JPH0389071A - Safety device for automatic transmission - Google Patents

Abstract

PURPOSE:To make the start of a vehicle impossible so as to ensure safety and facilitate production by providing an oil pressure supply stop mechanism for stopping the supply of oil pressure to a hydraulic clutch at the non-operating time of a shift servo valve. CONSTITUTION:The safety device for an automatic transmission is provided with a hydraulic clutch 58 for performing engaging/disengaging action by the supply/discharge of oil pressure so as to intermit driving force outputted from the automatic transmission, a forward/backward switching mechanism for switching the forward/backward engagement state of the automatic transmission, and a shift servo valve 106 for feeding/discharging oil pressure so as to actuate the switching action of the forward/backward switching mechanism. A manual shift valve 126 for performing switching action by the shift mechanism of the automatic transmission is further provided to feed/discharge oil pressure to/from the hydraulic clutch 58 as well as to feed oil pressure to the shift servo valve 106, as well as an oil pressure supply stop mechanism 176 for stopping the supply of oil pressure to the hydraulic clutch 58 is provided to impede the engagement of the hydraulic clutch 58 at the non-operating time of the shift servo valve 106.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a safety device for an automatic transmission, and in particular, when the shift servo valve that switches the forward/reverse switching mechanism provided in the automatic transmission is not activated, the vehicle is This invention relates to a safety device for an automatic transmission that ensures safety by making it impossible to start.

[Conventional technology]

2. Description of the Related Art Vehicles such as automobiles are equipped with a transmission in order to appropriately extract the driving force generated by an internal combustion engine depending on the driving condition. Transmissions include manual transmissions, in which the driver manually converts the driving force of the internal combustion engine to the required gear ratio depending on the driving condition, and automatic transmissions, in which the driving force of the internal combustion engine is converted to the required gear ratio according to the driving condition. There are automatic transmissions, etc. that can be converted and taken out automatically.

An example of an automatic transmission is disclosed in Japanese Patent Publication No. 64-11858. The automatic transmission disclosed in this publication is set to shift up earlier at low rotation speeds during low load and low rotation speeds than during steady driving, and to maintain the gear at higher rotation speeds than during steady driving. , while ensuring a good driving feel during steady driving, improved fuel consumption when driving in traffic jams, and improved driving performance by avoiding unnecessary shift amplifiers during temporary acceleration during traffic jams. It is something.

Further, as a hydraulic control device for controlling an automatic transmission using hydraulic pressure, there is one disclosed in Japanese Patent Publication No. 1703/1983. The hydraulic control device for an automatic transmission disclosed in this publication is configured to supply hydraulic pressure to a friction element via a pressure reducing valve, in which oil passages upstream and downstream of the pressure reducing valve are reversely connected. By communicating through a stop valve and discharging hydraulic pressure from the friction element via this check valve, when the pressure reducing valve stops operating due to a failure etc., the hydraulic pressure of the friction element is transferred to the check valve. This is to ensure that the fluid is discharged through the friction element, thereby preventing the occurrence of shift shock due to a delay in the opening operation of the friction element.

[Problem that the invention seeks to solve]

Incidentally, in some conventional automatic transmissions, a shift mechanism mechanically switches a forward/reverse switching mechanism for switching the forward/reverse engagement state of the automatic transmission, for example. In the case of such a mechanical shift mechanism, there is a problem that a smooth shift operation cannot be obtained.

Therefore, a manual shift valve is operated by a shift mechanism to supply and discharge hydraulic pressure to a shift servo valve, and this shift servo valve is used to switch, for example, a forward/reverse switching mechanism of an automatic transmission that switches the forward/reverse engagement state. There is. According to such a shift mechanism of hydraulic servo 2, a shift operation can be performed smoothly.

However, in the hydraulic servo type shift mechanism, the shift servo valve may become inoperative due to some mechanical cause, and the forward/reverse engagement state may not be switched. If a start operation is performed to start the vehicle when the shift servo valve is not activated, the direction of start of the vehicle will be opposite to the direction of operation, resulting in an inconvenience that safety will be impaired.

[Purpose of the invention]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to provide a safety device for an automatic transmission that ensures safety by making it impossible to start the vehicle when the shift servo valve that switches the forward/reverse switching mechanism provided in the automatic transmission is not activated. The aim is to realize this.

[Means for solving problems]

In order to achieve this object, the present invention provides an automatic transmission that automatically converts and extracts the driving force of an internal combustion engine according to the driving condition of the vehicle according to a required gear ratio. A hydraulic clutch is provided which is engaged and disengaged by supplying and discharging hydraulic pressure for intermittent engagement, and a forward/reverse switching mechanism for switching the forward/reverse engagement state of the automatic transmission is provided, and hydraulic pressure is supplied to switch the forward/reverse switching mechanism. a manual shift valve that is operated by a shift mechanism of the automatic transmission to supply and discharge hydraulic pressure to and from the hydraulic clutch and to supply hydraulic pressure to the shift servo valve; This hydraulic clutch is used to prevent engagement of the hydraulic clutch when the valve is not activated. It is characterized by the provision of a hydraulic pressure supply stop mechanism that stops the supply of hydraulic pressure to Sochi.

[Effect]

According to the configuration of the present invention, when the shift servo valve is inactive, the hydraulic pressure supply stop mechanism stops the supply of hydraulic pressure to the hydraulic clutch, thereby preventing engagement of the hydraulic clutch and driving the automatic transmission output. cut off power.

〔Example〕

Next, embodiments of the present invention will be described in detail based on the drawings.

1 to 9 show embodiments of this invention. In FIG. 9, 2 is an automatic transmission.

This automatic transmission 2 uses a belt to continuously and steplessly change the gear ratio, and automatically converts the driving force of an internal combustion engine (not shown) to the required gear ratio according to the running condition of the vehicle (not shown). and then take it out.

The automatic transmission 2 includes a driving pulley 6 on an input shaft 4 that communicates with an internal combustion engine (not shown), and a driven pulley 10 on an output shaft 8, with a A belt 12 is wrapped around it.

The driving side boo'J 6 includes a driving side fixed pulley piece 14 fixed to the input shaft 4, and a driving side movable pulley piece 16 mounted on the input shaft 4 so as to be movable in the axial direction but not rotatable. have. The driven pulley 10 includes a fixed driven pulley part 18 fixed to the output shaft 8 and a movable driven pulley part mounted on the output shaft 8 so as to be movable in the axial direction but not rotatable. 20.

The drive-side movable pulley piece 16 has a drive-side hydraulic chamber 22 . Further, the driven side movable pulley piece 20 has a driven side hydraulic chamber 24 . The hydraulic pressure receiving area of the driving side movable pulley part 16 of the driving side hydraulic chamber 22 is set to be larger than the hydraulic pressure receiving area of the driven side pulley part 20 of the driven side hydraulic chamber 24. Thereby, by controlling the hydraulic pressure acting on the drive-side hydraulic chamber 22, the belt ratio, which is the gear ratio, is changed.

Further, in the driven side hydraulic chamber 24, the driven side movable pulley piece 20 is arranged in a direction that reduces the groove width between the driven side fixed pulley piece 18 and the driven side movable bobbin piece 20. A biasing means 26 consisting of a spring or the like is provided for biasing. This biasing means 26 sets a large gear ratio on the full-low side when the oil pressure is low, such as at the time of starting, and maintains the holding force of the belt 12 to prevent slippage.

The manpower shaft 4 is provided with an oil pump 28. The oil pump 28 pumps oil stored in an oil pan 29. This oil pump 28 has first and second oil passages 30.
32, and are provided in communication with each other. A primary pressure control valve 34 is interposed in the middle of the first oil passage 30 to control a primary pressure, which is the input shaft sheave pressure. A constant pressure control valve 36 is provided in communication with the first oil passage 30 closer to the oil pump 28 than the primary pressure control valve 34 to control the line pressure to a constant control hydraulic pressure. A first three-way solenoid valve 40 for primary pressure control is provided in communication with the primary pressure control valve 34 through a third oil passage 38 .

Further, a line pressure control valve 42 having a relief valve function for controlling line pressure, which is pump pressure, is provided in communication with the second oil passage 32 that communicates the oil pump 28 and the driven side hydraulic chamber 24. . This line pressure control valve 42 is provided with a second three-way solenoid valve 46 for line pressure control in communication with it through a fourth oil passage 44 .

Further, in the middle of the second oil passage 32 on the side of the driven side hydraulic chamber 24 with respect to the communicating portion of the line pressure control valve 42, there is a clutch pressure control valve for controlling clutch pressure, which is a hydraulic pressure acting on a hydraulic clutch 58, which will be described later. 48 are provided in communication. A third three-way solenoid valve 52 for clutch pressure control is provided in communication with this clutch pressure control valve 48 through a fifth oil passage 50 .

Further, the constant pressure control hydraulic pressure taken out from the constant pressure control valve 36 is controlled by the primary pressure control valve 34, the first three-way solenoid valve 40 for primary pressure control, the line pressure control valve 42, and the second three-way solenoid valve 46 for line pressure control. and a clutch pressure control valve 48 and a third three-way solenoid valve 5 for clutch pressure control.
2, these valves 36.34.40.42 respectively.
．． 46, 48, and 52 are communicated with each other through a sixth oil passage 54.

The clutch pressure control valve 48 is provided in communication with a clutch hydraulic chamber 60 of a hydraulic clutch 58 through a seventh oil passage 56 . A pressure sensor 6 is provided in the middle of the seventh oil passage 56.
2 are provided in communication.

The hydraulic clutch 58 includes an input side casing 64 attached to the output shaft 8, the clutch hydraulic chamber 60 provided within the casing 64, and the clutch hydraulic chamber 6.
A piston 66 that is pushed forward by hydraulic pressure acting on the piston 66, an annular spring 68 that urges the piston 66 in the retiring direction, and the pushing force of the piston 66 and the urging force of the annular spring 68 allow the piston to move forward and backward. It consists of a first pressure plate 70 provided, a friction plate 72 on the output side, and a second pressure plate 74 fixed to the casing 64.

The hydraulic clutch 58 is provided so that the output shaft 8 and a final output shaft 76 rotatably fitted onto the output shaft 8 are connected to each other. This hydraulic clutch 58 has a hydraulic pressure acting on a clutch hydraulic chamber 60. When the pressure is increased, the piston 66
pushes forward and the first pressure plate 70 and the second pressure plate 7
4 are brought into close contact with the friction plate 72 and engaged, resulting in a so-called clutch connected state. On the other hand, when the clutch pressure, which is the hydraulic pressure applied to the clutch hydraulic chamber 60, is lowered, the biasing force of the annular spring 68 causes the piston 6 to
6 retires, the first pressure coupler plate 70 and the second pressure coupler plate 74 are separated from the friction plate 72 and are operated to separate, resulting in a so-called clutch disengaged state. By engaging and disengaging the hydraulic clutch 58, the driving force output from the output shaft 8 of the automatic transmission 2 to the final output means 6 is intermittent.

The final output shaft 76 is connected to drive wheels (not shown) via an intermediate shaft 78. Final output shaft 76 and intermediate shaft 7
8, there is provided a forward/reverse switching mechanism 80 for switching the forward/reverse engagement state.

The forward/reverse switching mechanism 80 includes a forward gear train 82, a reverse gear train 84, and a switching sleeve 86. The forward gear train 82 includes a forward output gear 88 fixed to the final output shaft 76 and a forward switching gear 90 rotatably supported on the intermediate shaft 78 so as to mesh with the forward output gear 88. ,
Consisting of Further, the reverse gear train 84 is connected to the final output shaft 78
a reverse output gear 92 fixed to the reverse output gear 92, a reverse switch gear 94 rotatably supported on the intermediate shaft 78, and an idler gear 96 that meshes and connects the reverse output gear 92 and the reverse switch gear 94; Consisting of The switching sleeve 86 is mounted on the intermediate shaft 78 so as to be movable in the axial direction but not rotatable, and
By moving in the axial direction, either the forward switching gear 90 or the reverse switching gear 92 is non-rotatably connected to the intermediate shaft 78, and the forward/reverse engagement state is switched.

A driving side rotational speed sensor 98 is provided to detect the rotational speed of the driving pulley 6, a driven side rotational speed sensor 100 is provided to detect the rotational speed of the driven pulley 10, and the rotational speed of the final output shaft 76 is determined. A maximum output rotation speed sensor 102 for detection is provided. The pressure sensor 62 and these rotation speed sensors 98
In conjunction with the signal ~102, the carburetor throttle opening,
A control unit 104 is provided as a control means for inputting and controlling various signals such as a carburetor idle position, an accelerator pedal signal, a brake signal, a power mode option signal, and a shift lever position.

The control unit 104 controls the automatic transmission 2 according to various input signals.
The first three-way solenoid valve 40 for primary pressure control, the second three-way solenoid valve 46 for line pressure control, and the third three-way solenoid valve for clutch pressure control are used to control the belt ratio, clutch engagement state, etc. in various control modes. The opening/closing operation of 52 is controlled.

In order to switch the forward/reverse switching mechanism 80, a shift servo valve 106 is provided to which hydraulic pressure is supplied and discharged. The shift servo valve 106 has a piston 11 slidably inserted into a cylinder 110 of a valve body 108, as shown in FIG.
2, and a shift servo loft 1 is provided on this piston 112.
The shift servo rod 11 is connected to one end of the shift servo rod 14.
The switching sleeve 8 of the forward/reverse switching mechanism 80 is disposed on the other end side of 4.
A shift fork 116 that is engaged with the shift fork 6 is fixedly installed.

In the shift servo valve 106, when hydraulic pressure is supplied to a first chamber 118 defined by a piston 112 in the cylinder 110 and hydraulic pressure from a second chamber 120 is discharged, the piston 112 moves the shift servo loft 114 in a direction indicated by arrow A.
direction, the switching sleeve 86 is moved toward the forward switching gear 90 by the shift fork 116, the forward switching gear 90 is rotatably connected to the intermediate shaft 78, and the switching sleeve 86 is switched to the forward engagement state. On the other hand, the shift servo valve 106 is
Hydraulic pressure is supplied to a second chamber 120 defined by a piston 112 in the cylinder 110, and the first chamber 11
When the hydraulic pressure of 8 is discharged, the piston 112 moves the shift servo rod 114 in the direction of arrow B, and the shift fork 116 moves the switching sleeve 86 to the reverse switching gear 94.
side, the reverse switching gear 94 is non-rotatably connected to the intermediate shaft 78, and switched to the reverse engaged state.

The operating rod 12 of the shift mechanism 122 of the automatic transmission 2 is used to supply and discharge hydraulic pressure to the hydraulic chamber 60 of the hydraulic clutch 58 and to supply and discharge hydraulic pressure to the shift servo valve 106.
Manual shift valve 126 which is switched by 4.
will be established.

As shown in FIGS. 3 to 7, the manual shift valve 126 has a spool valve body 132 slidably housed within a sliding hole 130 of a valve body 128. The valve body 128 is provided with annular first groove portions 134 to seventh'a portions 146 on the inner peripheral surface of the sliding hole 130. Further, the spool valve body 132 has one end connected to the operating rod 124 of the shift mechanism 122 and includes a first large diameter portion 148 to a fifth large diameter portion 156 that slide into contact with the inner circumferential surface of the sliding hole 130. In addition, first to fourth small diameter portions 158 to 164 are provided between the first to fifth large diameter portions 148 to 156, respectively.

Valve body 12 of the manual shift valve 126
The first groove portion 134 provided at 8 is communicated with the first passage 166. This first passage 166 communicates with the first chamber 118 of the shift servo valve. The second manual shift valve 126? The W portion 134 includes the second
It communicates with the oil passage 32 and is supplied with line pressure, which is the hydraulic pressure discharged by the oil pump 28. The third groove portion 138 of the manual shift valve 126 communicates with a second passage 168. This second passage 168 communicates with the second chamber 120 of the shift servo valve 106. The fourth groove portion 140 of the manual shift valve 126 communicates with the oil pan 29.

Furthermore, the fifth groove 142 provided in the valve body of the manual shift valve 126 communicates with the third passage 170. Sixth groove portion 1 of the manual shift valve 126
44 communicates with the seventh oil passage 56 and is supplied with clutch pressure, which is oil pressure that acts on the hydraulic clutch 58.

The seventh a section 146 of the manual shift valve 126 communicates with the fourth passage 172. The hydraulic chamber 60 of the hydraulic clutch 58 is supplied with clutch pressure, which is hydraulic pressure, through the third passage 170 and the fourth passage 172 and the fifth passage 174 .

In order to prevent engagement of the hydraulic clutch 58 when the shift servo valve 106 is not activated, the hydraulic clutch 58
A hydraulic pressure supply stop mechanism 176 is provided to stop the supply of clutch pressure, which is hydraulic pressure, to the hydraulic chamber 60.

The hydraulic pressure supply stop mechanism 176 is connected to the shift servo valve 1.
06. That is, the hydraulic pressure supply stop mechanism 176 is configured to operate through the sliding hole 1 of the valve body 178 that is integrally provided with the valve body 108 of the shift servo valve 106.
A spool valve body 182 is slidably housed inside the valve body 80 . This spool valve body 182 is integrally formed with the shift servo rod 114. The valve body 1
An annular first groove 1 is provided on the inner peripheral surface of the sliding hole 180 of 78.
84 to a sixth groove portion 194 are provided. The spool valve body 182 is provided with a first large diameter portion 196 to a third large diameter portion 200 that are in sliding contact with the inner circumferential surface of the sliding hole 180, and there are gaps between these first to third large diameter portions 196 to 200, respectively. First small diameter portion 20
2 to a second small diameter portion 204 are provided.

A first groove 184 provided in the valve body 178 of the hydraulic pressure supply stop mechanism 176 communicates with the oil pan 29. The second groove portion 186 of the hydraulic pressure supply stop mechanism 176 is
A sixth passage 206 communicates with the fifth passage 174 . The third groove portion 188 of the hydraulic pressure supply stop mechanism 176 communicates with the fourth passage 172. The fourth groove portion 190 of the hydraulic pressure supply stop mechanism 176 is connected to the third passage 17.
It is connected to 0. The fifth groove portion 192 of the hydraulic pressure supply stop mechanism 176 is connected to the fifth passage 1 by the seventh passage 208.
74. The sixth groove portion 194 of the hydraulic pressure supply stop mechanism 176 communicates with the oil pan 29.

Next, the action will be explained.

The driving force of the internal combustion engine mounted on the vehicle is converted into desired torque and rotational speed by the automatic transmission 2 and is extracted to drive drive wheels (not shown).

In such an automatic transmission 2, when the automatic transmission 2 is shifted to the parking range P by the shift mechanism 122, as shown in FIG. The first passage 166 is connected to the oil pan 29 side, and the second small diameter portion 16
0 communicates the second passage 168 with the second oil passage 32, the fourth large diameter part 154 and the fifth large diameter part 156 close the seventh oil passage 56, and the third small diameter part 162 connects the third passage 170. It communicates with the oil pan 29 side, and also communicates the fourth passage 172 with the oil pan side through the outer end of the fifth large diameter portion 156.

As a result, the shift servo valve 106
The line pressure of 8 is discharged and the line pressure is supplied to the second chamber 120, and the piston 112 moves the shift servo rod 114 in the direction of arrow B to move the shift fork 116.
The switching sleeve 86 is moved to the reverse switching gear 94 side, the reverse switching gear 94 is non-rotatably connected to the intermediate shaft 78, and switched to the reverse engagement state.

At this time, the hydraulic pressure supply stop mechanism 176
The fourth passage 172 and the sixth passage 206 are communicated by the first small diameter portion 202 of 82, but the manual shift valve 126 closes the seventh oil passage 56 and the third passage 170
and the fourth passage 172 is communicated with the oil pan 29 side.

Therefore, since clutch pressure is not supplied to the hydraulic chamber 60 of the hydraulic clutch 58, the hydraulic clutch 58 is not engaged.
The driving force output from the automatic transmission 2 is cut off, and the vehicle cannot go backwards.

When the automatic transmission 2 is shifted to the reverse range R by the shift mechanism 122, as shown in FIG. The second small diameter portion 160 communicates the second passage 168 with the second oil passage 32 , the third small diameter portion 162 communicates the third passage 170 with the oil pan 29 side, and the fourth small diameter portion 164 communicates the second passage 168 with the second oil passage 32 . The fourth oil passage 172 is connected to the seventh oil passage 56.
It will be communicated to.

As a result, the shift servo valve 106
The line pressure of 8 is discharged and the line pressure is supplied to the second chamber 120, and the piston 112 moves the shift servo rod 114 in the direction of arrow B to move the shift fork 116.
The switching sleeve 86 is moved to the reverse switching gear 94 side, the reverse switching gear 94 is non-rotatably connected to the intermediate shaft 78, and switched to the reverse engagement state.

At this time, the hydraulic pressure supply stop mechanism 176
The fourth passage 172 and the sixth passage 206 are communicated by the first small diameter portion 202 of 82 .

Therefore, the clutch pressure, which is the hydraulic pressure in the seventh oil passage 56, is supplied to the hydraulic chamber 60 of the hydraulic clutch 58 via the fourth passage 172, the sixth passage 206, and the fifth passage 174, and engages the hydraulic clutch 58. The driving force output from the automatic transmission 2 is connected, and the vehicle becomes able to move backward.

When the automatic transmission 2 is shifted to the neutral range N by the shift mechanism 122, the manual shift valve 126 shifts to the first position of the spool valve body 132, as shown in FIG.
The small diameter portion 158 connects the first passage 166 to the second oil passage 3.
2, the second small diameter section 160 communicates the second passage 168 to the oil pan 29 side, the fourth large diameter section 154 closes the seventh oil passage 56, and the third small diameter section 162 closes the third passage 170. is communicated with the oil pan 29 side, and the fourth passage 172 is communicated with the oil pan 29 side through the fourth small diameter portion 164.

As a result, the shift servo valve 106
B is supplied with line pressure, and the line pressure of the second chamber 120 is discharged, and the piston 112 moves the shift servo loft 114 in the direction of arrow A to move the shift fork 116.
The switching sleeve 86 is moved to the forward switching gear 90 side, the forward switching gear 90 is rotatably connected to the intermediate shaft 78, and is switched to the forward engagement state.

At this time, the hydraulic pressure supply stop mechanism 176
The third passage 170 and the seventh passage 208 are communicated by the first small diameter portion 204 of 82, but the manual shift valve 126 closes the seventh oil passage 56 and the third passage 170
and the fourth passage 172 is communicated with the oil pan 29 side.

Therefore, the latch pressure is not supplied to the hydraulic chamber 60 of the hydraulic clutch 58, so the hydraulic clutch 58 is not engaged.
The driving force output from the automatic transmission 2 is cut off, and the vehicle becomes unable to move backward.

When the automatic transmission 2 is shifted to the drive range D by the shift L-mechanism 122, the manual shift valve 126 moves the first passage 166 into the second drive range by the first small diameter portion 158 of the spool valve body 132, as shown in FIG. oil passage 32
The second small diameter section 160 communicates the second passage 168 to the oil pan 29 side, and the third small diameter section 162 communicates the second passage 168 to the oil pan 29 side.
The passage 170 communicates with the seventh oil passage 56, and the fourth small diameter portion 164 communicates the fourth passage 172 with the oil pan 29 side.

As a result, the shift servo valve 106
8 is supplied with line pressure, and the line pressure of the second chamber 120 is discharged, and the piston 112 moves the shift servo rod 114 in the direction of arrow A to move the shift fork 116.
The switching sleeve 86 is moved to the forward switching gear 90 side, the forward switching gear 90 is rotatably connected to the intermediate shaft 78, and is switched to the forward engagement state.

At this time, the hydraulic pressure supply stop mechanism 176
The third passage 170 and the seventh passage 208 are communicated by the second small diameter portion 204 of 82 .

Therefore, the clutch pressure, which is the hydraulic pressure in the seventh oil passage 56, is supplied to the hydraulic chamber 60 of the hydraulic clutch 58 via the third passage 170, the seventh passage 208, and the fifth passage 174, causing the hydraulic clutch 58 to engage. The driving force output from the automatic transmission 2 is connected, and the vehicle becomes ready to move forward.

When the automatic transmission 2 is shifted to the low range L by the shift mechanism 122, as shown in FIG.
58 communicates the first passage 166 with the second oil passage 32 , the second small diameter part 160 communicates the second passage 168 with the oil pan 29 side, and the third small diameter part 162 communicates the second passage 166 with the second oil passage 32 .
70 is communicated with the seventh oil passage 56, and the fourth small diameter portion 164
This allows the fourth passage 172 to communicate with the oil pan 29 side.

As a result, the shift servo valve 106
8 line pressure is discharged, and the line pressure of the second chamber 120 is also discharged, and the piston 112 moves the shift servo rod 114 in the direction of arrow A to move the shift fork 116.
The switching sleeve 186 is moved to the forward switching gear 90 side, the forward switching gear 90 is rotatably connected to the intermediate shaft 78, and is switched to the forward engagement state.

At this time, the hydraulic pressure supply stop mechanism 176
The third passage 170 and the seventh passage 208 are communicated by the second small diameter portion 204 of 82 .

Therefore, the clutch pressure, which is the hydraulic pressure in the seventh oil passage 56, is supplied to the hydraulic chamber 60 of the hydraulic clutch 58 via the third passage 170, the seventh passage 208, and the fifth passage 174, causing the hydraulic clutch 58 to engage. The driving force output from the automatic transmission 2 is connected, and the vehicle becomes ready to move forward.

When the shift servo valve 106 of the automatic transmission 2 becomes inoperable due to some mechanical cause, the hydraulic supply stop mechanism 176 stops the supply of clutch pressure to the hydraulic clutch 58 and prevents the hydraulic clutch 58 from engaging. to prevent

For example, when the automatic shift a2 is shifted to the reverse range R by the shift mechanism 122, the manual shift valve 126 is moved to the first position of the spool valve body 132, as shown in FIG.
The small diameter portion 158 communicates the first passage 166 with the oil pan 29, the second small diameter portion 160 communicates the second passage 168 with the second oil passage 32, and the third small diameter portion 162 communicates the third passage 170 with the oil pan. The fourth small diameter portion 164 communicates the fourth passage 172 with the seventh oil passage 56 .

At this time, as shown in FIG.
If the piston 112 of No. 6 is inactive and the shift servo rod 114 cannot be moved in the direction of arrow B, the forward/reverse switching mechanism 80 cannot be switched to the reverse engagement state but remains in the forward engagement state.

When the shift servo valve 106 is inactive, the hydraulic pressure supply stop mechanism 176:
The large diameter portion 198 closes the fourth passage 172 and the sixth passage 206, and the supply of clutch pressure to the hydraulic chamber 60 of the hydraulic clutch 58 is stopped. Further, the hydraulic pressure supply stop mechanism 176 communicates the third passage 170 and the seventh passage 208 through the second small diameter portion 204 of the spool valve body 182 and guides the clutch pressure in the hydraulic chamber 60 to the oil pan 29 side.

Therefore, engagement of the hydraulic clutch 58 is prevented and the driving force output from the automatic transmission 2 is cut off, making it impossible for the vehicle to start.

Further, for example, when the automatic transmission 2 is shifted to drive range D by the shift mechanism 122, as shown in FIG.
The manual shift valve 126 has a spool valve body 132
The first small diameter portion 158 communicates the first passage 166 with the second oil passage 32 , and the second small diameter portion 160 communicates the first passage 166 with the second oil passage 32 .
68 to the oil pan 29 side, and the third small diameter portion 162 communicates the third passage 170 to the seventh oil passage 56 side.
The fourth passage 172 is communicated with the oil pan 29 side.

At this time, as shown in FIG. 2, the shift servo valve 10
If the piston 112 of No. 6 is inactive and cannot move the shift servo rod 114 in the direction of arrow A, the forward/reverse switching mechanism 80 cannot be switched to the forward engagement state but is in the reverse engagement state.

When the shift servo valve 106 is inactive, the oil pressure supply stop mechanism 176 closes the third passage 170 and the seventh passage 208 with the second large diameter portion 198 of the spool valve body 182, thereby reducing the oil pressure of the hydraulic clutch 58. The supply of clutch pressure to the chamber 60 is stopped. Further, the hydraulic pressure supply stop mechanism 176 is
4i1 by the first small diameter portion 202 of the spool valve body 182
! The l passage 172 and the sixth passage 206 are connected to each other, and the hydraulic chamber 60
Lead the pressure of the clutch 7 to the oil van 29 side.

Therefore, engagement of the hydraulic clutch 58 is prevented and the driving force output from the automatic transmission 2 is cut off, making it impossible for the vehicle to start.

In this manner, when the shift servo valve 106 is inactive, the engagement of the hydraulic clutch 58 is blocked and the driving force output from the automatic transmission 2 is cut off, making it impossible for the vehicle to start. Therefore, safety can be ensured. Moreover, it is easy to manufacture without requiring any special processing, and is economically advantageous.

〔Effect of the invention〕

As described above, according to the present invention, when the shift servo valve is not activated, the hydraulic pressure supply stop mechanism stops the supply of hydraulic pressure to the hydraulic clutch, thereby preventing engagement of the hydraulic clutch and reducing the output of the automatic transmission. cutting off the driving force.

As a result, if the forward/reverse switching mechanism is not switched due to the shift servo valve not operating, the engagement of the hydraulic clutch is blocked and the driving force output from the automatic transmission is cut off, thereby reducing the becomes unable to start. Therefore, safety can be ensured when the shift servo valve is not activated. Further, it is easy to manufacture without requiring any special processing, and is economically advantageous.

[Brief explanation of drawings]

1 to 9 show embodiments of the present invention, FIG. 1 is an explanatory diagram of the operation of the shift servo valve when it is not activated in the reverse range, and FIG. 2 is an explanation of the operation of the shift servo valve when it is not activated in the drive range. Figure 3 is an explanatory diagram of the operation of the shift servo valve in the parking range, Figure 4 is an explanatory diagram of the operation of the shift servo valve in the reverse range, Figure 5 is an explanatory diagram of the operation of the shift servo valve in the neutral range, and Figure 6 is an illustration of the operation of the shift servo valve in the neutral range. Figure 7 is an explanatory diagram of the operation of the shift servo valve in the drive range, Figure 7 is an explanatory diagram of the operation of the shift servo valve in the low range, Figure 8 is a partial cross-sectional diagram of the valve body, and Figure 9 is an illustration of the belt type automatic transmission. It is a schematic explanatory diagram. In the figure, 2 is an automatic transmission, 4 is a human power shaft, 6 is a drive pulley, 8 is an output shaft, 10 is a driven pulley, 12 is a belt, 28 is an oil pump, 58 is a hydraulic clutch, 60
1 is a hydraulic chamber, 76 is a final output shaft, 78 is an intermediate shaft, 80 is a forward/reverse switching mechanism, 106 is a shift servo valve, 126 is a manual shift valve, and 176 is a hydraulic pressure supply stop mechanism.

Claims (1)

[Claims] 1. In an automatic transmission that automatically converts and extracts the driving force of an internal combustion engine according to the driving condition of the vehicle according to a required gear ratio, the driving force output from the automatic transmission is engaged by supplying and discharging hydraulic pressure in order to intermittent the driving force output from the automatic transmission. A hydraulic clutch that is disengaged is provided, and a forward/reverse switching mechanism is provided for switching the forward/reverse engagement state of the automatic transmission, and a shift servo valve is provided to supply and discharge hydraulic pressure to switch the forward/reverse switching mechanism; a manual shift valve that is operated by a shift mechanism of the automatic transmission to supply and discharge hydraulic pressure to the hydraulic clutch and to supply hydraulic pressure to the shift servo valve;
A safety device for an automatic transmission, comprising a hydraulic pressure supply stop mechanism that stops the supply of hydraulic pressure to the hydraulic clutch to prevent engagement of the hydraulic clutch when the shift servo valve is not activated.