JPH08312609A - Hydraulic cylinder with air vent mechanism - Google Patents

Abstract

PURPOSE: To surely discharge mixed air by discharging mixed air in a working chamber from an air vent hole to one supply/discharge passage, and supplying working oil from the other supply/discharge passage to the one supply/discharge passage. CONSTITUTION: By supplied working oil, a flow to the low pressure side is generated in one supply/discharge passage 36, and mixed air remaining in the one supply/discharge passage 36 is carried up to the low pressure side by the flow of the working oil and discharged. At this time, a supply hole 48 and an air vent hole 42 intersect at their extension, and hence mixed air passed through the air vent hole 42 is surely carried to the low pressure side through the passage 36 by the working oil supplied from the supply hole 48. Further, the working oil in the other working chamber 22 is supplied to the one passage 36, and hence the mixed air in the other working chamber 22 is also discharged together with the working oil to the one passage 36.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic cylinder with an air bleeding mechanism for discharging air mixed in a working chamber to the outside of the working chamber.

[0002]

2. Description of the Related Art When a hydraulic cylinder such as a hydraulic cylinder is used for a pressing operation such as a press or a forging machine, it may be required to start the hydraulic cylinder at an accurate timing. At this time, if air enters the working chamber of the hydraulic cylinder, it becomes difficult to operate at accurate timing due to the compressibility of air.

Therefore, conventionally, as a hydraulic cylinder for discharging the air mixed in the working chamber to the outside of the working chamber, the actual cylinder number 57 has been proposed.
The one described in Japanese Patent No. 23683 is known. In this hydraulic cylinder, since the hydraulic cylinder is generally arranged horizontally, a passage for supplying and discharging hydraulic oil is formed in the lid member that closes both ends of the cylinder tube, and this passage is formed in the lid member. The sealing member fitted is avoided to form an opening at the uppermost part of the working chamber, and the mixed air floating and accumulated at the uppermost part of the working chamber is preferentially discharged.

[0004]

However, in such a conventional device, even if the mixed air is discharged together with the hydraulic oil from the working chamber due to the movement of the piston, the movement of the piston stops and the movement of the hydraulic oil stops. The mixed air also stays in the passage. Then, when the piston moves in the opposite direction, the mixed air in the passage is returned to the working chamber together with the working oil. That is, there is a problem that the mixed air may move between the working chamber and the passage, and the mixed air may not be effectively discharged.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a hydraulic cylinder with an air bleeding mechanism, which is capable of effectively discharging mixed air, with the object of solving the above problems.

[0006]

In order to achieve such an object, the present invention has the following constitution as means for solving the problem. That is, in a hydraulic cylinder having working chambers formed on both sides of a piston slidably inserted in a sliding hole, and a supply / drain passage for supplying / discharging working oil to / from both working chambers, By forming a stop surface where the end surface of the piston is fitted by sliding to one side, a fitting hole into which the protrusion of the piston is fitted is provided, and the one supply / discharge passage is connected to the fitting hole. Hydraulic oil is supplied to and discharged from the one working chamber, and the one working chamber and the one working chamber are communicated with each other through an air vent hole opened in the stop surface, and the one working passage is also provided. A bypass passage for supplying hydraulic oil from the other supply / discharge passage is formed in, and a control valve that opens when the end surface of the piston matches the stop surface is provided in the bypass passage. The configuration of the hydraulic cylinder with an air vent mechanism is A.

The control valve may be a relief valve. Alternatively, the control valve includes a check valve interposed in the bypass passage, and further connects the other working chamber and the bypass passage when the end surface of the piston matches the stop surface. It may be configured to include a connection passage formed in the piston.

The control valve includes a check valve interposed in the bypass passage, and further, when the end surface of the piston matches the stop surface, the control valve is connected to the piston rod of the piston communicating with the bypass passage. The control valve may have a groove formed therein, and when the end surface of the piston matches the stop surface, the control valve moves the valve body to communicate the bypass passage, and the end surface stops the stop. The check valve may be configured to prevent outflow from the one operation chamber to the other operation chamber when the check valve is separated from the surface.

Further, the air vent hole may be opened in an annular groove formed along the stop surface, and the bypass passage may be connected to the annular groove.

[0010]

In the hydraulic cylinder with the air bleeding mechanism having the above-mentioned structure, the piston slides in the sliding hole when the working oil is supplied to the other working chamber through the other supply / discharge passage. And
When the end surface of the piston coincides with the stop surface, the piston stops and the working oil containing air is discharged to one of the supply / discharge passages through the air vent hole. Further, the control valve is opened to supply the working oil from the other supply / discharge passage to the one supply / discharge passage via the bypass passage to discharge the mixed air from the one supply / discharge passage.

When the control valve is a relief valve, when the pressure in the other supply / discharge passage becomes equal to or higher than the set pressure, the relief valve is opened to supply from the other supply / discharge passage to one supply / discharge passage. In the control valve having a check valve and a connection passage, when the end surface of the piston matches the stop surface, the other working chamber and the bypass passage are connected via the connection passage, and the other of the control valve and the bypass passage is connected. Supply from one supply / discharge passage to one supply / discharge passage.

In the control valve provided with a check valve and communicating with the groove of the piston rod, when the end surface of the piston matches the stop surface, the groove of the piston rod communicates with the bypass passage and the other supply valve via the check valve. Supply from the discharge passage to one supply / discharge passage.

In the check valve in which the control valve moves the valve body to communicate with the bypass passage, when the end surface of the piston matches the stop surface, the control valve moves to communicate the bypass passage, and The hydraulic oil is supplied from one of the supply / discharge passages to the other supply / discharge passage. In the case where the air vent hole is opened in the annular groove, the hydraulic oil from the other supply / discharge passage is supplied to the annular groove through the bypass passage, and the operating oil is supplied to the annular air through the air vent hole together with the mixed air. Discharge into the supply / discharge passage of.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings. In FIGS. 1 and 2, reference numeral 1 is a cylinder main body, and a bottomed sliding hole 2 is formed in the axial direction of the cylinder main body from one side. Piston 4 is in O-ring 6 in sliding hole 2.
It is prevented from leaking and is slidably inserted. A piston rod 8 is secured to the piston 4 by an O-ring 10 so that the piston rod 8 does not leak.

The sliding hole 2 has an O-ring 1 on the cylinder body 1.
It is closed by a lid member 14 which is leak-proofed by 2 and fixed. The piston rod 8 penetrates the lid member 14 slidably and is prevented from leaking by an O-ring 16 and a seal 18. The sliding hole 2 is partitioned by a piston 4, and working chambers 20 and 22 (in FIG. 1, the volume of the working chamber 20 is zero) are formed on both sides thereof.

A flat end face 24 and a protrusion 26 are formed on the one working chamber 20 side of the piston 4. A flat stop surface 28 is provided on the bottom side of the sliding hole 2.
Is formed, and the end surface 24 and the stop surface 28 are formed so as to match with each other without a gap.

Further, a fitting hole 30 into which the projection 26 is fitted is formed from the stop surface 28, and the fitting hole 30 has a supply / discharge hole 32 orthogonal to the axial direction of the sliding hole 2 and a fitting / discharging hole 32. A supply / discharge hole 34 communicating with each other is formed. In this embodiment, both supply / discharge holes 32, 3 are formed.
A supply / discharge passage 36 is constituted by 4. A supply / discharge hole 38 formed in the cylinder body 1 is formed in the other operation chamber 22, and a supply / discharge passage 40 is formed by the supply / discharge hole 38. Further, a small diameter air vent hole 42 opened in the stop surface 28.
The other end of is connected to the supply / discharge hole 32.

The cylinder body 1 is provided with a connection hole 44 communicating with the other working chamber 22 and a storage hole 46 communicating with the connection hole 44. A supply hole 48 is formed in communication with the storage hole 46, and the direction of the supply hole 48 is formed so as to intersect with the air vent hole 42. In this embodiment, the connection hole 44 and the storage hole 4
6. The bypass passage 49 is constituted by the supply hole 48. The connection hole 44 can be implemented even if it is connected to the supply / discharge hole 38.

A spring receiving member 52 having a through hole 50 formed therein is inserted into the accommodation hole 46, and a spring 54 is further brought into contact with the spring receiving member 52 and a ball valve body 56 is inserted therein. . In addition, a valve member 60, which is prevented from leaking by an O-ring 58, is inserted into the storage hole 46.
As shown in FIG.
Is formed with an annular groove 62.

A through hole 64 is formed in the valve member 60 so as to communicate with the annular groove 62 in the radial direction. The communication hole communicates with the through hole 64 and is axially opened to the ball valve body 56 side. 66
Has been drilled. Further, when the ball valve body 56 is seated on the valve seat 68 formed corresponding to the ball valve body 56 by the urging force of the spring 54, the communication hole 66 is closed. In this embodiment, the spring 54, the ball valve element 56, and the valve member 60 constitute a relief valve 69 as a control valve.

Next, the operation of the hydraulic cylinder with the air bleeding mechanism of this embodiment will be described. First, from the state shown in FIG. 1, when hydraulic oil is supplied to one supply / discharge passage 36 and the other supply / discharge passage 40 is connected to a low pressure side (hereinafter, referred to as a low pressure side) of a tank or the like, a fitting hole. 30 and air vent hole 4
The hydraulic oil flows into one of the working chambers 20 via 2. Further, the hydraulic oil is also supplied to the storage hole 46 via the supply hole 48, but the ball valve body 56 is seated on the valve seat 68 by the urging force of the spring 54, so the communication with the communication hole 66 is blocked. Therefore, the hydraulic oil does not flow into the other working chamber 22. The piston 4 slides in the sliding hole 2 to project the piston rod 8 under the action of the hydraulic pressure supplied to the one working chamber 20 and the fitting hole 30, and the piston 4 in the other working chamber 22. The hydraulic oil is discharged to the low pressure side through the supply / discharge hole 38 and the other supply / discharge passage 40.

Next, from this operating state, when working oil is supplied to the other supply / discharge passage 40 and one supply / discharge passage 36 is connected to the low pressure side, the other working chamber 22 is supplied via the supply / discharge passage 40.
Hydraulic fluid flows into. As a result, the piston 4 slides in the sliding hole 2 under the action of the working hydraulic pressure, and the one working chamber 2
The hydraulic oil in 0 is discharged from the fitting hole 30 and the air vent hole 42 to the low pressure side through the one supply / discharge passage 36.

By this operation, when the projection 26 of the piston 4 is inserted into the fitting hole 30, one working chamber 20 and the fitting hole 3 are inserted.
The communication with 0 is cut off, and the working oil in the working chamber 20 is discharged from the air vent hole 42 to the one supply / discharge passage 36. Since the air vent hole 42 has a small diameter, the pressure in the working chamber 20 rises due to its throttling action, and the hydraulic oil is vigorously ejected from the air vent hole 42. The air mixed in the working oil in the working chamber 20 is discharged from the air vent hole 42 into the one supply / discharge passage 36 together with the working oil.

When the projection 26 is inserted into the fitting hole 30 and the piston 4 further slides, the end surface 24 of the piston 4 matches the stop surface 28 and the sliding of the piston 4 is stopped. At that time, the volume of the working chamber 20 becomes zero, and all the working oil and the mixed air in the working chamber 20 are discharged from the air vent hole 42 to the one supply / discharge passage 36. As shown in FIG. 1, even if the piston rod 8 is installed horizontally, or
Even if the working chamber 20 is installed in a slanted or vertical state, the volume of the working chamber 20 is reduced to almost zero, so the air vent hole 4
The mixed air at a position distant from 2 is surely supplied to the supply / discharge passage 36.
Is discharged to.

Then, the end surface 24 of the piston 4 is stopped by the stop surface 2.
8 from the other supply / discharge passage 40 to the other working chamber 2
When the pressure in the other working chamber 22 rises due to the working oil pressure supplied to 2, the connection hole 44, the annular groove 62, the through hole 6
4. The acting force in the valve opening direction acts on the ball valve body 56 via the communication hole 66.

When this acting force exceeds the urging force of the spring 54, the ball valve body 56 moves and the communication hole 66 and the storage hole 46.
Communicate with. As a result, the hydraulic oil in the other working chamber 22 is connected to the connection hole 44, the annular groove 62, the through hole 64, and the communication hole 6.
6, and is supplied from the supply hole 48 to the one supply / discharge passage 36 through the storage hole 46.

The supplied hydraulic oil causes a flow to the low pressure side in one of the supply / discharge passages 36, and the mixed air remaining in the one supply / discharge passage 36 reaches the low pressure side due to the flow of the hydraulic oil. It is carried and discharged. At this time, the supply hole 48
Since the air vent hole 42 and the air vent hole 42 intersect with each other in the axial extension, the mixed air that has passed through the air vent hole 42 is reliably supplied by the working oil supplied from the supply hole 48 to the supply / discharge passage 36.
Is conveyed to the low pressure side via. Further, since the working oil in the other working chamber 22 is supplied to the one supply / discharge passage 36, the mixed air in the other working chamber 22 is also discharged to the one supply / discharge passage 36 together with the working oil.

Further, when hydraulic oil is supplied to one of the supply / discharge passages 36 again and the piston rod 8 is pushed out,
Since the mixed air does not remain in one working chamber 20,
For example, it can be operated at an accurate timing according to the switching of the switching valve (not shown) without being affected by the mixed air. In addition, since the mixed air is discharged from the other working chamber 22, it is possible to perform an operation that is not affected by the mixed air even when the piston rod 8 is pulled back.

Next, a hydraulic cylinder with an air venting mechanism according to a second embodiment, which is different from the above-mentioned embodiment, will be described with reference to FIGS.
It will be explained by. The same members as those in the above-described embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. The same applies below. In the second embodiment, an annular groove 80 having a diameter increased in the radial direction of the sliding hole 2 at the corner where the sliding hole 2 and the stop surface 28 intersect.
Are formed along the stop surface 28. The annular groove 80 and the air supply / exhaust hole 32 are communicated with each other by the air vent hole 82, and the communication hole 84 formed in the radial direction of the cylinder body 1 is connected to the annular groove 80.

As shown in FIG. 4, the communication hole 84 is communicated with a storage hole 86 formed in the cylinder body 1, and a small diameter hole 90 is continuously provided in the storage hole 86 via a valve seat 88. There is. The small-diameter hole 90 has a connection hole 92 opened in the sliding hole 2.
Is connected. A ball valve element 94 is inserted into the storage hole 86 so as to face the valve seat 88, and a spring 100 is interposed between a spring receiver 96 contacting the ball valve element 94 and a screwed plug member 98. , The ball valve element 94 is the valve seat 8
It is urged to sit at 8.

On the other hand, as shown in FIG. 4, when the end surface 24 of the piston 4 is aligned with the stop surface 28, the annular groove 1 is formed on the outer circumference of the piston 4 so as to communicate with the connecting hole 92.
04 are formed. This annular groove 104 has a connection hole 1
It is communicated with the other working chamber 22 via 06.

In the second embodiment, the valve seat 88, the ball valve body 94, the spring receiver 96, the plug member 98, and the spring 100 constitute the check valve 102, and the check valve 102, the small diameter hole 90, and the connection. The hole 92, the annular groove 104 of the piston 4, and the connection hole 106 constitute a control valve 103.

In the second embodiment, from the state shown in FIG. 3, one working chamber 20 is supplied with working oil from one supply / discharge passage 36, and the other working chamber 22 is supplied via the other supply / discharge passage 40. When connected to the low pressure side, the piston 4 slides in the sliding hole 2 and the piston rod 8 is projected. At that time, since the ball valve element 94 is seated on the valve seat 88, the hydraulic oil is not discharged to the small diameter hole 90 through the annular groove 80, the communication hole 84, and the storage hole 86. From this operating state, hydraulic oil is supplied to the other working chamber 22 from the other supply / discharge passage 40, and the other working chamber 20
Is connected to the low pressure side via one of the supply / discharge passages 36,
The piston 4 slides in the sliding hole 2 in the opposite direction.

Then, as in the above-described embodiment, the working oil in one working chamber 20 is supplied to the fitting hole 30 and the annular groove 80,
The hydraulic oil is discharged to the supply / discharge passage 36 through the air vent hole 82. When the protrusion 26 of the piston 4 is inserted into the fitting hole 30, the working hydraulic pressure in one working chamber 20 rises, and the annular groove 8
The hydraulic oil is vigorously ejected from the small-diameter air vent hole 82 to the supply / discharge passage 36 through 0.

When the end surface 24 of the piston 4 coincides with the stop surface 28, the volume of the working chamber 20 becomes substantially zero, and the annular groove 104 and the connection hole 92 communicate with each other. Therefore, the hydraulic oil from the other working chamber 22 is applied to the connection hole 106 and the annular groove 10.
4 and is supplied to the small diameter hole 90 via the connection hole 92.

The ball valve element 94 receives the action of this operating hydraulic pressure, and the ball valve element 94 moves, and the small diameter hole 90 and the storage hole 8 are received.
The hydraulic oil from the other working chamber 22 is supplied to the annular groove 80 through the communication hole 84. As a result, the working oil passes through the annular groove 80, and together with the mixed air remaining in the annular groove 80, the working oil is supplied from the air vent hole 82 to the supply / discharge passage 3.
Discharge to 6. The mixed air discharged to the supply / discharge passage 36 is
It is discharged to the low pressure side together with the hydraulic oil.

Further, by sliding the piston 4 to connect both connection holes 92 and 106 through the annular groove 104, the other working chamber 2 unlike the one using the relief valve.
Since it is not necessary to keep 2 at a high pressure and no high-pressure hydraulic oil is required for venting air, energy saving can be realized.

Next, the hydraulic cylinder with the air bleeding mechanism of the third embodiment will be described with reference to FIG. In the third embodiment, unlike the above-described embodiments, the cylinder body 120
The piston rod 8 is slidably inserted into the through hole 121 formed in the. Then, the sliding hole 2 is inserted into the lid member 122.
The cover member 122 is closed by the stop surface 28 and the fitting hole 30.
Are formed. One of the supply / discharge passages 36 is provided in the fitting hole 30.
Is connected to the supply / discharge hole 124.

An insertion hole 128 formed in the cylinder body 120 is connected to the supply / discharge hole 126 formed in communication with the supply / discharge hole 124. A storage hole 130 is formed continuously with the insertion hole 128, and the storage hole 130 is formed by the valve seat 1
It is connected to the connection hole 134 via 32.

The connecting hole 134 is opened in the through hole 121, and the connecting hole 136 is opened in the through hole 121 so as to face the connecting hole 134. The connecting hole 136 is the other working chamber 2
Connected to 2. An annular groove 138 is formed in the piston rod 8 to connect the connecting holes 134 and 136 when the end surface 24 of the piston 4 is in alignment with the stop surface 28.

On the other hand, in the storage hole 130, the ball valve body 14
0 is inserted, the spring 142 is inserted, and
A spring retainer 144 is inserted into the insertion hole 128 so that the ball valve element 140 is seated on the valve seat 132 by the urging force of the spring 142. In the third embodiment, the check valve 143 is composed of the valve seat 132, the ball valve element 140, and the spring 142, and the check valve 14
3, the connection holes 134 and 136, and the annular groove 138 form a control valve 145.

The spring retainer 144 has a through hole 14 in the axial direction.
6 is provided to connect the supply / discharge hole 126 and the storage hole 130, and one end is opened to the insertion hole 128 and the other end is opened to the stop surface 28 and the through hole 14 and the through hole 14.
A communication hole 150 that communicates with 6 is formed.

From the state shown in FIG. 5, when the working oil is supplied to the one working chamber 20 from the one supply / discharge passage 36 as in the above-described embodiment, the fitting hole 30, the supply / discharge hole 126, and the through hole. Hydraulic oil is supplied to the air vent hole 148 through the communication hole 146 and the communication hole 150. As a result, the piston 4 is slid in the sliding hole 2 and the piston rod 8 is projected. At that time, the ball valve element 140 is seated on the valve seat 132 to block the communication between the storage hole 130 and the connection hole 134.

When the working oil is supplied to the other working chamber 22 from the other supply / discharge passage 40, the piston 4 slides in the sliding hole 2 in the opposite direction to the above, and the projection 26 is fitted. When the end surface 24 of the piston 4 is brought into the hole 30 and the end surface 24 of the piston 4 meets the stop surface 28, the piston 4 stops. Meanwhile, the hydraulic oil in the one working chamber 20 is discharged to the supply / discharge passage 36 through the fitting hole 30, and the air vent hole 148, the communication hole 150, and
It is discharged together with the mixed air into the supply / discharge passage 36 through the through hole 146.

When the end surface 24 of the piston 4 is aligned with the stop surface 28, both connection holes 134 and 136 are formed in the annular groove 138.
The hydraulic oil in the other working chamber 22 is supplied to the supply / discharge passage 36 through both the connection holes 134 and 136, the annular groove 138, the storage hole 130, and the through hole 146. Therefore, the mixed air remaining in the supply / discharge passage 36 flows out to the low pressure side.

Next, a hydraulic cylinder with an air bleeding mechanism according to a fourth embodiment will be described with reference to FIGS. 6 and 7. In the fourth embodiment, the outer circumference of the end surface 24 of the piston 4 is cut out obliquely, and the outer circumference of the stop surface 28 of the lid member 122 is cut out obliquely to form the annular groove 160. The annular groove 160 has a supply / discharge hole 126 through an air vent 162.
Is communicated to.

Further, as shown in FIG. 7, the piston 4 is provided with a screw hole 164 and a housing hole 1 from the other working chamber 22 side.
66 and the communication hole 168 are successively provided in order, and the storage hole 16
A valve element 170 is slidably inserted into the valve 6. A gap 172 is formed between the storage hole 166 and the valve body 170 so that hydraulic oil can flow.

A plug member 174 is screwed into the screw hole 164, a through hole 176 is formed in the plug member 174, and a valve seat 178 on which the valve body 170 is seated is formed. Further, a valve seat 180 on which the valve body 170 is seated is also formed on the side of the communication hole 168, and moreover, the valve body 170 passes through the communication hole 168 and sticks out to the side of one working chamber 182. Are integrally formed.

Then, the end surface 24 of the piston 4 is stopped by the stop surface 2.
When it reaches the vicinity of 8, the rod-shaped portion 182 abuts on the stop surface 28 and moves the valve body 170 to a position separated from both valve seats 178 and 180 when the end surface 24 of the piston 4 matches the stop surface 28. Is configured. Also, the piston 4
A groove 184 that connects the communication hole 168 and the annular groove 160 to each other in the radial direction is formed on the end surface 24. still,
In the fourth embodiment, the communication hole 168, the storage hole 166, the valve body 1
70, both valve seats 178 and 180, and the through hole 176 form a control valve 186.

From the state shown in FIG. 6, when the working oil is supplied to the one working chamber 20 from the supply / discharge passage 36 as in the above-described embodiment, the fitting hole 30, the air vent hole 162, and the annular groove 1 are provided.
The hydraulic oil is also supplied to 60, the groove 184, and the communication hole 168. As a result, the piston 4 slides in the sliding hole 2, the valve body 170 is seated on the valve seat 178 to block the through hole 176, and the working oil is prevented from flowing out to the other working chamber 22.

The other working chamber 22 has a supply / discharge passage 40.
When the hydraulic oil is supplied from the piston 4, the piston 4 slides in the sliding hole 2 in the opposite direction to the above, the projection 26 is inserted into the fitting hole 30, and the end surface 24 of the piston 4 becomes the stop surface 28. When they match, the piston 4 stops. Meanwhile, one working chamber 2
The hydraulic oil of 0 is discharged to the supply / discharge passage 36 through the fitting hole 30, and is also discharged to the supply / discharge passage 36 through the annular groove 160 and the air vent 162.

When the end surface 24 of the piston 4 is aligned with the stop surface 28, the rod portion 182 contacts the stop surface 28,
The valve body 170 is separated from the valve seat 180, and the other working chamber 2
2 from the working oil through hole 176, gap 172, communication hole 16
8 and supply to the annular groove 160 via the groove 184. The hydraulic oil supplied to the annular groove 160 flows through the annular groove 160, together with the mixed air, from the air vent hole 162 to the supply / discharge passage 3.
Discharge to 6.

When the end surface 24 of the piston 4 matches the stop surface 28, the control valve 186 opens the valve body 170 by a mechanical operation, so that the working hydraulic pressure in the other working chamber 22 is controlled. It is possible to supply the hydraulic oil to the one working chamber 20 without keeping it high. Therefore, high pressure hydraulic oil is not consumed for venting air, so that energy saving can be realized. Also,
Since the control valve 186 can be formed in the piston 4, the outer shape of the cylinder body 1 can be made smaller than when the control valve is formed in the cylinder body 1.

Next, the hydraulic cylinder with an air bleeding mechanism of the fifth embodiment, which is equipped with a control valve 190 different from the control valve 186 of the fourth embodiment, will be explained with reference to FIG. This control valve 190 has two ball valve bodies 192 and 192 in a storage hole 166.
194 is inserted with a spring 196 interposed therebetween, and the ball valve body 194 on the stop surface 28 side is integrally formed with a rod-shaped portion 198 protruding through the communication hole 168. In the rod-shaped portion 198, the end surface 24 of the piston 4 is the stop surface 2
When it reaches the vicinity of 8, the ball valve element 19 comes into contact with the stop surface 28 and when the end surface 24 of the piston matches the stop surface 28.
4 is moved to a position separated from the valve seat 180.

In the fifth embodiment, the end surface 2 of the piston 4 is
When 4 is aligned with the stop surface 28, the rod portion 198 abuts on the stop surface 28 to separate the ball valve element 194 from the valve seat 180. Then, the ball valve body 192 is separated from the valve seat 178 against the urging force of the spring 196 by the hydraulic pressure of the other operating chamber 22, and the through hole 17 is provided from the other operating chamber 22.
6, the hydraulic oil is supplied to the annular groove 160 via the storage hole 166, the communication hole 168, and the groove 184.

Next, the hydraulic cylinder with the air bleeding mechanism of the sixth embodiment will be described with reference to FIG. In the sixth embodiment, a control valve 186 having the same structure as that of the fourth embodiment described above is incorporated in the piston rod 8, and a connecting hole 200 formed in the piston rod 8 allows the other working chamber 22 to be operated.
And the storage hole 166 are connected via the valve seat 202. Further, the rod-shaped portion 182 of the valve element 170 separates the valve element 170 from the valve seat 180 due to the contact with the bottom of the fitting hole 30 when the end surface 24 of the piston 4 matches the stop surface 28. The operating oil is supplied from the other working chamber 22 to the fitting hole 30 via the control valve 186. The working oil supplied from the fitting hole 30 to the supply / discharge passage 36 is discharged to the low pressure side together with the mixed air discharged from the air vent hole 42 to the supply / discharge passage 36.

The present invention is not limited to the embodiments as described above, and can be carried out in various modes without departing from the scope of the present invention.

[0058]

As described above in detail, in the hydraulic cylinder with the air vent mechanism of the present invention, the mixed air in the working chamber is discharged from the air vent hole into one of the supply / discharge passages and the hydraulic oil from the other supply / discharge passage is discharged. Since the mixed air is supplied to one of the supply / discharge passages to surely flow out the mixed air, the operation delay of the piston due to the compressibility of the mixed air can be reduced, and an accurate timing operation can be obtained. Further, regardless of the installation state of the hydraulic cylinder, since the mixed air is discharged by matching the end surface of the piston with the stop surface, it is possible to reliably discharge the mixed air that easily accumulates at the outer peripheral edge of the piston.

In the case where the relief valve is used as the control valve, when the pressure in the other supply / discharge passage increases, the valve is opened to supply the working oil to the one supply / discharge passage and prevent the flow opposite thereto. Therefore, it can be configured without using a check valve, and the configuration is simple. When the control valve has a check valve and a connection passage formed in the piston, the bypass passage is connected by sliding of the piston, so that the other supply / discharge passage is kept at a high pressure unlike the one using a relief valve. There is no need, and because high pressure hydraulic oil is not required for venting air, energy can be saved. Further, even if the control valve is provided with a check valve and the bypass passage is communicated by sliding the piston rod, energy saving can be similarly realized.

Further, in the case where the control valve is a check valve that moves the valve body to communicate the bypass passage, energy saving can be realized similarly, and the check valve can be provided in the piston, so that the cylinder can be provided. It can be miniaturized. Further, in the case where the air vent hole is opened in the annular groove, the operating oil can be supplied to the annular groove from the other supply / discharge passage to reliably discharge the mixed air.

[Brief description of drawings]

FIG. 1 is a sectional view of a hydraulic cylinder with an air bleeding mechanism as an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a control valve according to an embodiment.

FIG. 3 is a sectional view of a hydraulic cylinder with an air bleeding mechanism according to a second embodiment.

FIG. 4 is an enlarged sectional view of a control valve of a second embodiment.

FIG. 5 is a sectional view of a hydraulic cylinder with an air bleeding mechanism according to a third embodiment.

FIG. 6 is a sectional view of a hydraulic cylinder with an air bleeding mechanism according to a fourth embodiment.

FIG. 7 is an enlarged sectional view of a control valve according to a fourth embodiment.

FIG. 8 is an enlarged sectional view of a control valve of a fifth embodiment.

FIG. 9 is a sectional view of a hydraulic cylinder with an air bleeding mechanism according to a sixth embodiment.

[Explanation of symbols]

 1, 120 ... Cylinder body 2 ... Sliding hole 4 ... Piston 8 ... Piston rod 20, 22 ... Working chamber 24 ... End face 26 ... Projection 28 ... Stop face 30 ... Fitting hole 36, 40 ... Supply / discharge passage 42, 82 ... Air vent hole 49 ... Bypass passage 69 ... Relief valve 80, 104, 160 ... Annular groove 103, 145, 186, 190 ... Control valve 143 ... Check valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuhiro Karaki 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor Mikiya Nozaki 1 Toyota Town, Toyota City, Aichi Toyota Motor Co., Ltd. (72) Inventor Kenichi Okabe 145-1, Yufutsu, Tomakomai City, Hokkaido Toyota Automobile Hokkaido Co., Ltd.

Claims (6)

[Claims] 1. A hydraulic cylinder comprising a working chamber formed on both sides of a piston slidably inserted in a sliding hole, and a supply / discharge passage for supplying / discharging working oil to / from each of the working chambers. Sliding to one side of the piston forms a stop surface where the end surface of the piston matches, and a fitting hole into which the protrusion of the piston fits is provided, and the one supply / discharge passage is provided in the fitting hole. The hydraulic fluid is connected to and discharged from the one working chamber, and the one supply / drain passage and the one working chamber are communicated with each other by an air vent hole formed in the stop surface. A bypass passage for supplying hydraulic oil from the other supply / discharge passage is formed in the supply / discharge passage, and a control valve that opens when the end surface of the piston matches the stop surface is provided in the bypass passage. A hydraulic cylinder with an air venting mechanism. 2. The hydraulic cylinder with an air bleeding mechanism according to claim 1, wherein the control valve is a relief valve. 3. The control valve includes a check valve interposed in the bypass passage, and further, when the end face of the piston matches the stop face, the other working chamber and the bypass passage are provided. The hydraulic cylinder with an air bleeding mechanism according to claim 1, further comprising a connection passage formed in the piston for connecting the air cylinder. 4. The control valve includes a check valve interposed in the bypass passage, and further, when the end surface of the piston coincides with the stop surface, the piston of the piston communicating with the bypass passage. The hydraulic cylinder with an air bleeding mechanism according to claim 1, further comprising a groove formed in the rod. 5. The control valve moves the valve body to communicate the bypass passage when the end surface of the piston matches the stop surface, and the one of the one of the control valves moves when the end surface is separated from the stop surface. 2. A check valve for preventing outflow from an operating chamber to the other operating chamber.
Hydraulic cylinder with air removal mechanism described. 6. The air vent hole is opened in an annular groove formed along the stop surface, and the bypass passage is connected to the annular groove.
A hydraulic cylinder with an air bleeding mechanism according to claim 5.