JPH0198741A - Hydraulic control device for automatic transmission - Google Patents

Abstract

PURPOSE:To prevent breakage of a clutch and a shock of a vehicle by interrupting an oil path connecting a manual valve and a backward driving means through a hydraulic directional control valve by generated oil pressure of oil pressure generating means during forward running at a high speed ratio. CONSTITUTION:A signal oil pressure of a speed change ratio control solenoid valve 301 is input to a port 183 of a hydraulic directional control valve 180, and the signal oil pressure P1 is controlled by a controller 300 in such a manner as to become low at a low speed ratio and high at a high speed ratio. Accordingly, during forward running at a high speed ratio, even if a shift lever is switched from D range to R range in error, a backward hydraulic system is interrupted by the hydraulic directional control valve 180, and as a forward-backward switching piston 150 is always urged towards forward position F by a spring 155, the lever is kept from being switched to backward driving. Thus, reliable fail-safe for misshift can be accomplished so that breakage of a driving system such as a dog clutch or the like can be prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a hydraulic control system for an automatic transmission, particularly a safety mechanism when the shift lever is mistakenly switched to the reverse position (R range) during forward high speed ratio running. It is related to.

[Prior art and its problems]

Conventionally, in a continuously variable transmission, which is an example of an automatic transmission, a dog clutch for forward/reverse switching and a hydraulic starting clutch are provided as a forward/reverse switching mechanism. A device has been proposed that allows switching
Publication No.).

The hydraulic control device includes a manual valve that is manually operated;
It has a forward/reverse switching piston that switches the dog clutch, and a clutch control valve that controls the hydraulic pressure supplied to the starting clutch.When reversing, hydraulic pressure is introduced from the manual valve to the forward/reverse switching piston, and the hydraulic pressure is supplied to the clutch control valve. Hydraulic pressure is supplied from the above-mentioned manual valve except when switching forward or backward.

However, in the hydraulic control system U having the above configuration, when the driver is in a forward high-speed driving state such as in the D or L range, the driver accidentally switches the shift lever to the R range (reverse position).
If this occurs, the reverse hydraulic pressure is guided from the manual valve to the forward/reverse switching piston, causing the dog clutch to switch to the reverse position. Therefore, not only is there a sudden shock, but there is also a risk that the dog clutch may be damaged.

In addition, instead of the above-mentioned tongue clutch type forward/backward switching mechanism,
Even in a continuously variable transmission equipped with a forward hydraulic clutch and a reverse hydraulic clutch (for example, Japanese Patent Laid-Open No. 59-62761), when the shift lever is switched to the reverse position during forward driving as described above, Since the forward hydraulic clutch is disengaged and the reverse hydraulic clutch is engaged, there is a risk of clutch failure or shock.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problems, and its purpose is to prevent the reverse drive state from occurring even if the shift lever is switched to the reverse position during forward high speed ratio driving, improve safety and improve clutch An object of the present invention is to provide a hydraulic side TJ device for an automatic transmission that can prevent damage such as the above.

[Means for Solving the Problems] The hydraulic control device for an automatic transmission according to the present invention can be switched to each range position by manual I/O operation, and can supply hydraulic pressure from a hydraulic source to the forward drive means or the reverse drive means. A manual valve that selectively leads, a hydraulic pressure generating means that generates different hydraulic pressures in the high speed ratio range and low speed ratio range, and a hydraulic pressure generating means that operates by the hydraulic pressure generated by the hydraulic pressure generating means to open and close the oil passage from the manual valve to the reverse drive means. and a hydraulic switching valve, the hydraulic switching valve having:
The present invention is characterized in that when hydraulic pressure in a high-speed ratio range is introduced from the hydraulic pressure generating means, the oil passage from the manual valve to the reversing drive means is closed.

[Effect]

That is, during forward high-speed ratio running, the hydraulic cutoff valve shuts off the oil passage connecting the manual valve and the reverse drive means by the hydraulic pressure generated by the hydraulic pressure generating means, so even if the manual valve is accidentally switched to the reverse position. Also, the hydraulic pressure supplied from the hydraulic source is not supplied to the reversing drive means. Therefore, there is no switching to reverse drive, and damage to the clutch and vehicle shock are prevented.

〔Example〕

FIG. 1 shows a schematic configuration of a belt-type continuously variable transmission, which is an example of an automatic transmission according to the present invention.

In the drawing, a crankshaft 2 of an engine 1 is connected to an input shaft 5 via a flywheel 3 and a damper mechanism 4. A direct coupling clutch 6 and a rotatable direct coupling drive gear 7 are provided on the input shaft 5, and the direct coupling clutch 6 couples the direct coupling drive gear 7 to the input shaft 5 during direct coupling driving. An external gear 8 is fixed to the end of the input shaft 5.
This external gear 8 meshes with an internal gear 9 fixed to a drive shaft 11 of a continuously variable transmission 10 to decelerate the power of the input shaft 5 and transmit it to the drive shaft 11.

The continuously variable transmission 10 includes a drive pulley 1 provided on a drive shaft II.
2, a driven pulley 14 provided on the driven shaft 13, and a belt 15 wound between both pulleys. The drive pulley 12 has a fixed sheave 12a and a movable sheave 12b.
A gear ratio control oil chamber 16 for controlling the gear ratio is provided behind the movable sheave 12b. On the other hand, the driven side boot 4 also has a fixed sheave 14a and a movable sheave 14b like the drive side boot 14, and behind the movable sheave 14b is a belt that transmits the load thrust necessary for torque transmission. An oil chamber 17 for controlling the load thrust applied to the engine 15 is provided. The oil pressure in the gear ratio control oil chamber 16 and the load thrust control oil chamber 17 is controlled by a hydraulic control device described later.

A hollow shaft 19 is rotatably supported on the outer periphery of the driven shaft 13, and the driven shaft 13 and the hollow shaft 19 are connected to a starting clutch 20.
Interrupted by This starting clutch 20 is engaged or loosely engaged during belt drive, and is disconnected during direct drive. The forward gear 21 is mounted on the driven shaft 13, and the reverse gear 2
2 are rotatably supported on a hollow shaft 19, and either the forward gear 21 or the reverse gear 22 is connected to the hollow shaft 19 by a forward/reverse switching dog clutch 23. The reverse idler shaft 24 includes a reverse idler gear 25 that meshes with the reverse gear 22;
Another reverse idler gear 26 is fixed. Further, the reduction shaft 27 is provided with the above-mentioned direct drive gear 7 and the forward gear 21.
A reduction gear 28 and a final reduction gear 29 are fixed, which mesh with the reverse idler gear 26 at the same time, and the final reduction gear 29 is connected to the ring gear 31 of the differential device 30.
and transmits power to the output shaft 32.

In the continuously variable transmission with a direct coupling mechanism, the input shaft 5, the direct coupling clutch 6, the direct coupling drive gear 7, the reduction gear 28, the final reduction gear 29, the differential device 30, and the output shaft 32 constitute a direct coupling drive path, and the input shaft 5 , external gear 8, internal gear 9
, continuously variable speed bag ff1o, starting clutch 20, forward gear 21, reduction gear 28, final reduction gear 29, differential device 30, and output shaft 32 constitute a continuously variable speed path (during forward movement). The input shaft 5 in the direct drive path
The direct transmission ratio i between the input shaft 5 and the output shaft 32 is the highest speed ratio i between the input shaft 5 and the output shaft 32 in the continuously variable transmission path. , 7.

FIG. 2 shows a hydraulic control device, roughly showing the first pressure regulating valve 100.
, manual valve 110, second pressure regulating valve 120, direct control valve 130, three-way valve 140, forward/reverse switching piston 150, clutch control valve 160, hydraulic switching valve 180, gear ratio control valve 190, coast down control valve 200, load thrust Control valve 21O, controller 300, solenoid valve 30 for speed ratio control
1. Solenoid valve 302 for load thrust control, solenoid valve 3 for direct control
It consists of 03.

The oil pump 33 pumps the oil sucked up from the oil sump 34 into the 11th pump.
Right end boat 101 and intermediate boat 102 of the 1-pressure valve 100
The spool 103 moves to the left against the spring 104 due to the hydraulic pressure of the right end boat 101, and when the land 103a of the spool 103 reaches the position shown in the drawing, the intermediate boat 102 and the drain boat 105 communicate with each other. The oil is then returned to the suction side of the oil pump 33. Therefore, the spool 103 is balanced at this position, and the discharge oil pressure of the oil pump 33 is regulated to a predetermined line pressure PL. Note that the boat lO7 and port 10B provided at corresponding positions of the intermediate boat 102 are lubricating boats. A load thrust control hydraulic pressure Ps is introduced from a load thrust control valve 210 (described later) to the back pressure chamber 109 that accommodates the spring 104, and the line pressure P, the load thrust control hydraulic pressure P, and the spring 104 are
The hydraulic pressure is regulated to match the sum of the loads. Therefore, when the load thrust control oil pressure P increases, the line pressure PL
As a result, the load thrust control hydraulic pressure P increases synergistically, making it possible to speed up the shift to a low speed ratio.

The manual valve 110 operates in conjunction with the shift lever to control P and R.
, N, D, and L positions, and the spools 111 actuate the input capo 112.
For example, in the D range, line pressure is output from the boat 113 and the boat 114 is drained, as shown in the figure. The L range is the same as the D range, and in the R range, boat l13 is drained,
Line pressure is output from the boat 114. Furthermore, in the P range, the input port 112 is closed by the land 111a, and in the N range, the input port 112 and the output port 1 are closed.
Since the space between 13 and 114 is cut off by lands 1lla and 1llb, both output ports are drained.

The spool 121 of the second pressure regulating valve 120 has a spring 122
The spool 121 is biased to the left by the input capo 4123 to which line pressure is input from the second pressure regulating valve 100.
and the drain boat 124 are selectively opened and closed, and hydraulic pressure Pa is output from the output port 25. The output oil pressure P is fed back to the left end chamber 126 through a communication hole 121a provided inside the spool 121, so that the output oil pressure P0 is regulated to a constant pressure that is balanced only by the spring load. The above output oil pressure P6 is generated by three solenoid valves 301, 3.
It is input at 02,303.

The direct coupling control valve 130 is a valve for controlling the direct coupling clutch 6, and has a spool 131 biased leftward by a spring 132. During direct drive (shown in the lower half of the drawing), the spring load and the signal hydraulic pressure P of the direct control solenoid valve 303 led to the left end chamber 133 are opposed to each other, and the spool 131 receives line pressure from the manual valve 110. The input port 134 and the drain boat 135 are selectively opened and closed, and the hydraulic pressure P is input from the output port 136 to the boat 1 of the clutch control valve 160, which will be described later as a direct coupling clutch 6.
62. Output oil pressure P is spool 131
The spring 13 is connected through a communication hole 131a provided inside the
2 is placed in the right end chamber 137, and as a result, the sum of the output oil pressure P and the spring load,
In addition, the input port 13 is balanced with the signal oil pressure P.
4, the line pressure P is input from the output port 113 of the manual valve 110 only during forward movement (D, L), so in other ranges, especially in the R range, the output oil pressure P is independent of the signal oil pressure P. It becomes zero and does not become a direct drive. When belt driven (shown in the upper half of the drawing), the boat 13
8, the output oil pressure P4 of the clutch control valve 160 is input, so the spool 131 is forcibly moved to the left end position, and the oil pressure P of the direct connection clutch 6 is drained regardless of the operation of the direct connection control solenoid valve 203. Ru.

In addition, the direct control valve 13 (l is the direct control valve 1
By duty-controlling the magnetic valve 303, it is possible to gradually increase the oil pressure P to the direct coupling clutch 6 and perform an emergency start via the direct coupling drive path.

The three-way valve 140 is connected to the output capo r11 of the manual valve 110.
The line pressure PL during forward movement is introduced from the input port 134 of the direct-coupled control valve 130 from 3 to the human-powered boat 141, and the line pressure PL during backward movement is introduced from the output port 114 of the manual valve 110 through a hydraulic switching valve 180, which will be described later. has an input port 142 to which the hydraulic pressure is introduced, and an output port 143 that outputs hydraulic pressure to the input port 163 of the clutch control valve 160.
The ball 144 is reversed by the hydraulic pressure selectively input to the input boats 141, 142, and selectively outputs the hydraulic pressure.

The forward/backward switching piston 150 has left and right oil chambers 151, 152.
a piston member 153 that can be moved by hydraulic pressure acting on the piston member 153;
A fork shaft 154 is connected to this piston member 153 to operate a dog clutch 23 for forward/reverse switching. The fork shaft 154 is always urged toward the forward position (F) by a spring 155. Output capo 1 of the manual valve 110 in the right ventricle 152
When the line pressure PL is led from -113 through the input port 134 of the direct control valve 130 during forward movement, the state shown in the upper half of the drawing occurs, and the left ventricle 151 is connected to the hydraulic switching valve 180 (described later) from the output port 114 of the manual valve 110. When the line pressure PL is introduced through the vehicle during reversing, the state shown in the lower half of the drawing is reached. The right chamber 152 is connected to the outside oil via a one-way valve 156, and when the R range is switched to the P or N range, the spring 155 prevents the oil from flowing when the piston member 153 moves to the forward position. It makes inhalation easier and reduces operating time.

The clutch control valve 160 is a valve for controlling the starting clutch 20, and has a sleeve 161 forming a total of six boats 162 to 167, and a spool 168 is slidably disposed within the sleeve 161. .

The spool 16B is biased from the left by a first spring 169, biased from the right by a second spring 170 and a third spring 71, and the second and third springs 1
The sum of the loads 70.171 is greater than the load of the first spring 169. Oil pressure P is input to the boat 162 from the direct control valve 130, and the three-way valve 140 is input to the input port 163.
Forward hydraulic pressure or reverse hydraulic pressure is input from the boat 164.
outputs hydraulic pressure P4 to the starting clutch 20 and the signal hydraulic boat 138 of the direct connection control valve 130, and the boat 165 is a drain boat. Further, the boat 166 is connected to an output port 206 of a coastdown control valve 200, which will be described later, and a signal hydraulic pressure P3 is guided to the boat 167 at the right end from the IA electromagnetic valve 02 for load thrust control. In addition,? ! Magnetic valve 302
An orifice 35 and a one-way valve 36 are provided between the
are connected in parallel, and the orifice 35 reduces the pulsation of the signal oil pressure Pt, and drains the signal oil pressure P2 through the one-way valve 36 when the solenoid valve 302 is turned off.
It is possible to eliminate poor disengagement of the starting clutch 20. The output oil pressure P4 is fed back to the chamber 172 housing the first spring 169 through a communication hole 168a formed inside the spool 168. Further, a piston 174 is attached to the right end of the spool 168 with a fourth spring 173 in between.
is slidably arranged, and the signal oil pressure P2 input to the right end boat 167 is applied to the piston 174 and the fourth spring 1.
73 to push the spool 168 to the left, and the signal hydraulic pressure P
The pulsation of □ is absorbed by a kind of accumulator mechanism. The chamber housing the fourth spring 173 is connected to the drain port 165 through the communication hole 168b of the spool 168.
It communicates with

The back of the first spring 169 is supported by a plug 175 that is slidably fitted to the left end of the sleeve 161, and the back of the plug 175 is supported by a creep adjustment bolt 176.
It is supported by By turning the bolt 176, the load on the first spring 169 can be increased or decreased, and the creep torque of the starting clutch 20 can be finely adjusted.

The upper half of the clutch control valve 160 in FIG.
is OF F (P3 = 0), and the load thrust control solenoid valve 302 is in operation (P, = O ~ 3 kg/c + w'), so the load thrust control solenoid valve 30 is in the starting clutch 20.
2 signal oil pressure P2 and 2nd. Third spring 170, 17
1, the load of the first spring 169, and the chamber 17.
Output oil pressure P fed back to 2.

The output oil pressure P4 is regulated. Since the output oil pressure P is input to the port 138 of the direct coupling control valve 130 in addition to the starting clutch 20, the direct coupling control valve 130 moves to the left end position as shown in the upper half of FIG. It will definitely be blocked.

During idling in the driving range (D, L, R), the signal oil pressure P2 input to the right end port 167 becomes 0, but
The first spring 169 and the second spring. Third spring 170.
Since the hydraulic pressure P4 corresponding to the load difference of 171 is output to the starting clutch 2α, the starting clutch 20 generates a constant creep torque. In particular, the second spring 170 is made of a shape memory alloy, and the spring load is constant when warmed up, but when it is cold, the spring load is set to be lower as the temperature decreases, so clutch control is possible. The output oil pressure P of the valve 160 is also regulated low. Therefore, the increase in creep torque due to the increase in the friction coefficient and oil viscosity during cold conditions is corrected by reducing the transmission capacity of the starting clutch 20.

Creep torque can be controlled to be almost constant regardless of warm-up.

In addition, the lower half of the clutch control valve 160 in FIG.
g-0), the direct control solenoid valve 303 is ON (P s ”
3 kg/cm”), so the direct connection control valve 1
30 operates as shown in the lower half of Figure 2, and the direct control valve 1
An output oil pressure P of 30 is input to the signal oil pressure port 162, and the spool 16 is forcibly moved to the right end position. Therefore, the hydraulic pressure P is output from the direct coupling control valve 130 to the direct coupling clutch 6, and the direct coupling clutch 6 is engaged, and the output hydraulic pressure P4 of the clutch control valve 160 is drained, so that the starting clutch 20 is disconnected. In this way, the direct connection control valve 130 and the clutch control valve 160 output oil pressures P, , P
, to each other's ports 138 and 162, it is possible to supply hydraulic pressure to only one of the starting clutch 20 and the direct coupling clutch 6, thereby preventing a so-called double clutch.

The hydraulic switching valve 180 is a valve for switching between a retreat oil path and a lubricating oil path, and has a spool 182 biased leftward by a spring 181. The hydraulic switching valve 180 has six ports 183 to 188, and the left end boat 183
A signal oil pressure P of the solenoid valve 301 for speed ratio control is inputted to. Until the signal oil pressure P+ of the gear ratio control solenoid valve 301 exceeds a certain value (for example, 1.3 kg/cm),
As shown in the upper half of the figure, the spool 182 is at the left end position. In other words, the signal oil pressure Pt of the solenoid valve 301 for speed ratio control
is lower than the spring load near the low speed ratio, so the spool 182 is at the left end position and communicates with the ports 184 and 185, so that the reverse hydraulic pressure output from the output boat 114 of the manual valve 110 is transferred to the three-way valve 140 and the forward/reverse switching piston 150. supply to. At the same time, ports 186 and 187 are communicated, so the lubricating oil output from the first pressure regulating valve 100 is transferred to the boats 186, 187 and the oil cooler 3.
7 directly to the starting clutch 20. In other words,
At a low speed ratio position, the starting clutch 20 is often in a half-engaged state as at the time of starting, so a large amount of lubricating oil is guided to the starting flange 20 to prevent heat generation.

Moreover, the signal oil pressure P of the solenoid valve 301 for speed ratio control.

exceeds a certain value (for example, 1.3 kg/cm"),
As shown in the lower half of the figure, the spool 182 moves to the right end position. That is, when the gear is shifted to a high speed ratio, the signal oil pressure P of the gear ratio control solenoid valve 301 becomes larger than the spring load, so the spool 182 moves to the right end position, closes the boat 184, and moves the boat 185 to the drain boat 1-1. 188
communicate with. Therefore, when driving at high speed, the shift lever
Even if the vehicle is mistakenly switched from the D range to the R range, the reverse hydraulic system is shut off by the hydraulic pressure switching valve 180, so the forward/reverse switching piston 150 does not change to the reverse position. At the same time, the boat 186 is also closed, so lubricating oil is poured into the orifice 3.
8 to the starting clutch 20. In other words, since the starting clutch 20 is engaged at the high-speed ratio position, the need for lubrication is low, and lubricating oil is gradually supplied through the orifice 38. Note that in the direct-coupled crunch engine, there is no half-clutch state except during emergency start-up, so lubricating oil is always supplied through the orifice 39.

The gear ratio control valve 190 is a valve that controls the oil pressure of the gear ratio control oil chamber IG of the drive side boot 2, and the spring 19
It has a spool 192 that is biased leftward by 1. The signal oil pressure P of the gear ratio control solenoid valve 301 is input to the left end chamber 193 via the boat 183 of the oil pressure switching valve 180, and the signal oil pressure P1 is set to a constant value (for example, 1.
0 kg/cm"), the spring load is greater than the signal oil pressure P, so the spool 192 is at the left end position as shown in the upper half of the figure. Therefore, the input port 194 into which the line pressure PL is input is Since it is closed and the output port 195 communicates with the drain boat 196, the gear ratio control oil pressure P.

is drained. When the signal oil pressure P1 of the solenoid valve 301 for speed ratio control exceeds a certain value, the spool 192 overcomes the spring load and moves to the right as shown in the lower half of the figure, causing the spool 192 to move between the input capo 194 and the drain. boat 1
96 is maintained near the position where it is selectively opened and closed. Since the output oil pressure P is fed back to the signal oil pressure boat 197, the pressure is regulated so that the sum of the output oil pressure P6 and the spring load is balanced with the signal oil pressure P1.

The coast down control valve 200 is a valve for forcibly shifting to a low speed ratio during coast down (when the throttle is fully closed and sudden deceleration is performed while driving).
The spool 202 has a spool 202 biased to the right by the spool 202.

The signal oil pressure P of the gear ratio control solenoid valve 301 is input to the signal oil pressure boat 203 via the boat 183 of the oil pressure switching valve 180, and the signal oil pressure P is set at a constant value (for example, 1.0 kg/ cm"), the spool 202 is maintained near the position where the input port 204 into which the line pressure PL is input and the drain boat 205 are selectively opened and closed, as shown in the lower half of the figure. The output oil pressure P7 output from the port 206 is fed back to the right end boat 207 via the communication hole 202a of the spool 202, so the output oil pressure P7 is adjusted so that the sum of the output oil pressure P and the signal oil pressure P is balanced with the spring load. When the signal oil pressure P1 exceeds a certain value, the spool 202 overcomes the spring load and moves to the left end position as shown in the upper half of the figure. 1. Closes the input port 204 and closes the output port 20.
7 communicates with the drain boat 205.

Therefore, the output oil pressure P becomes zero.

The output oil pressure P is applied to the boat 166 of the clutch control valve 160 and the boat 219 of the load thrust control valve 210, which will be described later.
In particular, the output hydraulic pressure P7 input to the clutch control valve 160 urges the spool 168 to the right, and the starting clutch 2
0 clutch oil pressure to a constant value (for example, 0.5 kg/cm
”) is lowering.

The load thrust control valve 210 is a valve for controlling the oil pressure P8 in the load thrust control oil chamber 17 of the driven side boot 14, and includes a main spool 211 and a sub spool 212, and has a main spool 211 and a sub spool 212. A spring 213 is interposed therebetween. The load thrust control valve 210 has an input port 214 into which line pressure PL is constantly input, and an oil chamber 1 for load thrust control.
7 and the back pressure chamber 109 of the first pressure regulating valve 100, an output boat 215 and a drain boat 216 are formed to output the hydraulic pressure P6, and the output hydraulic pressure P is connected to the communication hole 21 of the main spool 211.
It is fed back to the right end chamber 217 via 1a. Therefore, the output oil pressure P.

is connected from the secondary spool 212 to the main spool 2 via the spring 213! ! The pressure is adjusted to balance the load acting on the right side. The sub spool 212 is biased to the right by a spring 218, and the boat 219 housing this spring 218 is equipped with the coast down control valve 20.
An output oil pressure P of 0 is input, and the boat 219
A solenoid valve 30 for load thrust control is installed on the boat 22o adjacent to the
2, the signal oil pressure P2 is input oil pressure. Therefore, the rightward load acting on the main spool 211 is determined only by the load of the spring 213 when the sum of the load of the spring 218 and the signal oil pressures Pg and Pt is smaller than the load of the spring 213 (as shown in the upper half of the drawing). ), spring 2
The sum of the load of 18 and the signal oil pressure Pg, Pt is the spring 2
13, the hydraulic pressure P of the load thrust control oil chamber 17 is determined by the sum of the load of the spring 218 and the signal hydraulic pressure P□+Pff (shown in the lower half of the drawing).
, increases with the oil pressure P4 of the starting clutch 20, and further increases during coasting down to speed up the shift to a low speed ratio.

Note that the line pressure P is input directly to the input port 1-214 of the load thrust control valve 210 without passing through the manual valve 110. The reason for this is that when the N range is set during high-speed driving, the oil pressure of both pulleys 12.14 is turned off, and the belt 15 loosens due to centrifugal force. This is to apply a minimum pressure to the belt 14 so that the belt 15 does not loosen.

The IX magnetic valves 301 to 303 control output oil pressures P+, Ps, and Ps by control signals (for example, duty signals) input from the controller 300, and execute shift control 1 start control and direct connection control, respectively.

Among the solenoid valves 301 to 303, load thrust control solenoid valve 302. The direct control solenoid valve 303 is a normally closed type, whereas the gear ratio control solenoid valve 301 is a normally open type.

Therefore, the solenoid valves 302 and 303 drain when the electric signal is OFF, and generate the maximum signal oil pressure when the electric signal is ON, whereas the solenoid valve 301 generates the maximum signal oil pressure when the electric signal is OFF, and drains when the electric signal is ON.

The reason why the solenoid valve 301 for speed ratio control is configured to be a normally open type is that even if this solenoid valve 301 should fail, the signal oil pressure P1 will be generated and the speed ratio control valve 190 will be actuated to control the speed ratio. This is to increase the control oil pressure P and always shift gears to the high speed ratio side to avoid lock-down caused by sudden downshifts.

In the hydraulic control device having the above configuration, the port H83 of the hydraulic switching valve 180 has the solenoid valve 301 for speed ratio control as described above.
A signal oil pressure P1 is input, and this signal oil pressure P1 is controlled so that it is low at low speed ratios and high at high speed ratios.Therefore, when driving at a forward high speed ratio, the shift lever may be accidentally switched from the D range to the R range. However, the reverse hydraulic system is shut off by the hydraulic switching valve 180, and the forward/reverse switching piston 150 is always biased toward the forward position (F) by the spring 155, so the switch to reverse drive does not occur.Therefore, a misshift occurs. It is possible to realize a reliable fail-safe against damage to the drive system, such as a dog clutch, and prevent damage to the drive system such as a dog clutch.

Also, when running at a ratio other than the forward high speed ratio, that is, when running at the forward low speed ratio.
However, the inertia of the vehicle increases when the vehicle speed exceeds a certain speed (for example, 10 kW+/h), so if the shift lever is mistakenly switched from the forward position to the reverse position, a shock may occur. In order to solve this problem, for example, when the shift lever is switched to R range while the vehicle is moving forward at a certain speed or higher, the electromagnetic gear ratio control electromagnetic Valve 301 generates a high signal oil pressure P1 that is different from the normal shift control pattern. In this way, even if the shift lever is accidentally switched to the R range, the forward/reverse switching piston 150 will not operate to the reverse position.In addition, when the vehicle is traveling backwards in the R range, the shift control pattern will change the speed to the lowest speed. ratio (Low) is maintained,
In other words, since the signal oil pressure P of the gear ratio control solenoid valve 301 is always controlled to be low, there is no risk of switching from reverse drive to forward drive even if the vehicle speed exceeds a certain value.

In the present invention, the gear ratio when the hydraulic switching valve 180 closes the backward oil passage is not limited to only the high speed ratio (a gear ratio smaller than the intermediate gear ratio), but also all gear ratios other than the lowest gear ratio or the vicinity thereof. May include. In the case of the embodiment, the hydraulic pressure when the hydraulic pressure switching valve 180 operates can be set by a spring load, so it is the simplest.

Further, in the above embodiment, the gear ratio control solenoid valve 301 was used as the oil pressure generating means, but Ti is not limited to the valve, and for example, the gear ratio control valve 1 which supplies the oil pressure P to the drive side boot 2.
90 may also be used. In this case as well, the same function can be achieved by manually applying the hydraulic pressure P6, which increases at high speed ratios, to the boat 183 of the hydraulic pressure switching valve 180. Note that the hydraulic pressure generating means is not limited to generating a higher hydraulic pressure in the high speed ratio range than in the low speed ratio range as in the embodiment, but may also generate a lower hydraulic pressure.

Further, in the above embodiment, the forward drive means and the backward drive means are constructed with a forward/reverse switching piston that switches a dog clutch, but they may also be constructed with a forward hydraulic clutch and a reverse hydraulic clutch, and in this case, the present invention also applies. Applicable.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, even if the manual valve is accidentally operated to the reverse position during forward high-speed ratio running, the hydraulic switching valve shuts off the reverse oil passage system, so the reverse drive means Hydraulic pressure is not applied to the drive, and the drive does not switch to reverse drive. Therefore, it is possible to achieve fail-safe against misshifts, and to prevent problems such as switching shock and damage to the drive system.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an example of a belt type continuously variable transmission which is an example of the present invention, and FIG. 2 is a circuit diagram of a hydraulic control device. l...Engine,...Input shaft, 10...Continuously variable transmission, 12...Drive side pulley, 14...Driver side pulley, 16...Oil chamber for gear ratio control, 17... ...Oil chamber for load thrust control, 20...Starting clutch, 32...Output shaft, 110...Manual valve, 150...Forward and backward switching piston, 180...Hydraulic pressure switching valve, 300... - Controller, 301... Solenoid valve for speed ratio control.

Claims (3)

[Claims] (1) A manual valve that can be switched to each range position by manual operation and selectively guides the hydraulic pressure supplied from the hydraulic source to the forward drive means or the backward drive means, and generates different hydraulic pressures in the high-speed ratio range and the low-speed ratio range. The hydraulic switching valve is equipped with a hydraulic pressure generating means, and a hydraulic switching valve that is operated by the hydraulic pressure generated by the hydraulic pressure generating means and opens and closes an oil passage from the manual valve to the retraction drive means, and the hydraulic switching valve operates from the hydraulic pressure generating means to the high-speed ratio range. A hydraulic control device for an automatic transmission, characterized in that when hydraulic pressure is introduced, an oil passage from a manual valve to a reverse drive means is closed. (2) The automatic transmission is a V-belt continuously variable transmission,
The hydraulic pressure of an automatic transmission according to claim 1, wherein the hydraulic pressure generating means is a solenoid valve that generates a signal hydraulic pressure for controlling the hydraulic pressure of a drive side pulley of a V-belt type continuously variable transmission. Control device. (3) According to claim 1 or 2, the forward driving means and the backward driving means are constituted by a forward/reverse switching piston for switching a dog clutch for forward/reverse switching. Hydraulic control device for the automatic transmission described.