JPH0925947A - Fluid pressure generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a hydraulic path from bubble mixture caused by negative pressure generation and realize an accurate manual operation by introducing pressure fluid into a fluid chamber provided between a first piston to pressurize working fluid and a second piston. SOLUTION: In a manual operation, both pistons 47, 48 are depressed together through a push rod 49 in the pedalling of a clutch pedal to pressurize working oil in a hydraulic chamber 46a and supply oil pressure from an oil pressure supply port 53. On the other hand, in the case of an automatic operation, air pressure is supplied from an air pressure introducing port 55 into an air pressure chamber 47g so that only the first piston 48 is movably pressed to pressurize the working oil. Further, then, the air pressure acts also on the second piston 47, while the move thereof is regulated by a snap ring 56, so that the piston 47 is held as it is. Also, in the automatic dividing operation of the clutch, air pressure is supplied somewhat earlier to the air pressure chamber 47g to properly movably press the piston 48 and press properly the interior of an oil pressure path, so that the generation of negative pressure in the oil pressure path can be completely prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid pressure generating device applied to a master cylinder for actuating a clutch or a brake of a vehicle.

[0002]

2. Description of the Related Art Recently, there has been an increasing demand for automatic shifting of large vehicles such as buses and trucks. Since these vehicles generally have a large vehicle weight and a large payload, and use of a fluid torque converter such as that employed in a passenger car as a clutch type causes a large loss and is disadvantageous in terms of fuel efficiency, so in such a large vehicle, In particular, the friction clutch is turned on and off by automatic operation, the output of which is sent to a transmission, and this transmission is also automatically operated, thereby achieving automatic transmission. As a clutch intermittent device for automatically operating the clutch, a device provided with a booster (clutch booster) for intermittently operating the friction clutch by supplying and discharging air pressure is generally used.

On the other hand, the operation of the clutch is delicate when the vehicle is started, and the device becomes complicated and expensive if the operation is automatically controlled. Therefore, only in this case, the manual operation using the clutch pedal (manual operation) is required. ) There are some aimed at simplifying the device and reducing the cost by making it possible to operate. In this case, the hydraulic pressure is supplied and discharged from the master cylinder by operating the clutch pedal, and the supply and discharge of the hydraulic pressure is performed to supply and discharge the pneumatic pressure to and from the booster. (Related technology; Japanese Utility Model Publication No. 4-8023)

[0004]

By the way, during automatic gear shifting except when starting, pneumatic force is supplied to and discharged from the booster without operating the clutch pedal. In particular, the booster is adapted to push the internal power piston to operate the clutch in the disengagement direction when pneumatic pressure is supplied.

However, in the conventional structure, the passage for sending the hydraulic pressure from the master cylinder communicates with the hydraulic cylinder of the booster whose volume changes according to the movement of the power piston, and the hydraulic pressure is generated by pushing the power piston. When the cylinder volume increases, a negative pressure is generated in the hydraulic passage, air bubbles are mixed, and there is a problem that an accurate manual operation of the clutch cannot be performed.

In order to prevent the occurrence of such negative pressure, it is necessary to equip the hydraulic pressure output portion of the booster with a cancel mechanism for manual operation and automatic operation, as in Japanese Utility Model Publication No. 4-8023. However, the mechanism is complicated and reliability is also problematic. Therefore, in order to prevent the generation of negative pressure without changing the booster, the master cylinder can be driven not only by the clutch pedal but also by the control system (pneumatic pressure supply circuit) and without interfering with each other. It is desirable to do.

[0007]

According to the present invention, there is provided a cylinder for defining a first fluid chamber in which a working fluid is accommodated, a first piston for sliding in the cylinder to pressurize the working fluid, and an inside of the cylinder. A second piston that is slidably provided on the first piston and defines a second fluid chamber between the first piston and the first piston; a rod that pushes the first and second pistons in a working fluid pressurizing direction; And an introduction passage for communicating pressure fluid into the second fluid chamber to push the first piston. According to this structure, the working fluid can be pressurized by pushing the first piston with the pressure fluid. Further, it is preferable that an intermediate chamber separated from the first and second fluid chambers is defined between the cylinder and the first piston, and thus, between the first and second fluid chambers. The sealing property of is improved.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A cylinder having a cylindrical shape with an arbitrary cross section is used. The working fluid may be liquid or gas, for example, working oil is used. Then, the first piston is loaded into the cylinder, the working fluid is accommodated between them, and the first piston is inserted.
Form a fluid chamber. Further, a second piston is loaded in the cylinder, and a second fluid chamber is formed between these pistons. The pressure fluid is introduced into the second fluid chamber from the introduction path. With this, the first piston can be pushed to pressurize the working fluid. Similarly, a liquid or gas such as hydraulic oil can be considered as the pressure fluid, but if this is used as air, a compressor normally equipped in a large vehicle can be effectively used. For example, a port formed in a cylinder is used as the introduction path. It should be noted that if the area of the first piston on the hydraulic oil pressurizing side is small and the area of the working side of the pressure fluid is large, a boosting effect is exerted and a large pressure can be obtained even if the pressure of the pressure fluid is small. The intermediate chamber can be formed, for example, by sliding only the first and second fluid chamber side end portions of the first piston and reducing the diameter except for these. Alternatively, it can be formed by expanding a part of the cylinder.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

[First Embodiment] FIG. 2 is an overall configuration diagram showing a clutch connecting / disconnecting device provided with a fluid pressure generating device according to the present invention, in which the fluid pressure generating device is applied as a master cylinder.

As shown, the clutch connecting / disconnecting device 1 is
It has pneumatic supply means 2 for supplying relatively high pressure air (pressure fluid). The air pressure supply means 2 is driven by an engine (not shown) to generate a relatively high air pressure (air pressure), an air dryer 4 for drying the air from the compressor 3, and an air dryer 4. It mainly comprises an air tank 5 that stores the received air at a high pressure, and a check valve 6 provided on the inlet side of the air tank 5. The air pressure from the air pressure supply means 2 is sent to a booster (clutch booster) 7, and the booster 7 operates the friction clutch 8 to the separating side (right side) A by supplying the air pressure. ing. Further, the booster 7 is configured such that high-pressure hydraulic fluid (working fluid), that is, hydraulic pressure, is also supplied from the master cylinder 10 by operating the clutch pedal 9.

FIG. 3 is a vertical sectional view showing details of the booster 7. The booster 7 is configured in the same manner as the conventional one. As shown, the booster 7 has a cylinder shell 12 connected to its body 11,
A piston plate (power piston) 13 is provided inside 2 by a return spring 14 urged to the pneumatic pressure introducing side (left side in the drawing). An air pressure nipple 15 is attached to one end of the cylinder shell 12, and this air pressure nipple 15 forms an air pressure introduction port to introduce air pressure from the air tank 5 from an air pressure pipe 35 (FIG. 2). When air pressure is introduced, the piston plate 13 is on the clutch 8 side (right side in the figure)
Then, the piston plate 13 pushes the piston rod 16, the hydraulic piston 17, and further the push rod 18 to push the clutch lever 8a (FIG. 2) to disconnect the clutch 8.

On the other hand, inside the body 11, a hydraulic passage 20 is formed which communicates with a hydraulic nipple 19 which is a hydraulic inlet. The hydraulic passage 20 includes a hole 21 formed at one end (lower end) of the body flange portion 11a, a hydraulic cylinder (hydraulic cylinder) 22 that accommodates the hydraulic piston 17 (formed on the body cylinder portion 11b), and a hydraulic cylinder. It is mainly formed by the control hole 23 on the other end (upper end) side communicating with the lick cylinder 22 via the small hole 23a. When the hydraulic pressure of the hydraulic pipe 54 (FIG. 2) is introduced from the hydraulic nipple 19, the hydraulic pressure passes through the passage and is controlled by the control hole 23.
And pushes the control piston 24 rightward along the control cylinder 25. In this way, the body flange portion 11a
A control valve portion 7a for manually operating the booster 7 is formed on the upper end side of the.

The control valve portion 7a is defined by a control body portion 26 protruding rightward. The control body portion 26 is formed with a control chamber 27 and a pneumatic port 28 that coaxially communicate with the control cylinder 25. A control valve 29 is slidably housed in the control chamber 27, and a poppet valve 30 is slidably housed in the pneumatic port 28. A nipple 31 is attached to the air pressure port 28, and a pneumatic pipe 67 (FIG. 2) is connected to the nipple 31 to constantly supply air pressure.

Normally, the poppet valve 30 is biased to the left side by pneumatic pressure and a poppet spring 32, and closes a communication port 33 that connects the control chamber 27 and the pneumatic pressure port 28. Therefore, the air pressure from the nipple 31 is cut off at the position of the poppet valve 30. However, when hydraulic pressure is supplied particularly by depressing the clutch pedal 9, the control piston 24 and the control valve 29 push the poppet valve 30 to the right to open the communication port 33. Then, the air pressure that has entered the control chamber 27 from the communication port 33 enters the aforementioned cylinder shell 12 through the pneumatic pipes 34 and 35 (FIG. 2) that communicate with the control chamber 27, and pushes the piston plate 13 to the right. Then, the clutch 8 is operated to the disengagement side.

When the clutch pedal 9 is manually operated by the clutch pedal 9, the booster 7 operates the clutch 8 for a predetermined stroke in accordance with the stroke amount of the clutch pedal 9. That is, for example, when the clutch pedal 9 is stroked or depressed relatively small, the piston plate 1 is operated by the above-mentioned pneumatic pressure.
3 is pushed to the right. However, when the hydraulic piston 17 is pushed rightward by a predetermined stroke in conjunction with this, the volume of the hydraulic passage 20 increases and the hydraulic pressure in the control hole 23 decreases. In this case, the control piston 24 presses the control valve 29 against the poppet valve 30, and the poppet valve 30 closes the communication port 33, so that a balance state occurs, which causes the control chamber 27, the pneumatic pipes 34 and 35, and the rear surface of the piston plate 13. A predetermined air pressure is held in the side chamber, the piston plate 13 is held at a predetermined stroke position, and the clutch 8 is held at a predetermined position.

When the clutch pedal 9 is completely returned,
The hydraulic pressure in the control hole 23 is further lowered, and the control piston 24 is returned to the leftmost original position as shown. In this case, the control valve 29 separates from the poppet valve 30, and the open port 36 provided inside the control valve 29 communicates with the control chamber 27 and the like. Then, the air pressure is supplied from the open port 36 to the bleeder 3
It is opened to the atmosphere through 7, so that the piston plate 1
The air pressure that was pressing 3 is released, and the clutch 8 is operated to the connecting side (left side) B.

As described above, the booster 7 has the control valve portion 7a for manual operation, and enables the manual operation of the clutch 8 mainly at the time of starting the vehicle. It also enables the automatic operation of.

In the booster 7, 38 is a seal member for partitioning the cylinder chamber 12a partitioned by the cylinder shell 12 and the hydraulic cylinder 22 into an oil-tight seal.
9 and 40 are atmospheric pressure ports communicating with the bleeder 37, 4
Reference numeral 1 is a bleeder capable of bleeding hydraulic oil when loosened.

FIG. 1 is a vertical sectional view showing details of the master cylinder 10. As shown, the master cylinder 10
Has a cylinder body 45 (cylinder) extending in the longitudinal direction. The cylinder body 45 is formed in a substantially cylindrical shape having a cylinder bore 46 having a constant inner diameter in the longitudinal direction inside. One end (left end) of the cylinder bore 46 is open, and the other end (right end) is closed except that it communicates with a hydraulic pressure supply port 53 formed inside the cylinder body 45. A hydraulic pipe 54 (FIG. 2) is connected to the hydraulic pressure supply port 53, and 53a is a pipe member used for the connection.

In particular, two pistons 47, 48 are independently slidably mounted in the cylinder bore 46. These pistons 47, 48 are arranged in series and are located on the right side of the first
The piston 48 defines a hydraulic chamber 46a (first fluid chamber) with the inner wall of the cylinder bore 46 on the right side of the piston 48.
In the hydraulic chamber 46a, a return spring 52 that biases the first piston 48 to the left side and a return spring 52
And the piston cup 5 disposed between the first piston 48
1 and are charged. The piston cup 51 is slidable on the inner wall of the cylinder bore 46.

The first piston 48 has its right end portion and left end portion slidable with respect to the inner wall of the cylinder bore 46, and its central portion is reduced in diameter so as to be separated from the hydraulic chamber 46a with the inner wall of the cylinder bore 46. Oil chamber 48a (intermediate chamber)
Are formed. The sliding portion 48b at the left end is provided with a pair of circumferential grooves 48c spaced apart in the longitudinal direction, and a sealing cup 48d is housed in these circumferential grooves 48c to seal around the sliding portion 48b. Right end sliding part 4
The piston cup 51 is always in contact with 8e, and the piston cup 51 substantially seals around the sliding portion 48e.

The second piston 47 located on the left side is also the first
Similar to the piston 48, sliding portions 47a and 47b between the right end and the left end
Is slidable on the inner wall of the cylinder bore 46.
A peripheral groove 47c is also provided on the sliding portion 47b at the left end,
A sealing cup 47d is housed in the circumferential groove 47c to perform sealing. The central portion of the second piston 47 has a reduced diameter, whereby an air chamber 47e is formed between the central portion of the second piston 47 and the inner wall of the cylinder bore 46. In particular, the right end sliding portion 47a is formed with a reduced diameter projecting portion 47f protruding rightward, and a gap between the reduced diameter projecting portion 47f and the inner wall of the cylinder bore 46 on the outer peripheral side is used to introduce air pressure. An air pressure chamber 47g (second fluid chamber) separated from 48a is defined. Further, in communication with the pneumatic chamber 47g, the cylinder body 45 is provided with a pneumatic introduction port 55 for connecting a pneumatic pipe 62 (FIG. 2) to form a pneumatic introduction passage.

The movement of the second piston 47 to the left is performed by a snap ring 56 attached to the inner wall of the cylinder bore 46.
Regulated by. Further, a tip end portion of a push rod 49 (rod) which is inserted / removed in accordance with the depression or the return operation of the clutch pedal 9 is inserted into the left end opening of the cylinder bore 46. Furthermore, the opening is the dust boot 50.
Is closed by. The tip end surface of the push rod 49 is formed in a hemispherical shape, and the left end surface of the second piston 47 is also recessed in a hemispherical shape accordingly. These end faces can come into contact with and separate from each other.

The cylinder body 45 is provided with an oil supply passage 45a for supplying hydraulic oil to the hydraulic chamber 46a and the oil chamber 48a via the small diameter port 60 and the large diameter port 61, respectively. The small diameter port 60 is closed by the sealing cup 47d or the right end sliding portion 48e as the first piston 48 is pushed or the hydraulic chamber 46a is moved in the hydraulic oil pressurizing direction, while the large diameter port 61 is always kept in the oil chamber. It communicates with 48a. An oil supply nipple 57 that connects to a reservoir tank 58 (FIG. 2) that stores hydraulic oil via an oil supply pipe 59 (FIG. 2) is attached to the oil supply passage 45a. In addition, the hydraulic pressure supply port 5 is provided in the hydraulic chamber 48a.
A check valve 53b for opening and closing 3 is also provided. 45b
Is a bolt insertion hole for fixing the master cylinder 10 to a vehicle body or the like.

In the master cylinder 10, the hydraulic oil can be pressurized to generate hydraulic pressure by both manual operation using the clutch pedal 9 and automatic operation by pneumatic pressure supply described later. That is, during manual operation,
When the clutch pedal 9 is depressed, the push rod 49
Both the pistons 48, 47 are pushed together via the, to thereby pressurize the hydraulic oil in the hydraulic chamber 46a and supply the hydraulic pressure from the hydraulic pressure supply port 53. On the other hand, in the case of automatic operation, air pressure is supplied from the air pressure introduction port 55 to the air pressure chamber 47g, whereby only the first piston 48 is pushed and the working oil is pressurized. At this time, the air pressure is the second piston 4
7 also pushes it to the left side, but since its movement is restricted by the snap ring 56, the second piston 4
7 is held as it is in the original position on the left end side.

When the first piston 48 is pushed by pneumatic pressure, the hydraulic chamber 46a and the pneumatic chamber 47g both become high pressure. At this time, if air in the pneumatic chamber 47g leaks to the hydraulic chamber 46a, bubbles are mixed into the hydraulic chamber 46a, the hydraulic pipe 54, etc., and a predetermined hydraulic pressure cannot be obtained. Therefore, the oil chamber 48a is formed in order to complete the seal between them. That is, the oil chamber 48a is connected to the reservoir tank 58 and is filled with hydraulic oil at atmospheric pressure. Even if the air in the air pressure chamber 47g enters the oil chamber 48a through the sealing cup 48c or the like, it is depressurized to atmospheric pressure and sent to the reservoir tank 58 through the oil supply passage 45a and the oil supply pipe 59. Therefore, the oil chamber 48a forms a buffer zone between the hydraulic chamber 46a and the pneumatic chamber 47g, whereby the sealing can be completed.

Further, since only the sliding portions 48e, 48b, 47a, 47b at both ends of the first and second pistons 48, 47 are slid, the sliding area is reduced to reduce the frictional resistance. As a result, smooth movement can be achieved.

Now, returning to FIG. 2, the master cylinder 10
The pneumatic introduction port 55 and the air tank 5 are connected to the pneumatic piping 62
The pneumatic piping 62 has two branches 63, 6
5 are provided. A pneumatic pipe 67 is connected to the branch 63, and the other end of the pneumatic pipe 67 is connected to the nipple 31 of the booster 7. A pneumatic pipe 68 is connected to the branch 65, and the other end of the pneumatic pipe 68 is connected to the pneumatic pipes 34 and 35 via a shuttle valve (double check valve) 69. The shuttle valve 69 switches according to the pressure difference so as to connect one of the pneumatic pipes 34 or 68 to the pneumatic pipe 35.

Here, the pneumatic pipes 62, 68 and 35 connecting the branch 65 from the air tank 5, the shuttle valve 69, and the pneumatic nipple 15 of the booster 7 in order form a first pneumatic supply passage a. A pneumatic pipe 62 that branches from the air tank 5 to a branch 63 and connects to the pneumatic nipple 15 of the booster 7,
67, 34, 35 form a second pneumatic supply path b. The first and second pneumatic supply paths a and b can be switched by a shuttle valve 69.

Here, the pneumatic piping 6 of the first pneumatic supply path a
8 is a computer type controller (controller) 72
Two electromagnetic switching valves 78, 79 are provided for switching control by. These switching valves 78 and 79 are opened to allow the supply of air pressure to the downstream side when ON, and shut off the air pressure supply when OFF to open the air pressure on the downstream side to the atmosphere. ing. And especially the switching valve 78 on the upstream side
Is designed to open the air pressure on the downstream side to the atmosphere through a throttle.

Therefore, if the combination of ON and OFF of the switching valves 78 and 79 is ON / ON, the pneumatic pressure supply to the booster 7 is turned ON.
With / OFF, pneumatic discharge is performed in a relatively short time, and with OFF / ON, pneumatic discharge is performed in a relatively long time. OFF / OF
F is substantially the same as ON / OFF. In particular, since two stages of clutch engagement speeds can be selected, it is possible to reduce clutch engagement shock by selecting an optimal combination. The disconnection of the clutch 8 is performed at a relatively high constant speed.

On the other hand, the air tank 5 and the master cylinder 10
And a pneumatic pipe 62 forming a third pneumatic supply path c,
In particular, an electromagnetic switching valve 81 is also provided in the pipe 62. The switching valve 81 is similar to the switching valves 78 and 79, and is switched by the control device 72. When ON, the air pressure is supplied to the master cylinder 10, and when OFF, the air pressure from the master cylinder 10 is applied to the atmosphere. It is designed to be open.
If the opening of the switching valve 81 is duty-controlled, the supply / discharge speed of air pressure can also be controlled.

The transmission 71 is configured to perform automatic shifting, that is, when the shift position is selected by the manual shift lever, the shift signal from the electric switch is transmitted to the control device 7.
2, the actuator (not shown) is operated to perform a substantial gear shift operation. Therefore, the driver only switches the switch.

In addition, the control device 72 includes an accelerator pedal 7
5, a stroke sensor 82 and an idle switch 83, an emergency switch 84 provided near the shift lever of the transmission 71, a vehicle speed sensor 85 provided near the output shaft of the transmission 71, and a pressure provided at the air tank 5. A switch 86, a pedal switch 87 provided on the clutch pedal 9, a clutch stroke sensor 88 provided on the clutch 8 and the like are connected.

The operation of the clutch connecting / disconnecting device 1 will be described below. At the time of gear shifting, the control device 72 controls both switching valves 78 and 79 by inputting a gear shifting signal by the driver's shift operation.
It is turned on or opened to supply pneumatic pressure to the booster 7 through the first pneumatic pressure supply path a. When the clutch 8 is disengaged and the gear shift operation of the transmission 71 is completed by an actuator (not shown), the switching valves 78 and 79 are turned off in a predetermined combination,
The pneumatic pressure of the booster 7 is released at a predetermined speed and the clutch 8 is connected to complete the shift. In this case, since the manual operation is not performed, the inside of the pneumatic pipe 34 is at a low pressure. Therefore, the shuttle valve 69 connects only the pipe 68 to the pipe 35 with the high pressure from the pneumatic pipe 68.

Referring now to FIG. 3, the hydraulic piston 17 moves to the right, particularly during the automatic disconnection operation of the clutch 8, so that the volume of the hydraulic cylinder 22 filled with hydraulic oil increases. Hydraulic passage 20
Further, negative pressure may be generated in the hydraulic pipe 54 and the like (collectively referred to as hydraulic passage), and bubbles may be mixed in the hydraulic oil. In this case, the hydraulic pressure cannot be supplied accurately, and in the worst case, the manual operation of the clutch 8 cannot be performed, which causes a problem that the vehicle cannot be started.

Therefore, in this structure, the pneumatic chamber 4 of the master cylinder 10 is operated when the clutch 8 is automatically disengaged.
Air pressure is supplied to 7 g through an air pressure pipe 62, and the first piston 48 is appropriately pushed to appropriately pressurize the inside of the hydraulic passage. In this way, it is possible to prevent negative pressure in the hydraulic passage and prevent troubles.

Particularly in such a structure, at the time of the automatic disconnection operation of the clutch 8, before the switching valves 78 and 79 are opened,
The switching valve 81 is opened slightly earlier to apply an appropriate initial pressure. Thereby, complete prevention of negative pressure can be achieved.

When the clutch 8 is automatically connected, the pressure inside the hydraulic passage is gradually increased, so that the air pressure in the air pressure chamber 47g is appropriately released from the switching valve 81 to the atmosphere. In this case, the first piston 48 can be returned to the original position. Also at this time, the switching valve 81 is closed with a delay after the switching valves 78 and 79 are closed, and air pressure is applied to the end to completely prevent negative pressure.

In addition, during manual operation using the clutch pedal 9, hydraulic pressure is sent from the master cylinder 10 at the moment when the clutch pedal 9 is depressed, whereby the control valve portion 7a is opened and the shuttle valve 69 is pneumatically operated. By switching, the pneumatic pipes 34 and 35 are connected to each other. In this case, pneumatic pressure is supplied to the booster 7, and the clutch 8 is disconnected. In particular, during this manual operation, negative pressure does not occur because the inside of the hydraulic passage is positively pressurized. In this way, even if the automatic operation is disabled due to an electric system trouble or the like, the clutch can be engaged and disengaged by the manual operation, and the starting and shifting can be performed.

By the way, during the automatic operation, that is, in the state where air pressure is supplied to the air pressure chamber 47g of the master cylinder 10,
When the clutch pedal 9 is depressed, the following occurs. At this time, the first piston 48 is pushed from the original position by a predetermined stroke, and the second piston 47 is acted on by air pressure at the original position, which is forced against the pneumatic reaction force. Will be pushed. In this case, although there is a pneumatic reaction force, the clutch pedal 9 can be depressed with normal pedaling force. The second piston 47 is depressed by the depression.
When is pushed, since the capacity of the air tank 5 is relatively large, the internal pressure of the pneumatic chamber 47g rises slightly, but the air in the pneumatic chamber 47g flows back to the pneumatic pipe 62. As a result, the internal pressure of the pneumatic chamber 47g can be kept substantially constant, the movement or overstroke of the first piston 48 can be prevented, and the malfunction of the clutch 8 can be prevented.

In such a structure, it is sufficient to pressurize the hydraulic passage to such an extent that the pressure in the hydraulic passage is not made negative.
8 and the like need not have a particularly large diameter, and the master cylinder 10
Can be set to a conventional outer diameter, and large size can be prevented.

The pressurization of the hydraulic passage as described above can be performed by changing the internal structure around the hydraulic cylinder 22 of the booster 7, but this makes it possible to adopt a complicated structure in a narrow space. Inevitably, there are problems such as sealing, which is disadvantageous in terms of reliability and maintainability.
Since this embodiment corresponds to the structure of the master cylinder 10 and the structure of the pneumatic circuit without changing the booster 7 similar to the conventional one, the structure is simple without any of the above-mentioned drawbacks and sufficient reliability is obtained. , Maintainability, etc. can be secured. Then, by the mechanical drive and pneumatic pressure supply control by the clutch pedal 9, it is possible to generate a desired hydraulic pressure without interfering with each other.

[Second Embodiment] As shown in FIG. 5, in this embodiment, the structure of the clutch connecting / disconnecting device according to the first embodiment is modified. Hereinafter, the changed points will be mainly described, and the description of the same matters will be omitted and only the same reference numerals will be given to the drawings.

As shown in the figure, in this embodiment, the control valve portion 7a of the booster 7 and the pneumatic nipple 15 are directly connected by the pneumatic pipe 34. The branch 65 in the first embodiment is not provided, and only the branch 63 connected to the inlet (nipple 31) of the control valve portion 7a by the pipe 67 is provided. In this way, the pneumatic pipes 62, 67, and 34 that branch from the air tank 5 to the branch 63 and connect to the pneumatic nipple 15 of the booster 7 form the first pneumatic supply path a. The pneumatic pipe 62 connecting the air tank 5 and the master cylinder 110 forms a second pneumatic supply path b. In the pneumatic pipe 62, switching valves 78 and 79 similar to the above are provided instead of the switching valve 81 in the first embodiment.

As shown in FIG. 4, the structure of the master cylinder is particularly different in this embodiment. Master cylinder 110
Has a cylinder body 111 (cylinder) extended in the longitudinal direction, and the cylinder body 111 has, inside thereof,
One end (left end) side in the longitudinal direction has a cylinder bore 112 having a large diameter and the other end (right end) side having a small diameter, and is formed into a stepped, substantially cylindrical shape. The left end of the cylinder bore 112 is open, and its right end is closed except that it communicates with a hydraulic pressure supply port 113 formed inside the cylinder body 111.
A hydraulic pipe 54 (FIG. 5) is connected to the hydraulic supply port 113.

In particular, two pistons 114 and 115 are independently slidably mounted in the cylinder bore 112. These pistons 114 and 115 are arranged in series, and the first piston 114 located on the right side defines a hydraulic chamber 116 (first fluid chamber) with the inner wall of the cylinder bore 112 on the right side thereof. In the hydraulic chamber 116, the first piston 11
A return spring 117 for urging No. 4 to the left is inserted.

In particular, the first piston 114 is constructed by dividing it from small-diameter and large-diameter piston members 114a and 114b,
The piston members 114a and 114b are inserted into the small diameter portion and the large diameter portions 112a and 112b of the cylinder bore 112, respectively. Center hole 11 of large-diameter piston member 114a
A pin 119 is press-fitted and fixed to the shaft 8, and the pin 119 is inserted into the center hole 120 of the small diameter piston member 114a so as to be freely inserted and removed. Therefore, the piston members 114a, 114
Although b can move in the dividing direction, in actuality, they are pressed against each other by hydraulic pressure, pneumatic pressure, or the urging force of the return spring 117, so they are not divided. Only the left and right ends of the small-diameter piston member 114a slide, and the large-diameter piston member 114b slides only the large-diameter portion 122 on the left side except the small-diameter portion 121 on the right side. As a result, the oil chamber 123 is provided between the small diameter portion 112a of the cylinder bore 112 and the central portion of the small diameter piston member 114a.
However, the first air chamber 1 is provided between the large diameter portion 112b of the cylinder bore 112 and the small diameter portion 121 of the large diameter piston member 114b.
24 will be formed respectively. A piston cup 125 is provided at the right end of the small-diameter piston member 114a, and a sealing cup 126 is provided at the left end, and the sealing cup 127 is also provided at the large-diameter portion 122 of the large-diameter piston member 114b.
Is provided. Further, at the right end of the small diameter piston member 114a, an insertion portion 128 to be inserted into the end portion of the return spring 117 is formed.

A tapered recess 129 is formed on the left end surface of the large-diameter piston member 114b, and the buffer member 13 for abutting the second piston 115 on the bottom of this recess 129.
0 is fixed. The cushioning member 130 is formed of an elastic body such as rubber to block hydraulic pressure pulsation or vibration. Second piston 1
The right end surface of 15 has a tapered protrusion 1 along a recess 129.
31 is formed, and the tip end surface of the protrusion 131 is the cushioning member 1.
It becomes a substantial contact surface to 30. Especially when these abut as shown, the first piston 114 and the second piston 1
A gap is formed between the air pressure chamber 15 and 15, and the gap defines a pneumatic chamber 133 (second fluid chamber) for introducing pneumatic pressure from the pneumatic introduction port 132 (introduction path).

Only the left and right ends of the second piston 115 slide along the large diameter portion 112b of the cylinder bore 112. And the central reduced diameter part,
The second air chamber 134 is defined by the inner wall of the large diameter portion 112b. The second piston 11 is provided at the left end of the large diameter portion 112b.
A snap ring 136 is provided that restricts the movement of 5 through the contact ring 135. In particular, the left end of the large diameter portion 112b remains open, and the push rod 49 (rod) is inserted into this opening. Push rod 49
Is inserted longer than the above, extends the bore portion 137 of the second piston 115, and contacts the second piston 115 on the back side of the tip end surface of the protrusion 131. In particular, the provision of the bore portion 137 makes the second piston 115 lightweight.

A sealing cup 138 is provided at the left end sliding portion of the second piston 115, and a seal ring 139 is fixed to the right end sliding portion thereof. An oil supply passage 142 is connected to the hydraulic chamber 116 and the oil chamber 123 through a small diameter port 140 and a large diameter port 141, respectively. The oil supply passage 142 is connected to the reservoir tank 58 (FIG. 5) via the oil supply pipe 59 (FIG. 5), as described above. 143 is a bolt insertion hole.

In this master cylinder 10 as well, air pressure can be supplied to the air pressure chamber 133 to generate oil pressure, as described above, but air pressure is applied to the large-diameter piston member 114b.
Since the small diameter piston member 114a is used to generate the hydraulic pressure, there is a merit due to the boosting effect that a large hydraulic pressure can be obtained with a small air pressure. Here, the oil chamber 123, the first
The second air chambers 124 and 134 form an intermediate chamber as a buffer zone similarly to the above, but in particular, the first air chamber 124 changes its volume, that is, expands / contracts in accordance with the movement of the first piston 114. It will be. So this is the first
The cylinder body 111 is provided with a breather 144 that communicates the first air chamber 124 with the outside so as not to act as a movement resistance of the piston 114. The breather 144 can supply / exhaust air to / from the outside when the first air chamber 124 expands / contracts, thereby making the operation of the first piston 114 smooth. Further, the air leaking from the pneumatic chamber 133 is also depressurized to the atmospheric pressure here and exhausted to the outside.

Further, since the first piston 114 is a sliding member, high machining accuracy is required, but since it is divided into a small diameter portion and a large diameter portion here, there is an advantage that machining can be easily performed. However, as long as the processing accuracy can be satisfied, it does not matter if they are integrated without being divided.

Now, the operation of the device 1 will be described. At the time of gear shifting, in the above-described first embodiment, pneumatic pressure is sent to the master cylinder 10 in accordance with pneumatic pressure supply to the booster 7 to pressurize the hydraulic passage. However, in the present embodiment, the air pressure supply to the master cylinder 110 positively pressurizes the hydraulic passage, and the booster 7 and the clutch 8 are operated by this air pressure supply.

That is, when the clutch 8 is automatically disengaged, both switching valves 78 and 79 are turned on or opened to supply air pressure to the air pressure chamber 133 of the master cylinder 10 through the second air pressure supply passage b. . Then, the pneumatic pressure pushes the first piston 114 to pressurize the hydraulic oil in the hydraulic chamber 116 to generate hydraulic pressure,
The inside of the hydraulic passage is pressurized. by this,
It is possible to prevent negative pressure in the hydraulic passage and prevent troubles. When the hydraulic pressure is sent to the booster 7, the control valve portion 7a is opened, air pressure is supplied to the booster 7 from the first pneumatic supply path a, and the clutch 8 is disengaged.
When the switching valves 78 and 79 are turned off or closed, the air in the pneumatic chamber 133 is discharged from the switching valves 78 and 79, the hydraulic pressure in the hydraulic passage is released, and the clutch 8 is connected.

Particularly, this is largely due to the boosting effect obtained by providing the first piston 114 with the large diameter portion and the small diameter portion (the large diameter piston member 114b and the small diameter piston member 114a). That is, the hydraulic oil can be strongly pressurized in a short time with normal air pressure, and thus the clutch 8 can be operated without any problem. The diameter may be small as long as sufficient hydraulic pressure can be generated.

The device 1 has a merit that the pneumatic circuit is simpler than that of the first embodiment and that the same effect can be obtained by this simple structure.

The preferred embodiment of the present invention has been described above, but the present invention can be modified in addition to the above embodiment. Further, the present invention can be applied to other than the master cylinder.

[0060]

The present invention exhibits the following excellent effects.

(1) When the clutch is automatically operated, it is possible to prevent a negative pressure state in the hydraulic passage and prevent bubbles from being mixed into the hydraulic fluid, so troubles such as manual operation of the clutch cannot occur. Can be prevented.

(2) Since the effect of (1) can be obtained with a simple structure without largely changing the conventional device, sufficient reliability can be secured.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a fluid pressure generating device according to a first embodiment.

FIG. 2 is an overall configuration diagram showing a clutch connecting / disconnecting device according to a first embodiment.

FIG. 3 is a longitudinal sectional view showing a booster.

FIG. 4 is a vertical sectional view showing a fluid pressure generator according to a second embodiment.

FIG. 5 is an overall configuration diagram showing a clutch connecting / disconnecting device according to a second embodiment.

[Explanation of symbols]

 10,110 Master cylinder (fluid pressure generating device) 46a, 116 Hydraulic chamber (first fluid chamber) 45,111 Cylinder body (cylinder) 48,114 First piston 47g, 133 Air pressure chamber (second fluid chamber) 47, 115 second piston 49 push rod (rod) 55, 132 pneumatic introduction port (introduction path)

Front page continuation (72) Inventor Nobuyuki Iwao No. 8 Tsutana, Fujisawa City, Kanagawa Prefecture Isuzu Central Research Institute Co., Ltd. (72) Takahiro Tani 3-25-1 Tonomachi, Kawasaki-ku, Kawasaki City, Kanagawa Isuzu Motors Limited Kawasaki Factory (72) Inventor Takao Takano 3-25-1, Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Isuzu Motors Limited Kawasaki Factory

Claims (2)

[Claims] 1. A cylinder that defines a first fluid chamber that accommodates a working fluid, a first piston that slides in the cylinder to pressurize the working fluid, and a cylinder that is slidably provided in the cylinder. A second piston defining a second fluid chamber between the first piston, a rod for pushing the first and second pistons in a working fluid pressurizing direction, and a second fluid chamber communicating with the second fluid chamber, The first fluid is introduced by introducing pressure fluid into the second fluid chamber.
A fluid pressure generator comprising: an introduction path for pushing a piston. 2. The fluid pressure generating device according to claim 1, wherein an intermediate chamber separated from the first and second fluid chambers is defined between the cylinder and the first piston.