201d, and is connected to the relay valve 26 from the B-3 control valve 25 via the oil passage 201e.

The other D-range pressure oil passage 202 connected to the manual valve branches via the 2-3 shift valve 22, and one oil passage 202a is connected to the oil passage 204 of the brake B-2 via an orifice. I have. This oil passage 204
Is connected to the oil passage 202a via the B-2 release valve 24 and the check valve, and is connected to the accumulator 27 via the orifice. The other branched oil passage 202b is connected to the hydraulic servo 29 of the clutch C-2 via the 3-4 shift valve 23.

The 3-4 shift valve 23 applies the signal pressure (PSL3) of the solenoid valve SL3 to the spool end of the B-2 release valve 24 in addition to the communication and cutoff of the two oil passages 201b and 202b. To do so, it is connected to the B-2 release valve 24 via a solenoid valve signal pressure oil passage 205.

The B-2 release valve 24 is connected to the brake B
-2 is provided to form a bypass circuit that speeds up the drain of the hydraulic pressure of the accumulator 27 at the end of release of the spool 241. The spool 241 loaded with the elastic force of the spring is provided.
The signal pressure (PSL3) of the solenoid valve SL3 via the 3-4 shift valve 23 to the spool 241.
Of the bypass oil passage 202d to and from the brake B-2 oil passage 204 and to the input port 254 of the B-3 control valve 25 of the D range pressure oil passages 201c and 201d. Switching of communication, application of signal pressure (PLSU) to pressure receiving surface A2 of B-3 control valve 25 via oil passage 206, and passage of oil passage 206
Of the drain connection. Therefore, the D range pressure (PD) can be supplied to the input port 254 of the B-3 control valve 25 in parallel from the two oil passages 201a and 201b via the B-2 release valve 24.

The B-3 control valve 25 controls the spool 251 by the feedback pressure applied to the end of the spool 251 via the feedback pressure input port 256.
The opening and closing of the input port 254 on one side and the opening and closing of the drain port 257 on the other side regulates the oil pressure of the oil passage 201e connected to the output port 255, and is coaxial with the spool 251. The plunger 252 is provided with a 2-3 shift valve 2 at the end face.
2 that is connected to the oil path 204 of the brake B-2
The engagement pressure of the brake B-2 of 04a is applied to press the spool 251. As described above, this B-3 control valve 25 has the spool 2
Plunger 2 that presses 51 via spring 258
53 is provided on the opposite side of the plunger 252,
One end face of the plunger 253 is capable of applying and releasing a solenoid signal pressure (PSLU) to the other end face via an oil passage 206 passing through a B-2 release valve 24.

The relay valve 26 is a spool-type switching valve loaded with a spring, and the B-2 brake pressure of the oil passage 204 is applied to the spool end on the spring load side, and the line is applied to the other spool end. The pressure (PL) is applied in opposition to the oil passage 201f and the oil passage 2 of the brake B-3.
01e and the oil passage 201h.

The operation of the circuit constructed as described above will now be described with reference to the circuit diagram of FIG. 2 and the time charts of FIGS. (1) 1 → 2 shift control operation (refer to FIG. 7) If the electronic control unit determines that 1 → 2 shift, the solenoid valve SL3 is switched from off to on and B-2
The release valve 24 is set to the left half position shown in FIG.
As a result, the signal pressure (PSLU) is applied through the B-2 release valve 24 and the oil passage 206, and the B-3 control valve 25 enters the small control gain state. Next, the 1-2 shift valve 21 is switched to the second speed state,
D range pressure (PD) via a manual valve (not shown), oil passage 201, 2-3 shift valve 22, oil passage 201g, B-2 release valve 24 and oil passage 201d.
Is supplied to the hydraulic servo 28 via the relay valve 26 and the oil passage 201f as the B-3 brake pressure via the B-3 control valve 25, while the C-0 clutch pressure is drained. Thereafter, the B-3 control valve 25 directly controls the B-3 brake pressure in the sections a, b, and c shown in FIG. Specifically, during the piston stroke of the hydraulic servo (section a), the hydraulic pressure level for the fast fill is set by the elastic force of the return spring 258.
In section b, the output pressure (PSLU) of the linear solenoid valve SLU is increased at a predetermined rate to cause a change in rotation. In the section c, the linear solenoid valve SLU is feedback-controlled according to the target rotation change. 1 → 2
At the time of determining the end of the shift (2nd synchronization), the solenoid valve SL3 is turned off to control the solenoid signal pressure (PSL).
3) is applied, the B-2 release valve 24 is switched to the right half position shown in the figure, the signal pressure (PSLU) on the pressure receiving surface A2 side of the plunger 253 of the B-3 control valve 25 is released, and the B-3 control is performed. Another path 201 via the 1-2 shift valve 21 with the valve 25 having a large gain
The D range pressure (PD) is continuously supplied to the hydraulic servo via the B-3 control valve 25 through the B-2 release valve 24 switched from the position c, and the B-3 brake pressure is rapidly increased to the line pressure (PL). The speed is raised to end the shift.
As a result, in the steady state of the second speed (2nd), the spool 251 is locked at the lowermost position in FIG.
The spool 241 of the release valve 24 is fixed at a lower position in the figure by supplying the signal pressure (PSL3) of the solenoid valve SL3. (2) 2 → 1 shift control operation (see FIG. 8) Simultaneously with the shift determination, the output of the linear solenoid valve SLU is set to 100% to prepare for drain control of the B-3 brake pressure. Next, the solenoid valve SL3 is switched from off to on to set the B-2 release valve 24 to the position shown in the left half of the figure, and the B-3 control valve 25 to a small gain state. After that, the linear solenoid valve SL
The output of U directly controls the drain of B-3 brake pressure. After the synchronization of the first speed (1st), the 1-2 shift valve 21 is switched to the first speed state, the supply of the B-3 brake pressure is cut off, and the C-0 exhaust valve is switched to switch the C-shift valve.
The supply of the 0 clutch pressure is started. After the completion of the 2 → 1 shift, the solenoid valve SL3 is switched from on to off, the B-2 release valve 24 is returned to the position shown in the right half of the figure, and a large drain state of the B-2 brake pressure is secured. . (3) 2 → 3 shift control operation (see FIG. 9) Based on the shift determination, the 2-3 shift valve 22 is switched to the third speed side, and the D range pressure (PD) is changed via the 2-3 shift valve 22. It is supplied to the hydraulic servo of the brake B-2. The B-3 control valve 25 adjusts the B-3 brake pressure to the required minimum pressure in accordance with the increase of the B-2 brake pressure (section a). The inertia phase performs feedback control by controlling the back pressure of the B-2 accumulator 27 (section b). B-2 accumulator 2
When the pressure accumulation in 7 ends, the relay valve 26 is switched, and the oil path to the brake B-3 is shut off, and the gear shift ends.

In the control device in the above example, 2
→ By setting the B-3 control valve 25 to a large gain even during the third shift, a force against the hydraulic pressure applied to the B-3 control valve 25 from the brake B-2, which is the frictional engagement element on the engagement side. Is ensured by increasing the pressure receiving area of the signal pressure (PSLU).

Therefore, in the above control device, the third pressure receiving surface A3 is made wider than the second pressure receiving surface A2, and the signal pressure (PSL)
U) is applied in a direction that allows the output port 255 and the input port 254 to communicate with each other, so that when the hydraulic pressure is discharged from the hydraulic servo 28, the linear solenoid valve S
The signal pressure (PSLU) from the LU is applied to both the second pressure receiving surface A2 and the third pressure receiving surface A3, whereby the signal pressure (PSLU) acts in a direction to connect the output port 255 and the input port 254. Since the discharge control of the hydraulic pressure is started from the state in which the pressure is reduced, it is possible to prevent a pressure drop due to a sudden communication between the output port 255 and the discharge port 257.
In addition, since the signal pressure (PSLU) is also applied to the second pressure receiving surface A2, it is possible to control the hydraulic pressure discharge from a high hydraulic pressure with a small control gain and high pressure regulation accuracy.

In the automatic transmission 10 described above, the brake B
When the second speed is set by engaging the third pressure, the solenoid valve SL3 is turned on, so that the signal pressure is applied from the B-2 release valve 24 to the second pressure receiving surface A2 of the B-3 control valve 25. (PSLU) is applied. As a result, the control gain becomes a small gain, and the engagement pressure of the brake B-3 decreases. Conversely, if the solenoid valve SL3 is controlled to be turned off, the signal pressure (PSLU) of the B-3 control valve 25 against the second pressure receiving surface A2 is cut off, so that the control gain becomes large and the brake B
-3 increases the engagement pressure.

On the other hand, as shown in the operation table of FIG. 5, when the engine brake is activated at the first speed lower than the second speed, the first solenoid valve SL1 is turned on (○) and the second solenoid valve is turned on. The solenoid valve SL2 is turned off (x), and the third solenoid valve SL3 is turned off (x). Therefore, from the viewpoint of fail-safe, the combination of ON / OFF of the solenoid valves SL1, SL2, SL3 for setting the second speed is determined by the solenoid valves SL1, SL2, S
It is preferable to use a combination that turns on all L3 (○). However, when the third solenoid valve SL3 is turned on, as described above, the control gain of the engagement pressure of the brake B-3 may decrease, and the torque capacity of the brake B-3 may become insufficient. Therefore, the control device according to the present invention performs control as described below.

FIG. 1 is a flow chart for explaining an example of the control. First, processing such as reading of an input signal (step 1) is performed, and the set traveling range (position) is shown in FIG. It is determined whether or not the indicated "2" position is present (step 2). When the automatic transmission is provided with an L range for applying the engine brake at the first speed, whether or not the L range is set in step 2 may be determined together. Good. In short, in step 2, it is determined whether or not a range (position) for applying the engine brake at the first speed is set.

If a negative determination is made in step 2, the control returns without performing any particular control. On the other hand, if an affirmative determination is made, it is determined whether or not the current gear is the second speed. Step 3). If it is not the second speed, the routine returns. On the other hand, if it is the second speed, it is determined whether the vehicle speed V is equal to or higher than a predetermined reference value V1 as a determination of satisfaction of the condition (step 4). That is, step 4 corresponds to the condition satisfaction determination means of the present invention.

If an affirmative determination is made in step 4, that is, if the vehicle speed V is equal to or higher than the reference vehicle speed V1, the first to third solenoids are used as a combination of ON and OFF of the solenoid valve for setting the second speed. Valve SL1, SL
2. A combination in which all of SL3 are turned on (o) is selected (step 5). This combination is different from the combination of ON / OFF of the solenoid valve (the first solenoid valve SL1 is ON and the second and third solenoid valves SL2 and SL3 are OFF) in order to apply the engine brake at the first speed. This is a combination in which the ON / OFF states of the two solenoid valves are different.

Therefore, even if a failure occurs, for example, in which the third solenoid valve SL3 is turned off in this state, this is a normal on / off pattern for setting the second speed as shown in FIG. No shifting takes place. When a failure occurs in which the second solenoid valve SL2 is turned off, the on / off pattern is as shown in FIG.
As shown in the figure, the first speed is such that the engine brake does not work. Even if a downshift occurs, if the accelerator pedal (not shown) is not depressed, the running state of the vehicle only becomes the coast state. Even if the accelerator pedal is depressed, the engine speed increases only.

As described above, when the third solenoid valve SL3 is turned on at the second speed, the third brake B
-3, the control gain of the engagement hydraulic pressure decreases, and the engagement pressure of the brake B-3, that is, the torque capacity, decreases. However, when the vehicle speed V is somewhat high, the torque applied to the brake B-3 decreases. , The second speed can be maintained.

On the other hand, if the vehicle speed V is lower than the reference vehicle speed V1 and a negative determination is made in step 4, the first and second combinations of the ON / OFF of the solenoid valve for setting the second speed are set. Solenoid valves SL1, SL2
Is turned on (o) and the third solenoid valve SL3 is turned off (x) (step 6). This on / off pattern is different from the first speed on / off pattern in which the engine brake works only in the on / off state of the second solenoid valve SL2. Therefore, if the second solenoid valve SL2 is turned off due to a failure, a shift to the first speed at which engine braking is effective occurs.

However, when this on / off pattern is selected, the vehicle speed V is in a low vehicle speed state.
Even if a downshift occurs, the shock is small and there is no particular problem. Further, since the third solenoid valve SL3 is off, the control gain (pressure regulation level) of the engagement pressure of the third brake B-3 increases, and a sufficiently high engagement pressure, that is, a torque capacity can be secured.

Therefore, steps 5 and 6 correspond to the pattern setting means of the present invention.

The first to third solenoid valves SL are used as on / off patterns for setting the second speed.
The pattern for turning on all of 1, 1, SL2 and SL3 is selected when a condition for avoiding a downshift to the first speed at which the engine brake works due to a failure is established. Therefore, the conditions are that the vehicle speed V is equal to or higher than the reference vehicle speed V1 as described above, and that the output shaft rotation speed NO of the automatic transmission 10 is set to the predetermined reference rotation speed N
O1 or more (step 4-1) may be adopted. Alternatively, both the vehicle speed V and the output shaft rotational speed NO may be set as conditions, and other conditions may be added or replaced.

When the vehicle speed V and the output shaft speed NO are set as conditions, step 5 is performed to avoid hunting.
It is preferable to set a hysteresis between the condition for executing the control of (1) and the condition for executing step 6.

In the above specific example, the on / off pattern of the solenoid valve for setting the second speed has been described as an example. However, the present invention is not limited to the above example. The present invention is also applicable to a case where an on / off pattern of a solenoid valve for setting a shift speed is selected. Further, the automatic transmission targeted by the present invention is not limited to the one provided with the gear train and the hydraulic circuit described above, and can be appropriately applied to a control device intended for various automatic transmissions.

[0048]

As described above, according to the present invention,
When a preset condition such as a vehicle speed or an output shaft rotation speed is equal to or higher than a preset reference value is satisfied, an engine brake is effective as a combination of ON / OFF of a solenoid valve for setting a predetermined shift speed. Since a combination in which the on / off state of at least two solenoid valves is different from the combination of on / off for the low-speed gear position is adopted, in setting the gear position, any one of the solenoid valves Even if a failure occurs, it is possible to prevent a shift to a lower gear position where engine braking is effective.
If the condition is not satisfied, the speed change is performed by a combination in which the ON / OFF state of one solenoid valve is different from the ON / OFF combination of the solenoid valve that sets the lower gear position where the engine brake works. The gear is set, but it is possible to avoid a special feeling of discomfort due to the failure of the solenoid valve by adopting a condition that does not hinder the occurrence of a shift to a lower gear where the engine brake is effective. it can.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an example of control by a control device according to the present invention.

FIG. 2 is a circuit diagram showing a part of a hydraulic circuit in the automatic transmission according to the present invention.

FIG. 3 is a schematic diagram showing the B-3 control valve.

FIG. 4 is a skeleton diagram of a gear transmission in the automatic transmission.

FIG. 5 is a table showing operating states of friction engagement elements for setting each shift speed in the automatic transmission.

FIG. 6 is a block diagram showing the overall control system.

FIG. 7 is a time chart at the time of 1 → 2 shift by the automatic transmission.

FIG. 8 is a time chart at the time of 2 → 1 shift by the automatic transmission.

FIG. 9 is a time chart at the time of 2 → 3 shift by the automatic transmission.

[Explanation of symbols]

 10 Automatic transmission SL1, SL2, SL3 Solenoid valve

Claims (1)

[Claims] A plurality of shift speeds are set in accordance with a combination of ON / OFF of a plurality of solenoid valves, and a combination of ON / OFF of a solenoid valve for setting any one of the shift speeds is set to a speed lower than the shift speed. A control device for an automatic transmission, wherein at least two solenoid valves have different on / off states with respect to a combination of on / off states of a solenoid valve for effecting an engine brake at a shift speed, Condition satisfaction determining means for determining that the determined condition is satisfied; andon / off of a solenoid valve for setting the shift speed when the satisfaction of the condition is determined by the condition satisfaction determining means. The number of combinations is smaller than the combination of ON / OFF of the solenoid valve for applying the engine brake at a speed lower than the speed. Control apparatus for an automatic transmission, characterized in that also a pattern setting unit that a combination having a different state of the on-off of the two solenoid valves.