JPH0523886Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

The present invention relates to a transmission switching device, and more particularly, a shift fork is engaged with a hub sleeve for switching gears of an auxiliary transmission, and the shift fork is coupled to a piston rod of a switching air cylinder. The present invention relates to a switching device that uses the air cylinder described above to switch gears.

[Summary of the idea]

This invention connects a solenoid valve to the low-pressure air supply pipe of the switching air cylinder, connects the solenoid coil of this solenoid valve to a temperature sensor via a relay contact, and further displays the temperature in conjunction with the movement of the piston rod. A low-speed side indicator lamp and a high-speed side indicator lamp are provided for operation, and a relay coil that controls the opening and closing of the relay contact is connected to the low-speed side indicator lamp, and the low-speed side indicator lamp is lit and the temperature sensor is at a low temperature. When the solenoid coil of the solenoid valve is detected, the solenoid coil of the solenoid valve is energized and one chamber of the air cylinder is released to atmospheric pressure via the solenoid valve. This is designed to prevent air leakage and prevent longer shift times.

[Conventional technology]

By further coupling an auxiliary transmission to the transmission, it is possible to perform switching with twice the number of stages. That is, for example, by providing a five-stage transmission with two auxiliary transmission stages, a ten-stage transmission is obtained. When switching such an auxiliary transmission, a shift fork is used to move the synchronizer hub sleeve between the main shaft and the output shaft, and an air cylinder is used for this purpose. .

[Problem that the invention attempts to solve]

When switching such an auxiliary transmission from a low speed side to a high speed side using an air cylinder, back pressure is applied to the low speed side chamber of this air cylinder. This is because if the piston moves with an impact, the synchronizer ring will forcefully press into the cone of the hub, and the connection may not be smooth. When applying back pressure, compressed air flows into the low-speed chamber through the low-speed air supply pipe and tries to move the piston to the low-speed side. This air pressure comes to act as back pressure. Then, the valve is switched to allow compressed air to flow into the high-speed chamber of the air cylinder through the high-speed air supply pipe, which moves the piston to the high-speed side and performs the switching operation. become. Due to the sliding resistance of the hub at this time, a bending moment is applied to the piston rod via the fork. At low temperatures, the oil has a high viscosity, resulting in large sliding resistance and a large bending moment. In this way, when compressed air flows into the low-speed chamber of the air cylinder at low temperatures, the piston is pressed downward by the above-mentioned bending moment.
The lower part of the O-ring sealing the piston will be crushed between the piston and the air cylinder. Next, when compressed air flows into the chamber on the high-speed side and a bending moment in the opposite direction is applied, the piston is pushed upward, and the upper part of the O-ring that seals the piston is pressed between the piston and the air cylinder. You will be crushed. This creates a gap between the lower side of the piston and the air cylinder. At low temperatures, the O-ring's ability to recover is slow, so the O-ring on the bottom of the piston
A gap will be created between the ring and the cylinder, resulting in air leakage. This has resulted in the problem that the shift operation is not performed or that it takes a long time to shift. The present invention has been developed in view of these problems, and is intended to prevent air leakage from the shift air cylinder, especially at low temperatures, and thereby prevent shifting from being impossible or taking a long time. It is an object of the present invention to provide a transmission switching device which prevents the transmission from occurring.

[Means to solve the problem]

The present invention engages a shift fork with a hub sleeve for switching gears of an auxiliary transmission, connects this shift fork to a piston rod of a switching air cylinder, and connects chambers on both sides of the piston of the air cylinder. are connected to a range control valve via a low-speed side air supply pipe and a high-speed side air supply pipe, respectively, and the range control valve is further connected to an air tank storing compressed air,
When switching to the high speed side, air is supplied to one chamber of the air cylinder through the low speed side air supply pipe to provide back pressure, and in this state, air is supplied to the other chamber of the air cylinder through the high speed side air supply pipe. In the device for moving the piston to the high speed side by supplying air, a solenoid valve is connected to the low speed side air supply pipe, and a solenoid coil of this solenoid valve is connected to a temperature sensor via a relay contact. , further provided with a low-speed side indicator lamp and a high-speed side indicator lamp that perform display operations in conjunction with the movement of the piston rod,
A relay coil for controlling opening/closing of the relay contact is connected to the low-speed side indicator lamp, and when the low-speed side indicator lamp is turned on and the temperature sensor detects that the temperature is low, the solenoid coil of the solenoid valve When the air cylinder is energized, one chamber of the air cylinder is released to atmospheric pressure via the solenoid valve.

[Effect]

Therefore, with this configuration, no back pressure is applied to the piston of the air cylinder at low temperatures.
When switching from the low-speed side to the high-speed side, no bending moment is applied to the piston rod on the low-speed side, the piston is no longer pressed downward, and seal members such as the O-ring on the lower side are no longer crushed. Therefore, there will be no gap between the lower seal member and the cylinder, preventing air leakage and ensuring reliable shifting, which will prevent the gear from being unable to shift or requiring a long time to shift. can be reliably prevented.

【Example】

The present invention will be explained below with reference to an illustrated embodiment.
FIG. 2 shows a transmission 10 having a switching device according to an embodiment of the present invention, and this transmission 10 is composed of five stages of transmissions. An auxiliary transmission 11 is provided on the rear side of the transmission 10. That is, a drive gear 13 is provided at the rear end of the main shaft 12 of the transmission 10, and this drive gear 13 meshes with a receiving gear 15 of an auxiliary countershaft 14. The auxiliary countershaft 14 is rotatably supported by a bearing 16 at the rear end of the countershaft 17. The auxiliary countershaft 14 is further provided with an auxiliary gear 18 which is adapted to mesh with a speed change gear 19. In addition, speed change gear 1
9 is rotatably supported by an output shaft 20. A synchronizer 21 is provided between the drive gear 13 and the transmission gear 19, and the hub sleeve 22 connects the hub 26 to the cones on both sides.
3 and 24 selectively. Note that the cones 23 and 24 are adapted to engage with the drive gear 13 and the transmission gear 19, respectively, via splines. Further, the hub 26 is coupled to the output shaft 20. The hub sleeve 22 is then moved by a shift fork 25. A shift fork 25 for moving the hub sleeve 22 is adapted to be moved by an air cylinder 30 shown in FIG. Piston rod 3 to which piston 31 of this cylinder 30 is fixed
The fork 25 is fixed to the fork 2. Furthermore, the piston rod 32 is connected to the slide plate 3.
3, and its detected portion 34 is detected by a detection switch 35. This detection switch 35 is connected to the high-speed side indicator lamp 36 and the low-speed side indicator lamp 37.
They are now connected to each other. Both sides of the piston 31 of the air cylinder 30 are connected to air supply pipes 38 and 39, respectively, and these pipes 38 and 39 are connected to a range control valve 49. Furthermore, the range control valve 49 is connected to an air tank that constitutes a pressure source. In particular, the air supply pipe 39 on the low speed side has a solenoid valve 4.
0 is now connected. This solenoid valve 4
The solenoid coil 0 is connected to a relay contact 41, and the relay contact 41 is further connected to a temperature sensor 42. The relay coil 43 that opens and closes the relay contact 41 is connected to the low-speed side indicator lamp 37. In the above configuration, when compressed air is supplied to the right chamber of the air cylinder 30 through the air supply pipe 38 shown in FIG.
1 will move to the left, and thereby the fork 25 will also move in the same direction. This fork 25 then moves the hub sleeve 22 to the left, and the hub 26 is engaged with the left cone 23 via the hub sleeve 22. Then, the drive gear 13 is engaged with the output shaft 20 via the synchronizer 21. That is, in this case, the main shaft 12 and the output shaft 20 are in the same state as being directly connected, and rotation can be extracted without performing a deceleration operation by the auxiliary transmission 11. On the other hand, when compressed air is supplied to the left chamber of the air cylinder 30 through the low-speed air supply pipe 39 shown in FIG. 1, the piston 31 moves to the right. Therefore, the fork 25 also moves in the same direction, and the hub sleeve 22 moves to the right and the hub 2
6 connects the right cone 24 through the hub sleeve 22
will be engaged with. Then, the rotation of the main shaft 12 is controlled by the drive gear 13 and the receiving gear 1.
5, auxiliary counter shaft 14, auxiliary gear 18,
Speed change gear 19, synchronizer 21, output shaft 20
As a result, rotation at a low rotational speed is extracted from the output shaft 20 while being decelerated by the auxiliary tri-mission 11. Next, a description will be given of the back pressure cutting operation of the air cylinder 30, which switches the auxiliary transmission 11, at low temperatures. Before switching the auxiliary transmission 11 from the low speed side to the high speed side, the air cylinder 30 is in a state shifted to the low speed side as shown in FIG. 1, and the slide plate 33 is moved by the piston rod 32. The detection switch 35 is operated by the detected portion 34, and the low speed side indicator lamp 37 is lit. At the same time, a current flows through the relay coil 43 connected to the lamp 37, and the relay coil 43 is excited.
Therefore, relay contact 41 is also closed. At this time, if the transmissions 10 and 11 are cold and their oil temperature is low, the temperature sensor 42 is also turned on and the solenoid coil of the electromagnetic valve 40 is energized. When the solenoid coil of the electromagnetic valve 40 is excited, the valve body 45 of the electromagnetic valve 40 connected to the low-speed air supply pipe 39 moves to the left in FIG. 1, and the air supply path 46 is closed. The exhaust port 47 is now opened. Therefore, the air in the chamber on the left side of the piston 31 of the air cylinder 30 will be exhausted to the atmosphere. Therefore, when switching the air cylinder 30 from the low speed side to the high speed side, no pressure is applied to the left side of the piston 31, and no back pressure on the low speed side is applied to the piston 31. Therefore, no bending moment is applied to the piston rod 32, and the piston 31 maintains its straight posture. Therefore, the piston 31 is prevented from being pressed downward or tilted, thereby preventing the O-ring 44 sealing the piston 31 from being deformed. Therefore, the air cylinder 30 does not cause air leakage, and the shift operation to the high speed side can be performed smoothly. This prevents air leakage from the air cylinder 30, prevents the shift from becoming impossible, and prevents the shift from taking a long time. FIG. 3 shows the operation of the back pressure cut at such low temperatures. By performing the back pressure cut, the air pressure on the high speed side, the air pressure on the low speed side, and the stroke of the air cylinder 30 are reduced. have the characteristics shown by solid lines A, B, and C in FIG. 3, respectively. This characteristic shows that the shift time is reduced to, for example, one-third compared to the conventional characteristic in which no back pressure cut is performed, as shown by the dotted line. This makes it possible to reliably prevent shift times from becoming longer. That is, by performing such a back pressure cut, it becomes possible to perform the shift operation by the air cylinder 30 in the same manner as at room temperature.
Alternatively, it is possible to reliably prevent the shift operation from being performed and to perform the shift operation quickly even at low temperatures. When the temperature of the transmissions 10, 11 rises and the oil temperature also rises, the temperature sensor 42 turns OFF, cutting off the current to the solenoid valve 40, and the valve body is forced to close to the built-in return spring. 48 to the right in FIG. 1, closing the exhaust port 47 and opening the air supply path 46. Therefore, back pressure is applied to the left chamber of the air cylinder 30, and this back pressure applies a bending moment to the piston rod 32, exerting a force that tends to tilt the piston 31. However, when the temperature is high, the O that seals the piston 31
Since the elasticity of the rubber of the ring 44 has been restored, air leakage will not occur and smooth shifting will occur. Note that the back pressure on the low speed side prevents the air cylinder 30 from shifting rapidly, and the synchronizer 2
This is effective in improving the durability of 1. Therefore, the back pressure of the air cylinder 30 is cut only at low temperatures, such as immediately after starting the engine, and an appropriate back pressure is normally applied to the air cylinder 30. Therefore, it is possible to minimize the adverse effects caused by cutting the back pressure of the air cylinder 30.

[Effect of the idea]

As described above, the present invention connects a solenoid valve to the low-speed air supply pipe, connects the solenoid coil of this solenoid valve to a temperature sensor via a relay contact, and further performs display operation in conjunction with the movement of the piston. A low-speed side indicator lamp and a high-speed side indicator lamp are provided, and a relay coil for controlling the opening and closing of the relay contact is connected to the low-speed side indicator lamp,
When the low speed side indicator lamp is lit and the temperature sensor detects that the temperature is low, the solenoid coil of the solenoid valve is energized and the low speed side chamber of the air cylinder is released to atmospheric pressure via the solenoid valve. This is what I did. Therefore, with this configuration, it is possible to cut the back pressure of the air cylinder at low temperatures by releasing it to the atmosphere through the solenoid valve, thereby preventing the sealing member from deforming and causing air leakage. will be reliably prevented.

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view of main parts showing a transmission switching device according to an embodiment of the present invention, and FIG.
The figure is a partially cutaway front view of a transmission equipped with this switching device, and FIG. 3 is a graph showing the operation of the switching device. In addition, in the symbols used in the drawings, 21... synchronizer, 22... shift sleeve, 25...
Shift fork, 30...Air cylinder, 31...
...Piston, 39...Air supply pipe, 40...
These are a solenoid valve, 42...temperature sensor, 44...O ring, and 49...range control valve.

Claims (1)

[Scope of utility model registration request] A shift fork is engaged with a hub sleeve for switching gears of the auxiliary transmission, and this shift fork is coupled to a piston rod of a switching air cylinder, and the chambers on both sides of the piston of the air cylinder are moved to the low speed side. Connect to the range control valve via the air supply pipe and high-speed side air supply pipe,
Further, the range control valve is connected to an air tank storing compressed air, and when switching to the high speed side, air is supplied to one chamber of the air cylinder through the low speed side air supply pipe to apply back pressure; In this device, air is supplied to the other chamber of the air cylinder through the high-speed side air supply pipe to move the piston to the high-speed side in this state, and a solenoid valve is connected to the low-speed side air supply pipe, and The solenoid coil of this electromagnetic valve is connected to a temperature sensor via a relay contact, and furthermore, a low-speed side indicator lamp and a high-speed side indicator lamp are provided that perform display operations in conjunction with the movement of the piston rod, and the opening/closing of the relay contact is controlled. A relay coil is connected to the low-speed side indicator lamp, and when the low-speed side indicator lamp is lit and the temperature sensor detects that the temperature is low, the solenoid coil of the solenoid valve is energized and the air cylinder is activated. 1. A transmission switching device characterized in that one chamber of the transmission is opened to atmospheric pressure via the solenoid valve.