Patent Grant
10662623
The present application claims priority under 35 U.S.C. ยง 119 to Japanese Patent Application No. 2017-55921, filed Mar. 22, 2017. The content of this application is incorporated herein by reference in their entirety.
The present invention relates to a hydraulic system for a working machine such as a skid steer loader, a compact track loader, and the like.
As for a working machine such as a skid steer loader and a compact track loader, a working machine is previously known, the working machine including a hydraulic system (refer to Japanese Unexamined Patent Application Publication No. 2011-231468). The hydraulic system has a first hydraulic pump and a second hydraulic pump, the first hydraulic pump being configured to supply an operation fluid to a hydraulic actuator, the second hydraulic pump being configured to increase a flow rate of the operation fluid that is to be supplied to the hydraulic actuator.
According to Japanese Unexamined Patent Application Publication No. 2011-231468, an increasing fluid tube to supply the operation fluid outputted from the second hydraulic pump is connected to an operation fluid supply tube of the operation fluid, the operation fluid supply tube extending from the first hydraulic pump to the hydraulic actuator, thereby increasing the operation fluid flowing into the hydraulic actuator. In particular, a high flow valve is configured to be switched between a non-increasing position and an increasing position by the pilot pressure. When the high flow valve is switched to the increasing position, the operation fluid outputted from the second hydraulic pump is supplied to the increasing fluid tube, and thus the operation fluid to be supplied to the hydraulic actuator is increased.
However, according to Japanese Unexamined Patent Application Publication No. 2011-231468, when the high flow valve is switched to the increasing position, the flow rate of a main fluid tube is rapidly increased, and the rapidly-increasing may generate a surge pressure.
According to International Publication No. 2016/051815, a throttling portion is disposed on a pilot fluid tube that is configured to connect the high flow valve to a high flow switching valve configured to switch the high flow valve, and a bleeding circuit is disposed on the pilot fluid tube, the bleeding circuit being configured to discharge the operation fluid, thereby reducing the surge pressure generated when the high flow valve is in the increasing position.
A hydraulic system for a working machine of the present invention, includes a hydraulic actuator configured to be operated by an operation fluid, a first hydraulic pump configured to output the operation fluid, a second hydraulic pump configured to output the operation fluid, a control valve to which the operation fluid outputted from the first hydraulic pump is supplied, the control valve being configured to control the operation fluid that is to be supplied to the hydraulic actuator, a first fluid tube connecting the control valve to the hydraulic actuator, a second fluid tube to which the operation fluid outputted from the second hydraulic pump is supplied, the second fluid tube being connected to the first fluid tube, and a first switching valve disposed on the second fluid tube. The first switching valve includes a pressure-receiving port configured to receive a pressure of the operation fluid, a first inner fluid passage configured to output the operation fluid, and a spool configured to move between a first position and a second position. The first position allows the operation fluid not to be supplied to the first fluid tube. The second position allows the operation fluid to be supplied to the first fluid tube due to the operation fluid applied to the pressure-receiving port. The spool includes a communicating fluid passage being configured to supply the operation fluid to the first inner fluid passage, the operation fluid being received by the pressure-receiving port.
Another hydraulic system for a working machine of the present invention, includes a hydraulic actuator configured to be operated by an operation fluid, a first hydraulic pump configured to output the operation fluid, a second hydraulic pump configured to output the operation fluid, a control valve to which the operation fluid outputted from the first hydraulic pump is supplied, the control valve being configured to control the operation fluid that is to be supplied to the hydraulic actuator, a first fluid tube connecting the control valve to the hydraulic actuator, a second fluid tube to which the operation fluid outputted from the second hydraulic pump is supplied, the second fluid tube being connected to the first fluid tube, a first switching valve disposed on the second fluid tube. The first switching valve includes a pressure-receiving port configured to receive a pressure of the operation fluid, and a spool configured to move between a first position and a second position. The first position allows the operation fluid not to be supplied to the first fluid tube. The hydraulic system further includes a first pilot fluid tube connected to the pressure-receiving port of the first switching valve, and a second switching valve including a first port to which the operation is supplied, a second port connected to the pilot fluid tube, an outputting port configured to output the operation fluid, a spool configured to move between a first position and a second position, a fifth inner fluid passage configured to connect the first port to the second port when the spool is in the first position, and a sixth inner fluid passage connected to the fifth inner fluid passage and connected to the outputting port.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
The embodiments will now be described with reference to the accompanying drawings, wherein like reference numerals designate corresponding or identical elements throughout the various drawings. The drawings are to be viewed in an orientation in which the reference numerals are viewed correctly.
Referring to drawings, the embodiments of the present invention, a hydraulic system for a working machine and the working machine having the hydraulic system, will be described below.
A working machine will be explained below.
As shown in
Hereinafter, in explanations of all the embodiments of the present invention, a forward direction (a left side in
A cabin 5 is mounted on a front portion and an upper portion of the machine body 2. A rear portion of the cabin 5 is supported by a supporting bracket 11 of the machine body 2, and is configured to be swung about a supporting shaft 12. A front portion of the cabin 5 is configured to be mounted on a the front portion of the machine body 2. A prime mover 32 is installed on a rear portion of the machine body 2. The prime mover 32 is constituted of an electric motor, an engine, or the like. In the embodiment, the prime mover 32 is constituted of the engine.
An operator 13 is disposed inside the cabin 5. The travel device 4 is constituted of a crawler type travel device. The travel device 4 is disposed under the machine body 2 and on the left side of the machine body 2. Another travel device 4 is disposed under the machine body 2 and on the right side of the machine body 2. Each of the travel devices 4 is configured to be driven by a driving force of a travel motor such as a hydraulic-driving wheel motor.
The operation device 3 includes a boom 22L, a boom 22R, and a working tool 11 (for example, a bucket) attached to tip ends of the booms 22L and 22R. The boom 22L is arranged on the left side of the machine body 2. The boom 22R is arranged on the right side of the machine body 2. The boom 22L and the boom 22R are connected by a connecting member to each other. The boom 22L and the boom 22R are supported by the first lift link 24 and the second lift link 25.
A lift cylinder 26 constituted of a double-acting hydraulic cylinder is disposed between a rear lower portion of the machine body 2 and a base portion side of the boom 22L. Another lift cylinder 26 constituted of a double-acting hydraulic cylinder is disposed between a rear lower portion of the machine body 2 and a base portion side of the boom 22R. The lift cylinder 26 and the other lift cylinder 26 are simultaneously stretched and shortened to swing the boom 22L and the boom 22R upward and downward. An attachment bracket 27 is supported on the tip end side of each of the boom 22L and the boom 22R, and is configured to be turned. A back surface side of the bucket 23 is attached to the attachment bracket 27.
A tilt cylinder 28 constituted of a double-acting hydraulic cylinder is installed between the attachment bracket 27 and an intermediate portion of the tip end side of each of the boom 22L and the boom 22R. The tilt cylinder 28 is stretched and shortened, and thereby the bucket 23 performs a swinging operation (the shoveling operation and the dumping operation).
The bucket 23 is configured to be attached to and detached from the attachment bracket 27. Not only the bucket 11, other working tools can be attached to the tip ends of the boom 22R and the boom 22L. The following attachments (spare attachments) are exemplified as the other working tools; for example, a hydraulic crusher, a hydraulic breaker, an angle broom, an earth auger, a pallet fork, a sweeper, a mower, a snow blower, and the like.
In addition, a connecting device 50 is disposed on the tip end of each of the boom 22L and the boom 22R, the connecting device 50 configured to be connected to the hydraulic actuator (the hydraulic cylinder, the hydraulic motor, and the like) 30 that is disposed on the auxiliary attachment. For convenience of the explanation, the hydraulic actuator disposed on the auxiliary attachment will be referred to as an auxiliary actuator below.
Next, the hydraulic system for the working machine 1 will be described below.
The operation fluid outputted from the first hydraulic pump P1 is used to drive the lift cylinder 26, the tilt cylinder 28, and the hydraulic actuator of the attachment attached to the tip end side of the boom 22. The operation fluid outputted from the second hydraulic pump P2 is used to increase the flow rate of the operation fluid supplied to the auxiliary actuator. The operation fluid outputted from the third hydraulic pump P3 is mainly used as an operation fluid for signal or control. Hereinafter, the operation fluid for signal or control may be referred to as a pilot fluid.
The first hydraulic pump P1 and the control valve 56 are connected each other by an outputting fluid tube 40. The control valve 56 is constituted of a control valve configured to control the hydraulic actuator that is disposed on the working machine 1. In the embodiment, the operating valve 56 controls the auxiliary hydraulic actuator configured to activate the auxiliary attachment. It should be noted that the control valve 56 is not limited to a control valve configured to control the auxiliary hydraulic actuator.
The control valve 56 is constituted of a direct-acting three-position switching valve having a spool operated by the pilot fluid. The direct-acting three-position switching valve is configured to be switched by a pilot pressure of the pilot fluid between a first position 56a, a second position 56b, and a neutral position 56c. The control valve 56 and the connecting device 50 are connected each other by a first fluid tube 41.
The first fluid tube 41 includes a first supplying-outputting fluid tube 41a and a second supplying-outputting fluid tube 41b. The first supplying-outputting fluid tube 41a connects the first port 56A of the control valve 56 to the first port 50A of the connecting device 50. The second supplying-outputting fluid tube 41b connects the second port 56B of the control valve 56 to the second port 50B of the connecting device 50.
An outputting fluid tube 42a is connected to the first supplying-outputting fluid tube 41a, and an outputting fluid tube 42b is connected to the second supplying-outputting fluid tube 41b. The outputting fluid tube 42a and the outputting fluid tube 42b are connected to a bypass fluid tube 43 in the discharge fluid tube 40, the bypass fluid tube 43 connecting the upstream side of the control valve 56 and the downstream side of the control valve 56 to each other. An outputting fluid tube 45 configured to output the operation fluid is connected to a connecting portion 44 in the discharge fluid tube 40, the connecting portion 44 being configured to connect the downstream side of the control valve 56 and the bypass fluid tube 43 to each other.
The control valve 56 is operated by a plurality of operation valves 60. The plurality of operation valves 60 include a first proportional valve 60A and a second proportional valve 60B. Each of the first proportional valve 60A and the second proportional valve 60B is constituted of a solenoid valve (an electromagnetic valve) whose degrees of an opening aperture can be changed by magnetic excitation or the like. The first proportional valve 60A and the second proportional valve 60B are connected to the second pilot fluid tube 46 that is connected to the third hydraulic pump P3. A pressure-receiving portion (also referred to as a pressure-receiving port) of the control valve 56 and the proportional valve 60 (the first proportional valve 60A and the second proportional valve 60B) are connected each other by fluid tubes 47a and 47b. The proportional valve 60 (the first proportional valve 60A and the second proportional valve 60B) is controlled by the control device 80.
A switch 86 is connected to the control device 80. The switch 86 is one of operation control members. The operation amount (the operation extent) such as the sliding amount (the sliding extent) and the swinging amount (the swinging extent) of the switch 86 is inputted to the control device 80. The switch 86 is, for example, constituted of a seesaw type switch configured to be swung, a slide type switch configured to be slid, a push type switch configured to be pushed, or the like. When the switch 86 is operated, the control device 80 outputs a control signal to magnetically excite the first proportional valve 60A or the second proportional valve 60B in accordance with the operation direction and the operation amount of the switch 86.
In this manner, the degree of opening aperture of the first proportional valve 60A or the second proportional valve 60B is set, and the control valve 56 is switched to the first position 56a or the second position 56b. Thus, the switch 86 is operated, thereby operating the auxiliary actuator of the auxiliary attachment.
Meanwhile, according to the hydraulic system for the working machine 1, it is possible to increase the hydraulic fluid that is to be supplied to the auxiliary actuator. The increasing of the hydraulic fluid supplied to the auxiliary actuator will be described below in detail.
As shown in
More specifically, the second fluid tube 73 has a first increasing fluid tube 73a and a second increasing fluid tube 73b. The first increasing fluid tube 73a is configured to connect the second hydraulic pump P2 and the first switching valve 71 to each other. The second increasing fluid tube 73b connects the first switching valve 71 and the first supplying-outputting fluid tube 41a of the first fluid tube 41 to each other. Meanwhile, the second increasing fluid tube 73b is connected to the first supplying-outputting fluid tube 41a of the first fluid tube 41. However, instead of that, the second increasing fluid tube 73b may be connected to the second supplying-outputting fluid tube 41b.
The first switching valve 71 has a first port 71A, a second port 71B, a third port 71C, and a fourth port 71D. The first increasing fluid tube 73a is connected to the first port 71A, and the second increasing fluid passage 73b is connected to the second port 71B. An outputting fluid tube 45 is connected to the third port 71C. The fourth port 71D is connected to connect an outputting fluid tube 48 that connects the first switching valve 71 and the second switching valve 72 to each other and is connected to the outputting fluid tube 45. Each of the third port 71C and the fourth port 71D is constituted of an outputting port configured to output the operation fluid to the outside.
The first switching valve 71 is a two-position switching valve configured to be switched between the first position 71a and the second position 71b. When the first switching valve 71 is in the first position 71a, the first port 71A and the third port 71C communicate with each other, and thereby the hydraulic fluid in the second fluid tube 73 is outputted to the hydraulic fluid tank 29 through the outputting fluid tube 45.
When the first switching valve 71 is in the second position 71b, the first port 71A and the second port 71B communicate with each other, and thereby the operation fluid in the first increasing fluid tube 73a is introduced into the second increasing fluid tube 73b. That is, the first switching valve 71 is configured to be switched between a first position 71a and a second position 71b. The first position 71a allows the operation fluid not to be supplied to the first fluid tube 41, and the second position 71b allows the operation fluid to be supplied to the first fluid tube 41. In other words, the first position 71a block the operation fluid from being supplied to the first fluid tube 41, and the second position 71b supplies the operation fluid to the first fluid tube 41.
The second switching valve 72 is constituted of a valve configured to switch the first switching valve 71 between the first position 71a and the second position 71b. The second switching valve 72 has a first port 72A, a second port 72B, a third port 72C, and a fourth port 72D. A second pilot fluid tube 46 is connected to the first port 72A. And, the second port 72B is connected to the first pilot fluid tube 49 that is connected to a pressure-receiving portion (also referred to as a pressure-receiving port) 92 of the first switching valve 71. The third port 72C and the fourth port 72D are connected to the outputting fluid tube 48. Each of the third port 72C and the fourth port 72D serves as an outputting port configured to output the operation fluid to the outside.
A throttling portion (throttle) 97 is disposed on the second pilot fluid tube 46 in the vicinity of the first port 72A of the second switching valve 72, the throttling portion (throttle) 97 being configured to reduce the flow rate of the pilot fluid.
The second switching valve 72 is constituted of a two-position switching valve configured to be switched between the first position 72a and the second position 72b. The second switching valve 72 has a spool (not shown in the drawings) and is switched between the first position 72a and the second position 72b by the movement of the spool (a second spool). The spool is pushed toward the first position 72a by a biasing member 74 such as a spring.
The second switching valve 72 is switched in accordance with a control signal outputted from the control device 80. A switch 81, for example, is connected to the control device 80, the switch 81 being configured to be turned ON/OFF. The switch 81 is disposed in the vicinity of the operator seat 13 and can be operated, for example, by an operator. When the switch 81 is turned ON, the control device 80 outputs a control signal for magnetically exciting (magnetizing) the solenoid of the second switching valve 72, and thereby switches the second switching valve 72 to the second position 72b. When the switch 81 is turned OFF, the control device 80 outputs a control signal for demagnetizing the solenoid of the second switching valve 72, and thereby switches the second switching valve 72 to the first position 72a.
When the second switching valve 72 is in the first position 72a, the second port 72B of the second switching valve 72 communicates with the third port 72C, and thereby the operation fluid in the first pilot fluid tube 49 is released to the outputting fluid tube 48. As the result, the pilot pressure of the pilot fluid is not applied to the pressure-receiving portion 92 of the first switching valve 71, and thus the first switching valve 71 is switched to the first position 71a.
When the second switching valve 72 is in the second position 72b, the first port 72A of the second switching valve 72 communicates with the second port 72B, and thereby the operation fluid in the second pilot fluid tube 46 flows to the first pilot fluid tube 49. As the result, the pilot pressure is applied to the pressure-receiving portion 92 of the first switching valve 71, and thus the first switching valve 71 is switched to the second position 71b.
The main body 90 is made by the casting, formed of a resin, or the like. A fluid passage (an inner fluid passage) 93 through which the hydraulic fluid flows is formed in the main body 90. The inner fluid passage 93 includes a first inner fluid passage 93a, a second inner fluid passage 93b, a third inner fluid passage 93c, and a fourth inner fluid passage 93d.
The first inner fluid passage 93a is constituted of an fluid tube formed in the main body 90, the fluid tube being configured to output the hydraulic fluid in the main body 90 to the outside of the main body 90. The first inner fluid passage 93a communicates with the third port 71C or the fourth port 71D. That is, the first inner fluid passage 93a is connected to a port through which the operation fluid is outputted.
The second inner fluid passage 93b is constituted of an fluid tube formed in the main body 90, that is, a fluid tube into which the operation fluid of the first increasing fluid tube 73a is introduced. The second inner fluid passage 93b communicates with the first port 71A.
The third inner fluid passage 93c is constituted of an fluid tube formed in the main body 90, that is, a fluid tube configured to supply the operation fluid to the second increasing fluid tube 73b, the operation fluid being introduced from the first increasing fluid tube 73a. The third inner fluid passage 93c communicates with the second port 71B.
The fourth inner fluid passage 93d is constituted of an fluid tube formed in the main body 90, that is, a fluid tube connected to the first inner fluid passage 93a and the second inner fluid passage 93b to communicate with the first inner fluid passage 93a and the second inner fluid passage 93b.
A through hole 94 having a straight shape is formed inside the main body 90. The first internal fluid tube 93a, the second internal fluid tube 93b, and the third internal fluid tube 93c reach a wall portion 94a constituting the through hole 94, the wall portion 94a having an annular shape. The through hole 94 and the fourth internal fluid tube 93d are shared with each other. Meanwhile, the first internal fluid tube 93a, the second internal fluid tube 93b, and the third internal fluid tube 93c are orthogonal to a direction of extension of the wall section 94a that constitutes the through hole 94.
The pressure-receiving portion 92 is a portion configured to receive a pressure of the operation fluid, and includes a port 92a into which the operation fluid of the first pilot hydraulic passage 49 is introduced and a pressure-receiving chamber 92b into which the operation fluid introduced from the port 92a flows.
In this embodiment, the pressure-receiving chamber 92b communicates with the through hole 94. In addition, the pressure-receiving chamber 92b is provided with a stopper 99 configured to restrict the movement of the spool 91 in the manner that the end surface of the spool 91 contacts to the stopper 99. In this embodiment, a hole communicating with the port 92 is formed in the stopper 99.
The spool 91 is configured to be moved inside the main body 90 by the operation fluid introduced into the pressure-receiving portion 92. The connecting destination of the first internal fluid tube 93a, the second internal fluid tube 93b, and the third internal fluid tube 93c are changed by the movement of the spool 91.
The spool 91 is configured to move to a first position 71a and a second position 71b, the first position 71a allowing the operation fluid not to be supplied to the first fluid tube 41, the second position 71b allowing the hydraulic fluid to be supplied to the first fluid tube 41. In other words, the first position 71a block the operation fluid from being supplied to the first fluid tube 41, and the second position 71b supplies the operation fluid to the first fluid tube 41. In addition, when the spool 91 is in the first position 71a, the spool 91 opens the fourth inner fluid passage 93d and, when the spool 91 is in the second position 71b, the spool 91 closes the fourth inner fluid passage 93d.
Hereinafter, the spool 91 will be described below in detail.
The spool 91 is formed in a cylindrical shape. The spool 91 having a cylindrical shape is inserted into the through hole 94 formed inside the main body 90. As shown in
In this manner, the one end of the spool 91 contacts to the stopper 99, and thereby the spool 91 is held at the first position 71a. As shown in
The spool 91 has a first connecting portion 91a and a second connecting portion 91b. The first connecting portion 91a is configured to connect the second inner fluid passage 93b and the third inner fluid passage 93c to each other. The second connecting portion 91b is configured to connect the first inner fluid passage 93a, the second inner fluid passage 93b, and the fourth inner fluid passage 93d to each other.
In particular, the first connecting portion 91a and the second connecting portion 91b are portions formed by annularly recessing the outer circumference surfaces of the spool 91. As shown in
As shown in
In addition, as shown in
As shown in
In other words, in the spool 91, the closing portion 91c having a convex shape is overlapped with (corresponds to) the fourth inner fluid passage 93d, the closing portion 91c being disposed between the first connecting portion 91a and the second connecting portion 91b, and thereby the connection (communicating) between the first inner fluid passage 93a and the second inner fluid passage 93b is blocked.
Meanwhile, the spool 91 has a communicating fluid passage 96. The communicating fluid passage 96 is constituted of a fluid tube allowing the operation fluid received by the pressure-receiving portion 92 (the pressure-receiving chamber 92b) to be supplied to the first inner fluid passage 93a. As shown in
Specifically, the communicating fluid passage 96 includes a first communicating passage 96a, a second communicating passage 96b, and a third communicating passage 96c. The first communicating passage 96a extends radially from the center of an outer surface (a lateral surface) of the spool 91, the outer surface being on one end side of the spool 91. The second communicating passage 96b communicates with the first communicating passage 96a and extends from the one side of the spool 91 to the other side in the interior of the spool 91. The third communicating passage 96c communicates with the second communicating passage 96a and radially extends in the interior of the spool 91.
One or more of the first communicating passages 96a are provided. One or more of the first communicating passages 96a communicate with the second communicating passage 96b on one end side (an inner diameter side) of the first communicating passages 96a, and the other end side (the outer diameter side) of the first communicating passages 96a reaches an outer circumference surface of the spool 91. The first communicating passage 96a is constituted of a groove formed to have a U-shape, a V-shape, a channel shape, or the like on the side surface of the spool 91.
As shown in
The second communicating passage 96b extends passing through the center (the cross-sectional center) of the spool 91 in the longitudinal direction. One end of the second communicating passage 96b communicates with the first communicating passage 96a. The other end of the second communicating passage 96b extends to a position corresponding to the second connecting portion 91b.
One or more of the third communicating passages 96c are provided. One or more of the third communicating passages 96c communicate with the second communicating passage 96b on one end side (the inner diameter side) of the third communicating passages 96c, and the other end side (the outer diameter side) of the third communicating passages 96c reaches the outer circumference surface of the spool 91 and communicates with the second connecting portion 91b. Meanwhile, as shown in
As shown in
As described above, when the second switching valve 72 is switched to the second position 72b, the pilot fluid outputted from the third hydraulic pump P3 is supplied to the pressure-receiving portion 92 (the pressure-receiving chamber 92b) of the first switching valve 71 through the second pilot fluid tube 46 and the first pilot fluid tube 49. At this time, as shown in
In this manner, the speed of the spool 91 moving from the first position 71a to the second position 72b is reduced, and thereby the shock generated by the first switching valve 71 is reduced in increasing the flow rate of the operation fluid. That is, by only changing the shape of the spool 91, it is possible to reduce the shock of the first switching valve 71 in increasing the flow rate of the hydraulic fluid, and thus the number of parts is reduced as compared with the prior art.
Specifically, the second switching valve 72 has a fifth inner fluid passage 76a, a sixth inner fluid passage 76b, and a throttling portion 76c. The fifth inner fluid passage 76a is constituted of an fluid tube, the fluid tube being formed in the main body of the second switching valve 72 and configured to connect the first port 72A and the second port 72B to each other in the second position 72b. In addition, the sixth inner fluid passage 76b is constituted of an fluid tube formed in the main body of the second switching valve 72, the fluid tube communicating with the fifth inner fluid passage 76a at the second position 72b and communicating with the third port (the exhaust port) 72C. The throttling portion 76c is disposed on an intermediate portion of the sixth inner fluid passage 76b, and thereby reduces the hydraulic fluid.
The throttling portion 76c may be configured by making the inner diameter of a part of the sixth inner flow path 76b smaller than the inner diameter of the other portion of the sixth inner flow path 76b, by providing a member having a different diameter on the sixth internal fluid tube 76b, or by other methods. Additionally, in the second pilot fluid tube 46, a throttling portion 97 is disposed in the vicinity of the first port 72A of the second switching valve 72, the throttling portion 97 being configured to reduce the flow rate of the pilot fluid.
As described above, when the second switching valve 72 is set to the second position 72b, the pilot fluid introduced from the first port 72A flows from the second port 72B to the pilot fluid tube 49 through the fifth inner fluid passage 76a. At this time, a part of the pilot fluid passing through the fifth inner fluid passage 76a passes through the sixth inner fluid passage 76b and is outputted from the third port 72C to the outputting fluid tube 48. In this manner, the pressure of the pilot fluid applied to the pressure-receiving portion 92 (the pressure-receiving chamber 92b) of the first operation valve 71 is reduced, and thus the shock generated by the first switching valve 71 is reduced in increasing the flow rate of the operation fluid.
In addition, an outputting fluid tube 102 is connected to an intermediate portion of the second increasing fluid tube 73b. The outputting fluid tube 102 is connected to the outputting fluid tube 100, and a relief valve 103 is connected to an intermediate portion of the outputting fluid tube 102. Further, in the second increasing fluid tube 73b, a check valve 104 is connected to a portion closer to the first fluid tube 41 side (the downstream side) than a connecting portion w102a to which the outputted fluid tube 102 is connected. A check valve 104 allows the operation fluid to flow from the second fluid tube 73 to the first fluid tube 41, and blocks the hydraulic fluid from flowing from the first fluid tube 41 to the second fluid tube 73.
As shown in
As shown in
As shown in
In the above description, the embodiment of the present invention has been explained. However, all the features of the embodiment disclosed in this application should be considered just as examples, and the embodiment does not restrict the present invention accordingly. A scope of the present invention is shown not in the above-described embodiment but in claims, and is intended to include all modifications within and equivalent to a scope of the claims.
In the embodiments described above, the output destination of the operation fluid is the operation fluid tank 29. However, any portion (any configuration) configured to adequately output the operation fluid may be employed. For example, that portion may be a suction portion of the hydraulic pump or another portion may be employed.
Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-55921 | Mar 2017 | JP | national |
| Number | Date | Country |
|---|---|---|
| 60-95272 | Jun 1985 | JP |
| 62-24080 | Feb 1987 | JP |
| 2-31006 | Feb 1990 | JP |
| 2002-536588 | Oct 2002 | JP |
| P2006-283852 | Oct 2006 | JP |
| 2011-231468 | Nov 2011 | JP |
| P2016-125559 | Jul 2016 | JP |
| WO-2016051815 | Apr 2016 | WO |
| 2016051815 | Apr 2017 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20180274209 A1 | Sep 2018 | US |
