JPH06341520A - Speed change control device for vehicular automatic transmission - Google Patents

Abstract

PURPOSE:To provide a speed change control device for a vehicular automatic transmission, which does not cause the degradation of shift quality even when a shift lever is switched over to an engine brake range at comparatively high vehicle speeds. CONSTITUTION:When an actual vehicle speed V is in excess of a judging reference vehicle speed A for 2 range or a judging reference vehicle speed B for 3 range which is set in advance, an engine brake relay valve 92 is switched over to the 'ON' side wherein the brake relay valve is provided in a place between a manual valve 88 and a control oil chamber 118 of a (2-3) shift valve 110 or between a (3-4) shift valve 120 and each control oil chamber 128 and 138 of a (4-5) shift valve 130. And it is blocked that (2) range pressure P2 or (3) range pressure P3 is applied to the control oil chamber. Therefore, when the shift lever is to be actuated from a D range to the (3) range or the (2) range, no shift clown operation to the highest acceleration step of gear shifting takes place in a range of speed change corresponding to an engine brake range before the actual vehicle speed V becomes lower than the judging reference value B or A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for an automatic transmission for a vehicle.

[0002]

2. Description of the Related Art In an automatic transmission for a vehicle having a plurality of forward gears, an engine load amount such as an accelerator pedal operation amount and a throttle valve opening amount and a vehicle speed can be calculated from a preset shift map. There is a shift control device of the type that determines the gear stage to shift based on. According to such a shift control device, there is an advantage that the automatic transmission can be automatically switched to the gear stage suitable for the running state of the vehicle. For example,
That is the shift control device for an automatic transmission for a vehicle, which is described in Japanese Patent Application No. 3-344124.

[0003]

By the way, in the above-mentioned conventional shift control device for an automatic transmission for a vehicle, the shift operation means is operated to the D range during normal traveling, and, for example, from the first speed gear to the fifth speed gear. It is designed to be selected based on the vehicle running parameters from the entire range of forward gears up to the gear, but the driver is intended to generate the engine braking action or the driving force of the vehicle. When the shift operating means is operated from the D range to the engine brake range such as the 3 range, the 2 range, the L range, etc., the engine brake range pressure generated from the manual valve connected to the shift operating means is It is supplied to the control oil chamber of the shift valve for controlling the gear change, and the shift valve is locked in its deceleration side position, which causes engine shift. So that the shift range is limited according to Kirenji. For example, the shift operation means is 3
When operated to the range, establishment of the fifth speed is blocked, automatic shifting is performed in the range from the first speed to the fourth speed, and when operated to the second range, the fourth speed is set to the fourth speed. The establishment of the high speed gear is blocked, and automatic shifting is performed in the range from the first speed to the third speed.

However, in the above conventional shift control device, since the engine brake range pressure is directly supplied to the control oil chamber of the shift valve, when the shift operating means is switched to the engine brake range at a relatively high vehicle speed, There was a possibility that a comparatively large shock would occur due to downshifting regardless of the running condition of.

The present invention has been made in view of the above circumstances, and an object thereof is to generate a shift-down shock even if the shift operation means is switched to the engine brake range at a relatively high vehicle speed. An object of the present invention is to provide a shift control device for an automatic transmission for a vehicle that does not allow the shift.

[0006]

The object of the present invention to achieve the above object is to provide a shift operating means in an automatic transmission for a vehicle having a plurality of forward gear stages,
A manual valve that can be switched by the shift operating means, and when the shift operating means is operated to the engine brake range, the engine brake range pressure generated from the manual valve is used to control the switching of the gear stage. A shift control device of the type for supplying to the control oil chamber of the shift valve to limit the shift range, wherein: (a) is provided between the manual valve and the control oil chamber of the shift valve, A switching valve that controls the output engine brake range pressure to be supplied to the control oil chamber; and (b) when the actual vehicle speed exceeds a preset reference vehicle speed, the switching valve is actuated to Switching valve control means for preventing the engine brake range pressure from being supplied to the control oil chamber of the shift valve.

[0007]

With this configuration, when the actual vehicle speed exceeds the preset judgment reference vehicle speed, the switching valve control means operates the switching valve provided between the manual valve and the control oil chamber of the shift valve. This prevents the engine brake range pressure from being supplied to the control oil chamber of the shift valve.

[0008]

Therefore, according to the present invention, when the shift operating means is operated to the engine brake range, the shift range corresponding to the engine brake range is maintained until the actual vehicle speed becomes lower than the judgment reference vehicle speed. Since the downshift to the highest speed stage is not performed, the occurrence of a large downshift shock accompanying the operation of the shift operating means to the engine brake range is prevented.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a skeleton view of an automatic transmission for a vehicle, the shift of which is controlled by a hydraulic control device according to an embodiment of the present invention. In the figure, the output of the engine 10 is input to the automatic transmission 14 via the torque converter 12 and transmitted to the drive wheels via a differential gear unit and an axle (not shown).

The torque converter 12 is the engine 1
0 pump impeller 18 connected to crankshaft 16
A turbine runner 22 connected to the input shaft 20 of the automatic transmission 14, a lock-up clutch 24 that directly connects the pump impeller 18 and the turbine runner 22, and a one-way clutch 26 prevent rotation in one direction. And a stator 28 that is installed.

The automatic transmission 14 includes a first transmission 30 for switching between high and low gears, and a second transmission 32 for switching between reverse gear and four forward gears. The first transmission 30 includes an HL planetary gear device 34 including a sun gear So, a ring gear Ro, and a planetary gear Po rotatably supported by the carrier Ko and meshed with the sun gear So and the ring gear Ro, a sun gear So and a carrier. It includes a clutch Co and a one-way clutch Fo provided between Ko and a brake Bo provided between the sun gear So and the housing 41.

The second transmission 32 is a first planetary gear unit 36 comprising a sun gear S1, a ring gear R1, and a planetary gear P1 rotatably supported by the carrier K1 and meshed with the sun gear S1 and the ring gear R1.
, Sun gear S2, ring gear R2, and carrier K
2 and a second planetary gear unit 38, which is rotatably supported by the sun gear S2 and a ring gear R2 and is meshed with the sun gear S2 and the ring gear R2, and the sun gear S3, the ring gear R3, and the carrier K3 are rotatably supported by the sun gear S2. S3 and a third planetary gear set 40 including a planet gear P3 meshed with the ring gear R3.

The sun gear S1 and the sun gear S2 are integrally connected to each other, the ring gear R1, the carrier K2 and the carrier K3 are integrally connected, and the carrier K3 is connected to the output shaft 42. The ring gear R2 is integrally connected to the sun gear S3. A clutch C1 is provided between the ring gear R2 and the sun gear S3 and the intermediate shaft 44, and the sun gear S1 and the sun gear S are provided.
A clutch C2 is provided between the shaft 2 and the intermediate shaft 44. In addition, a band-type brake B1 for stopping the rotation of the sun gear S1 and the sun gear S2 is provided on the housing 41.
It is provided in. A one-way clutch F1 is provided between the sun gear S1 and the sun gear S2 and the housing 41.
And the brake B2 are provided in series. The one-way clutch F1 is configured to be engaged when the sun gear S1 and the sun gear S2 try to rotate in the opposite direction to the input shaft 20.

A brake B3 is provided between the carrier K1 and the housing 41, and a brake B4 and a one-way clutch F2 are provided in parallel between the ring gear R3 and the housing 41. This one-way clutch F
2 is configured to be engaged when the ring gear R3 tries to rotate in the reverse direction. The clutch Co, C
1, C2, brake Bo, B1, B2, B3, B4,
It is a hydraulic friction engagement device in which a friction material is engaged when hydraulic pressure is applied.

In the automatic transmission 14 configured as described above, for example, according to the operation table shown in FIG. 2, the reverse first gear and the forward five gears are switched. In FIG. 2, the ∘ mark indicates the operating state, and the X mark indicates the non-operating state.

As shown in FIG. 3, the intake pipe of the engine 10 of the vehicle has a first throttle valve 52 and a throttle actuator 54 operated by an accelerator pedal 50.
And a second throttle valve 56 operated by. Further, an engine rotation speed sensor 58 that detects the rotation speed of the engine 10, an intake air amount sensor 60 that detects the intake air amount of the engine 10, an intake air temperature sensor 62 that detects the temperature of the intake air, the first throttle valve 5 described above.
The throttle sensor 64 for detecting the opening degree θth of 2 and the vehicle speed sensor 6 for detecting the vehicle speed V from the rotational speed of the output shaft 42 and the like.
6, a cooling water temperature sensor 68 for detecting the cooling water temperature of the engine 10, a brake switch 7 for detecting the operation of the brake
0, an operation position sensor 74 for detecting the operation position of the shift lever 72, etc. are provided.
Engine speed N _E , intake air amount Q, intake air temperature T
Signals representing Ha, the opening degree θth of the first throttle valve θ, the vehicle speed V, the engine cooling water temperature THw, the brake operating state BK, and the operation position Psh of the shift lever 72 are sent to the engine electronic control unit 76 and the shift electronic control unit 78. It is being supplied. Further, a signal indicating the turbine rotation speed N _T is supplied from the turbine rotation speed sensor 75 that detects the rotation speed of the turbine runner 22 to the electronic shift control device 78. Further, a signal indicating the manual shift operation is transmitted from the manual shift switch 77 that detects the manual shift operation of the shift lever 72, that is, the operation of the shift lever 72 in the left-right direction when operating the engine brake range. Is supplied to.

The engine electronic control unit 76 includes a CPU,
A so-called microcomputer having a RAM, a ROM, and an input / output interface, the CPU processes an input signal according to a program stored in the ROM in advance while utilizing a temporary storage function of the RAM, and executes various engine controls. For example, the fuel injection valve 80 is controlled to control the fuel injection amount, the igniter 82 is controlled to control the ignition timing, the bypass valve (not shown) is controlled to control the idle speed, and the throttle actuator is controlled to control the traction. The second throttle valve 56 is controlled by 54.

The electronic shift control device 78 is also a microcomputer similar to that described above, and the CPU uses the temporary storage function of the RAM while processing the input signal in accordance with the program stored in the ROM in advance, and the hydraulic control circuit 84. Each solenoid valve or linear solenoid valve is driven. For example,
The electronic shift control device 78 uses a linear solenoid valve SLT to generate an output pressure P _SLT having a magnitude corresponding to the opening degree θth of the first throttle valve 52, and a linear solenoid valve SLN to control the accumulator back pressure. To drive the linear solenoid valve SLU in order to control the slip amount of the lockup clutch 24. Further, the electronic shift control device 78 determines the gear position of the automatic transmission 14 and the engagement state of the lock-up clutch 24 based on the actual throttle valve opening θth and the vehicle speed V from the previously stored shift diagram. The solenoid valves S1, S2, S3 are driven so that the determined gear and engagement state are obtained, and the solenoid valve S4 is driven when engine braking is generated. The lock-up clutch 24 is released in the first gear stage and the second gear stage of the automatic transmission 14, but in the third gear stage and the fourth gear stage, the throttle valve opening θth and the vehicle speed V are.
Based on the above, the release, slip, or engagement region is determined, and if it is the slip region, the lockup clutch 2
4 is slipped, and if it is an engagement area, it is engaged. This slip control is for suppressing the rotational loss of the torque converter 12 as much as possible while absorbing the rotational fluctuation of the engine 10.

FIG. 4 shows the operating position of the shift lever 72. In the figure, the shift lever 72 is supported by a supporting device (not shown) that operably supports the shift lever 72 at eight operation positions by combining six operation positions in the front-rear direction of the vehicle and two operation positions in the left-right direction of the vehicle.
Is supported.

The hydraulic control circuit 84 includes, for example, the hydraulic circuit described in the drawing of Japanese Patent Application No. 3-344124, and FIGS. 5 and 6 show the main part thereof. In the figure, the manual valve 88 that is interlocked with the operation of the shift lever 72 in the front-rear direction has a first line pressure P _L1 that is regulated by a first pressure regulating valve (not shown) to a magnitude corresponding to the throttle valve opening θth. , The common D range pressure P _D is output in the D range and the range less than 4 ranges, and the 3 range pressure P ₃ is output in the range less than 3 ranges.
The two range pressures P ₂ common to the ranges and 2 ranges are output, while the R range pressure P _R is output in the R range. In this embodiment, the three range pressure P ₃ and the second range pressure P ₂ correspond to the engine brake range pressure.

The pressure control valve 90 has a first line pressure P _L1 when the engine brake relay valve 92 is operated.
The supplied to the engine brake relay valve 92 by regulating the smaller control pressure P _CT in response to the output pressure P _SLN of the linear solenoid valve SLN. Engine brake relay valve 9
No. 2 is provided with a spool valve 96 which is biased to the off side by the spring 94 during non-engine braking, but is biased to the on side according to the output pressure P _S4 of the engine braking electromagnetic valve S4 during engine braking. . As a result, the engine brake solenoid valve S4 is not operated (OF
When the output pressure P _S4 is generated in the F) state, the control pressure P _CT is supplied to the 1-2 shift valve 100. This control pressure _PCT is applied to the brake B1.
Alternatively, the engagement pressure of B4 is adjusted.

The engine brake relay valve 92 is also used.
2 range pressure input port 108 to which 2 range pressure P ₂ is supplied, and 2 range pressure input port 10 where 2 range pressure P ₂ is output when the spool valve 96 is in the ON position.
8b, 3 range pressure input port 108c to which 3 range pressure P ₃ is supplied, and 3 range pressure output port 10 to which 3 range pressure P ₃ is output when the spool valve 96 is in the ON position.
8d is provided, and the two-range pressure P ₂ is supplied to the control oil chamber 118 of the 2-3 shift valve 110 on condition that the spool valve 96 is switched to the ON position by the output pressure P _S4 of the solenoid valve _S4. Is allowed, and the above-mentioned three-range pressure P ₃ is controlled by the control oil chamber 1 of the 3-4 shift valve 120.
Supply to the control oil chamber 138 of the 28 and 4-5 shift valves 130 is allowed. In this embodiment, the engine brake relay valve 92 corresponds to the switching valve provided between the manual valve 88 and the shift valves 110, 120, 130.

The 1-2 shift valve 100 includes a spring 10
2 or 2-3 assist pressure P from shift valve 110
_The spool valve 104 is biased to the second speed side by the _asist, but is biased to the first speed side according to the output pressure P _S2 from the non-excited electromagnetic valve S2. The assist pressure P _asist is generated from the 2-3 shift valve 110 and is supplied to the spring chamber 106 when the gear is at the third speed or higher. As a result, the first gear, N
In the range range and the R range state, the spool valve element 104 is switched to the position shown on the right side of the center line, but in the second and higher gears, the spool valve element 104 is located at the position shown on the left side of the center line. .

The 2-3 shift valve 110 includes a spring 11
It is urged to the second speed side position according to the urging force of No. 4 but is set to the third position according to the output pressure P _S1 from the non-excited electromagnetic valve S1.
The engine brake relay valve 9 which accommodates the spool valve element 116 biased to the high speed side and the spring 114 and
And a control oil chamber 118 that receives the two-range pressure P ₂ supplied via the control oil chamber ₂ . As a result, the spool valve element 116 is at the position shown on the right side of the center line in the third and higher speed gear stages, but the spool valve element 116 is in the center line in the second and lower speed gear stages. The position is shown on the left side. When the two-range pressure P ₂ is supplied to the control oil chamber 118, the spool valve element 116 is preferentially positioned on the second speed side.

The 3-4 shift valve 120 includes a spring 12
According to the biasing force of 2, the D range pressure P _D from the 2-3 shift valve 110, or the thrust transmitted through the plunger 124 based on the 3 range pressure P ₃ , it is biased to the third speed position. , The spool valve element 126 that is biased to the fourth speed position according to the output pressure P _S2 of the solenoid valve S2 in the non-excited state
And a control oil chamber 128 that receives the above-mentioned three-range pressure P ₃ supplied via the engine brake relay valve 92. As a result, the spool valve element 126 is located at the position shown on the right side of the center line in the gear steps of the fourth speed and higher, but conversely, in the gear steps of the third speed and lower, the spool valve 126 is It is located at the position shown to the left of its centerline. Further, when the three-range pressure P ₃ is supplied to the control oil chamber 128, the spool valve 126
Is preferentially positioned on the third speed side.

The 4-5 shift valve 130 includes a spring 13
It is urged to the fourth speed side position according to the urging force of 2 or the 3rd range pressure P _3, but is in the non-excited state that is supplied through the 3-4 shift valve 120 when the gear is higher than the fourth speed. a spool valve element 134 is biased in accordance with the output pressure P _S3 from the solenoid valve S3 is the fifth speed-side position, the 3-range pressure P supplied via and engine brake relay valve 92 accommodates the spring 132 ₃ and a control oil chamber 138 for receiving ₃ . As a result, the spool valve element 134 is normally located at the position shown on the left side of the center line when the gear position is equal to or lower than the fourth speed gear position.
In the state of the high speed gear, the spool valve element 134 is located at the position shown on the right side of its center line. Further, the three-range pressure P ₃ is applied to the control oil chamber 1 via the engine brake relay valve 92.
When supplied to No. 38, the spool valve element 134 is preferentially positioned at the fourth speed position.

The Co exhaust valve 140 is urged to the position shown on the left side of the center line according to the urging force of the spring 142 or the output pressure P _S4 of the solenoid valve S4 which is not excited during engine braking. The engagement pressure P _B3 of the brake B3 for establishing the high speed gear stage, or the third pressure output through the 1-2 shift valve 100 when the 1-2 shift valve 100 is switched to the first speed side position. a spool valve element 144 which is biased into the position shown on the right side of the center line in accordance with the output pressure P _S3 of the solenoid valve S3, the spool valve element 144 in accordance with whichever is higher oil pressure of the engagement pressure P _B3 or the output pressure P _S3 The plunger 146 for applying thrust to the valve and the spring 142 are housed and the output pressure P _{S4 of the} solenoid valve S4 is received.
And an oil chamber 148 for receiving the oil. This allows
The clutch C is in the first gear and the second gear.
Although o is drained, the D range pressure P _D from the 4-5 shift valve 130 is supplied to the clutch Co in the third speed gear and the fourth speed gear. Further, when the output pressure P _S4 output from the electromagnetic valve S4 is supplied to the oil chamber 148 during engine braking, the Co exhaust valve 140
Is preferentially switched to the state shown on the left side of its center line, and the clutch Co is engaged.

The accumulator control valve 150 uses the first line pressure P _L1 as a source pressure, and the accumulator control valve 150 increases in accordance with the output pressure P _SLT of the linear solenoid valve SLT and decreases in accordance with the output pressure P _SLN of the linear solenoid valve SLN. The back pressure P _ACC is regulated and supplied to the back pressure chamber 154 of the B3 accumulator 152 and also supplied to the back pressure chamber 160 of the Co accumulator 158 through the cutoff valve 156. The cut-off valve 156 is always open between the accumulator control valve 150 and the back pressure chamber 160 in order to cut off the supply of the accum back pressure P _ACC to the back pressure chamber 160 of the Co accumulator 158 as needed. However, the above linear solenoid valve
When the output pressure P _{SLT of SLT} exceeds a predetermined value, it is closed to prevent the accumulator back pressure P _{ACC from} being supplied to the back pressure chamber 160. The solenoid modulator valve 162 regulates a constant solenoid pressure and supplies it to each linear solenoid valve SLN and linear solenoid valve SLT as a source pressure.

Below, the main parts of the operation of the electronic control unit 78 for shifting relating to the operation of the shift lever 72 to the engine brake in the 3 range, 2 range, etc. will be described with reference to the flow charts shown in FIGS. 7 and 8. explain.

FIG. 7 shows a predetermined range for setting the judgment reference vehicle speed A for the second range and the judgment reference vehicle speed B for the third range when the operation of the shift lever 72 to the engine braking range, that is, the manual shift is detected. 3 shows a routine executed in a cycle. Step SS1 in the figure
After the input signal processing is executed in step SS2
At, it is determined whether the shift lever 72 has been operated to the D range or the 4 range. If the determination in step SS2 is affirmative, this routine is ended. However, if denied, the following step SS3
At, it is determined whether or not shift lever 72 has been operated in three ranges. If the determination in step SS3 is affirmative, the determination reference vehicle speed B for the three ranges is set in step SS4 based on a predetermined calculation formula, and then this routine is ended. For example, based on the gear ratio γ of the gear stage that should be established by downshifting by operating the three ranges in the running state at that time and the maximum allowable rotational speed N _{emax of the} engine 10, when the gear stage is actually established, The limit vehicle speed at which the engine rotation speed N _e becomes the maximum allowable rotation speed N _emax is calculated, and a value equivalent to the limit vehicle speed or a value obtained by subtracting a predetermined margin value from the limit vehicle speed is used as the determination reference vehicle speed B for the three ranges. It is set. The determination reference vehicle speed B for the three ranges is, for example, 1
The value is about 80 km / h.

If the determination in step SS3 is negative, the shift lever 72 is operated in the following step SS5.
Is determined to have been operated in two ranges. If the determination in step SS5 is negative, this routine is ended, but if the determination is positive, step SS6
In step 2, the reference vehicle speed A for the two ranges is set based on a predetermined calculation formula, and then this routine is ended. Also in this case, similarly to the above, based on the gear ratio γ of the gear stage and the maximum allowable rotation speed N _{emax of the} engine 10 that should be established by the downshift by the operation to the two ranges in the traveling state at that time, the gear is determined. When the gear is established, the actual engine rotation speed N _e is the maximum allowable rotation speed N _e.
The limit vehicle speed that becomes _emax is calculated, and a value equal to the limit vehicle speed or a value obtained by subtracting a predetermined margin value from the limit vehicle speed is 2
It is set as the judgment reference vehicle speed A for the range. The determination reference vehicle speed A for the two ranges is, for example, a value of about 100 km / h.

FIG. 8 shows that when the shift lever 72 is operated to the 3 range or the 2 range, the actual vehicle speed V is the 2 range judgment reference vehicle speed A or the 3 range judgment reference vehicle speed B set by the above routine. In the following cases, the routine executed in a predetermined cycle is shown in order to turn off the engine brake solenoid valve S4 to execute the downshift and to generate the engine brake action. In the figure, after the input signal processing is performed in step SR1, the shift lever 72 is operated in step SR2.
Is determined to have been operated in three ranges.

If the determination at step SR2 is affirmative, at step SR3 the actual vehicle speed V is as shown in FIG.
It is determined whether the vehicle speed is equal to or lower than the three-range determination reference vehicle speed B set in the routine. This step SR3
If the determination is positive, the engine brake solenoid valve S4 is turned off in step SR4.
As a result, the engine brake relay valve 92 is switched to the ON position, and the three-range pressure P ₃ passes through the engine brake relay valve 92 and the control oil chamber 128 of the 3-4 shift valve 120 and the control oil chamber of the 4-5 shift valve 130. Since it is supplied to 138, shift down to the third speed gear on the highest speed side in the above three ranges is executed. However, if the determination in step SR3 is negative, step SR
In 5, the engine brake electromagnetic valve S4 is prohibited from being turned off, so that the downshift is prevented.

If the determination in step SR2 is negative, the shift lever 72 is moved to 2 in step SR6.
It is determined whether or not the range has been operated. If the determination in step SR6 is negative, the routine is terminated, but if the determination is affirmative, the actual vehicle speed V in step SR7 is the determination reference vehicle speed A for the two ranges set in the routine of FIG. It is determined whether or not the following. If the determination in step SR7 is affirmative,
In step SR4, the engine brake solenoid valve S4
Is turned off. As a result, the engine brake relay valve 92 is switched to the ON position, and the three-range pressure P ₃ passes through the engine brake relay valve 92 and the control oil chamber 128 of the 3-4 shift valve 120 and the 4-5 shift valve 1
The second range pressure P ₂ is supplied to the control oil chamber 138 of the 2-3 shift valve 110 as well as being supplied to the control oil chamber 138 of 30 of the second range gear. Shift down is executed. However, if the determination in step SR7 is negative, the engine down solenoid valve S4 is prohibited from being turned off in step SR5, so that the downshift is prevented.

As described above, according to this embodiment, when the actual vehicle speed V exceeds the preset two-range judgment reference vehicle speed A or three-range judgment reference vehicle speed B, it functions as a switching valve control means. The electronic control unit 78 for gear shifting controls the control oil chamber 118 of the manual valve 88 and the 2-3 shift valve 110.
Alternatively, the engine brake relay valve 92 provided between the 3-4 shift valve 120 and the 4-5 shift valve 130 and the control oil chambers 128 and 138 is switched to the off side, and the 2 range pressure P ₂ or the 3 range pressure is obtained. Since P ₃ is prevented from being supplied to the control oil chamber, the actual vehicle speed V is lower than the judgment reference value B or A when the shift lever 72 is operated from the D range to the 3 range or the 2 range. Until that time, the gear is not downshifted to the highest speed within the gear shift range corresponding to the engine brake range, so a large shift-down shock due to the operation of the shift lever 72 to the engine brake range is prevented. It is.

Although one embodiment of the present invention has been described above with reference to the drawings, the present invention can be applied to other aspects.

For example, in the above-described embodiment, the automatic transmission 14 is provided with the fifth forward gear, but the fourth forward gear is used.
It may be of a type having a high speed gear.

Further, in the above-mentioned embodiment, FIG. 5 and FIG.
Although the description has been made using the hydraulic circuit shown in FIG. 5, the configuration of each valve that constitutes the hydraulic circuit may be different as necessary.

Although not illustrated one by one, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a skeleton diagram illustrating a configuration of an automatic transmission for a vehicle in which a gear stage is controlled by a shift control device according to an embodiment of the present invention.

FIG. 2 is a table showing a relationship between a combination of operations of a plurality of friction engagement devices and gear stages established by the combination in the automatic transmission of FIG.

FIG. 3 is a block diagram illustrating a hydraulic control circuit and an electric control circuit for controlling the automatic transmission of FIG.

FIG. 4 is a diagram illustrating an operating position of a shift lever of FIG.

5 is a diagram illustrating a main part of the hydraulic control circuit of FIG. 3, showing a circuit located on the left side of FIG.

6 is a diagram illustrating a main part of the hydraulic control circuit of FIG. 3, showing a circuit located on the right side of FIG. 5.

FIG. 7 is a flowchart for explaining an essential part of the operation of the electronic shifting control device of FIG. 3, showing an operation of setting a judgment reference vehicle speed.

FIG. 8 is a flowchart illustrating an essential part of the operation of the electronic shift control device of FIG. 3, and is a diagram showing an operation of preventing downshifting when the actual vehicle speed is higher than the determination reference vehicle speed.

[Explanation of symbols]

 14: Automatic transmission 72: Shift lever (shift operating means) 76: Electronic control device for shifting (switching valve control means) 88: Manual valve 92: Engine brake relay valve (switching valve)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Hojo, 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Corporation (72) Inventor, Hiromichi Kimura, 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation ( 72) Inventor Masato Kaikawa 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Tetsuro Hamashima 1 Toyota Town, Toyota City, Aichi Toyota Motor Corporation (72) Inventor Masahiko Ando 10 Takane, Fujii-cho, Anjo-shi, Aichi Aisin AW Co., Ltd. (72) Inventor Akira Fukatsu 10 Takane, Fujii-cho, Anjo-shi, Aichi Aisin AW Co., Ltd. (72) Inventor Yoshihisa Yamamoto 10 Takane, Fujii-cho, Anjo City, Aichi Prefecture

Claims (1)

[Claims] 1. An automatic transmission for a vehicle having a plurality of forward gears, comprising a shift operating means and a manual valve switched by the shift operating means, wherein the shift operating means is operated to the engine brake range. In this case, there is provided a shift control device of a type in which an engine brake range pressure generated from the manual valve is supplied to a control oil chamber of a shift valve for controlling switching of gear stages to limit a shift range, A switching valve provided between the manual valve and the control oil chamber of the shift valve for controlling the engine brake range pressure output from the manual valve to be supplied to the control oil chamber, and an actual vehicle speed are set in advance. When the set judgment standard vehicle speed is exceeded,
A shift valve control means for activating the shift valve to prevent the engine brake range pressure from being supplied to the control oil chamber of the shift valve; and a shift control for an automatic transmission for a vehicle, comprising: apparatus.