KR100495346B1 - Hydraulic cylinder - Google Patents

Abstract

The present invention relates to a hydraulic cylinder, in which a small diameter cylinder (1a) and a large diameter cylinder (1b) are connected to each other in a housing, and the stepped piston (8) inserted into the cylinder includes a large diameter portion (8b) and a small diameter portion ( 8a), the first pressure chamber 14a is formed on the side of the small-diameter cylinder, and the third pressure chamber 14c is formed on the side of the large-diameter cylinder by the stepped piston 8. The pressure chamber 14b is formed on the outer circumferential surface of the small diameter portion of the stepped piston 8, and the intermediate cylinder 10 is formed inside the stepped piston 8 to form the fourth pressure chamber 14d. The piston 5 slides freely therein, and the fourth pressure chamber 14d is always in communication with the third pressure chamber 14c, while the rod 4 connected to the piston 5 Penetrating coaxially with the stepped piston 8 and limiting the maximum stroke L1 of the piston 5 By setting the maximum stroke L2 of the stepped piston 8 while having the front stopper 11, and controlling the hydraulic pressure supplied from the first pressure chamber 14a to the fourth pressure chamber 14d, the The stroke of the rod 4 can be adjusted to four positions (0, L1, L2, L1 + L2).

Description

Hydraulic cylinder {HYDRAULIC CYLINDER}

The present invention relates to a hydraulic cylinder that can be moved in three or four stages of position.

In a transmission of a vehicle, a hydraulic cylinder is used as a shift actuator and a select actuator for operating a gear transmission (for example, Japanese Patent Application No. Hei 5-17243 published by the Japanese Patent Office in 1994).

In the above-mentioned patent, the hydraulic cylinder for shift and select operation is controlled by the hydraulic pressure supplied through a solenoid valve controlled by a microcomputer, and when the vehicle shift is required, the hydraulic cylinder is moved to a gear shifting position. Activate

In this case, since the three-stage position shift function is required for the hydraulic cylinder, a conventional hydraulic cylinder for enabling the three-stage position shift function is shown in FIG.

That is, two free pistons 211, 212 are received in the cylinder 206, and another piston 210 is interposed therebetween, the piston 210 passing through the cylinder 206 with a rod 201. And a pressure chamber 202 facing the free piston 211 and a pressure chamber 203 facing the free piston 211 are provided in the cylinder 206, and these pressure chambers 202, 203 are provided with a solenoid valve ( 204, 205 is connected to a high-pressure air source supplied through.

As shown in the figure, when the high pressure air is supplied to the pressure chamber 202 through the solenoid valve 204 and the pressure chamber 203 is in communication with the atmosphere through the solenoid valve 205, the free piston 211 and piston 210 are moved due to the pressure acting on their pressure receiving surfaces.

In this process, the free piston 211 stops at an intermediate position corresponding to the intermediate stage of the drawing, but the piston 210 moves to the right side of the drawing until it contacts the right front end of the cylinder 206.

Meanwhile, when the high pressure air is supplied to the pressure chamber 203 through the solenoid valve 205 and the pressure chamber 202 communicates with the atmosphere through the solenoid valve 204, the free piston 212 and the piston 210 move to the left together due to the pressure acting on their pressure receiving surfaces.

When the intermediate position (neutral position) shown in the drawing is reached, the free piston 212 comes into contact with the end and stops at this position, but the piston 210 is combined with the other free piston 211 and the cylinder ( Continue to the left until it contacts the left end of 206).

On the other hand, when high pressure air is simultaneously supplied to the pressure chambers 202 and 203 via the solenoid valves 204 and 205, the piston 210 moves to a neutral position with the free pistons 211 and 212 to stop at this position. .

In such a case, the rod 201 can be moved to three stages, for example, the maximum extension position and the minimum extension position and the neutral position therebetween, depending on the opening and closing of the solenoid valves 204 and 205.

However, when the pressure chambers 202 and 203 are in communication with the atmosphere after the solenoid valves 204 and 205 are stopped in the neutral position, there is a difference in the responsiveness of the solenoid valves 204 and 205 or a pressure loss in the passage or There is a difference in the volume of (202,203), which causes a differential pressure to be applied to one side of the piston (210) so that the operating pressure acting on the piston (210) is not balanced, so that the piston (210) is left Or move to the right or displace.

Fast responsive solenoids can be used to correct for this piston drift, and throttles can be provided in the passages to adjust for non-uniformity of pressure drop, as well as to add resistance to the load connected to the output shaft. have.

In addition, there are some scatters in the response speed of the solenoid valve, and the response speed of the solenoid valves may vary according to the supply voltage and the supply pressure. Attempts have been made to use controls that increase the sliding resistance of the piston or allow displacement.

However, some instability of the battery voltage of the vehicle was unavoidable, and reducing the passage resistance or reducing the difference between the left and right pressure chambers must be symmetrical in design, which not only limits design freedom. The hydraulic cylinder was made essentially larger and heavier.

In addition, in a control device in which such a displacement is generated during the select operation in the neutral position, it is necessary to first maintain the neutral position by the shift hydraulic cylinder, which causes a delay in the control and reduces the consumption of compressed air. Is increased.

In addition, if the transmission has a reverse gear of the first stage and a forward gear of the seventh stage, a hydraulic cylinder capable of three-position movement as a shift actuator is required, and a hydraulic cylinder capable of four-position movement as a select actuator is required.

If two types of hydraulic cylinders with different elements are provided, the manufacturing cost is increased compared to the case of manufacturing only one hydraulic cylinder.

It is therefore an object of the present invention to provide a hydraulic cylinder which can be precisely positioned without displacement at any stroke position.

In addition, an object of the present invention is to provide a hydraulic cylinder capable of moving in three stages and a hydraulic cylinder capable of moving in four stages while reducing manufacturing costs by using a large number of joint parts.

In order to achieve the above object, the present invention provides a small diameter cylinder, a large diameter cylinder connected to each other in a housing, a large diameter portion that is freely slid in the large diameter cylinder, and a small diameter portion that is slid freely in the small diameter cylinder. A differential pressure chamber, a first pressure chamber formed on the side of the small diameter cylinder, a third pressure chamber formed on the side of the large diameter cylinder by the stepped piston, and an annular second pressure chamber formed on an outer circumferential surface of the small diameter portion of the stepped piston. An intermediate cylinder formed in the stepped piston and opened into the first pressure chamber, a piston inserted to slide freely in the intermediate cylinder to form a fourth pressure chamber, the second pressure chamber and the fourth pressure chamber; Through passages that always communicate with each other, rods connected to the pistons to axially penetrate the stepped pistons, Means for providing a leading stopper for limiting the maximum stroke of the piston to L1, for limiting the maximum stroke of the stepped piston to L2, a first valve for controlling the hydraulic pressure in the first pressure chamber, and the second pressure chamber; And a second valve for controlling the hydraulic pressure in the fourth pressure chamber, and a third valve for controlling the hydraulic pressure in the third pressure chamber, wherein the rod is selectively controlled through the first, second, and third valves. Is stopped at four stroke positions (0, L1, L2, L1 + L2).

It is preferable that the maximum stroke L1 of the piston is set equal to the maximum stroke L2 of the stepped piston, and a shift lever having a gear shift function is connected to the rod.

Further, it is preferable that a shift lever having a gear shift function is connected to the rod, while having a spacer for changing the maximum stroke L1 of the piston to half of the maximum stroke L2 of the stepped piston.

According to the present invention, the rod stroke can be adjusted to four positions (0, L1, L2, L1 + L2) by the first to third solenoid valves which are selectively opened and closed.

By setting the maximum stroke L1 of the piston and the maximum stroke L2 of the stepped piston equally, the rod stroke is divided into three equidistant positions by the first to third solenoid valves that are selectively opened and closed. For example, 0, L1 (L1 = L2), L1 + L2 can be adjusted. Therefore, the position movement can be controlled in three stages.

Furthermore, by setting the maximum stroke L1 of the piston to half of the maximum stroke L2 of the stepped piston, the rod stroke is divided into four equidistant positions by the first to third solenoid valves, which are selectively opened and closed. For example, it can stop at 0, L1, L2, L1 + L2. In this case, the parts except for the spacer are the same as the hydraulic cylinder for enabling the three-stage position shift, and the hydraulic cylinder can be applied to the three-stage position shift or the four-stage position shift cylinder depending on whether the spacer is applied. have. In other words, these two types of hydraulic cylinders can increase productivity by using the same part of both.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 illustrates a shift control apparatus of a transmission using a hydraulic cylinder according to the present invention, wherein a transmission that performs automatic or manual shift control includes a first gear and a seventh gear.

The hydraulic cylinder 102 is to enable three-stage position shift as a shift actuator, and the hydraulic cylinder 101 is to enable three-stage position shift as a select actuator.

The output shaft 109 of the hydraulic cylinder 102 for the shift operation is connected to one end of the reverse lever 105 via the link rod 104, and the link rod 106 is mediated at the other end of the reverse lever 105. Low power shifter 116 is connected to the input shaft 107, the output shaft 108 of the hydraulic cylinder 101 for the select operation is connected to the select lever 120 of the transmission via a link rod 103, An unshown output shaft of the power shifter 116 is connected to the shift lever of the transmission.

Mechanical and manual transmissions that transmit select and shift operations resulting from manual shifts in the driver's seat to the select levers 120 and the shift levers of the transmission are linked to the side of the transmission for linkages 119 and 123 in the driver's seat and for each shift path. It consists of link rods 117 and 121 which are arranged, and lever devices 118 and 122 are interposed between this linkage and the link rod.

The input shaft 107 of the power shifter 116 is connected to one end of the lever device 118 via a link rod 117, the linkage 119 is connected to the other end of the lever device 118, the transmission The select lever 120 is connected to one end of the lever device 122 via the link rod 121, the linkage 123 is connected to the other end of the lever device 122.

Sensors (not shown) for detecting the stroke positions of the output shafts 108 and 109 are installed in the hydraulic cylinders 101 and 102, respectively, and input corresponding sensing signals 113 and 111 to the control device 110.

When the control device 110 issues a shift command corresponding to the driving state of the vehicle or any operation, the control signals 112 and 114 of the control device 110 are moved so that the gear position of the transmission can be moved to the required gear position. Are applied to the hydraulic cylinders (101, 102).

On the other hand, when a switch command to the mechanical manual shift mode is applied by any means not shown, the control device 110 releases the hydraulic cylinders 101 and 102 in a free state while stopping the gear shift control of the transmission.

While the shift request is made by the manual shift operation, the shift operation is performed in the cab, and this shift operation is transmitted from the linkage 119 to the link rod 117 via the lever device 118, and the shift lever of the transmission It is operated by the output shaft of the power shifter 116, the select operation is transmitted from the linkage 123 to the link rod 121 via the lever device 122 to operate the select lever 120 of the transmission.

In other words, when a manual shift operation is required, since the hydraulic cylinders 101 and 102 are in a free state, the shift of the transmission (reverse gear of 1st stage and forward gear of 7th stage) is performed by manual operation of a mechanical transmission in the cab. .

2 and 3 show the structure of the hydraulic cylinder 102 that can be moved in three stages for the shift operation.

A large diameter cylinder 1b is formed in the housing 1, a small diameter cylinder 1a is coaxially connected to the rear end, and a bearing 2a is formed in front of the small diameter cylinder 1a inside the housing 1. It is provided coaxially with 1a, 1b).

One end of the large diameter cylinder 1b of the housing 1 is opened, and a tip cap 3 for sealing the open portion is fitted. A bearing 2b is formed coaxially with the cylinders 1a and 1b in the tip cap 3, and the rod 4 is inserted through the bearings 2a and 2b so as to be freely slidably inserted therein. have.

The piston 8 in which the intermediate portion is formed in a stepped shape is accommodated in the cylinders 1a and 1b, and the stepped piston 8 thus slides freely in the large-diameter cylinder 1b and the small-diameter cylinder. It consists of the small diameter part 8a which slides freely in (1a), and the above-mentioned rod 4 slides freely through the center of the bearing 2c. The annular pressure chamber 14b (second pressure chamber) is formed between the outer circumferential surface of the small diameter portion 8a and the inner circumferential surface of the cylinders 1a and 1b, and the small diameter portion 8a is formed in a cylindrical shape while the intermediate cylinder ( 10 is provided inside the small diameter part 8a.

A piston (5) which slides freely is provided in the intermediate cylinder (10), the piston (5) is fixed at a determined position on the rod (4) via stoppers (6a, 6b), and the tip stopper (11) (5) and the stopper 6c, 6d are fixed at the determined position on the opposite side surrounding the bearing 2c.

The pressure chamber 14d (fourth pressure chamber) is formed in the intermediate cylinder 10 by the piston 5, and the passage 16d for permanently connecting the pressure chamber 14d to the outer pressure chamber 14b is It is formed in the intermediate cylinder 10.

The pressure chamber 14a (first pressure chamber) is formed in the small diameter cylinder, and the pressure chamber 14c (third pressure chamber) is formed in the large diameter portion by the stepped piston 8 which accommodates the piston 5.

The pressure chambers 14a to 14c are connected to the solenoid valves 15a to 15c through the passages 16a to 16c, and the solenoid valves 15a to 15c are compressed air into the pressure chambers 14a to 14c. The compressed air is discharged from the pressure chambers 14a to 14c while supplying the air, and the solenoid valves 15a to 15c are connected to the high pressure air source 100, while the high pressure air source 100 is air. Air storage tank 51 for storing the compressed air from the compressor (not shown), and the pressure reducing valve 50 to adjust the pressure of the air supplied to the solenoid valve (15a, 15b) to a predetermined pressure.

Dampers on both sides of the bearing 2c of the stepped piston 8 to alleviate the collision between the piston 5 arranged on both sides of the stepped piston 8 and the tip stopper 11. 12c and 12d are provided, and dampers 12a and 12b are provided on both front ends of the large diameter cylinder 1b so as to alleviate the collision with the large diameter portion 8b of the stepped piston 8.

In this case, the relationship between the maximum stroke L of the piston 5 and the maximum stroke L2 of the stepped piston 8 is set equally so that the hydraulic cylinder can be moved in three stages. .

The airtight member 9a seals the sliding surface between the piston 5 and the intermediate cylinder 10, and the airtight member 7a is the small diameter portion 8a and the small diameter cylinder 1a of the stepped piston 8. Is to seal the sliding surface between), and the airtight member 7b seals the sliding surface between the large diameter part 8b and the large diameter cylinder 1b, while the airtight member 9b is the bearing 2c. And a sliding surface between the rod 4 and the airtight members 13a and 13b seal the sliding surface between the bearings 2a and 2b on both sides of the cylinders 1a and 1b and the rod 4. To seal.

When the solenoid valves 15a to 15c are turned off, the pressure chambers 14a to 14d communicate with the atmosphere. In this case, when the rod 4 is operated by an external force, the range of the sum L1 + L2 of the maximum stroke L1 of the piston 5 and the maximum stroke L2 of the stepped piston 8. May be set arbitrarily.

When compressed air is selectively supplied into the solenoid valves 15a to 15c, a three-step positional shift of the rod 4 is made. This operation will be described based on FIGS. 3 and 4.

9 shows the operation pattern of the solenoid valves 15a to 15c.

In FIG. 4, when one end of the rod 4 moves from the F position to the N position, the solenoid valve 15b is turned on while compressed air is supplied into the pressure chamber 14b.

At the same time, the solenoid valves 15a and 15c are turned off while the pressure chambers 14a and 14c communicate with the atmosphere. Due to the on of the solenoid valve 15b, the pressure in the pressure chamber 14b rises, and the pressure in the pressure chamber 14d connected to the pressure chamber 14b via the passage 16d also rises.

Due to the pressure rise of the pressure chamber 14d, the piston 5 moves together with the rod 4 in the intermediate cylinder 10, in which the tip stopper 11 of the rod 4 is stepped. When it hits the piston 8, the movement is stopped.

That is, due to the pressure acting in the pressure chamber 14b, the stepped piston 8 moves by the distance L2 toward the right side of the drawing, for example, in the direction to compress the pressure in the pressure chamber 14c, It comes in contact with the tip of the large-diameter cylinder 1b (damper 12b). As a result, the rod 4 moves with the stepped piston 8 and its tip moves by the distance L2 from the F position, and stops at the N position, as shown in 1- (1).

After stopping at the N position. The solenoid valve 15b is turned off.

Accordingly, the high pressure air in the pressure chambers 14b and 14d is discharged to the outside through the passages 16b and 16d, and the pressure in the pressure chambers 14b and 14d is discharged while the high pressure air is discharged to the outside. Higher than atmospheric pressure.

On the contrary, as the pressure in the pressure chambers 14a and 14c is atmospheric pressure, the above-described relationship between the piston 5 and the stepped piston 8 is continued, while these (stepped with the piston 5) The piston 8 is kept stopped at this position, so that no displacement of the rod 4 occurs.

When the front end of the rod 4 moves to the R position at the N position, the solenoid valve 15a is turned on, and high pressure air is supplied into the pressure chamber 14a, and at the same time, the solenoid valve 15b, While 15c) is off, the pressure chambers 14b and 14c communicate with the atmosphere.

At this time, due to the pressure of the pressure chamber 14a, the piston 5 moves toward the rear of the intermediate cylinder 10 by L1 distance, and comes into contact with the front end of the intermediate cylinder 10 (damper 12c). In addition, the pressure in the pressure chamber 14a presses the stepped piston 8 in the direction in which the pressure chamber 14c is compressed.

As the stepped piston 8 comes into contact with the base end of the large-diameter cylinder 1b, it cannot move in this direction, and accordingly, the front end of the rod 4 is retracted by an L1 distance from the N position, and thus shown. As in 1- (2), it stops at the R position. After stopping at the R position, the solenoid valve 15a is turned off, and the high pressure air in the pressure chamber 14a is discharged to the outside via the passage 16a.

While the high pressure air is discharged, the pressure in the pressure chamber 14a drops to atmospheric pressure while the piston 5 and the stepped piston 8 are immovably fixed. As a result, the rod 4 does not move in the axial direction.

When the front end of the rod 4 moves from the R position to the N position, the solenoid valve 15b is turned on and high pressure air is supplied into the pressure chambers 14b and 14d, and at the same time the solenoid valve 15a. 15c is turned off while the pressure chambers 14a and 14c communicate with the atmosphere.

At this time, while the pressure acts on the pressure receiving surface of the stepped piston 8 toward the pressure chamber 14b, the stepped piston 8 is pushed in the direction to pressurize the pressure chamber 14c. As 8) comes into contact with the base end of the large diameter cylinder 1b, it can no longer be moved.

Due to the pressure in the pressure chamber 14d, the piston 5 moves at a distance L1 from the base of the intermediate cylinder 10 in the direction of expanding the pressure chamber 14d, and the piston 5 is The tip stopper 11 stops when it comes in contact with the pressure receiving surface of the stepped piston 8.

As a result, the leading end of the rod 4 stops at the N position as shown in 1- (3) as it is advanced from the R position to the L1 distance.

When the rod 4 stops at the N position, the solenoid valve 15b is turned off, and the high pressure air in the pressure chambers 14b and 14d is discharged to the outside via the passages 16b and 16d. While the high pressure air is discharged, the pressure in the pressure chambers 14b and 14d drops below atmospheric pressure while the stepped piston 8 and the piston 5 remain stationary, so that the rod 4 There is no displacement of.

When the front end of the rod 4 moves from the N position to the F position, the solenoid valves 15b and 15c are turned on, and high pressure air is supplied into the pressure chambers 14b and 14c, on the contrary, the solenoid The valve 15a is turned off and the pressure chamber 14a is in communication with the atmosphere.

Three possible examples of the operation sequence of the solenoid valve 15b and the solenoid valve 15c are as follows.

(1) After the solenoid valve 15b is turned on, the solenoid valve 15c is turned on.

(2) The solenoid valve 15c is turned on and then the solenoid valve 15b is turned on.

(3) The solenoid valve 15b and the solenoid valve 15c are turned on at the same time.

Any of the above (1) to (3) may occur.

First, in the case of (1), the high-pressure air is supplied through the passage 16b due to the on of the solenoid valve 15b, and the pressure in the pressure chambers 14b and 14d rises. This rising pressure acts in the direction in which the pressure chambers 14b and 14d are expanded, while pushing the stepped piston 8 in the direction of pressing against the distal end of the large-diameter cylinder 1b, and at the same time, the piston 5 is disconnected. Pressurization in the direction away from the differential piston (8).

When the solenoid valve 15c is turned on after the solenoid valve 15b is turned on, high pressure air is supplied to the pressure chamber 14c via the passage 16c. The pressure in the pressure chamber 14c is raised, and this rising pressure acts to move the stepped piston 8 in the direction in which the pressure chamber 14c is expanded. In the initial stage of pressure rise, the operating pressure based on the pressure in the pressure chamber 14b becomes dominant, so that the stepped piston 8 does not move. However, when the pressure of the pressure chamber 14c further rises and the expression described later is satisfied, the stepped piston 8 starts to move.

[Pressure of the pressure chamber 14c]> [Pressure of the pressure chamber 14b] × [Pressure receiving surface of the stepped piston 8 toward the pressure chamber 14b] / [Step difference towards the pressure chamber 14c] Pressure receiving surface of piston (8)] ----------------------------------------- ----------------------- {One}

In other words, when the state of the inequality {1} is satisfied, the stepped piston 8 starts to move in the direction of expanding the volume of the pressure chamber 14c, and the end (damper 12a) of the large diameter cylinder 1b. Move to L2 distance limited by

On the other hand, the piston 5 is pressurized in the direction of expanding the volume of the pressure chamber by the pressure of the pressure chamber 14d while being restricted by the tip stopper 11, so that the tip of the rod 4 is N Advance to L2 distance from position and stop at position F as shown 1- (4).

After stopping at the F position, the solenoid valves 15b and 15c are switched to the off position. The operation sequence of the solenoid valves 15b and 15c will be as follows.

(1) After the solenoid valve 15b is turned off, the solenoid valve 15b is turned off.

(2) After the solenoid valve 15c is turned off, the solenoid valve 15c is turned off.

(3) The solenoid valve 15b and the solenoid valve 15c are turned off at the same time.

The relationship between the pressure in the pressure chamber 14c and the pressure in the pressure chamber 14b does not satisfy the state of the inequality {1}, and the stepped piston 8 moves.

In the case of (1) above, the state of inequality {1} will definitely be satisfied.

In the case of (2) above, it is easily generated that the state of inequality {1} is not satisfied.

In the case of (3), the pressure in the pressure chamber 14c decreases as the pressure in the pressure chamber 14b decreases, but as the pressure decreases faster in the pressure chamber 14b, the inequality { 1} is satisfied.

5 illustrates another mode of operation for a three-step positional shift of the rod 4. When the tip of the rod 4 moves from the F position to the N position, the solenoid valves 15a and 15c are turned on, and high pressure air is supplied to the pressure chambers 14a and 14c, and at the same time the solenoid valve 15b is turned off, and the pressure chamber 14b is in communication with the atmosphere.

The operation sequence of the solenoid valve 15a and the solenoid valve 15c will be as follows.

(1) After the solenoid valve 15a is turned on, the solenoid valve 15c is turned on.

(2) After the solenoid valve 15c is turned on, the solenoid valve 15a is turned on.

(3) The solenoid valve 15a and the solenoid valve 15c are turned on at the same time.

If only the last position is important, the same result can be obtained in all of the cases (1) to (3) mentioned above, but for the purpose of preventing excessive movement during operation, the state of the inequality described below must be satisfied. do.

[Pressure of the pressure chamber 14c]> [Pressure of the pressure chamber 14b] × [Pressure receiving surface of the stepped piston 8 toward the pressure chamber 14b + Piston 5 toward the pressure chamber 14c Pressure receiving surface] / [pressure receiving surface of the stepped piston 8 toward the pressure chamber 14c] -------------------- {2}

In the case of (2) and (3), the state of the inequality {2} is well satisfied, but the case of (2) is more preferable. In the case of (2), when the solenoid valve 15c is turned on, high pressure air is supplied to the pressure chamber 14c via the passage 16c, and the pressure in the pressure chamber 14c is increased. do. This rising pressure acts on the pressure receiving surface of the stepped piston 8 toward the pressure chamber 14c while the stepped piston 8 moves in the direction to expand the volume of the pressure chamber 14c, This movement is limited by the end of the large diameter cylinder 1b.

When the solenoid valve 15a is turned on after the solenoid valve 15c is turned on, high pressure air is supplied to the pressure chamber 14a via the passage 16a. Although the pressure in the pressure chamber 14a is raised, this rising pressure tends to act to move the stepped piston 8 and the piston 5 in the direction of expanding the volume of the pressure chamber 14a, As the working pressure on the side of the pressure chamber 14c prevails over the working pressure of the stepped piston 8, the stepped piston 8 remains in a stopped state. The piston 5 moves at a distance L1 toward the rear of the intermediate cylinder 10 to come into contact with the base portion of the intermediate cylinder 10.

As a result, as the relationship between the pressure in the pressure chamber 14a and the pressure in the pressure chamber 14c satisfies the state of the inequality {2}, the stepped piston 8 and the piston 5 It will not move. Therefore, the tip of the rod 4 stops at the N position as shown in 2- (1) while retreating from the F position to the L1 distance. After stopping at the N position, the solenoid valves 15a and 15c are turned off.

The following operation sequence is possible here.

(1) After the solenoid valve 15a is turned off, the solenoid valve 15a is turned on.

(2) After the solenoid valve 15c is turned off, the solenoid valve 15a is turned on.

(3) The solenoid valve 15a and the solenoid valve 15c are turned off at the same time.

The state of inequality described below must be satisfied in order to prevent displacement of the rod 4 when the solenoid valves 15a and 15c are turned off.

[Pressure of the pressure chamber 14c]> [Pressure of the pressure chamber 14a] × [Pressure receiving surface of the stepped piston 8 toward the pressure chamber 14a + Piston 5 toward the pressure chamber 14a Pressure receiving surface] / [pressure receiving surface of the stepped piston 8 toward the pressure chamber 14c] -------------------- {3}

Although (1) and (3) satisfy | fill the state of the said inequality {3} well, the case of (1) is more preferable.

In the case of (1), when the solenoid valve 15a is turned off, the pressure in the pressure chamber 14a decreases. If the pressure in the pressure chamber 14a is sufficiently reduced and then the solenoid valve 15c is turned off, the pressure in the pressure chambers 14a and 14c can be reduced to atmospheric pressure while completely satisfying the inequality {3}. . When the tip of the rod 4 is moved from the N position to the R position, the solenoid valve 15a is turned on while high pressure air is supplied to the pressure chamber 14a. At the same time, the solenoid valves 15b and 15c are turned off while the pressure chambers 14b and 14c communicate with the atmosphere. As the high pressure air is supplied to the pressure chamber 14a through the passage 16a, the pressure in the pressure chamber 14a rises.

This rising pressure acts on the pressure receiving surface of the stepped piston 8 and the pressure receiving surface of the piston 5 toward the pressure chamber 14a. As a result, the stepped piston 8 moves with the piston 5 in the direction to expand the volume of the pressure chamber 14a by L2 distance, and comes into contact with the tip of the large diameter cylinder 1b. Thus, the tip of the rod 4 retreats from the N position to the L2 distance and stops at the R position as shown in 2- (2). After stopping at the R position, the solenoid valve 15a is turned off, and the high pressure air in the pressure chamber 14a is discharged to the outside via the passage 16a. While the high pressure air is being discharged, the larger the pressure in the pressure chamber 14a is greater than the pressure in the pressure chambers 14b to 14d, the more the piston 5 and the stepped piston 8 are forced to open the pressure chamber 14a. It is pressed in the direction to expand.

In other words, the pressure in the pressure chamber 14a is reduced to atmospheric pressure while the movement of the stepped piston 8 and the piston 5 is limited. As a result, the displacement of the rod 4 does not occur.

When the front end of the rod 4 moves from the R position to the N position, the solenoid valves 15a and 15c are turned on while high pressure air is supplied to the pressure chambers 14a and 14c. At the same time, the solenoid valve 15b is turned off and the pressure chamber 14b is in communication with the atmosphere.

Here, the operation sequence described later of the solenoid valves 15a and 15b is possible.

(1) After the solenoid valve 15a is turned on, the solenoid valve 15c is turned on.

(2) After the solenoid valve 15c is turned on, the solenoid valve 15a is turned on.

(3) The solenoid valve 15a and the solenoid valve 15c are turned on at the same time.

Even when the solenoid valve 15a is off, the stepped piston 8 and the piston 5 can be moved together at a distance L2 toward the small-diameter cylinder 1a due to the solenoid valve 15c being turned on. have. However, when the rod 4 reaches the N position, the stepped piston 8 stops quickly as it comes into contact with the end of the large diameter cylinder 1b, while the piston 5 stops its moving speed. Inertia may overshoot due to inertia.

In order to prevent such overshooting, the stepped piston 8 must be moved while the piston 8 is pressurized by the pressure of the pressure chamber 14a at the base of the intermediate cylinder 10.

In the case of (1), the piston 5 (e.g. rod 4) may obviously prevent overshooting, but the stepped piston starts to move 8 (e.g. the inequality). {2}) is not immediately satisfied.

On the other hand, in the case of (2), the stepped piston 8 starts to move early in time, but the piston 5 tends to overshoot.

In the case of (3), the high pressure air is simultaneously supplied to the pressure chambers 14a and 14c, but from the viewpoint of the volume of the pressure chambers 14a and 14c, the pressure in the pressure chamber 14a is further increased. Ascend quickly. As a result, the movement to the N position starts fairly quickly while clearly preventing overshooting of the piston 5.

After stopping at the N position, the solenoid valves 15a and 15c are turned off, at which time the solenoid valve 15c is turned off after the solenoid valve 15a is turned off to prevent displacement of the rod 4. Is off.

When the tip portion of the rod 4 is moved from the N position to the F position, the solenoid valves 15b and 15c are turned on while high pressure air is supplied to the pressure chambers 14b and 14c, while the solenoid valve 15a is provided. Is turned off, and the pressure chamber 14a communicates with the atmosphere.

Here, three operation sequences for the solenoid valves 15b and 15c are possible.

(1) After the solenoid valve 15b is turned on, the solenoid valve 15c is turned on.

(2) After the solenoid valve 15c is turned on, the solenoid valve 15b is turned on.

(3) The solenoid valve 15b and the solenoid valve 15c are turned on at the same time.

The case of (2) is the most preferable from the viewpoint of preventing the irregular movement during operation, and will be described later.

When the solenoid valve 15c is turned on, the pressure in the pressure chamber 14c rises. This rising pressure acts on the pressure receiving surface of the stepped piston 8 toward the pressure chamber 14c while the stepped piston 8 moves in the direction to expand the volume of the pressure chamber 14c, This movement is limited by the end of the large diameter cylinder 1b while the stepped piston 8 remains stationary.

When the solenoid valve 15b is turned on after the solenoid valve 15c is turned on, the pressure in the pressure chamber 14b and the pressure chamber 14d rises.

This elevated pressure acts on the pressure receiving surface of the stepped piston 8 toward the pressure chamber 14b, but as the working pressure applied to the pressure receiving surface toward the pressure chamber 14c prevails, The differential piston 8 remains stationary.

While pressure acts on the pressure receiving surface of the piston 5 facing the pressure chamber 14d, the piston 5 acts to move in the direction of expanding the pressure chamber 14d.

When the piston 5 moves to the distance L1 and the tip stopper 11 comes into contact with the stepped piston 8, further movement is suppressed.

As a result, the tip of the rod 4 stops at the F position as shown in 2- (4) while advancing the L1 distance from the N position. After stopping at the F position, the solenoid valves 15b and 15c are turned off.

The above operation sequence is possible with the following three examples.

(1) After the solenoid valve 15b is turned off, the solenoid valve 15c is turned off.

(2) After the solenoid valve 15c is turned off, the solenoid valve 15b is turned off.

(3) The solenoid valve 15b and the solenoid valve 15c are turned off at the same time.

In order to prevent displacement of the rod 4, the high pressure air in the pressure chambers 14b and 14c must be discharged while satisfying the condition of inequality {1}.

In the case of (1), the state of the inequality {1} is best satisfied.

In the case of (2), a state in which the inequality {1} is not satisfied may easily appear.

In the case of (3), the pressure in the pressure chambers 14b and 14c simultaneously decreases, but the pressure decrease in this pressure chamber 14c is much faster than the reduction in the pressure chamber 14b, so that the state of inequality {1} Is satisfied.

6 and 7 show another embodiment of the present invention, in which the hydraulic cylinder 101 can be moved in four steps. (FIG. 1)

The hydraulic cylinder 102 shown in FIG. 2 in order for a damper 12e (spacer) to change the relationship between the maximum stroke L1 of the piston 5 and the maximum stroke L2 of the stepped piston 8. It is attached on the base portion of the intermediate cylinder 10 in place of the damper 12c therein.

The same reference numerals are assigned to the same parts as in FIG. 2, and repeated descriptions are omitted.

Apart from the damper 12e, the same parts are used to move the position in the hydraulic cylinder 101 in three stages. In other words, depending on whether the damper 12c or the damper 12e is mounted, the arrangement can exert the same function as the shift hydraulic cylinder 102 or the select hydraulic cylinder 101.

In the manufacture of the two types of hydraulic cylinders (101, 102) all efforts have been made to use the same parts to greatly improve the productivity.

8 illustrates the operation of the four-step position movement of the hydraulic cylinder 101.

10 shows the operation pattern of the solenoid valves 15a to 15c.

When the tip of the rod 4 is moved from position 1 to position 2, the solenoid valves 15a and 15c are turned on and high pressure air is supplied to the pressure chambers 14a and 14c. At the same time, the solenoid valve 15b is off while the pressure chamber 14b is in communication with the atmosphere.

Possible order of operation of the solenoid valves 15a and 15c is as follows.

(1) After the solenoid valve 15a is turned on, the solenoid valve 15c is turned on.

(2) After the solenoid valve 15c is turned on, the solenoid valve 15a is turned on.

(3) The solenoid valve 15a and the solenoid valve 15c are turned on at the same time.

For the final purpose of position shift, the same result is obtained in all of the above cases (1) to (3), but for the purpose of preventing overshooting during operation, the state of the inequality {2} mentioned above is It must be satisfied.

From this point of view, the case of (2) or (3) is satisfactory, but the case of (2) is more preferable. In the case of (2), when the solenoid valve 15c is turned on, the pressure in the pressure chamber 14c rises. This rising pressure acts on the pressure receiving surface of the stepped piston 8 toward the pressure chamber 14c while acting to move the stepped piston 8 in a direction to expand the volume of the pressure chamber 14c, This movement is limited by the end of the large diameter cylinder 1b (damper 12a).

When the solenoid valve 15c is turned on and then the solenoid valve 15a is turned on, high pressure air is supplied to the pressure chamber 14a via the passage 16a.

Although the pressure in the pressure chamber 14a rises and the rising pressure tends to move the stepped piston 8 and the piston 5 in the direction in which the volume of the pressure chamber 14a increases, the pressure chamber 14c As the pressure acting on the side of the dominant force prevails over the pressure acting on the stepped piston 8, the stepped piston 8 remains stationary.

The piston 5 moves toward the rear of the intermediate cylinder 10 at a distance L1 to come into contact with the base portion (damper 12e) of the intermediate cylinder 10.

As a result, as the relationship between the pressure in the pressure chamber 14a and the pressure chamber 14c satisfies the state of the inequality {2}, the stepped piston 8 and the piston 5 It will not move.

Therefore, the tip of the rod 4 retracts by the distance L1 from position 1 and stops at position 2 as shown in 3- (1). After stopping at position 2, the solenoid valves 15a and 15c are turned off.

The following operation sequence is possible here.

(1) After the solenoid valve 15a is turned off, the solenoid valve 15c is turned off.

(2) After the solenoid valve 15c is turned off, the solenoid valve 15a is turned off.

(3) The solenoid valve 15a and the solenoid valve 15c are turned off at the same time.

As mentioned above, the state of inequality {2} must be satisfied to prevent displacement of the rod 4. From this point of view, the case of (1) or (3) is satisfactory, but the case of (1) is more preferable.

In the case of (1), when the solenoid valve 15a is turned off, the pressure in the pressure chamber 14a is reduced. When the solenoid valve 15c is turned off while the pressure in the pressure chamber 14a is sufficiently reduced, the pressure in the pressure chambers 14a and 14c can be reduced to atmospheric pressure while fully satisfying the state of inequality {2}.

When the front end of the rod 4 moves from position 2 to position 3, the solenoid valve 15b is turned on and compressed air is supplied to the pressure chamber 14b. At the same time, the solenoid valves 15a and 15b are turned off while the pressure chambers 14a and 14c communicate with the atmosphere.

Due to the pressure in the pressure chamber 14d, the piston 5 moves by L1 distance in the direction of expanding the pressure chamber 14d, but further movement of the piston 5 is carried out by the tip stopper 11. Limited. Due to the pressure in the pressure chamber 14b, the stepped piston 8 moves in the direction to compress the pressure chamber 14c, and comes into contact with the base portion of the large diameter cylinder (damper 12b).

Therefore, the tip of the rod 4 stops at position 3, as shown in 3- (2), while retreating by the distance L2 to L1. After stopping at position 3, the solenoid valve 15b is turned off. The high pressure air in the pressure chambers 14b and 14d is discharged to the outside through the passages 16b and 16d. While the high pressure air is discharged, the piston 5 is pressurized in the direction to expand the pressure chamber 14d while the stepped piston 8 is pressurized in the direction to expand the pressure chamber 14b.

In other words, the pressure in the pressure chambers 14b and 14d is the atmospheric pressure while the stepped piston 8 is pressurized to the base portion of the large diameter cylinder 1b while the movement of the piston 5 is limited by the tip stopper 11. As it decreases, the displacement of the rod 4 is not generated. When the front end of the rod 4 moves from position 3 to position 4, the solenoid valve 15a is turned on while compressed air is supplied to the pressure chamber 14a. At the same time, the solenoid valves 15b and 15c are turned off while the pressure chambers 14b and 14c communicate with the atmosphere.

Due to the pressure in the pressure chamber 14a, the piston 5 moves in the direction to compress the pressure chamber 14d by L1 distance, and comes into contact with the base portion of the intermediate cylinder 10.

In addition, the pressure in the pressure chamber 14a acts on the stepped piston 8 in the direction for compressing the pressure chamber 14c, but the stepped piston 8 is coupled with the base portion of the large diameter cylinder 1b. Upon contact, this stepped piston 8 remains stationary.

Therefore, the tip of the rod 4 is moved by the distance L1 from position 3 to stop at position 4 as shown in 3- (3). After stopping at position 4, the solenoid valve 15a is turned off.

As the pressure chambers 14b and 14d and the pressure chamber 14c are at atmospheric pressure, the pressure in the pressure chamber 14a is also fixed while preventing the piston 5 and the intermediate cylinder 10 from moving (the pressure chamber). (14a) is expanded to maximum). Therefore, the position of the rod 4 does not change.

When the tip of the rod 4 moves from position 4 to position 3, the solenoid valve 15b is turned on while high pressure air is supplied to the pressure chamber 14b. At the same time, the solenoid valves 15a and 15c are turned off while the pressure chambers 14a and 14c communicate with the atmosphere.

Due to the pressure in the pressure chamber 14b, the stepped piston 8 is pressed to the base of the large diameter cylinder 1b. Due to the pressure in the pressure chamber 14d, the piston 5 moves in the direction to expand the pressure chamber 14d by L1 distance, while the front stopper 11 contacts the stepped piston 8, Further movement is suppressed.

Therefore, the tip of the rod 4 stops at position 3 as shown in 3- (4) while moving by L1 distance. After stopping at position 3, the solenoid valve 15b is turned off, and the high pressure air in the pressure chambers 14b and 14d is discharged through the passages 16b and 16d, and in the pressure chambers 14b and 14d. The pressure drops to atmospheric pressure while the piston 5 and the stepped piston 8 are pressurized to expand the volume of these pressure chambers. Therefore, the displacement of the rod 4 does not occur.

When the tip of the rod 4 moves from position 3 to position 2, the solenoid valves 15a and 15c are turned on while high pressure air is supplied to the pressure chambers 14a and 14c. At the same time, the solenoid valve 15b is turned off while the pressure chamber 14b is in communication with the atmosphere.

Due to the pressure in the pressure chamber 14a, the piston 5 comes into contact with the base portion of the intermediate cylinder 10 while moving the L1 distance in the direction to compress the pressure chamber 14d.

In addition, due to the pressure in the pressure chamber 14c, the stepped piston 8 comes into contact with the base portion of the large-diameter cylinder 1b while moving by the distance L2 in the direction to compress the pressure chamber 14b. Therefore, the tip of the rod 4 moves from the position 2 to the distance L2 to L1 and stops at position 3 as shown in 3- (5).

The operation sequence of the solenoid valves 15a and 15c is as follows.

(1) After the solenoid valve 15a is turned on, the solenoid valve 15c is turned on.

(2) After the solenoid valve 15c is turned on, the solenoid valve 15a is turned on.

(3) The solenoid valve 15a and the solenoid valve 15c are turned on at the same time.

When the stepped piston 8 comes into contact with the end of the large diameter cylinder 1b due to inertia, the movement of the piston 5 is suppressed by the pressure in the pressure chamber 14a so as not to overshoot.

The case of (1) is the most effective for preventing overshooting of the piston 5, but it takes more time for the rod 4 to move. In the case of (2) and (3), overshooting of the piston 5 is still suppressed, but from the viewpoint of shortening the movement time of the rod 4, the operation sequence of (3) is more preferable. Do.

After the rod stops in position 2, the solenoid valves 15a and 15c are turned off.

The operating sequence for preventing displacement of the rod 4 should be reduced to atmospheric pressure while the pressure in the pressure chambers 14a and 14c satisfies the above-mentioned inequality {2}, and the solenoid valve 15a It is preferable that the solenoid valve 15c be turned off after?

When the tip portion of the rod 4 moves from position 2 to position 1, the solenoid claws 15b and 15c are turned on and high pressure air is supplied to the pressure chambers 14b and 14c. At the same time, the solenoid valve 15a is turned off while the pressure chamber 14a is in communication with the atmosphere.

In order to prevent displacement of the rod 4, the operation order of the solenoids 15b and 15c is preferably the solenoid valve 15b is turned on after the solenoid valve 15c is turned on.

In the above case, after the solenoid valve 15c is turned on, the pressure in the pressure chamber 14c rises. Due to this rising pressure, the stepped piston 8 is pressed in the direction to compress the pressure chamber 14b, but the movement in this direction is limited by the end of the large diameter cylinder 1b.

When the solenoid valve 15c is turned on and then the solenoid valve 15b is turned on, due to the pressure in the pressure chamber 14d, the piston 5 is moved by the distance L1 in the direction to expand the pressure chamber 14d. Further movement is suppressed by the tip stopper 11.

This pressure also acts on the pressure receiving surface of the stepped piston 8 toward the pressure chamber 14b, but as the applied pressure based on the pressure of the pressure chamber 14c prevails, the stepped piston (8) maintains the stopped state.

Therefore, the tip of the rod 4 stops at position 1 as shown in 3- (6) while moving from the position 2 to the L1 distance. After stopping at position 1, the solenoid valves 15b and 15c are turned off.

The operation sequence is as follows.

(1) After the solenoid valve 15b is turned off, the solenoid valve 15c is turned off.

(2) After the solenoid valve 15c is turned off, the solenoid valve 15b is turned off.

(3) The solenoid valve 15b and the solenoid valve 15c are turned off at the same time.

From the viewpoint of preventing displacement of the rod 4, the cases (1) and (3) are preferred, but the case of (1) is most preferred.

In the case of (2), since the state in which the inequality {1} is not satisfied can easily be generated, the above operation sequence is not preferable.

In the case of (1), while the solenoid valve 15b is turned off, the high pressure air in the pressure chambers 14b and 14c is discharged to the outside via the passage 16b. During this discharge, as the pressure in the pressure chamber 14d is much higher than the pressure in the pressure chamber 14a, the tip stopper 11 of the piston 5 is stepped to the pressure in the pressure chamber 14d. (8) is pressed.

When the solenoid valve 15c is turned off and then the solenoid valve 15c is turned off, the pressure in the pressure chamber 14c is reduced. As the relationship between the pressures in the pressure chambers 14b and 14c satisfies the state of inequality {1}, the stepped piston 8 does not move in the direction to compress the pressure chamber 14c.

11 and 12 illustrate another embodiment of the present invention. As shown, (a) shows that the hydraulic cylinder 102 can be moved in three steps, (b) shows that the hydraulic cylinder 101 can be moved in four steps.

FIG. 11 illustrates the above-mentioned bearing 2b (shown in FIGS. 1 and 6) of the large-diameter cylinder 1b used in the shift hydraulic cylinder 102 of FIG. 2 and the select hydraulic cylinder 101 of FIG. 6. It is shown that it is different from the embodiment.

Further, the rod 4 has one end at the front end stopper 11, and the other end only extends outward from the bearing 2a of the small diameter cylinder 1a.

In FIG. 12, in the hydraulic cylinders 102 and 101 of FIGS. 2 and 6, one end of the rod 4 is completed by the piston 5, and the bearing (2b in FIGS. 1 and 6) of the large-diameter cylinder 1b is used. The bearing of the stepped piston 8 (2c in FIGS. 2 and 6) is omitted.

A tip stopper 11, which limits the maximum stroke of the piston 5, is attached to the opening of the intermediate cylinder 10.

In Figs. 11 and 12, those designated by the same reference numerals as those in Figs. 2 and 6 are parts having the same function.

As the operation of the cylinder having the optional structure as described above is the same as that shown in Figs. 4 and 5 and 8, description thereof will be omitted here.

Although particular embodiments of the present invention have been shown in the drawings and illustrated in the description, the invention is not limited to the embodiments described herein, but is limited to the claims set forth below which add other implementations, changes, equivalents and / or elements. As will be included within the scope of the present invention.

As described above, according to the present invention, a hydraulic cylinder is required to be capable of three-step position movement as a shift actuator in a transmission having a first gear and a seventh gear, and a four-step position shift is possible as a select actuator. The hydraulic cylinder required to be able to be precisely positioned without displacement at a predetermined stroke position during the shifting operation, as well as the hydraulic cylinder which is moved in three steps and the hydraulic cylinder which is moved in four steps, can manufacture a large part of the components. By being designed to share, it is possible to reduce the manufacturing cost.

1 is a perspective view of a shift control apparatus of a transmission using a hydraulic cylinder according to the present invention;

Figure 2 is a cross-sectional view of the hydraulic cylinder portion capable of moving in three stages,

3 is a schematic view of a hydraulic cylinder capable of moving in three stages,

4 is a schematic diagram of a hydraulic cylinder capable of moving in three stages;

5 is a schematic view of a hydraulic cylinder capable of moving in three stages;

6 is a cross-sectional view of the hydraulic cylinder portion capable of moving in four stages;

7 is a schematic diagram of a hydraulic cylinder capable of moving in four stages;

8 is a schematic diagram showing a position movement operation in four steps;

Figure 9 is a schematic diagram showing the operation pattern of the solenoid valve for position movement in three steps,

10 is a schematic diagram showing an operation pattern of the solenoid valve for position movement in four steps;

11 (a), (b) is a schematic diagram showing an operating state of the hydraulic cylinder according to another embodiment of the present invention, respectively;

12 (a) and 12 (b) are schematic diagrams each showing an operating state of a hydraulic cylinder according to another embodiment of the present invention;

13 is a schematic view of a conventional hydraulic cylinder.

<Description of the symbols for the main parts of the drawings>

1: housing 1a: small diameter cylinder

1b: large diameter cylinder 2a, 2b: bearing

4: rod 5: piston

8: stepped piston 10: intermediate cylinder

14a, 14b, 14c, 14d: pressure chamber 15a, 15b, 15c: solenoid valve

16a, 16b, 16c, 16d: passage 100: air supply source

101, 102: hydraulic cylinder 103,104,106: link rod

105: reversing lever 107: input shaft

108: output shaft 110: control device

111, 112, 113, 114: detection signal

Claims (5)

Small diameter cylinder and large diameter cylinder connected to each other in the housing, A stepped piston having a large diameter part which is slid freely in the large diameter cylinder and a small diameter part which is slid freely in the small diameter cylinder, A first pressure chamber formed on the side of the small diameter cylinder and a third pressure chamber formed on the side of the large diameter cylinder by the stepped piston, an annular second pressure chamber formed on an outer circumferential surface of the small diameter part of the stepped piston, the step An intermediate cylinder formed inside the differential piston and opened into the first pressure chamber, A piston inserted to slide freely in the intermediate cylinder to form a fourth pressure chamber, Through passages for always communicating between the second pressure chamber and the fourth pressure chamber, A rod connected to the piston and penetrating in the axial direction of the stepped piston, Means for installing a tip stopper for limiting the maximum stroke of the piston to L1, and for limiting the maximum stroke of the stepped piston to L2, A first valve controlling the hydraulic pressure in the first pressure chamber, A second valve controlling the hydraulic pressure in the second pressure chamber and the fourth pressure chamber, and And a third valve for controlling the hydraulic pressure in the third pressure chamber, and selectively controlling the hydraulic pressure via the first, second and third valves so that the rod has four stroke positions (0, L1, L2, L1 +). A hydraulic cylinder, characterized in that the stop at L2). The hydraulic cylinder according to claim 1, wherein the maximum stroke (L1) of the piston is set equal to the maximum stroke (L2) of the stepped piston. The hydraulic cylinder according to claim 2, wherein a shift lever having a gear shift function is connected to the rod. The hydraulic cylinder according to claim 1, further comprising a spacer for changing the maximum stroke (L1) of the piston to half of the maximum stroke (L2) of the stepped piston. The hydraulic cylinder according to claim 4, wherein a shift lever having a gear shift function is connected to the rod.