JPH059658B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an automatic transmission for a vehicle that includes a main transmission and an auxiliary transmission capable of switching between a high speed gear and a low speed gear. [Prior Art] Conventionally, an automatic transmission for a vehicle has a gear transmission mechanism having a plurality of gears connected to a fluid transmission device such as a torque converter. The gear transmission mechanism is designed to automatically change gears. When such a vehicle automatic transmission is installed in a four-wheel drive vehicle, four-wheel drive vehicles often travel on steep slopes, and a large driving force is required on steep slopes. Even if the gear transmission mechanism is automatically shifted to the lowest gear, the driving force may still be insufficient. Therefore, in addition to the gear transmission mechanism, an auxiliary transmission capable of switching between high gear and low gear is provided. An automatic transmission for a vehicle has been proposed in which a driver can operate an auxiliary transmission to shift to a lower gear to obtain the necessary driving force. [Problems to be Solved by the Invention] However, in the conventional automatic transmission for a vehicle, the driver does not operate the auxiliary transmission to a low gear while driving on a steep slope. In some cases, this results in a lack of driving power and a large slippage between the pump and the turbine of the fluid transmission system. In particular, when a torque converter is used as a fluid transmission device, even though a large amount of slip occurs, the torque amplification effect due to the slip occurs, so the vehicle can still run, but there are cases where the driver does not operate the auxiliary transmission to a low gear. be. Driving with a large amount of slippage in the fluid transmission system is not only extremely inefficient, but the heat generated by the slippage of the fluid transmission system causes the oil temperature in the transmission to rise, which has an adverse effect on parts. , which may reduce the durability of the transmission. Therefore, the present invention has been developed to generate an appropriate driving force depending on the vehicle running condition, prevent the rise of hydraulic oil, prevent adverse effects on transmission parts due to rise in oil temperature, and provide a vehicle with excellent durability. The purpose is to provide automatic transmissions for [Means for Solving the Problems] The automatic transmission for a vehicle of the present invention comprises a pump 11 connected to the output shaft of an engine, and a turbine 13 drivingly connected to the pump 11 via hydraulic oil. A main transmission 10 having a transmission device T, a gear transmission 0D, UD which is drivingly connected to the turbine 13 of the fluid transmission device T and can be switched according to vehicle running conditions; A vehicular automatic transmission comprising a sub-transmission 40 capable of switching between a high speed and a low speed, and a control device 600 that controls switching of the sub-transmission 40 between a high speed and a low speed. Reference numeral 600 denotes a hydraulic oil temperature detecting means 602 for detecting a hydraulic oil temperature in order to detect an increase in the hydraulic oil temperature due to a slip between the pump 11 and the turbine 13 of the fluid transmission device T, and a temperature detected by the hydraulic oil temperature detecting means 602. Judgment means 71 for judging whether or not the hydraulic oil temperature is equal to or higher than a predetermined value.
1, and a switching means 712 for switching the auxiliary transmission from a high speed gear to a low speed gear when the determining means 711 determines that the hydraulic oil temperature is equal to or higher than a predetermined value. [Function and Effects of the Invention] With the above configuration, the automatic transmission for a vehicle of the present invention can prevent insufficient driving force from increasing the driving force only by shifting the main transmission while the vehicle is running on a steep uphill road. In this case, slippage occurs between the pump and turbine of the fluid transmission device and the temperature of the hydraulic oil rises. If the value is higher than a predetermined value, the switching means switches the auxiliary transmission from a high gear to a low gear, so that the lack of driving force is compensated for by shifting the auxiliary transmission to a low gear, and the switching means switches the auxiliary transmission from a high gear to a low gear. Appropriate driving force can be obtained, and the slippage between the pump and turbine of the fluid transmission device can be reduced by providing an appropriate driving force, thereby preventing adverse effects on transmission parts due to increases in hydraulic oil temperature. Durability can be improved. [Example] Next, the present invention will be explained based on an example shown in the drawings. Figure 1 shows a four-wheel drive automatic transmission, and Figure 2 shows its gear train. 10 is a 4-speed automatic transmission with overdrive that is a main transmission, and 40 is a 4-wheel drive transfer that is a sub-transmission connected to the output shaft 32 of a planetary gear transmission of the 4-speed automatic transmission 10. show. The four-wheel drive transfer 40 is engine E.
attached to the 4-speed automatic transmission 10 installed in the
The first output shaft 42 is a propeller shaft C for rear wheel drive.
The second output shaft 52 is connected to a front wheel drive propeller shaft B. The 4-speed automatic transmission 10 includes a hydraulic torque converter T, an overdrive mechanism OD, and a forward speed 3.
Equipped with an underdrive mechanism UD with one reverse stage. The torque converter T includes a pump 11 connected to the output shaft of the engine, a turbine 13 connected to the output shaft 12 of the torque converter T, and a stator 1 connected to a fixed part via a one-way clutch 14.
5 and a direct coupling clutch 16, and the output shaft 12 of the torque converter T serves as the input shaft of the overdrive mechanism OD. The overdrive mechanism OD includes frictional engagement elements such as a multi-disc clutch C ₀ , a multi-disc brake B ₀ and a one-way clutch F ₀ , and the selective engagement of these frictional engagement elements allows the components to be attached to a fixed member such as a transmission case. It consists of a planetary gear set P ₀ that is fixed to the input shaft, output shaft, or other components, or is released from the fixation or connection. The planetary gear set _P0 is connected to the input shaft 12.
The carrier 21 is connected to the ring gear 2, which is connected to the output shaft 25 of the overdrive mechanism OD.
2. Rotatably fitted onto the input shaft 12 and fixed to the transmission case via the brake _B0 ,
A sun gear 23 is connected to the carrier 21 via a clutch C ₀ and a one-way clutch F ₀ parallel to the clutch C ₀ , and is rotatably supported by the carrier 21 and has teeth on the sun gear 23 and ring gear 22. It consists of a planetary pinion 24 that is fitted together. The output shaft 25 of the overdrive mechanism OD also serves as the input shaft of the underdrive mechanism UD, which has three forward stages and one reverse stage. The underdrive mechanism UD includes multi-disc clutches C1 and C2, which are frictional engagement elements, multi-disc brakes B1, B2 and B3, and a one-way clutch F1.
and F2, and front planetary gear set P1
and a rear planetary gear set P2. The rear planetary gear set P2 is the clutch C.
1 and the output shaft 3 of the underdrive mechanism UD.
2, a carrier 33 connected to the input shaft 25 via a clutch C2, a brake B1, a brake B2 parallel to the brake B1, and a one-way clutch F1 connected in series with the brake B2. A sun gear 34 is fixed to the transmission case, and a sun gear 34 and a ring gear 31 are rotatably supported by the carrier 33.
It consists of a planetary pinion 35 meshed with. The front planetary gear set P1 is the brake B
3, a carrier 36 fixed to the transmission case via a one-way clutch F2 parallel to the brake B3, and the rear planetary gear set P2.
Sun gear 3 integrally formed with sun gear 34 of
7 and a ring gear 38 connected to the output shaft 32
and a planetary pinion 39 rotatably supported by a carrier 36 and meshed with a sun gear 37 and a ring gear 38. This four-wheel drive automatic transmission is operated by a hydraulic control device 100 of a four-speed automatic transmission 10 shown in FIG. The brakes are selectively engaged or released, resulting in four automatic forward speeds including overdrive (O/D) and one reverse speed only with manual shifting. A shift lever (not shown) provided at the driver's seat for driving the manual valve of the hydraulic control device 100
has a shift position SP in each range of P (park), R (reverse), N (neutral), D (drive), S (second), and L (low), and this shift position SP and gear change Stage 4th speed (4), 3rd speed (3),
Table 1 shows the operational relationship between second gear (2), first gear (1), and the clutch and brake. In Table 1, ◯ indicates engagement of the friction engagement element, × indicates release, F (free) indicates free rotation of the one-way clutch, and L (lock) indicates engagement of the one-way clutch.

【table】

[Table] The hydraulic control device 100 of the 4-speed automatic transmission 10 is
Hydraulic pump 101, pressure regulating valve (regulator valve) 130, second pressure regulating valve 150, cooler bypass valve 105, pressure relief valve 106, reverse clutch sequence valve 110, throttle that generates throttle pressure according to throttle opening degree. valve 200, cutback valve 145, direct clutch control valve 120, manual valve 210, 1-2 shift valve 220, 2-3 shift valve 230, 3-4 shift valve 240, the 1-2 shift valve 220 and 3-4 shift Solenoid valve S that controls valve 240
1, 2-3 Solenoid valve S2 that controls the shift valve 230, solenoid valve S3 that controls the direct clutch control valve 120, intermediate coast modulator valve 245 that adjusts the oil pressure supplied to the brake B1, to the brake B3 A low coast modulator valve 250 that adjusts the supply hydraulic pressure of the clutch C1, an accumulator 260 of the clutch C1, and a clutch C2.
Accumulator 270 of brake B2, accumulator 280 of brake B2, clutch C0, C1, C2
and flow control valves 301, 302, 303, 304, 3 with check valves that control the flow rate of pressure oil supplied to each hydraulic servo of brakes B0, B1, and B2.
05,306, Brake B0, B1, B2, B
3, B4 hydraulic servo B-0, B-1, B-2,
B-3, B-4, clutch C0, C1, C2, C
3, C4 hydraulic servo C-0, C-1, C-2,
It consists of oil passages that communicate between C-3, C-4, each valve, and the hydraulic cylinders of the clutch and brake.
The solenoid valves S1, S2, and S3 are turned on and off by an electronic control device (not shown) according to vehicle running conditions such as vehicle speed and engine load, thereby controlling the 1-2 shift valve 220, 2-3 shift valve 230,
A 3-4 shift valve 240 is controlled. These shift valves 220, 230, 240 are manual valves 21
The hydraulic power source is selectively connected to the hydraulic servo of each clutch and brake according to the set position of zero. The manual valve 210 is connected to a shift lever provided on the driver's seat, and is manually operated to select P (park), R (reverse), N (neutral), D (drive), or S depending on the range of the shift lever.
(second) and L (low) positions. Table 2 shows the communication state between oil passage 1 and oil passages 2 to 5 in each shift range of the shift lever. ○ indicates the case where line pressure is supplied through communication, ×
indicates a state where the pressure is exhausted.

[Table] The transfer 40 in FIG. 2 has a clutch C3, a brake B4, and a clutch C4, which are frictional engagement elements, and an output shaft 32 of a planetary gear set P1, P2 as input shafts, and is connected in series with the input shaft 32. a first output shaft 42 of a transfer shaft 40 arranged;
a planetary gear set Pf disposed between the input shaft 32 and the first output shaft 42; the first output shaft 4;
2, a four-wheel drive sleeve 51 rotatably fitted to the outside of the input shaft 32, a second output shaft 52 arranged parallel to the input shaft 32 and mounted in the opposite direction to the first output shaft 42, and the sleeve 51. and a second output shaft 52. planetary gear set
Pf includes a sun gear 44 spline-fitted to the end of the input shaft 32, a planetary pinion 45 that meshes with the sun gear 44, a ring gear 46 that meshes with the planetary pinion 45, and rotatably holds the planetary pinion 45. and a carrier 47 connected to the tip of the first output shaft 42 of the transfer shaft 40. In this embodiment, as shown in FIG. 4, the brake B4 is a multi-disc friction brake for engaging the ring gear 46 with the transfer case 48. Hydraulic servo B consisting of piston 49P mounted on
-4 is activated. The clutch C3 is disposed on the 4-speed automatic transmission 10 side of the planetary gear set Pf, and connects and disconnects the sun gear 44 and the carrier 47, and is connected to the cylinder 50 connected to the carrier 47 and the clutch C3 installed in the cylinder 50. It is operated by a hydraulic servo C-3 composed of a piston 50P. Clutch C4 is a multi-plate friction clutch for connecting and connecting the first output shaft 42 connected to carrier 47 and sleeve 51 connected to one sprocket 56 of transmission mechanism 53 for driving second output shaft 52 of transfer 40. The clutch is actuated by a hydraulic servo C-4, which is comprised of a cylinder 58 rotatably supported by the transfer case 48 and a piston 58P mounted within the cylinder 58. The transmission mechanism 53 consists of a sprocket 56 spline-fitted to the sleeve 51, a sprocket 55 formed on the second output shaft 52, and a chain 57 stretched between these sprockets. Cylinder 5 of hydraulic servo C-3 of clutch C3
A parking gear 59 is provided around the outer periphery of the 4-speed automatic transmission 10, and when the shift lever of the 4-speed automatic transmission 10 is set to the parking position, the pawl engages with a parking pawl (not shown) to rotate the first output shaft 42. Fix it. 60 is clutch C3, C4 of transfer 40
and brake B4 hydraulic servo C-3, C-4
and a transfer valve body provided with a hydraulic control device for supplying and discharging hydraulic pressure to B-4, and 61 is its oil pan. Pressure oil supplied to the hydraulic servos C-3, C-4 and B-4 of the clutches C3 and C4 and the brake B4 is transferred to the transmission case 62 and the transfer case 48 through oil passages 64 provided in the transfer case 48. A control device 40
Transfer valve body 6 provided with 0
It leads to 0. During normal driving, the line pressure supplied to the hydraulic control device of the automatic transmission is supplied to hydraulic servo C-3 to engage clutch C3, and hydraulic servos B-4 and C-4 are exhausted to engage brake B4 and clutch. Release C4. As a result, the sun gear 44 and carrier 47 of the planetary gear set Pf are connected, and power is transmitted from the input shaft 32 to the first output shaft 42.
The transmission is transmitted at a reduction ratio of 1 to achieve two-wheel drive driving with only the rear wheels. At this time, the power from the input shaft 32 is transmitted from the carrier 47 to the first output shaft 42 via the clutch C3 without passing through the sun gear 44, planetary pinion 45, or ring gear 46, so that a load is applied to the tooth surface of each gear. This increases the life of the gear. During this two-wheel drive driving, when four-wheel drive driving becomes necessary, a shift lever 40 installed at the driver's seat etc.
1 manually and transfer control device 400
When line pressure is gradually supplied to the hydraulic servo C-4 to smoothly engage the clutch C4, the first output shaft 42 and the sleeve 51 are connected, and the transmission mechanism 53,
Power is also transmitted to the front wheels via the second output shaft 52 and the front wheel drive propeller shaft B (shown in FIG. 1), and the power is transmitted from the input shaft 32 to the first output shaft 42 and the second output shaft 52 at a reduction ratio of 1. A four-wheel drive directly coupled driving state (high-speed four-wheel drive state) is obtained.
During this four-wheel drive driving, when the shift lever 401 is manually shifted when an increase in output torque is required, such as on a steep slope, the hydraulic pressure is applied to the hydraulic servo, which is a switching valve between a high-speed four-wheel drive state and a low-speed four-wheel drive state. By activating the inhibitor valve 440 and the accumulator control valve 460, which is a spool valve, line pressure is gradually supplied to the hydraulic servo B-4, and at the same time, the hydraulic pressure of the hydraulic servo C-3 is discharged at an appropriate timing, and the brake B4 is gradually applied. Clutch C3 is engaged and smoothly released. As a result, sun gear 44 and carrier 47 are released, ring gear 46 is fixed, and power is transferred to input shaft 32.
is decelerated and transmitted to the first output shaft 42 and second output shaft 52 via the sun gear 44, planetary pinion 45, and carrier 47.
A wheel drive deceleration driving state (low speed four-wheel drive state) is obtained. Table 3 shows the brake B4 of transfer 40,
The engagement and release of clutches C3 and C4 and the running state of the vehicle are shown.

[Table] In Table 3, ○ indicates the engaged state of the friction engagement element, and × indicates the released state. The reduction ratio (3.0 in the example) is
The ratio of the number of teeth between the sun gear 44 and the ring gear 46 of the planetary gear set is λ, and the reduction ratio is calculated as follows: (1+λ)/λ=3.0, where λ is 0.5. The transfer control device 400 of the four-wheel drive transfer 40 has a transfer manual valve 410 that is connected to a shift lever 401 provided in the driver's seat via a link mechanism 402, and a transfer manual valve 410 that is connected to a shift lever 401 provided in the driver's seat through a link mechanism 402. ) and low speed (deceleration); and an upshift device provided between the inhibitor valve 440 and the hydraulic servo C-3 and consisting of an accumulator control valve 460, an accumulator 490, and an aperture 491. (L4 → H4 shift) When the timing mechanism 430 and shift lever 401 are in H4, the solenoid valve S5 is turned on and off to change H4 to L4, H
4←The high/low speed switching valve 480 that performs L4 controls the input oil pressure (hydraulic pressure related to the vehicle speed) of the inhibitor valve 440 to the oil path 1M connected to the oil path 1, and when the vehicle speed exceeds the set value 4 An automatic transfer control mechanism 500 for automatically switching between high and low speeds of wheel drive, and a throttle 5 with a check valve provided in the supply and discharge path 1N of hydraulic oil to the hydraulic servo B-4.
20, a check valve-equipped throttle 530 provided in the oil supply/drainage path 7 for hydraulic oil to the hydraulic servo C-4, an inhibitor valve 440, and an upshift timing mechanism 4.
30 and a check valve equipped throttle 540 provided in the communication oil passage 1P. The transfer manual valve 410 has a spool 420 connected to a shift lever 401 provided at the driver's seat via a link mechanism 402, and is connected to a line pressure generating oil path of the hydraulic control circuit of the four-speed automatic transmission 10. import 411, contacting 1;
Out port 413 communicating with oil passage 6, Out port 415 communicating with oil passage 7, Drain port 4
17, 419, and when the spool 420 is set to the two-wheel drive H2, it connects the oil passage 1 and the oil passage 6, and also connects the oil passage 7 to the drain port 419, and sets the four-wheel drive high speed stage H4 position. When set, the oil passage 1 is connected to the oil passage 6 and the oil passage 7, and when the four-wheel drive low gear stage L4 position is set, the oil passage 1 and the oil passage 7 are connected.
The oil passage 6 is connected to the drain port 417. The inhibitor 440 has a spool 441 on which a spring 450 is placed on its back from the bottom in the drawing, and a plunger 442 in series with the spool 441.The spools 441 have the same diameter and a sleeve-like shape at the bottom end on which the spring 450 is placed on its back. 44
5, the illustrated upper end land 447, and the intermediate land 4
It has 46. The plunger 442 has a lower end land 448 having a larger diameter than the spool 441 land.
and an upper end land 4 having a larger diameter than the lower end land 448.
It has 49. These spool 441 and plunger 442 provide a lower end oil chamber 451, first and second intermediate oil chambers 452, 4 between the sleeve-shaped land 445, intermediate land 446, and upper end land 447.
53, an oil chamber 454 between the spool 441 and the plunger 442, and an upper end oil chamber 456. This inhibitor valve 440 is connected to a lower end oil chamber 451 when the spool 441 is set upward in the figure.
communicates with the vehicle speed pressure oil passage 1M via the oil port 443 of the sleeve-shaped land 445, the first intermediate oil chamber 452 communicates with the line pressure oil passage 1 and the deceleration oil passage 1N, and the second
The intermediate oil chamber 453 communicates with the direct connection oil passage 1P and the drain port 457, and when the spool 441 is set downward in the figure, the lower end oil chamber 451 communicates with the drain port 458 via the oil port 443 of the sleeve-shaped land 445. The first intermediate oil chamber 452 connects the deceleration oil path 1N and the drain port 459, and the second intermediate oil chamber 453 connects the line pressure oil path 1 and the direct connection oil path 1P.
The oil chamber 454 is always in communication with the oil passage 1M for generating oil pressure related to the vehicle speed, and the upper oil chamber 45
6 is always in communication with the oil passage 6. The accumulator control valve 460 has a spool 4 with a spring 470 mounted on its back in the lower part of the figure.
71, and the spool 471 has a lower end land 473.
and an intermediate land 475, and an upper end land 477 with a larger diameter than these two lands 473, 475 by a predetermined dimension, and has a lower end oil chamber 46 from the lower side in the figure.
1. Middle oil chamber 463, 465, upper end oil chamber 467
is formed. This accumulator control valve 460
In this case, the lower intermediate oil chamber 463 is always operated by the hydraulic servo C-
3, the upper intermediate oil chamber 465 is always in communication with the line pressure oil path 1, the upper end oil chamber 467 is fed back with the oil pressure of the oil path 1Q, and the lower end oil chamber 461 is Oil passage 1 connected to oil passage 1Q via throttle 491 and accumulator 490
R oil pressure is being supplied. The high-speed/low-speed switching valve 480 has a spool 482 on which a spring 481 is placed on its back in the lower part of the figure, and the spool 482 has a lower end land 483 and an upper end land 484, and a lower end oil chamber 485,
An intermediate oil chamber 486 and an upper end oil chamber 487 are formed. The intermediate oil chamber 486 is always in communication with the upper end oil chamber 456 of the inhibitor valve 440 via the oil passage 6A. Furthermore, when the line pressure is supplied to the oil passage 7 and the solenoid valve S5 is ON, the spool 482 discharges the line pressure from the lower end oil chamber 485 and the upper end oil chamber 4
Line pressure is supplied to 87 and set downward in the figure.
When solenoid valve S5 is OFF, the lower end oil chamber 485
Line pressure is supplied to the upper end oil chamber 487, and the upper end oil chamber 487 is set upward in the figure by the force of the spring 481, regardless of whether line pressure is supplied to or discharged from the upper end oil chamber 487. The automatic transfer control mechanism 500 includes a vehicle speed sensor 501, a cooler bypass valve 1 in a discharge oil passage 100A of the torque converter T, as shown in FIG.
05 and the oil cooler 107, a shift lever position sensor 603 that detects the set position of the shift lever 401, and a throttle opening sensor 6 that detects the throttle opening.
04, a mode switch 605 that is provided near the shift lever 401 and selects automatic switching between high gear and low gear in the H4 range, which is turned on and off by the driver's operation; when these outputs are input, the shift control circuit 600; It consists of a throttle 511 provided in the oil passage 1M communicating with the oil passage 1, and electromagnetic solenoid valves S4 and S5 that are turned on and off by the output of the speed change control circuit 600. (For example, 20km/h/
h) When it is above, it is turned OFF to generate the line pressure of oil passage 1 in oil passage 1M, and when it is less than the set value, it is turned ON and the oil pressure in oil passage 1M is discharged. As a result, oil pressure related to the vehicle speed is generated in the oil path 1M. The solenoid valve S5 is turned off when the vehicle speed is above a set value (for example, 10 km/h) or the oil temperature of the hydraulic oil is below a set value (for example, 100°C),
Line pressure is generated in the lower end oil chamber 485 of the high/low speed switching valve 480, and when the vehicle speed is below a set value and the oil temperature of the hydraulic oil is above the set value, it is turned ON and the oil pressure in the lower end oil chamber 485 is discharged. Press. As a result, a hydraulic pressure related to the vehicle speed and the temperature of the hydraulic oil is generated in the lower end oil chamber 485. The solenoid valve S
For example, the ON/OFF setting value of 4 is the vehicle speed sensor 5.
Since the shift control circuit 600 that controls the solenoid valve S4 can be configured to be easily changed by the input signals from the oil temperature sensor 602 and the oil temperature sensor 602, the driver can change the speed according to the driving conditions of the vehicle such as road conditions. It's easy. Line pressure enters the intermediate oil chamber 465 from oil path 1,
The oil passage 7 is connected to a hydraulic servo C-4 via a check valve-equipped throttle 530. The operation of the transfer 40 in each setting range will be explained. (a) When the transfer manual valve 410 is set to the H2 range, the pressure in the oil passage 7 is exhausted, so no power is transmitted to the sleeve 51 and the two-wheel drive state is maintained. In addition, since the oil passage 7 is depressurized, the spool 482 is set upward by the force of the spring 481 of the high-speed/low-speed switching valve 480 regardless of whether the solenoid valve S5 is ON or OFF. Line pressure is supplied to the upper end oil chamber 456 of the inhibitor valve 440 through the spool 441 and the plunger 44.
2 is set at the lower side in the figure, and the oil passage 1N is connected to the drain port 459 and is evacuated, thereby the brake B4 is evacuated, and since the oil passage 7 is evacuated, the clutch C4 is evacuated. Oil road 1
P connects to oil path 1 and is a throttle with check valve 540;
It communicates with the oil passage 1Q via the accumulator control valve 460 and engages the clutch C3. Therefore, the transfer gear 40 becomes H2 (two-wheel drive directly connected state). (b) When transfer manual valve 410 is set to H4 range, line pressure is supplied to both oil passage 6 and oil passage 7. The line pressure supplied to oil passage 7 engages clutch C4. As a result, the transfer shaft 40 enters a four-wheel drive state. (a) When the solenoid valve S5 is OFF, line pressure is supplied to the lower oil chamber 485 of the high-speed/low-speed switching valve 480, the spool 482 is set upward by the force of the spring 481, and the line pressure is supplied to the intermediate oil chamber 486. , and is supplied to the upper end oil chamber 456 of the inhibitor valve 440 through the oil path 6A. The line pressure supplied to the upper end oil chamber 456 is set so that the spool 441 and plunger 442 of the inhibitor valve 440 are positioned downward in the figure.
The oil passage 1N communicates with the drain port 459 and is evacuated, thereby evacuating the brake B4. As a result, the transfer 40 becomes H
4 (four-wheel drive directly connected state). (b) When the solenoid valve S5 is ON, line pressure is exhausted from the lower end oil chamber 485 of the high-speed/low-speed switching valve 480, and when line pressure is supplied from the oil path 7 to the upper end oil chamber 487, the spool 482 is activated by the spring. 481 and is set downward, the oil passage 6A communicates with the drain port 488, and the line pressure is exhausted from the upper end oil chamber 456 of the inhibitor valve 440. Solenoid valve S5
The vehicle speed at which solenoid valve S4 turns ON is determined by
Since it is set lower than the vehicle speed to be turned on, when solenoid valve S5 is turned on, solenoid valve S4 is turned on, and oil path 1 is turned on.
Since M is exhausted, the spool 441 is set upward in the drawing by the action of the spring 450, and as a result, the oil passage 1 and the oil passage 1N communicate with each other, and hydraulic oil is supplied to the hydraulic servo B-4.
P is connected to the drain port 457 and the pressure is discharged, and the hydraulic pressure of the hydraulic servo C-3 of the clutch C3 is discharged. As a result, the transfer gear 40 becomes L4 (four-wheel drive deceleration state). (c) When the transfer manual valve 410 is set to the L4 range, the pressure in the oil passage 6 is exhausted and the oil passage 7 is
Since line pressure is supplied to solenoid valve S
5 is ON or OFF, the high/low speed switching valve 480 is set to the lower position in the figure by the line pressure supplied to the upper end oil chamber 457, and the inhibitor valve 44
The oil pressure in the upper end oil chamber 456 is exhausted, and the plunger 442 is set upward in the drawing. Further, since line pressure is supplied to the oil passage 7, the clutch C4 is engaged and the four-wheel drive state is maintained. Solenoid valve S4 turns OFF when the vehicle speed exceeds the set value
transfer manual valve 41 when
When 0 is set to the L4 range, line pressure is supplied to the oil path 1M. Therefore, the spool 441 of the inhibitor valve 440 remains set at the lower position in the drawing due to the line pressure applied to the oil chamber 454, and the gear is not changed, thereby preventing the engine from overrunning. When the vehicle speed is below the set value and the solenoid valve S4 is turned on, the transfer manual valve 410
is set to the L4 range, or when the vehicle speed is above a predetermined value and the solenoid valve S4 is OFF, the transfer manual valve 410 is in the L4 state and the vehicle speed goes from above the predetermined value to below the set value, so the solenoid valve S
4 is turned ON from OFF, the pressure in the oil passage 1M is exhausted, so the spool 441 is set upward in the figure by the action of the spring 450, and as a result, the oil passage 1 and the oil passage 1N communicate with each other, and the hydraulic servo B-4 Hydraulic oil is supplied to the hydraulic servo C-3 of the clutch C3, and the oil passage 1P communicates with the drain port 457 to discharge pressure, thereby discharging the hydraulic pressure of the hydraulic servo C-3 of the clutch C3. This results in a transfer of 40
becomes a low-speed four-wheel drive state. After the vehicle enters the low-speed four-wheel drive state, even if the vehicle speed exceeds the set value and the solenoid valve S4 is turned OFF, the line pressure of the oil passage 1M is applied to the oil chamber 454 of the inhibitor valve 440 and at the same time the spool 441 is turned off. Sleeve land 4
Since the oil is applied to the lower end oil chamber 451 through the oil port 443 of No. 45, the spool 441 is not displaced and the low-speed four-wheel drive state is maintained. A speed change control circuit (computer) 600 that opens and closes the first to fifth solenoid valves S1, S2, S3, S4, and S5 according to the vehicle running conditions is connected to a vehicle speed sensor 501 that detects vehicle speed, and a torque control circuit as shown in FIG. As shown in FIG. 3, the hydraulic oil temperature detection means is arranged between the cooler bypass valve 105 and the oil cooler 107 in the discharge oil passage 100A of the torque converter T to detect the oil temperature of the hydraulic oil of the converter T. Oil temperature sensor 602, shift lever 40
A shift lever position sensor 603 that detects the set position of 1, a throttle opening sensor 604 that detects the throttle opening, and an H4 that is provided near the shift lever 401 and is turned on and off according to the driver's will.
An input port 610 that inputs a signal from a mode switch 605 that selects automatic switching between high and low gears in the range, an automatic transmission shift control device 612 that includes solenoid valves S1 to S3, and H4 that includes solenoid valves S4 and S5. It consists of an output port 611 to →L4, H4←L4 switching device 613, a central processing unit CPU, a read-only memory ROM that stores preset vehicle speed and preset oil temperature, and random access memory RAM. Next, the operation of the speed change control circuit 600 according to the present invention will be explained based on the flowchart shown in FIG. Turn on the starter key, start the engine, set the transfer manual valve 410 to H4 701, then check the vehicle speed (v) with the vehicle speed sensor 501,
The oil temperature (tx) of the hydraulic oil of the torque converter T is read from the oil temperature sensor 602, the set position of the shift lever 401 is read from the shift lever position sensor 603, the throttle opening sensor 604, and the input signal from the mode switch 605 is read 702, and the shift lever position is read. Automatic transmission 1 based on signal, throttle opening signal, and vehicle speed signal
0 control 703, read the vehicle speed (V1) that can be shifted from H2 or H4 to L4 by manual shift from the ROM 704, determine whether v<V1 or not 705, v
<When it is not V1 (region where L4 gear cannot be shifted by manual shift), turn off solenoid valve S4 and shift to H2.
Alternatively, continue H4 running and proceed to step 706 and then step 708. When v<V1 (L4 shift possible area by manual shift), solenoid valve S4 is turned on to switch from H4 to L4 (707), and the process then proceeds to 708. Since the transfer manual valve 410 has the highest priority, only the H4 range is valid in the flowchart below, and even if solenoid valve S5 is turned on and off in the H2 and H4 ranges, the gear will not be changed. Next, it is determined whether the mode switch 605 is ON or not (708), and when the mode switch 605 is ON,
Determine whether the solenoid valve 5 is OFF or not 709;
When OFF, H4 → L4 stored in ROM in advance
Vehicle speed during gear shifting: V2 = V, set oil temperature: (T1) = (T), 710, in the judgment means v
Determine whether <V, t>T or not 711, v<V, t>
When T, the switching means switches the solenoid valve S5.
By turning it on, the gear changes from H4 to L4.7
12. Then return. mode switch 60
5 is OFF, solenoid valve S5 is OFF,
The shift is performed from L4 to H4 at step 713, and then the process returns. When solenoid valve S5 is ON, ROM is activated in advance.
Vehicle speed when shifting from L4 to H4 stored in:
V3=V and set oil temperature: T2=T 71
4. Then proceed to 711.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of an automatic transmission for four-wheel drive;
The figure is a schematic diagram of the gear train, Figure 3 is a hydraulic circuit diagram of a 4-speed automatic transmission, Figure 4 is a sectional view and hydraulic circuit diagram of a four-wheel drive transfer, and Figure 5 is a transmission according to the present invention. A block diagram of the control circuit, FIG. 6 is a flowchart of the speed change control circuit according to the present invention. In the figure, B4...Multi-disc brake which is a frictional engagement element for deceleration, C3...Multi-disc clutch which is a frictional engagement element for direct coupling, C4...Multi-disc clutch which is a frictional engagement element for four-wheel drive, 1...Line pressure oil path, 32...
...transfer input shaft, 42...first output shaft,
51... Four-wheel drive sleeve, 52... Second output shaft, 53... Transmission mechanism, Pf... Planetary gear set, 410... Transfer manual valve,
430...Upshift timing mechanism, 440...
...inhibitor valve, 500...transfer automatic control mechanism, 501...vehicle speed sensor, 600...shift control circuit, 602...oil pressure sensor (hydraulic oil temperature detection means), 711...judgment means, 712...switching means , CPU... central processing unit, ROM... read-on memory, RAM... random access memory.

Claims (1)

[Scope of Claims] 1. A fluid transmission device consisting of a pump connected to the output shaft of an engine and a turbine drivingly connected to the pump via hydraulic oil, and a vehicle running driven by the turbine of the fluid transmission device. a main transmission having a gear transmission that can be switched according to conditions; a sub-transmission that is drive-coupled to the main transmission and capable of switching between a high speed gear and a low gear; and a high speed gear and a low gear gear of the sub-transmission. In the automatic transmission for a vehicle, the control device controls the temperature of the hydraulic oil in order to detect an increase in the temperature of the hydraulic oil due to slippage between the pump and the turbine of the fluid transmission device. A hydraulic oil temperature detecting means for detecting, a determining means for determining whether the hydraulic oil temperature detected by the hydraulic oil temperature detecting means is equal to or higher than a predetermined value, and the determining means determines that the hydraulic oil temperature is equal to or higher than the predetermined value. An automatic transmission for a vehicle, comprising a switching means for switching the auxiliary transmission from a high speed gear to a low speed gear. 2. The automatic transmission for a vehicle according to claim 1, wherein the hydraulic oil detection means is an oil temperature sensor provided in a hydraulic oil discharge path of the fluid transmission device.