JP5791185B2 - Fluid pressure cylinder - Google Patents

Description

  The present invention relates to a hydraulic cylinder, and more particularly to an improvement of a hydraulic cylinder having a cushion function used as a lift cylinder of a forklift.

  Conventionally, as this type of fluid pressure cylinder, for example, a fluid pressure cylinder as shown in FIGS. 7 and 8 has been proposed (Patent Document 1).

  7 and 8 includes a cylinder tube 102, a cylinder bottom 103, a piston 104, a piston rod 105, a supply / discharge port 106, a seat 107, a cylindrical hole 108, and a valve element 109. A piston rod 105 is provided through the piston 104 and a valve element 109 is movably provided in a cylindrical hole 108 formed in the piston rod 105.

  FIG. 7 shows a state in which the piston 104 and the piston rod 105 are lowered to the maximum and the hydraulic cylinder 101 is contracted most. The piston rod 105 is engaged with the cylinder bottom 103 and the seat 120 of the valve element 109. Is seated on the seat 107.

  In such a state, when the pressure fluid is supplied from the supply / discharge port 106, it reaches the bottom chamber 111 through the vertical hole 121 → the horizontal hole 122 → the slit 118 of the piston rod 105 of the valve element 109, so that the piston 104 is Be raised. At this time, the pressure fluid from the supply / discharge port 106 reaches the upper side of the valve element 109 in the cylindrical hole 108 through the vertical hole 121 of the valve element 109, and the pressure receiving area of the upper side of the valve element 109 is larger than the lower side. However, since the weight of the valve element 109 works, the piston 104 is raised while the seat 120 of the valve element 109 is seated on the seat 107. Then, as shown in FIG. 8, the valve element 109 is lifted together with the piston 104 while maintaining the state in which the flange portion 119 is engaged with the stopper 123 and protrudes downward from the piston rod 105. Thereafter, the seat portion 120 of the valve element 109 is separated from the seat 107, so that the piston 104 is raised by supplying the pressure fluid to the bottom chamber 111 from the flow path formed therebetween.

  When the pressure fluid in the bottom chamber 111 is discharged from the supply / discharge port 106 after the piston 104 is raised, the piston 104 is lowered. When the piston 104 approaches the bottom 103, as shown in FIG. 8, the seat portion 120 of the valve element 109 is seated against the seat 107 and the flow path between them is blocked, so that the pressure fluid in the bottom chamber 111 is The valve element 109 is discharged through the horizontal hole 122 → the vertical hole 121 → the supply / discharge port 106, and the valve element 109 is accommodated in the cylinder hole 108 while the piston 104 is lowered. As shown in FIG. It will be in the lowest state. At this time, since the pressure fluid in the bottom chamber 111 is narrowed by the horizontal hole 122 and the vertical hole 121 of the valve element 109, a cushion function is exhibited.

JP 2000-352404 A

  In this type of fluid pressure cylinder, a so-called down safety valve is generally built in the cylinder bottom in order to prevent piping and pipes from being damaged and abrupt lowering of the lift cylinder. This down safety valve does not operate at the normal lowering speed of the lift cylinder, but when the lift cylinder suddenly lowers due to damage to the hydraulic oil piping or pipes, the lowering speed is controlled by controlling the flow rate of the hydraulic oil. Limit.

  However, when the lift cylinder is increased in size, the down safety valve is also increased in size, and the down safety valve does not fit properly in the cylinder bottom and protrudes from the cylinder bottom.

  Further, when the piston is lifted, the valve element may be separated from the seat with insufficient protrusion, and the cushion function may be insufficient.

  The main object of the present invention is to provide a fluid pressure cylinder that can be compactly accommodated in the cylinder bottom even if the down safety valve is enlarged, and that can appropriately exhibit a cushion function.

  In order to achieve the above object, as a first means, a fluid pressure cylinder according to the present invention includes a cylinder tube, a cylinder bottom closing one end of the cylinder tube, and a slidable provided in the cylinder tube. And a piston rod divided into a rod chamber, a piston rod connected to the piston, and a vertical hole opened on the upper surface of the cylinder bottom and a lateral hole opened on the side surface. A supply / discharge port, a down safety valve accommodated in the lateral hole of the supply / discharge port, a cylindrical recess formed concentrically with the piston and communicated with the bottom side chamber, and movable to the cylindrical recess Provided, and a valve element capable of contacting an area including the vertical hole on the upper surface of the cylinder bottom, and the vertical hole of the cylinder bottom includes the Formed at a position eccentric from the axis of the child, the valve element is formed by penetrating along the axis of the valve element so as to communicate the bottom side chamber and the inside of the cylindrical recess, An oil passage formed in a concave shape on the bottom surface of the valve element and extending radially outward from the throttle passage and without penetrating the peripheral side surface of the valve element, and the valve element is in contact with the cylinder bottom Sometimes, at least a part of the oil passage is formed so as to always overlap the vertical hole of the cylinder bottom.

  In the first means, the oil passage formed on the bottom surface of the valve element is a plurality of groove-like oil paths extending radially from the throttle channel without penetrating the peripheral side surface of the valve element, The central angle of adjacent groove oil passages is set so that at least one of the plurality of groove oil passages always overlaps the vertical hole of the cylinder bottom when the valve element is in contact with the cylinder bottom. It is preferable.

  Further, as a second means, a fluid pressure cylinder according to the present invention includes a cylinder tube, a cylinder bottom that closes one end of the cylinder tube, and a slidably provided on the cylinder tube. A piston to be divided, a piston rod connected to the piston, and an L-shaped supply / exhaust port formed by communicating a vertical hole opened on the upper surface of the cylinder bottom and a horizontal hole opened on the side surface; A down safety valve accommodated in the lateral hole of the supply / exhaust port; a cylindrical recess concentrically formed in the piston and communicating with the bottom side chamber; and the cylinder provided movably in the cylindrical recess A valve element capable of contacting an area including the vertical hole on the upper surface of the bottom, and the valve element communicates the bottom side chamber with the inside of the cylindrical recess. The cylinder bottom is formed at a position where the vertical hole is eccentric from the axis of the valve element, and the cylinder bottom is located at the eccentric position. An oil passage extending from the opening of the vertical hole to a position directly below the throttle passage of the valve element is formed in an area of a contact surface with the valve element.

  It is preferable to further include a coil spring that elastically biases the valve element toward the cylinder bottom.

  It is preferable that an accommodating recess for accommodating the coil spring is formed in the valve element.

  An accommodating recess for accommodating the coil spring may be formed in the piston.

  According to the present invention, the upper surface opening of the cylinder bottom is formed at a position eccentric from the axial center of the valve element, and the valve is communicated with the valve chamber so that the bottom side chamber communicates with the inside of the cylindrical recess. A throttle passage formed through the axis of the child, and an oil passage formed on the bottom surface of the valve element and extending radially outward from the throttle passage, the valve element contacting the cylinder bottom The oil passage formed so that at least a part of the oil passage always overlaps with the vertical hole of the cylinder bottom when the cylinder bottom is provided. It is possible to accommodate the down safety valve from the side opening of the cylinder bottom to the depth in the horizontal direction as much as possible, and properly accommodate it in the cylinder bottom even if the down safety valve becomes larger It can be. Moreover, a cushion function can be appropriately exhibited by setting it as the structure extended without penetrating an oil path to the surrounding side surface of the said valve | bulb.

  The valve element includes a throttle channel formed so as to penetrate along the axis of the valve element so as to communicate the bottom side chamber and the inside of the cylindrical recess. By forming an oil path on the contact surface with the valve element from the upper surface opening at the eccentric position to a position directly below the throttle flow path of the valve element. The bottom hole of the cylinder bottom can be made longer, and it is possible to accommodate the down safety valve deeply in the horizontal direction from the side opening of the cylinder bottom. Can be properly accommodated. Further, by forming the oil passage in an area with the contact surface with the valve, a cushion function can be appropriately exhibited.

It is a central longitudinal cross-sectional view which shows the principal part of 1st Embodiment of the fluid pressure cylinder which concerns on this invention. FIG. 2 is a partial cross-sectional view taken along line AA in FIG. 1. It is a center longitudinal cross-sectional view which shows the operating state of the fluid pressure cylinder of FIG. It is a center longitudinal cross-sectional view which shows the other operating state of the fluid pressure cylinder of FIG. It is a center longitudinal cross-sectional view which shows the principal part of 2nd Embodiment of the fluid pressure cylinder which concerns on this invention. FIG. 6 is a partial cross-sectional view taken along the line B-B in FIG. 5. It is a center longitudinal cross-sectional view which shows the principal part of the conventional fluid pressure cylinder. It is a center longitudinal cross-sectional view which shows the operating state of the fluid pressure cylinder of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a central longitudinal sectional view showing a first embodiment of a fluid pressure cylinder according to the present invention, and FIG. 2 is a partial sectional view taken along the line AA of FIG. As shown in FIG. 1, the fluid pressure cylinder 1 includes a cylinder tube 2, a cylinder bottom 3 that closes one end of the cylinder tube 2, and a cylinder tube 2 that is slidably provided in a bottom side chamber 4 and a rod chamber 5. An L-shape formed by communicating a piston 6 to be divided, a piston rod 7 connected to the piston 6, and a vertical hole 8a that opens to the upper surface 3a of the cylinder bottom 3 and a horizontal hole 8b that opens to the side surface 3b. Supply / exhaust port 8, down safety valve 9 accommodated in lateral hole 8 b of supply / discharge port 8, cylindrical recess 10 formed concentrically with the axis of piston 6 on the bottom surface of piston 6, and cylindrical A valve element 11 that is movably provided in the recess 10 and that can contact an area including the opening of the vertical hole 8a on the upper surface of the cylinder bottom 3;

  As shown in FIGS. 1 and 2 (shown in phantom lines in FIG. 2), the vertical hole 8 a of the cylinder bottom 3 is formed at a position eccentric from the axis X of the valve element 11. The valve element 11 is formed in a groove shape on the bottom surface of the valve element 11, and a throttle channel 12 formed through the axis X of the valve element 11 so as to communicate the bottom side chamber 4 and the inside of the cylindrical recess 10. And a plurality of groove-like oil passages 13 that extend radially from the throttle passage 12 and do not penetrate the peripheral side surface of the valve element 11.

  The plurality of groove-like oil passages 13 extending radially are always overlapped by at least one groove-like oil passage 13 in the opening of the vertical hole 8a of the cylinder bottom 3 in a state where the valve element 11 is in contact with the cylinder bottom 3. Thus, the central angle (intersection angle) α of the adjacent groove-like oil passages 13 and 13 is set. That is, since the rotation of the valve element 11 around the axis line X is not restricted, the position of the groove-like oil passage 13 around the axis line X may change. At least one groove-like oil passage 13 of the extending plurality of groove-like oil passages 13 is always connected to the vertical hole 8a, and an oil passage communicating from the vertical hole 8a to the throttle passage 12 is secured.

  An accommodating recess 15 for accommodating the coil spring 14 is formed in the valve element 11. The coil spring 14 elastically biases the valve element 11 toward the cylinder bottom 3 side. In the cylindrical recess 10 of the piston 6, a guide 6g of the coil spring 14 is protruded downward. In the illustrated example, the accommodating recess for accommodating the coil spring 14 is formed in the valve element 11, but it can also be formed on the bottom surface of the cylindrical recess 10 of the piston 6 (not shown).

  The upper side of the cylinder tube 2 is omitted in the illustrated example, and the bottom side is connected to the cylinder bottom 3 by welding or the like.

  The fitting convex portion 6a of the piston 6 is fitted into the fitting concave portion 7a formed on the lower end surface of the piston rod 7 through the retaining O-ring 16, and the piston rod 7 and the piston 6 are connected. In order to maintain the sealing performance between the inner peripheral surface of the cylinder tube 2 and the piston 6, a sealing material 17 is attached to the outer periphery of the piston 6.

  The valve element 11 is prevented from falling off from the cylindrical recess 10 of the piston 6 through the O-ring 18. Specifically, the O-ring 18 is fitted in a concave groove formed around the upper part of the valve element 11, and is formed on the inner peripheral surface of the lower end of the cylindrical concave part 10 at the lowest position of the valve element 11. It can be locked to the inner flange 6b (see FIGS. 3 and 4). The O-ring 18 does not have a sealing function between the valve element 11 and the cylindrical recess 10 so that the valve element 11 can easily move up and down in the cylindrical recess 10. Also, a certain clearance is provided between the inner flange portion 6b of the cylindrical recess 10 and the outer peripheral surface of the valve element 11 so that the valve element 11 can easily move up and down. Further, an outer flange portion 19 is formed on the outer periphery of the lower part of the valve element, and the outer flange portion 19 is engaged with a step portion 6c formed at the boundary between the inner peripheral surface of the cylindrical recess 10 of the piston 6 and the bottom surface of the piston 6. By stopping, a gap G through which hydraulic oil can enter is formed between the upper end surface of the valve element 11 and the bottom surface of the cylindrical recess 10 of the piston 6. Accordingly, the hydraulic oil having a pressure of a certain value or more can leak into the bottom chamber 4 from the inside of the cylindrical recess 10 through the gap where the O-ring 18 is interposed.

  The down safety valve 9 includes a poppet 9b that is pressed to the left in the drawing by a spring 9a. The poppet 9b has a cylindrical shape with one end open and the other end closed, an orifice 9c is formed at the closed end, and a plurality of oil holes 9d are formed on the side surface near the closed end. At a normal flow rate, the poppet 9b is pressed against the left end of the figure by the pressing force of the spring 9a, so that hydraulic oil flows through all of the oil holes 9d on the side surface of the poppet 9b. When hydraulic oil piping (not shown) is damaged and a large amount of hydraulic oil flows in a rising state, a differential pressure is generated between the hydraulic pressure in the bottom side chamber 4 and the hydraulic pressure in the hydraulic oil piping (not shown) due to the flow rate difference. Due to the pressure difference, the poppet 9b is pushed rightward in the drawing against the spring 9a, the side oil hole 9d is closed, and the hydraulic oil flows out only from the orifice 9c at the tip of the poppet 9b. The descending speed of 6 is suppressed.

  Next, the cushion function of the fluid pressure cylinder 1 having the above configuration will be described. FIG. 1 shows a state in which no hydraulic oil is supplied, the piston 6 is in contact with the upper surface of the cylinder bottom 3, and the fluid pressure cylinder 1 is in the most contracted state. The hydraulic oil supplied from the state of FIG. 1 through the supply / discharge port 8 is supplied from the groove-like oil passage 13 through the throttle passage 12 into the cylindrical recess 10 of the piston 6 and presses the piston 6 upward. Since the groove-like oil passage 13 does not penetrate the peripheral side surface of the valve element 11, the hydraulic oil flows from the groove-like oil passage 13, the throttle passage 12, and the cylindrical recess 10 into the gap between the O-ring 18 and the valve element 11. Enters the bottom chamber 4 through a gap between the piston 6 and the inner peripheral surface of the cylindrical recess 10 of the piston 6 (see arrow in FIG. 3).

  In this way, the hydraulic oil is sent into the cylindrical recess 10 and the bottom chamber 4 so that the piston 6 rises. However, the valve element 11 is pushed by the coil spring 14 until the piston 6 rises a predetermined distance. And the state which contact | abutted to the cylinder bottom 3 with the hydraulic pressure of the hydraulic fluid supplied in the cylindrical recessed part 10 is maintained (refer FIG. 3).

  Although the cushion function does not work unless the valve element 11 is pushed out from the cylindrical recess 10, the hydraulic oil is pushed out from the cylindrical recess 10 of the valve element 11 by passing through the path as described above. The state of being in contact with the head is reliably maintained and the cushion function is secured. Further, the maintenance coil spring 14 is pushed out from the cylindrical recess 10 of the valve element 11 and is in contact with the cylinder bottom 3, so that the cushion function is further ensured.

  When the hydraulic oil is further supplied and the piston 6 is raised by a predetermined distance and the O-ring 18 is locked to the flange portion 6b, the valve element 11 is raised by the piston 6 as shown in FIG.

  When the piston 6 descends, the reverse procedure is followed. If the hydraulic fluid in the bottom side chamber is removed from the state of FIG. 4, the piston 6 descends to enter the state of FIG. 3, and the valve element 11 contacts the cylinder bottom 3. When the valve element 11 comes into contact with the cylinder bottom 3, the hydraulic oil in the bottom side chamber 4 is discharged from the supply / discharge port 8 through the throttle channel 12 in a path opposite to the arrow in FIG. The flow rate is limited, the descending speed of the piston 6 is reduced, and the cushion mechanism is activated.

  According to the fluid pressure cylinder 1 having the above-described configuration, the upper surface opening 8 of the cylinder bottom 3 is formed at a position eccentric from the axial center of the valve element 11, and the throttle channel 12 and the throttle channel 12 are formed in the valve element 11. Since the center angle α of the adjacent groove-like oil passages among the plurality of groove-like oil passages 13 extending radially from the cylinder bottom 3 is always set to overlap the upper surface opening of the cylinder bottom 3, the horizontal hole 8b of the cylinder bottom 3 It is possible to accommodate the down safety valve 9 from the side opening of the cylinder bottom 3 to the depth in the horizontal direction, and to accommodate it properly in the cylinder bottom even if the down safety valve is enlarged. Can do. Further, since the groove-like oil passage 13 is formed so as not to penetrate the peripheral side surface of the valve element 11, the cushion function acts reliably.

  In the said 1st Embodiment, although the oil path formed in the bottom face of the valve element 11 illustrated the example which is the some groove-shaped oil path 13 extended radially, the oil path formed in the bottom face of the valve element 11 is It extends radially outward from the throttle channel 12 so as not to penetrate the outer peripheral surface of the valve element 11, and when the valve element 11 is in contact with the cylinder bottom 3, at least a part of the oil passage is a vertical hole 8 a in the cylinder bottom 3. It is sufficient that it is a concave oil passage that can communicate with the throttle passage 12 from the vertical hole 8a regardless of the rotational position of the valve element 11 around the axis X. Instead of the path 13, for example, the number of cutting processes may increase, but oil paths (not shown) having various shapes such as a star shape and a circular shape in bottom view may be employed.

  Next, a second embodiment of the fluid pressure cylinder according to the present invention will be described below with reference to FIGS. FIG. 5 is a central longitudinal sectional view showing the fluid pressure cylinder of the second embodiment, and FIG. 6 is a partial sectional view taken along the line BB of FIG. In addition, about the structure and effect | action similar to the said 1st Embodiment, the same code | symbol is attached | subjected and duplication description is abbreviate | omitted suitably.

  A fluid pressure cylinder 1 </ b> A according to the second embodiment is divided into a cylinder tube 2, a cylinder bottom 3 that closes one end of the cylinder tube 2, and a cylinder tube 2 that is slidable, and is divided into a bottom side chamber 4 and a rod chamber 5. An L-shaped supply / discharge port formed by communicating a piston 6, a piston rod 7 connected to the piston 6, and a vertical hole 8 a that opens to the upper surface of the cylinder bottom 3 and a horizontal hole 8 b that opens to the side surface. 8, a down safety valve 9 accommodated in the horizontal hole 8 b of the supply / discharge port 8, a cylindrical recess 10 formed concentrically on the bottom surface of the piston 6, and a cylinder provided movably in the cylindrical recess 10 And a valve element 11A capable of contacting an area including the opening of the vertical hole 8a on the upper surface of the bottom 3. The valve element 11 </ b> A includes a throttle channel 12 formed so as to penetrate along the axis X of the valve element 11 </ b> A so as to communicate the bottom side chamber 4 and the inside of the cylindrical recess 10.

  The cylinder bottom 3 is formed at a position where the vertical hole 8a is eccentric from the axis X of the valve element 11A, and extends from the opening of the vertical hole 8a at the eccentric position to a position directly below the throttle channel 12 of the valve element 11A. A groove-like oil passage 13A is formed in the area of the contact surface with the valve element 11A. Since the groove-like oil passage 13A does not extend in the outer circumferential direction of the cylinder bottom 3, when the valve element 11A is in contact with the cylinder bottom 3 (the state shown in FIG. 5), the bottom side chamber 4 extends from the vertical hole 8a. The hydraulic oil does not flow directly to.

  In the first embodiment, a plurality of radial groove-like oil passages 13 are formed on the bottom surface of the valve element 11, whereas in the second embodiment, the one groove-like oil passage 13A described above is a cylinder bottom. 3 is different from the first embodiment in that it is formed on the upper surface of the third embodiment, and the other components of the second embodiment are the same as those in the first embodiment. Therefore, the fluid pressure cylinder B of the second embodiment can achieve the same effects as the first embodiment. In addition, in 2nd Embodiment, although the form provided with one stripe-like groove-like oil path 13A was illustrated, it replaced with one stripe-like groove-like oil path 13A, for example, an ellipse in bottom view, It can also be set as the oil path (not shown) which consists of recessed parts of various shapes, such as circular.

  The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1, 1A Fluid pressure cylinder 2 Cylinder tube 3 Cylinder bottom 4 Bottom side chamber 5 Rod chamber 6 Piston 7 Piston rod 8 Supply / exhaust port 9 Down safety valve 10 Cylindrical recessed part 11, 11A Valve element 12 Restriction flow path 13, 13A Groove oil Road (oil path)
14 Coil spring

Claims (6)

A cylinder tube,
A cylinder bottom for closing one end of the cylinder tube;
A piston that is slidably provided in the cylinder tube and divides into a bottom chamber and a rod chamber;
A piston rod connected to the piston;
An L-shaped supply / discharge port formed by communicating a vertical hole opened on the upper surface of the cylinder bottom and a horizontal hole opened on the side surface;
A down safety valve accommodated in the lateral hole of the supply / discharge port;
A cylindrical recess formed concentrically on the bottom surface of the piston;
A valve element movably provided in the cylindrical recess and capable of contacting an area including the vertical hole on the upper surface of the cylinder bottom,
The vertical hole of the cylinder bottom is formed at a position eccentric from the axial center of the valve element,
The valve element includes a throttle channel formed through the valve element so as to communicate with the bottom side chamber and the cylindrical recess, and a recess formed on the bottom surface of the valve element. An oil passage extending radially outward from the flow path and without penetrating the peripheral side surface of the valve element
A fluid pressure cylinder, wherein at least a part of the oil passage is always overlapped with the vertical hole of the cylinder bottom when the valve element is in contact with the cylinder bottom. The oil passage formed on the bottom surface of the valve element is a plurality of groove-like oil paths extending radially from the throttle channel and without penetrating the peripheral side surface of the valve element,
The central angle of adjacent groove oil passages is set so that at least one of the plurality of groove oil passages always overlaps the vertical hole of the cylinder bottom when the valve element is in contact with the cylinder bottom. The fluid pressure cylinder according to claim 1, wherein the fluid pressure cylinder is provided. A cylinder tube,
A cylinder bottom for closing one end of the cylinder tube;
A piston that is slidably provided in the cylinder tube and divides into a bottom chamber and a rod chamber;
A piston rod connected to the piston;
An L-shaped supply / discharge port formed by communicating a vertical hole opened on the upper surface of the cylinder bottom and a horizontal hole opened on the side surface;
A down safety valve accommodated in the lateral hole of the supply / discharge port;
A cylindrical recess formed concentrically on the bottom surface of the piston;
A valve element movably provided in the cylindrical recess and capable of contacting an area including the vertical hole on the upper surface of the cylinder bottom,
The valve element includes a throttle channel formed so as to penetrate along the axis of the valve element so as to communicate between the bottom side chamber and the cylindrical recess.
The cylinder bottom is formed in a position where the vertical hole is eccentric from the axial center of the valve element, and extends from the opening of the vertical hole at the eccentric position to a position directly below the throttle passage of the valve element. A fluid pressure cylinder characterized in that a passage is formed in an area of a contact surface with the valve element.   The fluid pressure cylinder according to any one of claims 1 to 3, further comprising a coil spring that elastically biases the valve element toward the cylinder bottom.   The fluid pressure cylinder according to claim 4, wherein a housing recess for housing the coil spring is formed in the valve element.   The fluid pressure cylinder according to claim 4, wherein a housing recess for housing the coil spring is formed in the piston.

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