JP2007232036A - Cylinder cushion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To positively alleviate an impact at a stroke end of a hydraulic cylinder with a simple structure in a cylinder cushion device. <P>SOLUTION: The cylinder cushion device is equipped with: a hydraulic circuit provided with the hydraulic cylinder for extending/contracting to turn one member 10 with respect to another member 3a, and a control valve for controlling distribution of operating oil supplied to the hydraulic cylinder; a pilot circuit for supplying pilot pressure to the control valve; a proportional valve 40 mounted on the other member 3a and interposed over the pilot circuit; a spool member 42 slidably inserted inside the proportional valve 40 for changing the pilot pressure of the pilot circuit according to the sliding amount; and operating device 52, 44, and 45 mounted on at least the one member 10 for sliding the spool member 42 interlockingly with the turning of the one member 10 upon the one member 10 turning to the position corresponding to the stroke end of the hydraulic cylinder. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cylinder cushion device suitable for use in a boom cylinder of a work machine such as a hydraulic excavator.

A work machine such as a hydraulic excavator generally includes a work device having a boom, an arm, and a bucket at the front of the machine body.
The boom, arm, and bucket are each driven by expansion and contraction of a hydraulic cylinder. When the piston of each hydraulic cylinder stops at the stroke end, there is a risk that an impact will occur as the piston tries to collide with the cylinder body vigorously due to inertia. In particular, when the boom hydraulic cylinder stops at the stroke end, the large impact generated by the inertia of the entire work equipment may cause spillage of dirt from the bucket, or the impact will be transmitted to the operator, causing deterioration of ride comfort and fatigue. ing.

For this reason, for example, in Patent Document 1, in the middle of the pilot circuit from the boom control valve raising side to the boom direction switching valve raising side, when the rotation of the boom is equal to or higher than a predetermined angular velocity, the throttle is controlled at a predetermined angular position by the controller. There is disclosed a technique with a given boom raising stop electromagnetic proportional valve. According to this, a throttle is given to the boom raising / stopping solenoid proportional valve in proportion to the magnitude of the current from the controller to reduce the peak pressure generated at the boom cylinder raising side stroke end, and the impact at the time of stopping It is possible to relax and prevent spillage.
Japanese Patent Laid-Open No. 5-280075

However, according to the technique described in Patent Document 1, an expensive controller, an angle detector potentiometer, an electric circuit, and the like are required, and the structure is complicated and expensive. In addition, since a process for converting electrical signals and electronic controls to hydraulic controls is necessary, errors and response delays occur.
The present invention has been devised in view of such problems, and an object of the present invention is to provide a cylinder cushion device that can reliably reduce the impact at the stroke end of a hydraulic cylinder with a simple configuration.

  In order to achieve the above object, the cylinder cushion device of the present invention according to claim 1 is an oil pressure which is interposed between two pivotally attached members and expands and contracts to rotate one member relative to the other member. A cylinder, a hydraulic pump that discharges hydraulic oil supplied to the hydraulic cylinder, and a control valve that is interposed between the hydraulic pump and the hydraulic cylinder and controls flow of the hydraulic oil supplied to the hydraulic cylinder And a cylinder cushion device for controlling the control valve so as to loosen the expansion and contraction operation at the stroke end of the hydraulic cylinder, and controls the flow of the hydraulic oil by the control valve. A pilot circuit for supplying a pilot pressure to the control valve, a proportional valve attached to the other member and interposed on the pilot circuit, and slidable inside the proportional valve A spool member that is inserted and changes the pilot pressure of the pilot circuit according to the sliding amount, and is attached to at least one member, and the one member rotates to a position corresponding to the stroke end of the hydraulic cylinder. And an operating device that slides the spool member in conjunction with the rotation of the one member.

  A cylinder cushion device according to a second aspect of the present invention is the cylinder cushion device according to the first aspect, wherein the one member has an outer peripheral surface formed in an arc shape in a side view and pivots to the other member. The actuating device includes a roller that is urged against the outer peripheral surface of the base end portion so as to freely rotate, a roller that supports the roller at one end and the proportional valve at the other end. A swing lever that slides the spool member by pressing one end portion of the spool member in a sliding direction at an intermediate portion between the one end and the other end, and the one member includes: A protrusion formed in a position facing the roller on the outer peripheral surface of the base end portion when rotated to a position corresponding to the stroke end of the hydraulic cylinder, and protruding from the outer peripheral surface in the diameter increasing direction of the arc; It is characterized by having.

  A cylinder cushion device according to a third aspect of the present invention is the cylinder cushion device according to the first aspect, wherein the one member includes a base end portion pivotally attached to the other member, The link mechanism comprises a link mechanism that presses one end of the spool member in conjunction with the rotation of one member and slides the spool member. The link mechanism is pivotally supported at one end on the rotation fulcrum of the one member. A rotating node having the other end fixed at a position facing the spool member at the base end when the one member is rotated to a position corresponding to the stroke end of the hydraulic cylinder; A sliding node pivotally attached to the other end of the rotating node, and the other end of the sliding node are slidably held, and one end is fixed to one end of the rotating node. A fixed joint that extends in the moving direction and is fixed to the spool member at the other end. It is characterized in that it is.

  The cylinder cushion device according to a fourth aspect of the present invention is the cylinder cushion device according to the first aspect, wherein the operating device uses a spring to apply an elastic force to the spool member in conjunction with the rotation of the one member. A spring-type interlocking device for applying and sliding the spool member. The spring-type interlocking device includes a first spring having both ends connected to the one member and the spool member, and both ends to the spool. A second spring respectively connected to the member and the casing of the proportional valve, and the resultant force of the elastic force of the first spring and the elastic force of the second spring acting in the sliding direction of the spool member, The elastic force of the first spring and the elastic force of the second spring are set so that the spool member slides when the one member rotates to a position corresponding to the stroke end of the hydraulic cylinder. It is characterized by being To have.

  A cylinder cushion device according to a fifth aspect of the present invention is the cylinder cushion device according to the first aspect, wherein the one member has an outer peripheral surface formed in an arc shape in a side view and pivots to the other member. The actuating device includes a wire having one end fixed to a predetermined position of the base end and the other end fixed to the spool member, and the tensile force of the wire A wire reel winding type interlocking device that slides the spool member, and the length of the wire is such that when the one member rotates to a position corresponding to the stroke end of the hydraulic cylinder, The wire is wound around the base end in conjunction with the rotation of the member, and is set to a length that pulls the spool member.

  A cylinder cushion device according to a sixth aspect of the present invention is the cylinder cushion device according to any one of the first to fifth aspects, wherein the hydraulic cylinder is pivoted upward with respect to the boom to swing the boom of the work machine. A boom cylinder interposed between the body and the pilot circuit, wherein the pilot circuit supplies the pilot pressure to the control valve such that a flow direction of the hydraulic oil in the control valve is a direction in which the boom is raised A pilot circuit for raising, wherein the proportional valve is interposed on the pilot circuit for raising the boom.

  According to the cylinder cushion device of the present invention as set forth in claim 1, when the operating device rotates to a position corresponding to the stroke end of the hydraulic cylinder, in conjunction with the rotation of the one member, Since the spool member of the proportional valve interposed in the pilot circuit is slid, for example, the pilot pressure of the pilot circuit decreases as the sliding amount of the spool member increases, and the operation is supplied to the hydraulic cylinder via the control valve. The amount of oil can be reduced.

Therefore, the impact at the stroke end of the hydraulic cylinder can be reliably mitigated with a simple configuration in which the actuator is operated in conjunction with the rotation of one member and the stroke end of the hydraulic cylinder is mechanically detected. .
Moreover, since it is a mechanical structure, a response delay can be eliminated as compared with an electric cylinder cushion device using an electric circuit or the like as in the technique described in Patent Document 1.

According to the cylinder cushion device of the second aspect of the present invention, when one member rotates to a position corresponding to the stroke end of the hydraulic cylinder, the roller comes into contact with the protruding portion and pushes the protruding portion of the protruding portion. Thus, the swing lever swings, and one end of the spool member is pressed at the intermediate portion of the swing lever, so that the spool member can be slid with a simple configuration.
According to the cylinder cushion device of the present invention described in claim 3, when one member rotates to a position corresponding to the stroke end of the hydraulic cylinder, one end of the spool member is pressed at the other end of the sliding node. Therefore, the spool member can be slid with a simple configuration.

According to the cylinder cushion device of the present invention, the resultant force of the elastic force of the first spring and the elastic force of the second spring when one member rotates to a position corresponding to the stroke end of the hydraulic cylinder. Since this works in the direction in which the spool member slides, the spool member can be slid with a simple configuration.
According to the cylinder cushion device of the present invention according to claim 5, when one member rotates to a position corresponding to the stroke end of the hydraulic cylinder, the wire is wound around the base end portion and is in a tensioned state. Since the spool member is pulled in the sliding direction, the spool member can be slid with a simple configuration.

  According to the cylinder cushion device of the present invention as set forth in claim 6, the impact can be reduced at the stroke end when the boom is raised, in which a particularly large impact occurs due to the inertia of the entire working device of the work machine.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[One Embodiment]
1 to 4 show a cylinder cushion device according to an embodiment of the present invention. FIG. 1 is a side view of the boom lowered, FIG. 2 is a side view of the boom raised, and FIG. Is a hydraulic circuit diagram of the boom cylinder, and FIG. 4 is a perspective view of the hydraulic excavator.

<Configuration>
As shown in FIG. 4, a hydraulic excavator 1, which is a typical example of a work machine, includes a lower traveling body 2, an upper swing body 3 that is rotatably coupled to the lower traveling body 2, and an upper swing body 3. It is comprised from the working apparatus 4 attached so that it might extend ahead.
The upper swing body 3 has a swing frame (the other member) 3a serving as a pedestal. A counterweight 5 is provided at the rear end of the swing frame 3a. An engine room 6 is provided for housing the apparatus and the like, a cab 7 on which an operator is boarded is provided at the left front part, and a work device 4 is provided at the center front part.

As shown in FIGS. 1 and 2, the swing frame 3 a has a pair of main plates 3 b erected and extending in the front-rear direction of the machine body at the center portion thereof.
As shown in FIGS. 1 and 4, the working device 4 has a boom (one member) whose base end portion 10a is connected to a boom foot bracket (to be described later) of the main plate 3b of the swing frame 3a. ) 10, an arm 11 that is flexibly connected to the tip of the boom 10, and a bucket 12 that is rotatably attached to the tip of the arm 11. The boom 10 is provided with a hydraulic boom cylinder (hydraulic cylinder) 20. An arm cylinder 13 and a bucket cylinder 14 are also provided for the arm 11 and the bucket 12, respectively.

  As shown in FIG. 3, the boom cylinder 20 includes a cylinder tube (cylinder body) 21, a piston 22 that is slidably fitted on the inner peripheral surface of the cylinder tube 21, and a rod that is integrally fixed to the piston 22. 23, on both sides in the axial direction of the piston 22 inside the cylinder tube 21, with a piston 22 as a boundary, a bottom side oil chamber (first oil chamber) 24 and a rod side oil chamber (second oil chamber) 25, Is formed.

  Then, the hydraulic oil is supplied to and discharged from the oil chambers 24 and 25 and the piston 22 moves in the cylinder tube 21, so that the boom cylinder 20 is expanded and contracted, and accordingly, the boom 10 is rotated up and down. ing. Specifically, when the hydraulic oil is supplied to the bottom side oil chamber 24 and the boom cylinder 20 is extended, the boom 10 is raised (the state shown in FIG. 2), and conversely, the hydraulic oil is supplied to the rod side oil chamber 25. When the boom cylinder 20 is contracted, the boom 10 is lowered (state shown in FIG. 1).

A hydraulic circuit is provided for hydraulic control of the boom cylinder 20. When described with reference to FIG hydraulic circuit of the boom cylinder 20, the hydraulic circuit includes a main circuit C _M indicated by a thick line in the figure, and a pilot circuit C _P indicated by the solid line in FIG.
On the main circuit C _M, a main hydraulic pump (main pump) 31 is a hydraulic source, a hydraulic oil tank 32 for storing hydraulic oil, a boom cylinder 20 is interposed between the main pump 31 and the boom cylinder 20 A pilot-type control valve 33 that controls the supply of hydraulic oil to the boom cylinder 20 is disposed. The hydraulic oil discharged from the main pump 31 is controlled by the control valve 33 and supplied to the boom cylinder 20.

Here, the control valve 33 is configured as a three-position switching valve that controls the direction, pressure, and flow rate of the hydraulic flow. In the normal neutral position S ₀ that is held by the urging force of the spring 33a, the control valve 33 operates to the boom cylinder 20. Oil supply is cut off. Further, hydraulic oil is supplied to the bottom side oil chamber 24 of the boom cylinder 20 at the first position S ₁ , and hydraulic oil is supplied to the rod side oil chamber 25 of the boom cylinder 20 at the second position S _2. Yes. The position switching of the control valve 33 is adapted to be effected by the pressure of the pilot oil flowing through the pilot circuit C _P (pilot pressure).

Proportional On pilot circuit C _P, a pilot hydraulic pump (pilot pump) 34, a hydraulic oil tank 32, a boom control lever 35, the control valve 33, which is interposed in up side oil passage of the boom control lever 35 A valve 40 is provided.
The boom control lever 35 is provided in the cab 7 and is manually operated by an operator to raise and lower the boom 10. The spring boom control lever 35 when brought down to boom-up direction A, the pilot pressure is applied to the first position S ₁ side of the control valve 33 through a proportional valve 40 attempts to hold the neutral position S ₀ The control valve 33 is switched to the first position S ₁ against the elastic force of 33a. Conversely, when the boom control lever 35 is tilted in the boom-down direction B, the control valve to the second position S ₂ side of the 33 given a pilot pressure, the control valve 33 against the elastic force of the spring 33a and the second so that the switch to the position S _2.

In addition, although description is abbreviate | omitted here, the arm cylinder 13 and the bucket cylinder 14 are also hydraulically controlled by the hydraulic circuit similarly to the boom cylinder 20, respectively.
As shown in FIGS. 1 and 2, the swing frame 3a has a front portion of the main plate 3b formed in a substantially triangular shape in a side view, and the front portion functions as a boom foot bracket. . A pin hole is formed in the center of the boom foot bracket so that the boom foot pin 60 can be inserted therethrough.

On the other hand, a pin hole is also formed in the base end portion (boom base end portion) 10a of the boom 10, and the boom 10 and the main plate 3b of the swing frame 3a are overlapped with both pin holes and the boom is placed in both pin holes. Connection is made by inserting the foot pin 60. Thereby, the boom 10 is rotatable about the boom foot pin 60 as the central axis O.
The boom base end portion 10a has an outer peripheral surface formed in an arc shape in a side view. And the cam 51 formed along the shape of an outer peripheral surface is adhering to the outer peripheral surface of this base end part 10a. That is, here, the cam 51 is a cam plate formed in a semi-annular shape. Further, the cam 51 is formed with a protrusion (actuating device) 52 that protrudes in the diameter-expanding direction from the outer peripheral surface of the base end portion 10a. The protruding portion 52 is disposed so as to be positioned at the lower end of the base end portion 10a in a state where the boom 10 is raised to the maximum (when the boom 10 is at the maximum ascending rotation angle), and protrudes downward in the body.

On the other hand, on the swing frame 3a, the pilot circuit C _P boom-up oil passage interposed (boom-up pilot circuit) was above the proportional valve 40 is mounted so as to be opposed to the cam 51 and the projections 52 ing. In other words, the proportional valve 40 is disposed below the center point of the boom foot pin 60 (the center point of the rotating shaft of the boom base end portion 10a, the rotation fulcrum of the boom 10) O.

  The proportional valve 40 is a mechanically operated proportional valve having a roller (actuating device) 44. That is, as shown in FIG. 1, the proportional valve 40 is provided with a valve main body 41 that is a casing, and is slidably disposed in the valve main body 41 so as to extend in the vertical direction. A spool (spool member) 42 protruding from the upper surface, a base portion 43 fixed to the upper surface of the valve body 41, and a roller 44 are rotatably attached to one end portion thereof, and the other end portion is attached to the base portion 43. A swing lever (actuating device) 45 is provided which is swingably attached and capable of pressing the spool 42 downward at an intermediate portion. In the present embodiment, the operation device for the spool 42 of the proportional valve 40 is constituted by a roller 44, a swing lever 45, and a protrusion 52 provided on the cam 51.

  The spool 42 is disposed below the center point O of the boom foot pin 60. Further, the pilot pressure is lowered as the sliding amount increases. In other words, the position of the spool 42 in the vertical direction slides and changes, whereby a part or all of the pilot oil is returned to the hydraulic oil tank 32, and the pilot pressure flowing to the control valve 33 is throttled to act on the control valve 33. The pilot pressure is reduced. The pilot pressure decreases as the spool 42 slides downward (in the sliding amount increasing direction), and conversely, the pilot pressure increases as the spool 42 slides upward (in the sliding amount decreasing direction). It should be noted that the sliding amount of the spool 42 is set to 0 so that all pilot oil flows to the control valve 33 in a normal state (at a rotation angle other than the vicinity of the boom maximum upward rotation angle).

  The roller 44 is disposed vertically below the center point O of the boom foot pin 60 and is urged upward together with the spool 42 by a spring (not shown). That is, it is pressed against the surface of the cam 51 by the spring so as to be in contact with the cam 51 and the protrusion 52 so as to be freely rotatable. Accordingly, the roller 44 and the cam 51 come into contact with each other as shown in FIG. 1 in a normal state, and the boom 10 turns upward as shown in FIG. When coming to the lower end of the portion 10a, the roller 44 and the protrusion 52 come into contact with each other.

<Action and effect>
Since the cylinder cushion device according to the embodiment of the present invention is configured as described above, the following operations and effects are obtained.
When lowering the boom 10, the boom control lever 35 shown in FIG. 3 is operated in the boom lowering direction B by the operator. Then, the pilot circuit C _P, the control valve the second position S ₂ side of 33 (boom-down oil passage) pilot oil flows, increased pilot pressure, the control valve 33 against the elastic force of the spring 33a and the second It switched to the position S _2. Then, hydraulic oil is supplied from the main pump 31 to the rod-side oil chamber 25 of the boom cylinder 20, the boom cylinder 20 is contracted, and the boom 10 is lowered.

On the other hand, when raising the boom 10, the boom control lever 35 is operated in the boom raising direction A by the operator. Then, the pilot circuit C _P, via the proportional valve 40, pilot oil flows through the first position S ₁ side of the control valve 33, control valve 33 against the spring 33a is switched to the first position S _1. Then, hydraulic oil is supplied from the main pump 31 to the bottom side oil chamber 24 of the boom cylinder 20, the boom cylinder 20 is extended, and the boom 10 is raised.

  At this time, the projection 52 formed on the cam 51 of the boom base end portion 10 a gradually moves toward the roller 44 as the boom 10 approaches the maximum ascending rotation angle (as the stroke end on the raising side of the boom cylinder 20 approaches). To approach. In the vicinity of the lifting stroke end, the protrusion 52 comes into contact with the roller 44. As a result, the roller 44 is pushed down by the protrusion 52 and is lowered downward by the protrusion in the diameter increasing direction of the protrusion 52, and the swing lever 45 connected to the roller 44 swings around the base 43. The spool 42 of the proportional valve 40 is pushed downward at the intermediate portion.

By pushing the spool 42 of the proportional valve 40, part of the pilot oil in the boom raising side oil passage is returned to the hydraulic oil tank 32. Then, since the pilot pressure of the boom-up oil passage is weakened, the control valve the force acting against the spring 33a of 33 weakens, the control valve 33 as to return to the neutral position S _0, the boom cylinder 20 via the control valve 33 The amount of oil supplied to is reduced. Therefore, the extension operation of the boom cylinder 20 becomes gentle, the boom 10 stops slowly, and the cushion can be used reliably.

That is, it is possible to mechanically detect that the boom cylinder 20 has approached the lifting stroke end, and to reduce the pilot pressure in the boom raising oil passage immediately before becoming the lifting stroke end, thereby reducing the impact at the stroke end. .
Further, since the spool 42 is moved in conjunction with the rotation of the boom 10, the configuration is compared with an electric cylinder cushion device using an electric circuit or the like as in the technique described in Patent Document 1. It is simple and can reduce costs and can be applied to existing work machines. In addition, unlike the technique described in Patent Document 1, a process for converting electrical signals and electronic control into hydraulic control is not required, so that excellent responsiveness can be obtained.

[Others]
As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, A various deformation | transformation is possible in the range which does not deviate from the meaning of this invention.
For example, it is preferable that the shape of the protrusion 52 of the above-described embodiment is appropriately set. By changing the shape of the projection 52, the timing and method of throttle reduction of pilot pressure can be changed in various ways, so the timing at which the cylinder cushion is applied and the effectiveness of the cylinder cushion are changed according to the preference of the operator and the specifications of the aircraft be able to. That is, for example, as shown in FIG. 5, if the protrusion height H of the protrusion 52 from the cam 51 is increased, the cylinder cushion can be made more effective. Further, if the protrusion length L of the protrusion 52 in the boom rotation direction (the circumferential direction of the base end portion 10a) is increased, the time during which the cylinder cushion is effective can be shortened or lengthened.

At this time, if the cam 51 and the protrusion 52 are configured to be detachable from the base end portion 10a and the cam 51, the effectiveness of the cushion can be easily changed.
Further, the cam 51 is not always necessary, and the protrusion 52 may be directly formed on the boom base end portion 10a.

  Further, in the above-described embodiment, the proportional valve 40 is disposed below the pivot fulcrum O of the boom 10 and the roller 44 is disposed vertically below the pivot fulcrum O of the boom 10, but these positions are not limited. . That is, the proportional valve 40, the roller 44, the protrusion 52, and the like may be appropriately disposed at a position where the spool 42 can be slid in conjunction with the rotation of the boom 10.

  In the cylinder cushion device according to the above-described embodiment, a force is applied to the upper portion (one end portion) of the spool 42 of the proportional valve 40 by the projection 52 of the cam 51, the roller 44, and the swing lever 45. Although the proportional valve actuator that slides in the vertical direction is provided, the proportional valve actuator may be changed to the following device.

For example, the proportional valve actuator may be a link type instead of the roller cam type of the above-described embodiment.
That is, as shown in FIG. 6, in the link type proportional valve actuator 70, for example, the position where the protrusion 52 is formed in the above-described embodiment (the lower end of the base end 10 a at the boom 10 maximum turning angle). The first point P ₁ is set, the center point O of the boom foot pin 60 is set as the second point P _2, and the upper end of the spool 42 of the proportional valve 40 is set as the third point P ₃ . These points are connected by connecting axes, and the axis connecting the first point P ₁ and the second point P ₂ is the first node (rotating node) 71, the second point P ₂ and the third point P _3. The axis connecting the second node (fixed node) 72 and the axis connecting the first point P ₁ and the appropriate point P ₄ on the second node 72 as the third node (sliding node) 73, the second node 72, a link mechanism (a so-called crank slider mechanism) in which one end P ₄ of the third joint 73 is slidably held by the second joint 72 and linearly slides on the second joint 72. Form.

According to such a link type proportional valve actuator 70, the first point P ₁ of the first node 71 rotates around the second point P ₂ as the boom 10 rotates, and one end of the third node 73 is rotated. Since P ₄ slides linearly on the second node 72, as the boom 10 approaches the maximum ascending rotation angle, one end P ₄ of the third node 73 gradually pushes the upper part of the spool 42 downward, and the upper part of the spool 42. The spool 42 can be slid by applying a force.

  Therefore, when the spool 42 of the proportional valve 40 is pushed downward by the link mechanism, it is mechanically detected that the boom cylinder 20 has approached the lifting stroke end, and the boom raising oil immediately before the boom raising stroke end is reached. The road pilot pressure can be reduced to mitigate the impact at the stroke end.

Further, for example, the proportional valve actuator may be a spring-type interlocking device.
That is, as shown in FIG. 7, in the spring proportional valve operating device 80, one end is fixed at the position P ₁ where the protrusion 52 is formed in the above embodiment, and the other end is connected to the upper end P ₃ of the spool 42. A fixed first spring 81 is provided. A second spring 82 that urges the spool 42 upward is disposed with respect to the spool 42. Here, both ends of the second spring 82 are connected to the upper end of the spool 42 and the upper surface of the valve body 41.

  In the normal state, the spring constants of the first spring 81 and the second spring 82 are the vertical component of the elastic force (spring force) by the first spring 81 (the component acting in the sliding direction of the spool 42) and the second spring 82, respectively. The resultant force is set so that the resultant force with the elastic force works upward and the force is applied upward on the spool 42. That is, for example, in the normal state, the first spring 81 is set so as to exert an upward force to contract. Alternatively, the normal first spring 81 exerts a downward force while trying to extend, but the downward force is set to be smaller than the upward force of the second spring 82.

  Further, as the boom 10 approaches the maximum ascending rotation angle, the resultant force of the vertical component of the elastic force by the first spring 81 and the elastic force by the second spring 82 acts downward, and a force is gradually applied downward on the spool 42. Is set as follows. In other words, for example, the first spring 81 at this time is set so that a downward force is exerted so as to extend, and the downward force of the first spring 81 is larger than the upward force of the second spring 82.

According to such a spring type proportional valve actuator 80, as the boom 10 approaches the maximum ascending rotation angle, a downward (sliding) force is applied to the upper portion of the spool 42 to slide the spool 42. Can be made.
Therefore, when the boom cylinder 20 approaches the lifting stroke end, the spool 42 slides due to the resultant force of the elastic force of the first spring 81 and the elastic force of the second spring 82, and the lifting stroke end is mechanically detected. Immediately before the boom raising stroke end is reached, the pilot pressure in the boom raising oil passage can be reduced to mitigate the impact at the stroke end.

Further, for example, the proportional valve operating device may be a wire reel winding type interlocking device.
That is, as shown in FIG. 8 (a), (b) , a wire reel retractable proportional valve actuating device is fixed at one end to an appropriate position to Q ₁ boom base end portion 10a, the upper end of the spool 42 ' A wire 90 having the other end fixed to Q ₂ is disposed.
The length of the wire 90 is appropriately set. As shown in FIG. 8A, the wire 90 is in a slack state when the boom 10 is lowered, while the boom 10 is fully raised as shown in FIG. 8B. Sometimes, the wire 90 is set so as to be wound around the arcuate outer peripheral surface of the boom base end portion 10a. The boom base end portion 10a functions as a reel for winding the wire 90.

  According to this, as the boom 10 approaches the maximum ascending rotation angle, the wire 90 becomes taut, and the spool 42 'is gradually pulled upward. By the way, the proportional valve 40 'here is different from the proportional valve 40 in each of the above embodiments, and the spool 42' slides upward, the sliding amount increases, the pilot pressure decreases, and conversely slides downward. Accordingly, the sliding amount decreases and the pilot pressure increases. Further, the spool 42 ′ is normally set to have a sliding amount of 0 so that all pilot oil flows to the control valve 33.

  Therefore, an upward force (sliding direction) is applied to the upper portion of the spool 42 'so that the spool 42' slides, and the lift stroke end is mechanically detected. Depending on the amount of movement, the pilot pressure in the boom raising oil passage can be reduced to reduce the impact at the stroke end.

The wire 90 may be other wire as long as it can slide the spool 42 ′, and may be replaced with a hemp rope, for example.
The spool 42 ′ only needs to be able to change the pilot pressure in accordance with the sliding amount. For example, as the spool 42 of one embodiment, the sliding amount increases as it slides downward. Alternatively, the pilot pressure may be increased by decreasing the sliding amount as the pressure decreases, and conversely sliding upward. In this case, an appropriate device is provided for the wire 90, and the spool 42 'is gradually slid downward as the boom 10 approaches the maximum ascending rotation angle.
Thus, any mechanism (mechanism) that can convert the pivoting motion of the boom 10 into the sliding motion of the spools 42 and 42 ′ can be applied.

Further, in each of the above-described embodiments, the proportional valve 40 is interposed in the boom raising oil passage. However, an impact at the stroke end on the boom lowering side may be reduced by interposing in the boom lowering oil passage. However, since the earth is often excavated by the bucket 12 when the boom is lowered, it is preferable to set the cylinder cushion degree appropriately from the viewpoint of excavation workability.
Moreover, although the case where the cylinder cushion apparatus of this invention was applied to the boom cylinder 20 of the hydraulic excavator 1 was demonstrated, it deform | transforms and applies suitably also to the arm cylinder 13, the bucket cylinder 14, another general hydraulic cylinder, etc. be able to.

It is a figure which shows the cylinder cushion apparatus which concerns on one Embodiment of this invention, Comprising: It is a side view of the state in which the boom is falling. It is a figure which shows the cylinder cushion apparatus which concerns on one Embodiment of this invention, Comprising: It is a side view of the state which has raised the boom. It is a figure which shows the hydraulic circuit of the boom cylinder which concerns on one Embodiment of this invention. 1 is a perspective view of a hydraulic excavator provided with a cylinder cushion device according to an embodiment of the present invention. It is a principal part enlarged view which shows the cylinder cushion apparatus which concerns on other embodiment of this invention. It is a side view which shows the cylinder cushion apparatus which concerns on other embodiment of this invention. It is a side view which shows the cylinder cushion apparatus which concerns on other embodiment of this invention. It is a figure which shows the cylinder cushion apparatus which concerns on other embodiment of this invention, Comprising: (a) is a side view of the state in which the boom is falling, (b) is a side view of the state in which the boom is raised.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydraulic excavator 2 Lower traveling body 3 Upper turning body 3a Swing frame (the other member)
3b Main plate 4 Working device 5 Counterweight 6 Engine room 7 Cab 10 Boom (one member)
10a Base end 11 Arm 12 Bucket 13 Arm cylinder 14 Bucket cylinder 20 Boom cylinder (hydraulic cylinder)
21 Cylinder tube (cylinder body)
22 Piston 23 Rod 24 Bottom side oil chamber (first oil chamber)
25 Rod side oil chamber (second oil chamber)
31 Main hydraulic pump (main pump)
32 Hydraulic oil tank 33 Control valve 33a Spring 34 Pilot hydraulic pump (pilot pump)
35 Boom control lever 40, 40 'Proportional valve 41, 41' Valve body (casing)
42, 42 'spool (spool member)
43 Base 44 Roller (actuator)
45 Swing lever (actuator)
51 Cam 52 Projection (actuator)
60 Boom foot pin 70 Link-type proportional valve actuator (link mechanism)
71 First Section (Rotating Section)
72 Second Section (Fixed Section)
73 Section 3 (sliding section)
80 Spring-type proportional valve actuator (spring-type interlocking device)
81 1st spring 82 2nd spring 90 wire (wire reel winding type proportional valve actuator)
_CM main circuit (hydraulic circuit)
C _P pilot circuit H Projection height of the projection from the cam L Projection length of the projection in the direction of boom rotation O Rotation fulcrum of the boom base end P ₁ First point of the link mechanism P _{2 Second of the} link mechanism the second position of the first position S ₂ control valve in the neutral position S ₁ control valve of the other end S ₀ control valve at one end Q ₂ wire end Q ₁ wire of the third point P ₄ Section III point P ₃ linkage

Claims (6)

A hydraulic cylinder that is interposed between two pivotally attached members and expands and contracts to rotate one member relative to the other member; a hydraulic pump that discharges hydraulic oil supplied to the hydraulic cylinder; and the hydraulic pressure A hydraulic circuit provided between the pump and the hydraulic cylinder and provided with a control valve for controlling the flow of the hydraulic oil supplied to the hydraulic cylinder is expanded and contracted at the stroke end of the hydraulic cylinder. A cylinder cushion device for controlling the control valve to be loose,
A pilot circuit for supplying the control valve with a pilot pressure for controlling the flow of the hydraulic oil by the control valve;
A proportional valve attached to the other member and interposed on the pilot circuit;
A spool member that is slidably inserted into the proportional valve and changes the pilot pressure of the pilot circuit in accordance with the sliding amount;
At least one member is attached, and when the one member rotates to a position corresponding to the stroke end of the hydraulic cylinder, the spool member slides in conjunction with the rotation of the one member. A cylinder cushion device comprising an actuating device. The one member has an outer peripheral surface formed in an arc shape in a side view, and includes a base end portion pivotally attached to the other member.
The actuating device is urged against the outer peripheral surface of the base end portion and rotatably contacts with the roller, the roller is pivotally supported at one end, and the other end is swingably supported by the proportional valve. A swing lever that slides the spool member by pressing one end portion of the spool member in a sliding direction at an intermediate portion between the one end and the other end, and the one member corresponds to a stroke end of the hydraulic cylinder A protrusion formed in a position facing the roller on the outer peripheral surface of the base end portion when rotated to a position, and protruding from the outer peripheral surface in a diameter increasing direction of the arc. The cylinder cushion device according to claim 1. The one member includes a proximal end pivotally attached to the other member;
The operating device includes a link mechanism that presses one end of the spool member in conjunction with the rotation of the one member and slides the spool member.
The link mechanism is pivotally supported at one end by a rotation fulcrum of the one member, and the spool at the base end when the one member rotates to a position corresponding to the stroke end of the hydraulic cylinder. A rotating node having the other end fixed at a position facing the member, a sliding node having one end pivotally attached to the other end of the rotating node, and the other end of the sliding node being slidably held And one end fixed to one end of the rotary node, the spool member extending in the sliding direction, and the other end fixed to the spool member. The cylinder cushion device according to claim 1. The actuating device comprises a spring-type interlocking device that applies an elastic force to the spool member in conjunction with the rotation of the one member using a spring, and slides the spool member.
The spring-type interlocking device has a first spring having both ends connected to the one member and the spool member, and a second spring having both ends connected to the spool member and the casing of the proportional valve. And
When the resultant force of the elastic force of the first spring and the elastic force of the second spring acting in the sliding direction of the spool member is rotated to a position corresponding to the stroke end of the hydraulic cylinder The cylinder cushion device according to claim 1, wherein an elastic force of the first spring and an elastic force of the second spring are set so that the spool member is slid on the cylinder member. The one member has an outer peripheral surface formed in an arc shape in a side view, and includes a base end portion pivotally attached to the other member.
The actuating device includes a wire having one end fixed at a predetermined position of the base end and the other end fixed to the spool member, and a wire reel that slides the spool member by a tensile force of the wire Consists of a winding-type interlocking device,
The length of the wire is such that when the one member is rotated to a position corresponding to the stroke end of the hydraulic cylinder, the wire is wound around the proximal end in conjunction with the rotation of the one member. The cylinder cushion device according to claim 1, wherein the cylinder cushion device is set to a length for pulling the spool member. The hydraulic cylinder is a boom cylinder interposed between the boom and the upper swing body to swing the boom of the work machine.
The pilot circuit is a boom raising pilot circuit for supplying the pilot pressure to the control valve so that a flow direction of the hydraulic oil in the control valve is a direction to raise the boom,
6. The cylinder cushion device according to claim 1, wherein the proportional valve is interposed on the boom raising pilot circuit.

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