JPH0134167B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a four-wheel drive automatic transmission. [Conventional technology] Four-wheel drive vehicles that are more suitable for driving on rough terrain than before are
It has one output shaft connected to the rear wheel drive propeller shaft and the other output shaft connected to the front wheel drive propeller shaft, and the power from the output shaft of the main transmission is transmitted to the two output shafts. A four-wheel drive transmission equipped with a transfer device capable of transmitting information is installed, and the transfer device has two
An engagement device for selectively connecting one of the two output shafts.In the case of vehicles that require especially large driving force, multiple gears can be achieved by selectively operating the engagement device. A possible sub-transmission device etc. is provided. [Problems to be Solved by the Invention] However, since the conventional transfer device uses a mesh type engagement device as the above-mentioned engagement device, it is difficult to obtain synchronous rotation of the mesh type engagement device during driving. It is difficult to switch the engagement device, and the switching operation must be performed after the vehicle has been stopped, which makes the switching operation seem troublesome. In order to solve this problem, it is conceivable to use a hydraulic friction engagement device as the engagement device of the transfer device, but if the main transmission is an automatic transmission, the hydraulic friction engagement device of the transfer device may be used. In order to simplify the structure of the automatic transmission for four-wheel drive, it is desirable to supply hydraulic pressure to the automatic transmission with the hydraulic pressure generated by the oil pump of the automatic transmission, similar to the hydraulic friction engagement device of the automatic transmission. . Similar to the hydraulic friction engagement device of an automatic transmission, when the hydraulic pressure generated by the oil pump of the automatic transmission is supplied to the hydraulic friction engagement device of the transfer device, the driver operates the automatic transmission with power. When the manual valve is operated to set the transmission state, the oil pressure generated by the oil pump is supplied to the hydraulic friction engagement device of the automatic transmission via the manual valve, and the hydraulic friction engagement device is engaged. The power from the engine is transmitted to the output shaft of the automatic transmission, while the hydraulic pressure generated by the oil pump is supplied to the hydraulic control device of the transfer device via the manual valve. The hydraulic control device of the transfer device includes a switching valve that switches the communication of the oil passage so as to selectively supply and discharge hydraulic pressure to the hydraulic friction engagement device of the transfer device, and a switching valve that switches the communication of the oil path to selectively supply and discharge hydraulic pressure to the hydraulic friction engagement device of the transfer device. A selection valve is provided that supplies hydraulic pressure to the switching valve to switch the valve. However, in such a configuration, the hydraulic pressure supplied by the selection valve to the switching valve is generated after the manual valve of the automatic transmission is switched, so the switching of the switching valve is not performed after the manual valve of the automatic transmission is switched. There may be cases where this occurs. For this reason, the engaging or disengaging operation of the hydraulic frictional engagement device of the transfer device is started a little later than the start of engagement of the hydraulic frictional engagement device of the automatic transmission. After the operator operates the manual valve of the automatic transmission and until the power transmission state of the four-wheel drive automatic transmission set by the selection valve is achieved, the hydraulic friction engagement device of the automatic transmission must be engaged. Shock occurs twice: when the transfer device is engaged and when the hydraulic friction engagement device of the transfer device is engaged or disengaged. The present invention improves the switching operability of a transfer device by using a hydraulic friction engagement device as an engagement device of the transfer device as described above, and also improves the switching operability of the transfer device by using a hydraulic friction engagement device as an engagement device of the transfer device. In a four-wheel drive automatic transmission whose structure is simplified by using the oil pressure generated by the oil pump of the automatic transmission, which is a manual transmission, as the oil pressure supplied to the device, An object of the present invention is to provide an automatic transmission for four-wheel drive that can reduce the shock that occurs when a power transmission state is achieved. [Means for Solving the Problems] The four-wheel drive automatic transmission of the present invention includes a first hydraulic friction engagement device C1 that is engaged by supplying hydraulic pressure.
and a main transmission 1 having an output shaft 2 to which power from the engine is transmitted through engagement of the first hydraulic friction engagement device; A main hydraulic control device 100 that selectively supplies hydraulic pressure to the engagement devices, second hydraulic friction engagement devices 5, 7, and 8 that are engaged by supplying hydraulic pressure, and the second hydraulic friction engagement devices. output shafts 3, 17 to which power from the output shaft of the main transmission is transmitted through engagement of the coupling device;
and an auxiliary hydraulic control device 200 that selectively supplies and discharges the hydraulic pressure supplied from the main hydraulic control device to the second hydraulic friction engagement device in accordance with a driver's operation. In the four-wheel drive automatic transmission, the main hydraulic control device includes an oil pump 102, a line oil pressure output oil passage 104 to which oil discharged from the oil pump is supplied, and an oil pressure that regulates the oil pressure of the line oil pressure output oil passage. The auxiliary hydraulic pressure control device includes a control valve 103 and a manual valve 105 that selectively supplies the hydraulic pressure of the line hydraulic output oil path to the first hydraulic friction engagement device according to an operation by a driver. are switching valves 220, 250, 2 that selectively supply the supplied hydraulic pressure to the second hydraulic friction engagement device;
60, 320, 330, and selection valves 201, 230, 24 that selectively supply the supply hydraulic pressure to the switching valve to switch the switching valve according to the driver's operation.
0, 300, and 310, and the oil pressure supplied from the main oil pressure control device to the auxiliary oil pressure control device is supplied from the line oil pressure output oil path. [Operation and Effects of the Invention] According to the four-wheel drive automatic transmission of the present invention, the hydraulic pressure supplied from the main hydraulic control device of the main transmission having an oil pump is transmitted to the output shaft from the main transmission. a switching valve for selectively supplying and discharging the hydraulic frictional engagement device of the transfer device that is engaged for the transfer operation; The sub-hydraulic control device has a selection valve for switching valves, and hydraulic pressure is supplied to the sub-hydraulic control device from the line hydraulic oil path of the main hydraulic control device, so when the oil pump is started, the line hydraulic pressure is increased. When hydraulic pressure is generated in the oil passage, hydraulic pressure is supplied to the auxiliary hydraulic control device, so the selection valve of the auxiliary hydraulic control device selectively supplies hydraulic pressure to the switching valve according to the driver's operation, and the switching valve It switches according to the hydraulic pressure from the speed selection valve, and hydraulic pressure is supplied to and discharged from the hydraulic friction engagement device of the transfer device. For this purpose, before the driver operates the manual valve of the main transmission to put the main transmission into the power transmission state, the transfer device can be switched to the power transmission state set by the driver using the selection valve in advance. , it is possible to smoothly bring the four-wheel drive automatic transmission into a power transmission state. [Example] The present invention will be explained based on an example shown in the drawings. 1 is a main transmission which is a gear type automatic transmission; 10 is a transfer device connected to the rear of the main transmission 1; 2 is an output shaft of the main transmission 1 and an input shaft of the transfer device 10; 3 is a first output shaft of the transfer device 10 arranged in series behind the input shaft 2 (on the right side in FIG. 2); 110 is fixed to the input shaft 2, and indicates a vehicle speed signal oil pressure corresponding to the vehicle speed; The governor valve 4 is a planetary gear set, which includes a sun gear 41 spline-fitted to the rear of the input shaft 2, a pinion 42 that meshes with the sun gear 41, a ring gear 43 that meshes with the pinion 42, and a carrier 44 that rotatably holds the pinion 42 and is connected to the tip of the first output shaft 3 of the transfer device 10. Reference numeral 5 denotes a friction brake for engaging the ring gear 43 with the transfer case 18, which is operated by a hydraulic servo 50 composed of a cylinder 18A formed within the transfer case 18 and a piston 51 mounted within the cylinder 18A. , 7 is a cylinder 71 connected to the carrier 44 and the cylinder 7
This is a friction clutch operated by a hydraulic servo 70 consisting of a piston 72 mounted in the planetary gear set 4, and is arranged on the main transmission side of the planetary gear set 4, and connects the sun gear 41 and the carrier 44. be. In this embodiment, a planetary gear set 4, a friction brake 5, and a friction clutch 7 constitute an auxiliary transmission of the transfer. Reference numeral 8 denotes a friction clutch 80 for connecting the first output shaft 3 connected to the carrier 44 and the sleeve 9 connected to one sprocket 12 for driving the second output shaft of the transfer device 10 to be described later.
A cylinder 81 is welded to a sleeve 9 which is rotatably held within transfer cases 19 and 20, and a piston 8 is mounted within the cylinder 81.
17 is the second output shaft of the transfer shaft, 14 is the sprocket 12 fitted with a spline to the sleeve 9, the sprocket 15 is fitted with the spline to the second output shaft 17, and the sprocket is connected between these sprockets. This is a transmission mechanism consisting of a stretched chain 16. A parking gear 73 is formed on the outer periphery of the hydraulic cylinder 71 of the friction clutch 7, and when the shift lever of the main transmission 1 is selected to the parking position, a pawl 74 meshes with the parking gear 73 to fix the first output shaft 3. do. 90 is an oil pan of the main transmission 1; 200 is an auxiliary hydraulic control device (valve body) for supplying and discharging hydraulic pressure to the clutches 7, 8 of the transfer device 10 and the hydraulic servos 70, 80, and 50 of the brake 5; 92 is a corresponding hydraulic control device; This is the oil pan of the sub-hydraulic control device 200. Hydraulic servos 70, 8 for clutches 7, 8 and brakes 5
The oil pressure supplied to 0 and 50 is from the oil pan 90.
The hydraulic pressure is then guided through the auxiliary hydraulic control device 200 via a pipe 95 attached to the case 93 and transfer case 94 of the main transmission 1. This transfer device 10 is attached to a main transmission T attached to an engine E of a vehicle as shown in A shown in FIG. The shaft 17 is used while being connected to a propeller shaft B for driving the front wheels. During normal driving, line pressure generated by the main hydraulic control device of the main transmission 1 is supplied to the hydraulic servo 70 to engage the clutch 7, and the hydraulic servo 50 and 8
0 to release the brake 5 and clutch 8. As a result, the sun gear 41 and the carrier 44 of the planetary gear set 4 are connected, and the power is transmitted from the input shaft 2 to the first output shaft 3 for rear wheel drive at a reduction ratio of 1, thereby providing two-wheel drive driving for the rear wheels. At this time, the power from the input shaft 2 is transmitted to the gears 41, 42, 4.
Since the signal is transmitted from the carrier 44 to the first output shaft 3 via the clutch 7 without going through the gears 3, no load is applied to the tooth surfaces of each gear, increasing the life of the gears. When four-wheel drive driving becomes necessary during this two-wheel drive driving, a lever or switch provided on the driver's seat or the like is operated to control the auxiliary hydraulic control device 20 of the transfer device 10.
0 and gradually supplies line pressure to the hydraulic servo 80 to smoothly engage the clutch 8, the first output shaft 3 and the sleeve 9 are connected, and the transmission mechanism 14, the second output shaft 17, and the propeller are connected. Power is also transmitted to the front wheels via the shaft B, and power is transmitted from the input shaft 2 to the output shafts 3 and 11 for driving the front wheels and rear wheels at a reduction ratio of 1, thereby providing direct four-wheel drive driving. When it is necessary to increase the output torque such as when driving on a steep slope while directly connected to this 4-wheel drive, the hydraulic servo 50
While gradually supplying line pressure, the hydraulic pressure of the hydraulic servo 70 is discharged at appropriate timing, the brake 5 is gradually engaged, and the clutch 7 is smoothly released. As a result, the sun gear 41 and the carrier 44 are released, and the ring gear 43 is fixed, and the power is decelerated from the input shaft 2 via the sun gear 41, pinion 42, and carrier 44, and is transmitted to the output shafts 3 and 17. A four-wheel drive deceleration running state is obtained. Table 1 shows the engagement and release of the brake 5, clutches 7 and 8, and the running condition of the vehicle.

[Table] In Table 1, ○ indicates the engaged state of the friction engagement element, and × indicates the released state. The reduction ratio λ is the ratio of the number of teeth between the sun gear 41 and the ring gear 43 of the planetary gear mechanism, and the value of the reduction ratio is when λ is 0.5. Next, a hydraulic control system will be described with reference to FIG. 3 when an automatic transmission with three forward speeds and one reverse speed is applied as the main transmission of the four-wheel drive automatic transmission. In the figure, 100 is a main hydraulic control device, which is an example of a known hydraulic control device for an automatic transmission with three forward speeds and one reverse speed. The pressure is regulated to a predetermined oil pressure (line pressure) and guided to the line oil pressure output oil path 104. Line hydraulic output oil path 104
The pressure oil introduced into the clutch is guided through a manual valve 105 to hydraulic servo C1, C2, 1-2 shift valve 106 and 2-3 shift valve 107 of the clutch. A throttle valve 108 generates oil pressure (throttle pressure) in an oil passage 109 in accordance with the accelerator opening. Governor valves 1 and 10 generate oil pressure (governor pressure) in an oil passage 111 in accordance with the vehicle speed. 1-2 shift valve 106 and 2-3 shift valve 1
07 controls the opening and closing of oil passages 112, 113, and 114 in relation to the magnitude of the throttle pressure and governor pressure supplied from oil passages 109 and 111, and hydraulic servos C2, B1, and B for clutches and brakes.
2. Controls the supply and discharge of line pressure to and from B3. In this embodiment, pressure oil is supplied to the hydraulic servo C1 during the first forward speed, pressure oil is supplied to the hydraulic servos C1 and B2 during the second forward speed, and pressure oil is supplied to the hydraulic servo C1 and B2 during the third forward speed.
Pressure oil is supplied to the hydraulic servos C1, C2, and B2 when the vehicle is moving at high speed, and pressure oil is supplied to the hydraulic servos C2 and B3 when the vehicle is moving in reverse. The auxiliary hydraulic control device 200 of the transfer device 10 in this embodiment includes a selection valve 201, a modulator valve 210, an inhibitor valve 220, and a selection valve 201.
an oil passage 202 that communicates with the hydraulic servo 80 and an oil passage 2 that communicates the selection valve 201 with the modulator valve 210.
03, Modulator valve 210 and inhibitor valve 22
0, an oil path 225 that connects the inhibitor valve 220 and the hydraulic servo 70, and an oil path 22 that connects the inhibitor valve 220 and the hydraulic servo 50.
The selection valve 201 and the inhibitor valve 220 are supplied with line pressure from the oil passage 104 of the hydraulic control device 100, and the inhibitor valve 220 is supplied with governor pressure from the oil passage 111 of the main hydraulic control device 100. be done. The selection valve 201 is connected to the line oil pressure output oil passage 104 and oil passage 2 by operating the shift lever on the driver's seat.
02 and the oil passage 203 to select the power transmission state of the transfer device 10. When the driver selects two-wheel drive driving, the line oil pressure output oil passage 104 is connected to the selection valve 201. The oil passage 20 is closed by the spool 204.
No oil pressure is generated in the oil passage 202 and the oil passage 203. When the driver selects 4-wheel drive direct connection driving, the line oil pressure output oil passage 104 connects to the oil passage 202 and the oil passage 20
2, hydraulic pressure is generated. When the driver selects four-wheel drive deceleration traveling, the line oil pressure output oil passage 104 communicates with the oil passage 202 and the oil passage 203, and oil pressure is generated in the oil passage 202 and the oil passage 203. The modulator valve 210 includes a spool 211 and a spring 212, and when the driver selects four-wheel drive deceleration traveling, the pressure oil generated in the oil passage 203 is regulated to a constant modulator pressure and supplied to the oil passage 213. The inhibitor valve 220 is composed of a spool 221, a spring 222, and oil chambers 223, 224, and includes a modulator pressure acting on the oil chamber 223 according to the driver's selection and a governor pressure acting on the oil chamber 224 from the oil passage 111 according to the vehicle speed. and the force of the spring 222, the line hydraulic output oil passage 104 and the oil passage 225
This is a switching valve that selectively supplies line pressure to the hydraulic servo 50 and the hydraulic servo 70 by switching communication with the hydraulic servo 50 and the hydraulic servo 70. Next, its operation will be explained. <When the driver selects two-wheel drive driving> The line hydraulic output oil path 10 is set by the selection valve 201.
4 is not communicated with the oil passage 202 and the oil passage 203, so that no pressure oil is introduced into the oil chamber 223 of the hydraulic servo 80 and the inhibitor valve 220. As a result, the clutch 8 is released, and the spool 221 of the inhibitor valve 220 is positioned upward in the figure by the spring 222, connecting the line oil pressure output oil passage 104 and the oil passage 225, and controlling the line pressure of the oil passage 104. Hydraulic servo 70 of clutch 7 through passage 225
Since the clutch 7 is engaged, the transfer device 10 becomes in a two-wheel drive state. <When the driver selects 4-wheel drive direct connection driving> The line hydraulic output oil path 10 is set by the selection valve 201.
4 is connected to the oil path 202, so the hydraulic servo 8
Line pressure is supplied to 0 to engage clutch 8. Further, the inhibitor valve 220 is supplied with the line pressure of the line oil pressure output oil passage 104 to the hydraulic servo 70 to engage the clutch 7 in the same manner as in the case of two-wheel drive.
As a result, the transfer device 10 becomes directly connected to four-wheel drive. <When the driver selects 4-wheel drive deceleration traveling> The selection valve 201 controls the line hydraulic output oil path 10.
4 is connected to the oil passage 202 and the oil passage 203, so that the line pressure supplied to the oil passage 202 is supplied to the hydraulic servo 80 to engage the clutch 8 and the oil The line pressure led to the passage 203 is regulated by a modulator valve 210 to generate a modulator pressure in the oil passage 213. When the vehicle speed is above a predetermined value (when the governor pressure is above a certain value A), the governor pressure guided from the oil passage 111 to the oil chamber 224 of the inhibitor valve 220 is the modulator pressure that acts on the oil chamber 223 from the oil passage 213. The spool 221 is set upward as shown in the figure.
As a result, the inhibitor valve 220 supplies the line pressure of the line hydraulic output oil passage 104 to the hydraulic servo 70, engages the clutch 7, and transfers the transfer device 10.
maintains 4-wheel drive direct connection. When the vehicle speed is less than a predetermined value (when the governor pressure is less than a certain value A), the spool 221 moves downward in the figure due to the modulator pressure acting on the oil chamber 223, and the line oil pressure output oil passage 104 and oil The passage 226 is connected to connect the oil passage 225 to the oil drain port 227. The pressure oil of the hydraulic servo 70 of the clutch 7 is discharged from the oil drain port 227 and the clutch 7 is released, and the line pressure of the line hydraulic output oil passage 104 is led to the hydraulic servo 50 of the brake 5 through the oil passage 226 to discharge the brake. 5 and enters the four-wheel drive deceleration state. In the 4-wheel drive deceleration state, the vehicle speed increases and the governor pressure reaches the set value B (B>A)
When the pressure exceeds that level, the governor pressure overcomes the modulator pressure and moves the spool 221 upward in the figure, cutting off the communication between the oil passage 104 and the oil passage 226, and the oil passage 226 is disconnected from the oil passage 226.
26 is connected to the oil drain port 228, and further the line oil pressure output oil passage 104 and the oil passage 225 are connected. The pressure oil of the hydraulic servo 50 is discharged through the oil passage 226 and the oil drain port 228, and the brake 5 is released.
Line pressure is supplied to the hydraulic servo 70 through the oil passage 225, the clutch 7 is engaged, and the transfer device 10 becomes directly connected to four-wheel drive. The governor pressure A when changing from the 4-wheel drive direct connection state to the 4-wheel drive deceleration state, and the governor pressure B when changing from the 4-wheel drive deceleration state to the 4-wheel drive direct connection state are the pressures applied to the lands 221a and 221b of the spool 221. Due to the difference in area, the force that urges the spool 221 downward in the figure by the modulator pressure against the governor pressure is stronger when the spool 221 is located at the lower side in the figure than when the spool 221 is located at the upper side in the figure. increases, which causes (governor pressure B
>Governor pressure A). In this embodiment, the oil pressure in the line oil pressure output oil passage 104, which is supplied from the oil pump 102 of the main oil pressure control device 100 and regulated by the oil pressure control valve 103, is used as the power source for the main transmission 1 via the manual valve 105. Clutch hydraulic servo C to achieve transmission
1 is selectively supplied to hydraulic servo 5 to supply hydraulic pressure to hydraulic servo 5.
an auxiliary hydraulic pressure having an inhibitor valve 220 which is a switching valve that selectively supplies oil pressure to either 0 or 70; and a selection valve 201 that selectively supplies supply oil pressure to the inhibitor valve 220 and switches the inhibitor valve 220 according to the driver's operation; Since oil pressure is also supplied to the control device 200 from the line oil pressure output oil path 104, when the oil pump is started and oil pressure is generated in the line oil pressure output oil path 104, oil pressure is supplied to the auxiliary oil pressure control device 200. The selection valve 201 of the auxiliary hydraulic control device 200 selectively supplies hydraulic pressure to the inhibitor valve 220 according to the driver's operation, and the inhibitor valve 220 is switched according to the hydraulic pressure from the speed selection valve 201, and the transfer device 10 Hydraulic pressure is supplied to the hydraulic servo 50 or 70. For this purpose, the main transmission 1 is operated so that the driver puts the four-wheel drive automatic transmission into the power transmission state.
Before the driver operates the manual valve 105, the transfer device 10 is in a state where it can transmit the output from the main transmission 1 to the first output shaft 3, so when the driver operates the manual valve 105, the transfer device 10 There is no engagement shock associated with engagement of the clutch 7 or brake 5 of the device 10, and a smooth power transmission state is achieved. FIG. 4 shows a hydraulic control device according to a second embodiment, in which the auxiliary hydraulic control device 20 of the transfer device 10
0 is solenoid valve 230, 240, switching valve 25
0, an oil passage 237 that communicates with the inhibitor valve 260, the solenoid valve 230 and the switching valve 250, and an oil passage 2 that communicates the solenoid valve 240 and the inhibitor valve 260.
47, an oil passage 290 that communicates the inhibitor valve 260 and the hydraulic servo 70, an oil passage 291 that communicates the inhibitor valve 260 and the hydraulic servo 50, an oil passage 292 that communicates the switching valve 250 and the hydraulic servo 80, an oil passage 29
0 and check valves 270 and 280 provided in the oil passage 291, respectively, and the solenoid valve 2
30, 240, the switching valve 250 and the inhibitor valve 260 are supplied with line pressure from the line hydraulic output oil passage 104 of the main hydraulic control device 100, and the inhibitor valve 260 is supplied with governor pressure from the oil passage 111 of the main hydraulic control device 100. is supplied. In this embodiment, a two-wheel drive/four-wheel drive selection solenoid valve 230 and a gear stage selection solenoid valve 240 are used as selection valves.
30 generates hydraulic pressure according to the selection operation between two-wheel drive driving and four-wheel drive driving by the driver, and selectively supplies the line pressure of the line hydraulic output oil passage 104 to the hydraulic servo 80 via a switching valve to be described later. Exhaust, solenoid valve 2
Reference numeral 40 supplies hydraulic pressure to the inhibitor valve 260 according to the speed selection operation for direct drive and deceleration drive performed by the driver, and the moving core 23
1,241, solenoids 232, 242, springs 233, 243, openings 234, 244, oil drain ports 235, 245;
When 242 is energized, moving cores 231, 2
41 upward in the drawing to open the openings 234 and 244, and the pressure oil in the oil passages 237 and 247 partitioned by the orifices 236 and 246 is drained to the oil drain ports 235 and 2.
Discharge from 45. When the solenoids 232 and 242 are de-energized, the moving cores 231 and 24
1 is moved downward in the drawing by springs 233 and 243 to close the openings 234 and 244, and the oil passage 23
7,247 generates hydraulic pressure (line pressure). The solenoid valves 230 and 240 are operated as shown in Table 2 by operating a switch provided at the driver's seat.

[Table] The switching valve 250 has a spool 251 and a spring 2.
52, an oil chamber 253, and a solenoid valve 230
The communication between the line oil pressure output oil passage 104 and the oil passage 292 is controlled in accordance with the pressure oil acting on the oil chamber 253 by the operation. The inhibitor valve 260 has spools 261, 26
2. An oil chamber 264 to which hydraulic pressure is supplied according to the operation of the solenoid valve 240 via a spring 263 and an oil passage 247, an oil chamber 265 to which governor pressure is supplied via an oil passage 111, and a spool 262 are located in the upper part of the figure. It consists of an oil chamber 266 to which governor pressure is supplied from the oil passage 111 through a hole 269 provided in the spool 262 when the spool 262 is in the position. This is a switching valve that restricts communication between the line oil pressure output oil passage 104 and the oil passages 290 and 291 according to the governor pressure. Next, its operation will be explained. <When the driver selects two-wheel drive driving> Both the solenoid valves 230 and 240 are de-energized, and line pressure is generated in the oil passages 237 and 247.
The line pressure of the oil passage 237 is the oil chamber 25 of the switching valve 250.
3, the spool 251 is moved downward in the figure, the line oil pressure output oil passage 104 and the oil passage 292 are cut off, and the clutch 8 is released. The line pressure of the oil passage 247 acts on the oil chamber 264 of the inhibitor valve 260 to move the spools 261 and 262 downward in the figure, thereby communicating the oil passage 104 and the oil passage 290, and connecting the oil passage 291 to the oil drain port 268. Then, the pressure oil in the line oil pressure output oil passage 104 is guided to the hydraulic servo 70 via the check valve 270 to engage the clutch 7 and release the brake 5. This puts the transfer device 10 in a two-wheel drive state. <When the driver selects 4-wheel drive direct connection> Since the solenoid valve 230 is energized, the oil path 2
37 pressure oil is discharged from the oil drain port 235 and the switching valve 2
A spool 251 of 50 is moved upward in the drawing by a spring 252 to connect the line oil pressure output oil passage 104 and the oil passage 292. Line hydraulic output oil path 10
4 is led to the hydraulic servo 80 through the oil passage 292, and the clutch 8 is engaged. Further, since the solenoid valve 240 is de-energized, the clutch 7 is also engaged in the same manner as in the case of two-wheel drive. As a result, the transfer device 10 becomes directly connected to four-wheel drive. <When the driver selects 4-wheel drive deceleration traveling> The solenoid valve 230 is energized, and the clutch 8 is engaged in the same manner as when the 4-wheel drive is directly connected.
Also, the solenoid valve 240 is energized and the oil path 24
Pressure oil 7 is discharged from the oil drain port 245. When the vehicle speed is above a predetermined value (when the governor pressure is above a certain value A), when the governor pressure acting on the oil chamber 265 is above a certain value A, the spool 262 is moved against the spring 263 to the lower position shown in the figure. The clutch 7 is engaged in the same way as when the four-wheel drive is directly connected, and the transfer device 10 maintains the four-wheel drive directly connected state. When the vehicle speed is less than a predetermined value (when the governor pressure is less than the constant value A), the spring 26
The force of 3 moves the spool 262 upward in the figure, disconnects the line hydraulic output oil passage 104 from the oil passage 290, connects the oil passage 290 to the oil drain port 267, and discharges the pressure oil from the hydraulic servo 70. When the clutch 7 is released, the line hydraulic output oil passage 104 and the oil passage 2 are
91, pressure oil is supplied to the hydraulic servo 50 via the check valve 280, and the brake 5 is engaged.
When the clutch 7 is released and the brake 5 is engaged, the transfer system 10 is in a four-wheel drive deceleration state. When the spool 262 moves upward in the figure, governor pressure is supplied to the oil chamber 266 through the hole 269, and the governor pressure in the oil chamber 266 urges the spool 262 upward in the figure, so the vehicle speed increases from this state. Even if the governor pressure increases, the spool 262 does not move, and the transfer device 10 maintains the four-wheel drive deceleration state. In this embodiment, the oil pressure in the line oil pressure output oil passage 104, which is supplied from the oil pump 102 of the main oil pressure control device 100 and regulated by the oil pressure control valve 103, is used as the power source for the main transmission 1 via the manual valve 105. Clutch hydraulic servo C to achieve transmission
The inhibitor valve 260 is a switching valve that selectively supplies the supplied hydraulic pressure to the hydraulic servo 50 or 70, and selectively supplies the supplied hydraulic pressure to the inhibitor valve 260 according to the operation of the driver. Hydraulic pressure is also supplied to the sub-hydraulic control device 200 having a solenoid valve 240 that switches the inhibitor valve 260 from the line hydraulic output oil passage 104. Hydraulic pressure is supplied to the sub-hydraulic control device 200 at the time when The hydraulic pressure is switched depending on the hydraulic pressure from the solenoid valve 240, and the hydraulic pressure is supplied to the hydraulic servo 50 or 70 of the transfer device 10. For this purpose, before the driver operates the manual valve 105 of the main transmission 1 to put the four-wheel drive automatic transmission into the power transmission state, the transfer device 10 transfers the output from the main transmission 1 to the first output. Since the power can be transmitted to the shaft 3, when the driver operates the manual valve 105, no engagement shock occurs when the clutch 7 or brake 5 of the transfer device 10 is engaged, and the power is smoothly transmitted. is achieved. Further, in this embodiment, the switching valve 250 is switched not to supply hydraulic pressure to the hydraulic servo 80 by the hydraulic pressure generated by the solenoid valve 230, but when the driver selects the two-wheel drive state, the oil pump 102 is switched off. Started and line oil pressure output oil line 1
04, the solenoid valve 230 supplies hydraulic pressure to the switching valve 250 according to the driver's operation, and the switching valve 250 is switched by the hydraulic pressure from the solenoid valve 230, and the hydraulic pressure of the transfer device 10 is changed. Hydraulic pressure is not supplied to the servo 80. For this purpose, the manual valve 105 of the main transmission 1 is operated so that the driver puts the four-wheel drive automatic transmission into the power transmission state.
Since the transfer device 10 cuts off the power transmission from the main transmission 1 to the second output shaft 17 before operating the manual valve 105, there is a delay in releasing the clutch 8 of the transfer device 10 when the driver operates the manual valve 105. No accompanying shock occurs, and a two-wheel drive power transmission state is achieved smoothly. FIG. 5 shows a hydraulic control device according to a third embodiment, in which the sub-hydraulic control device 20 of the transfer device 10
0 is solenoid valve 300, 310, switching valve 23
0, an oil passage 237 that communicates the inhibitor valve 330, the solenoid valve 300 and the switching valve 320, and an oil passage 2 that communicates the solenoid valve 310 and the inhibitor valve 330.
47, oil passage 290 that communicates the inhibitor valve 330 and the hydraulic servo 70, oil passage 291 that communicates the inhibitor valve 330 and the hydraulic servo 50, oil passage 292 that communicates the switching valve 320 and the hydraulic servo 80, oil passage 29
0 and check valves 340 and 350 provided in the oil passage 291, respectively, and the solenoid valve 3
00, 310, the line pressure is supplied to the switching valve 320 and the inhibitor valve 330 from the line hydraulic output oil passage 104 of the main hydraulic control device 100, and the governor pressure is supplied to the inhibitor valve 380 from the oil passage 111 of the main hydraulic control device 100. is supplied. In this embodiment, a solenoid valve 30 for selecting two-wheel drive and four-wheel drive is used as a selection valve, similarly to the second embodiment.
0, a solenoid valve 310 for gear selection is used, and the solenoid valve 300 generates hydraulic pressure according to the driver's selection operation between two-wheel drive driving and four-wheel drive driving, and the line hydraulic pressure is generated via the switching valve 320. The line pressure of the output oil passage 104 is selectively supplied to and discharged from the hydraulic servo 80, and the solenoid valve 310 supplies hydraulic pressure to the inhibitor valve 330 according to the speed selection operation between direct driving and deceleration driving performed by the driver. . The solenoid valves 300 and 310 have the same structure as that shown in FIG. 4, and their operation is as shown in Table 3.

[Table] The switching valve 320 has a spool 321 and a spring 3.
22, an oil chamber 323, and a solenoid valve 300
The communication between the line oil pressure output oil passage 104 and the oil passage 292 is controlled according to the pressure oil acting on the oil chamber 323 by the operation of the oil passage 292 . The inhibitor valve 330 has spools 331 and 33
2. An oil chamber 335 to which hydraulic pressure is supplied according to the operation of the solenoid valve 310 via a spring 333 and an oil passage 247, an oil chamber 336 to which governor pressure is supplied via an oil passage 111, and a spool 331 are located in the upper part of the figure. It consists of an oil chamber 337 to which governor pressure is supplied from the oil passage 111 through a hole 339 provided in the spool 331 when the spool 331 is in the position. This is a switching valve that restricts communication between the line oil pressure output oil passage 104 and the oil passages 290 and 291 according to the governor pressure. Next, its operation will be explained. <When the driver selects two-wheel drive driving> Since the solenoid valves 300 and 310 are both energized and the oil passages 237 and 247 are exhausted, the switching valve 32
The spring 322 of 0 moves the spool 321 upward in the drawing, cuts off the line oil pressure output oil passage 104 and the oil passage 292, and releases the clutch 8. The spools 261 and 262 of the inhibitor valve 330 are positioned downward in the drawing by a spring 334, and communicate the line oil pressure output oil passage 104 and the oil passage 290, and also connect the oil passage 291 with the oil drain port 338, and the line oil pressure output oil passage Pressure oil 104 is introduced to the hydraulic servo 70 through the check valve 340 to engage the clutch 7 and release the brake 5. This puts the transfer device 10 in a two-wheel drive state. <When the driver selects direct 4-wheel drive driving> Since the solenoid valve 300 is de-energized, line pressure is generated in the oil passage 237, and the spool 321 of the switching valve 320 moves downward in the figure, causing line hydraulic output oil to flow. The passage 104 and the oil passage 292 are connected. The pressure oil in the line hydraulic output oil passage 104 is led to the hydraulic servo 80 through the oil passage 292, and the clutch 8 is engaged. Also, since the solenoid valve 240 is energized, the 2
The clutch 7 is also engaged in the same manner as when driving the wheels. As a result, the transfer device 10 becomes directly connected to four-wheel drive. <When the driver selects 4-wheel drive deceleration traveling> The solenoid valve 300 is de-energized, and the clutch 8 is engaged in the same manner as when the 4-wheel drive is directly connected. In addition, the solenoid valve 310 is also de-energized, and line pressure is generated in the oil passage 247, causing the inhibitor valve 33
0 oil chamber 335, and the inhibitor valve 330
The spool 332 is located at the top in the figure. When the vehicle speed is above a predetermined value (when the governor pressure is above a certain value A), when the governor pressure acting on the oil chamber 336 is above a certain value A, the spool 331 is moved against the spring 333 to the lower position shown in the figure. The clutch 7 is engaged in the same manner as when the four-wheel drive is directly connected, and the transfer device 10 maintains the four-wheel drive directly connected state. When the vehicle speed is less than a predetermined value (when the governor pressure is less than a certain value A), the spool 331 is moved upward in the figure by the force of the spring 333, and the line oil pressure output oil passage 104 and oil passage 290 are moved. The line hydraulic output oil path 104 and the oil path 291 are connected and the check valve 350 is opened. Via hydraulic servo 5
0 and engages the brake 5. When the clutch 7 is released and the brake 5 is engaged, the transfer system 10 is in a four-wheel drive deceleration state. When the spool 331 moves upward in the figure, the oil chamber 337
is supplied with governor pressure through the hole 339, and the governor pressure in the oil chamber 337 urges the spool 331 upward in the figure, so even if the vehicle speed increases and the governor pressure increases from this state, the spool 331 will not move. No, 4
Maintain wheel drive deceleration state. In this embodiment, as in the second embodiment, the transfer device 10 is activated before the driver operates the manual valve 105 of the main transmission 1 so that the four-wheel drive automatic transmission is in the power transmission state. The output from the transmission 1 can be transmitted to the first output shaft 3,
When the driver operates the manual valve 105, no engagement shock accompanies the engagement of the clutch 7 or brake 5 of the transfer device 10, and a smooth power transmission state is achieved. Further, in this embodiment, the switching valve 320 is switched to supply hydraulic pressure to the hydraulic servo 80 by the hydraulic pressure generated by the solenoid valve 300, but when the driver selects the four-wheel drive state, the oil pump 102 is switched on. Started and line hydraulic output oil line 10
4, the solenoid valve 300 supplies hydraulic pressure to the switching valve 320 according to the driver's operation, and the switching valve 320 is switched by the hydraulic pressure from the solenoid valve 300, and the hydraulic pressure of the transfer device 10 is changed. Hydraulic pressure is supplied to the servo 80. For this purpose, before the driver operates the manual valve 105 of the main transmission 1 to bring the four-wheel drive automatic transmission into the power transmission state, the transfer device 10 transfers the power to the main transmission 1.
Since the output from the transfer device 10 can be transmitted to the second output shaft 17, when the driver operates the manual valve 105, there is no engagement shock caused by the engagement of the clutch 8 of the transfer device 10, and the operation is smooth. It is possible to set the vehicle to four-wheel drive mode.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a transfer device, FIG. 2 is a schematic diagram showing a power transmission system of a vehicle, and FIG. 3 is a hydraulic circuit diagram showing an embodiment of a hydraulic control device for a four-wheel drive automatic transmission. FIGS. 4 and 5 are hydraulic circuit diagrams showing other embodiments of the hydraulic control device for the four-wheel drive automatic transmission. DESCRIPTION OF SYMBOLS 1...Main transmission, 2...Output shaft of main transmission, 5...Friction brake, 7, 8...Friction clutch, 10...Transfer device, 100...Main hydraulic control device, 102
...Oil pump, 103...Hydraulic control valve, 104...
Line hydraulic output oil path, 105...Manual valve, 2
00...Auxiliary hydraulic control device, 201, 230, 24
0,300,310...selection valve, 220,260,
330...inhibitor valve, 250,320...switching valve.

Claims (1)

[Claims] 1. A first hydraulic friction engagement device that is engaged by the supply of hydraulic pressure, and the power from the engine is transmitted through the engagement of the first hydraulic friction engagement device. a main transmission having an output shaft; and a main transmission having an output shaft;
a main hydraulic control device that selectively supplies hydraulic pressure to the hydraulic friction engagement device; a second hydraulic friction engagement device that is engaged by the supply of hydraulic pressure; and the second hydraulic friction engagement device. a transfer device having an output shaft to which power is transmitted from the output shaft of the main transmission by engagement of the transfer device; In a four-wheel drive automatic transmission equipped with an auxiliary hydraulic control device that selectively supplies and discharges oil to and from a hydraulic friction engagement device, the main hydraulic control device includes an oil pump and a line to which oil discharged from the oil pump is supplied. a hydraulic output oil passage, a hydraulic control valve that regulates the oil pressure of the line oil pressure output oil passage, and selects the oil pressure of the line oil pressure output oil passage to the first hydraulic friction engagement device in accordance with an operation by a driver. a manual valve that selectively supplies the supplied hydraulic pressure to the second hydraulic friction engagement device; and a manual valve that selectively supplies the supplied hydraulic pressure to the second hydraulic friction engagement device; and a selection valve that selectively supplies hydraulic pressure to the switching valve to switch the switching valve, and the hydraulic pressure supplied from the main hydraulic control device to the auxiliary hydraulic control device is supplied from the line hydraulic output oil path. A four-wheel drive automatic transmission characterized by: 2. The output shaft of the transfer device is a second output shaft connected to the first output shaft of the transfer device connected to the output shaft of the main transmission via the second hydraulic friction engagement device. An automatic transmission for four-wheel drive according to claim 1, characterized in that: 3. The output shaft of the transfer device is connected to the output shaft of the main transmission via a gear device, and the gear device changes a predetermined gear stage by engagement of the second hydraulic friction engagement device. An automatic transmission for four-wheel drive according to claim 1, which achieves the following: