JP2009293631A - Hydraulic system for working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic system capable of achieving smooth change in a flow rate of working fluid supplied to an actuator when the actuator is driven by increasing the flow rate of the working fluid supplied from a main pump to the actuator by a sub-pump. <P>SOLUTION: The hydraulic system is provided with the main pump P1 for supplying working fluid to the hydraulic actuator 34; the sub-pump P3 for increasing the flow rate of the working fluid supplied to the hydraulic actuator 34; a control valve 65 for controlling the flow rate of the working fluid supplied from the main pump P1 to the hydraulic actuator 34; a flow rate increase passage u for supplying working fluid from the sub-pump P3 to a working fluid flowing passage i for supplying working fluid from the control valve 65 to the hydraulic actuator 34; and a high flow valve 83 provided on the flow rate increase passage u and controlling the flow rate of the working fluid supplied from the sub-pump P3 to the working fluid flowing passage i. The flow rate of the working fluid controlled by the high flow valve 83 is made proportional to the flow rate of the working fluid controlled by the control valve 65. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a hydraulic system for a working machine.

2. Description of the Related Art Conventionally, there is a working machine including a main pump that supplies hydraulic oil to a hydraulic actuator of a hydraulically driven work tool, and a sub pump for increasing the flow rate of hydraulic oil supplied to the hydraulic actuator (see Patent Document 1). ).
U.S. Patent No. 7017674

  In the conventional work machine, for example, a hydraulic drive type equipped with a hydraulic actuator that performs normal work by rotating in one direction such as a hydraulic drive type mower or a hydraulic breaker as a hydraulic drive type work tool used by increasing the amount of hydraulic oil When a work implement is used, an increase oil passage that supplies hydraulic fluid from the sub pump is connected to the hydraulic fluid passage on the supply side that supplies hydraulic fluid to the hydraulic actuator from the control valve that controls the flow rate of hydraulic fluid from the main pump. Then, it has been considered to provide a high flow valve for selecting whether or not to supply hydraulic oil from the sub-pump to the supply side hydraulic oil flow passage in the increasing oil passage.

  In this case, the high flow valve can be switched to only two positions: a non-increasing position where the discharge oil from the sub pump does not flow through the hydraulic oil flow passage and an increase position where the discharge oil from the sub pump flows through the hydraulic oil flow passage. And when the control valve is operated to drive the hydraulic actuator, the high flow valve is switched from the non-operating position to the operating position, so that the control valve is driven to drive the hydraulically driven mower or hydraulic breaker. When the operation is performed, the entire amount of the sub-pump discharge oil flows to the supply-side hydraulic oil supply passage, but the control valve is not operated so much (the control valve is not opened much). When the total amount of the sub-pump discharge oil flows into the supply-side hydraulic oil flow passage, the return-side hydraulic oil flows the return hydraulic oil from the hydraulic actuator. Since the opening of the circuit return to drain into the tank through the control valve from the passageway is not sufficiently secured, a problem that the flow rate of the hydraulic fluid supplied to the hydraulic actuator is rapidly changed occurs.

  Then, an object of this invention is to provide the hydraulic system of the working machine which can solve the said problem.

Technical means taken by the present invention to solve the technical problem include a main pump that supplies hydraulic oil to the hydraulic actuator, a sub-pump for increasing the flow rate of the hydraulic oil supplied to the hydraulic actuator, A control valve for controlling the flow rate of the hydraulic oil supplied from the main pump to the hydraulic actuator, and an increase for supplying the hydraulic oil from the sub pump to the hydraulic oil flow passage for supplying the hydraulic oil from the control valve to the hydraulic actuator An oil passage, and a high flow valve that is provided in the increasing oil passage and controls the flow rate of the hydraulic oil from the sub pump supplied to the hydraulic oil passage,
The flow rate of hydraulic fluid controlled by the high flow valve is proportional to the flow rate of hydraulic fluid controlled by the control valve.

Further, the high flow valve and the control valve are controlled by a command signal from a control unit so that the flow rate of the hydraulic oil controlled by the high flow valve is proportional to the flow rate of the hydraulic oil controlled by the control valve. It may be.
Other technical means include a main pump that supplies hydraulic oil to the hydraulic actuator, a sub pump for increasing the flow rate of the hydraulic oil supplied to the hydraulic actuator, and a hydraulic pump that is supplied from the main pump to the hydraulic actuator. A pilot-type control valve that controls the flow rate of hydraulic oil, an operation valve that operates the control valve by applying a pilot pressure proportional to the operation amount of the operation means to the pressure-receiving portion of the control valve, and the control valve An increase oil passage for supplying the operation oil from the sub pump to the operation oil flow passage for supplying the operation oil to the hydraulic actuator, and a pilot-type high flow valve provided in the increase oil passage;
The high flow valve is configured such that a flow rate of hydraulic oil from a sub pump supplied to the hydraulic oil flow passage is controlled by a pilot pressure acting on a pressure receiving portion of the high flow valve,
The pilot pressure is applied to the pressure receiving portion of the high flow valve when the operating means is operated, and the pilot pressure applied to the pressure receiving portion of the high flow valve is applied to the pressure receiving portion of the control valve. It is characterized by being proportional.

Moreover, you may provide the interlocking oil path which makes the pilot pressure which acts on the pressure receiving part of the said control valve act on the pressure receiving part of a high flow valve.
Further, a high flow switching valve that can be switched between an operating position where pilot pressure is applied to the pressure receiving portion of the high flow valve and a non-operating position where pilot pressure is not applied to the pressure receiving portion may be provided in the interlocking oil passage.
Further, the operation valve may be constituted by a proportional electromagnetic pilot valve.
In addition, a pair of hydraulic oil flow passages are provided, and when one of the pair of hydraulic oil flow passages is on the hydraulic oil supply side for supplying hydraulic oil to the hydraulic actuator, the other circulates return oil from the hydraulic actuator. The hydraulic oil return side may be used, and the increase oil passage may supply the hydraulic oil from the sub pump to one hydraulic oil passage.

  According to the present invention, when the hydraulic actuator is driven by increasing the flow rate of the hydraulic oil supplied from the main pump to the hydraulic actuator by the sub pump, the flow rate change of the hydraulic oil supplied to the hydraulic actuator can be made smooth. it can.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
5 and 6, a work machine 1 (track loader) according to the present invention includes a machine frame 2, a work device 3 attached to the machine frame 2, and a pair of left and right traveling devices 4 that support the machine frame 2. The cabin 5 (driver protection device) is mounted on the upper front side of the body frame 2.
The body frame 2 is made of an iron plate or the like, and includes a bottom wall 6, a pair of left and right side walls 7, a front wall 8, and a support frame 9 provided at the rear of each of the left and right side walls 7. A space between the pair of left and right support frames 9 is provided at the rear end of the machine body frame 2 so as to be openable and closable.

The cabin 5 has a front and lower end abuttingly mounted on an upper edge portion 8a of the front wall 8 of the body frame 2, and a vertical middle portion on the back is attached to the support bracket 11 of the body frame 2 in the horizontal direction. It is supported so as to be able to swing around 12 and is configured so that maintenance or the like in the body frame 2 can be performed by swinging the cabin 5 upward around the support shaft 12.
A driver's seat 13 is provided in the cabin 5, and a traveling operation device 14 for operating the traveling device 4 is disposed on one side of the driver's seat 13 (for example, the left side). A work operation device 15 for operating the work device 3 is disposed on the other side (for example, the right side).

The cabin 5 is covered with a roof on the upper surface, the left and right side surfaces are closed with side walls formed with a number of square holes, the upper back is covered with rear glass, and the center in the front-rear direction is closed with the bottom wall. The front side is formed in a box shape, and the front side is the entrance.
Each of the left and right traveling devices 4 includes a pair of front and rear driven wheels 16, a drive wheel 17 disposed between the front and rear driven wheels 16 and closer to the rear, and a plurality of wheels 18 disposed between the front and rear driven wheels 16. And a crawler type traveling device including an endless belt-like crawler belt 19 wound around the front and rear driven wheels 16, the drive wheels 17, and the rollers 18.

The front and rear driven wheels 16 and the wheels 18 are attached to a track frame 20 attached and fixed to the body frame 2 so as to be rotatable about a horizontal axis, and the drive wheels 17 are hydraulically driven travel motors attached to the track frame 20. 21L, 21R (foil motor) is attached to a rotating drum, and the crawler belt 19 is circulated in the circumferential direction by rotating the driving wheel 17 around the left and right axes by the traveling motors 21L, 21R. The machine 1 is configured to move forward and backward.
The working device 3 includes a pair of left and right booms 22 and a bucket 23 (working tool) attached to the tip of the boom 22.

The pair of left and right booms 22 are disposed on both the left and right sides of the body frame 2 and the cabin 5, and the left and right booms 22 are connected to each other by a connecting body at a midway portion on the front side.
Each of the left and right booms 22 has a first lift link 24 and a second lift link on the rear upper part of the body frame 2 so that the front end side of the boom 22 moves up and down on the front side of the body frame 2. 25 and is supported so as to be swingable up and down.
Further, a lift cylinder 26 composed of a double-acting hydraulic cylinder is provided between the base side of each of the left and right booms 22 and the rear lower part of the body frame 2, and the left and right lift cylinders 26 can be expanded and contracted simultaneously at the left and right. As a result, the left and right booms 22 swing up and down.

A mounting bracket 27 is pivotally connected to the front end side of each of the left and right booms 22 so as to be rotatable about a left and right axis, and the back side of the bucket 23 is attached to the left and right mounting brackets 27.
Further, a tilt cylinder 28 composed of a double-acting hydraulic cylinder is interposed between the mounting bracket 27 and the middle part on the front end side of the boom 22. Dump operation).
The bucket 23 is detachable with respect to the mounting bracket 27. By removing the bucket 23 and attaching various attachments (hydraulic drive work tools) to the mounting bracket 27, various operations other than excavation (or others) Excavation work).

An engine 29 is provided on the rear side on the bottom wall 6 of the body frame 2, and a fuel tank 30 and a hydraulic oil tank 31 are provided on the front side on the bottom wall 6 of the body frame 2.
A hydraulic drive device 32 that drives the left and right travel motors 21L and 21R is provided in front of the engine 29, and first to third pumps P1, P2, and P3 are provided in front of the hydraulic drive device 32, and the right side of the body frame 2 A control valve 33 (hydraulic control device) for the working device 3 is provided in the midway portion of the wall 7 in the front-rear direction.
Next, the hydraulic system of the work machine 1 will be described with reference to FIGS.

  The first to third pumps P1, P2, and P3 are constituted by constant displacement gear pumps driven by the power of the engine 29, and the first pump P1 (main pump) is a lift cylinder 26, a tilt cylinder 28, or a boom 22 Used to drive the hydraulic actuator 34 of the attachment attached to the distal end side, the second pump P2 is mainly used for supplying the control signal pressure, and the third pump P3 (sub pump) is disposed on the distal end side of the boom 22. When the hydraulic actuator 34 of the attached hydraulic drive attachment is a hydraulic actuator 34 that requires a large capacity, it is used to increase the flow rate of hydraulic fluid supplied to the hydraulic actuator 34.

First, a traveling hydraulic system will be described with reference to FIGS.
The traveling operation device 14 includes a forward pilot valve 36, a reverse pilot valve 37, a right turn pilot valve 38, a left turn pilot valve 39, and these pilot valves 36, 37, 38. , 39 has a common travel lever 40 and first to fourth shuttle valves 41, 42, 43, 44.
The pilot valves 36, 37, 38, 39 of the travel operation device 14 can be supplied with pressure oil from the second pump P2 by exciting the travel lock valve 46, which is an electromagnetic two-position switching valve. The travel lock valve 46 is demagnetized so that the pressure oil from the second pump P2 cannot be supplied and the travel operation device 14 cannot be operated.

Each of the left and right traveling motors 21L and 21R includes a hydraulic motor 47 configured by a swash plate type variable displacement axial motor that can change speed between high and low speeds, and switching the angle of the swash plate of the hydraulic motor 47 to change the hydraulic motor 47. A swash plate switching cylinder 48 for shifting the speed between high and low speeds, a brake cylinder 49 for braking an output shaft of the hydraulic motor 47 (output shafts of the travel motors 21L and 21R), a flushing valve 50, and a relief valve 51 for flushing Have
In the swash plate switching cylinder 48, when the control signal pressure from the second pump P2 is not acting, the hydraulic motor 47 is set to the first speed state, and the two-speed switching valve 45 comprising the electromagnetic two-position switching valve is excited by the operating means. As a result, the control signal pressure from the second pump P2 acts on the swash plate switching cylinder 48, and the hydraulic motor 47 is switched to the second speed state.

The brake cylinder 49 brakes the output shaft of the hydraulic motor 47 by the biasing force of the spring, and excites the brake release valve 52, which is an electromagnetic two-position switching valve, to control the brake cylinder 49 from the second pump P2. The signal pressure acts to release the braking of the output shaft of the hydraulic motor 47.
For example, a demagnetization signal is simultaneously sent to the travel lock valve 46 and the brake release valve 52 by a lock lever operated when getting off the cabin 5, and an excitation signal is simultaneously sent by a release switch.

The flushing valve 50 and the relief valve for flushing will be described later.
The hydraulic drive device 32 includes a drive circuit 32A (left drive circuit) for the left travel motor 21L and a drive circuit 32B (right drive circuit) for the right travel motor 21R, and each of the drive circuits 32A and 32B includes When the pressures of the hydraulic pumps 53 connected to the hydraulic motors 47 of the corresponding traveling motors 21L and 21R by the pair of speed change oil paths a and b and the high pressure side speed change oil paths a and b become equal to or higher than a set value, the low pressure side High pressure relief valve 54 that escapes to the transmission oil passages a and b, and charge oil passage c for replenishing the low pressure transmission oil passages a and b via the check valve 55 with the pressure oil from the second pump P2. And.

The charge oil passage c can be supplied with pressure oil from the second pump P2 via the charge pressure supply passage d, and the left drive circuit 32A has a circuit of the charge oil passage c of each of the drive circuits 32A and 32B. A charge relief valve 56 for setting the pressure is provided.
The hydraulic pump 53 of each drive circuit 32A, 32B is a swash plate type variable displacement axial pump driven by the power of the engine 29 and a pilot type hydraulic pump in which the angle of the swash plate is changed by the pilot pressure. A forward pressure receiving portion 53a and a reverse pressure receiving portion 53b to which pressure acts are provided, and the swash plate angle is changed by the pilot pressure acting on these pressure receiving portions 53a and 53b, and the discharge direction and discharge amount of hydraulic oil are changed. Thus, the rotational output of the travel motors 21L and 21R can be steplessly shifted in the direction in which the work machine 1 is moved forward (forward rotation direction) or in the direction in which the work machine 1 is moved backward (reverse rotation direction). Yes.

The flushing valves 50 of the travel motors 21L and 21R are switched so as to connect the low-pressure side shifting oil passages a and b to the flushing relief valve 51 by the pressure of the high-pressure side shifting oil passages a and b. Part of the hydraulic fluid in the low-pressure side shifting oil passages a and b is relieved through the flushing relief valve 51 in order to replenish the operating oil in the transmission oil passages a and b.
The hydraulic motor 47 and the flushing valve 50 of the travel motors 21L and 21R, the drive circuits 32A and 32B, and the pair of speed change oil passages a and b constitute a hydrostatic transmission (HST).

The travel lever 40 of the travel operation device 14 can be tilted from the neutral position in an oblique direction between front and rear, left and right and front and rear left and right, and by tilting the travel lever 40, Each pilot valve 36, 37, 38, 39 is operated, and a pilot pressure proportional to the operation amount from the neutral position of the traveling lever 40 is output from the operated pilot valve 36, 37, 38, 39. It is configured.
When the traveling lever 40 is tilted forward (in the direction of arrow A1 in FIG. 4), the forward pilot valve 36 is operated to output a pilot pressure from the pilot valve 36, and the pilot pressure is passed through the first shuttle valve 41. Acting on the forward pressure receiving portion 53a of the hydraulic pump 53 of the left drive circuit 32A and acting on the forward pressure receiving portion 53a of the right drive circuit 32B via the second shuttle valve 42, whereby the left and right traveling motors 21L, The output shaft of 21R rotates forward (forward rotation) at a speed proportional to the tilting amount of the travel lever 40, and the work implement 1 moves straight forward.

  When the traveling lever 40 is tilted rearward (in the direction of arrow A2 in FIG. 4), the reverse pilot valve 37 is operated and pilot pressure is output from the pilot valve 37. The pilot pressure is the third shuttle valve. 43 acts on the reverse pressure receiving portion 53b of the hydraulic pump 53 of the left drive circuit 32A via the 43 and acts on the reverse pressure reception portion 53b of the hydraulic pump 53 of the right drive circuit 32B via the fourth shuttle valve 44. As a result, the output shafts of the left and right traveling motors 21L and 21R are reversely rotated (reversely rotated) at a speed proportional to the tilting amount of the traveling lever 40, and the work machine 1 moves straight backward.

Further, when the traveling lever 40 is tilted to the right (in the direction of arrow A3 in FIG. 4), the right turn pilot valve 38 is operated and pilot pressure is output from the pilot valve 38, and the pilot pressure is the first shuttle. Acting on the forward pressure receiving portion 53a of the hydraulic pump 53 of the left drive circuit 32A via the valve 41 and acting on the backward pressure receiving portion 53b of the hydraulic pump 53 of the right drive circuit 32B via the fourth shuttle valve 44, As a result, the output shaft of the left traveling motor 21L rotates in the forward direction and the output shaft of the right traveling motor 21R rotates in the reverse direction, so that the work machine 1 turns to the right.
When the traveling lever 40 is tilted to the left (in the direction of arrow A4 in FIG. 4), the left turn pilot valve 39 is operated to output pilot pressure from the pilot valve 39, and the pilot pressure is the second shuttle valve. 42 acts on the forward pressure receiving portion 53a of the hydraulic pump 53 of the right drive circuit 32B, and acts on the backward pressure receiving portion 53b of the hydraulic pump 53 of the left drive circuit 32A via the third shuttle valve 43. As a result, the output shaft of the right traveling motor 21R rotates in the forward direction and the output shaft of the left traveling motor 21L rotates in the reverse direction, so that the work machine 1 turns to the left.

  Further, when the traveling lever 40 is tilted in the oblique direction, the output shafts of the traveling motors 21L and 21R are generated by the differential pressure between the pilot pressures acting on the forward pressure receiving portion 53a and the reverse pressure receiving portion 53b of the drive circuits 32A and 32B. The rotation direction and the rotation speed of the travel lever 1 are determined, and the work implement 1 turns right or left while moving forward or backward (that is, when the travel lever 40 is tilted to the left front side, it corresponds to the tilt angle of the travel lever 40). When the work machine 1 turns left while moving forward at a speed, and the travel lever 40 is tilted to the right front side, the work machine 1 turns right while moving forward at a speed corresponding to the tilt angle of the travel lever 40, and the travel lever 40 is moved. When the tilting operation is performed to the left rear side, the work machine 1 turns left while moving backward at a speed corresponding to the tilt angle of the travel lever 40, and the travel lever 40 is tilted to the right rear side. Right turning while the working machine 1 at a speed corresponding to the tilt angle of the travel lever 40 is reverse).

Next, a working hydraulic system will be described with reference to FIGS.
The work operating device 15 includes a boom raising pilot valve 57, a boom lowering pilot valve 58, a bucket dumping pilot valve 59, a bucket squeeze pilot valve 60, and these pilot valves 57, 58, 59, 60. And a common operation lever 61.
Pressure oil from the second pump P2 can be supplied to each pilot valve 57, 58, 59, 60 of the work operation device 15 by exciting a work lock valve 62 formed of an electromagnetic two-position switching valve. The work lock valve 62 is demagnetized so that the pressure oil from the second pump P2 cannot be supplied, and the work operation device 15 cannot be operated.

For example, in the same manner as the travel lock valve 46 and the brake release valve 52, the work lock valve 62 is supplied with a demagnetization signal by a lock lever operated when getting off the vehicle and an excitation signal by a release switch.
The control valve 33 for the working device 3 includes a boom control valve 63 that controls the lift cylinder 26, a bucket control valve 64 that controls the tilt cylinder 28, and an attachment hydraulic actuator 34 that is attached to the tip of the boom 22. The control valve 63, 64, 65 is composed of a pilot-type direct acting spool type three-position switching valve.

The boom control valve 63, the bucket control valve 64, and the SP control valve 65 are connected to the working system supply oil passage f connected to the discharge passage e of the first pump P1 from the upstream side. The control valve 64 and the SP control valve 65 are provided in this order. The hydraulic oil from the first pump P1 is tilted to the lift cylinder 26 via the boom control valve 63 or tilted via the bucket control valve 64. It can be supplied to the cylinder 28 or the hydraulic actuator 34 of the attachment via the SP control valve 65.
The working system supply oil passage f is connected to the drain oil passage g after passing through the SP control valve 65.

One end side of the bypass oil passage h is connected to the work system supply oil passage f upstream of the boom control valve 63, and the other end side of the bypass oil passage h is for the SP of the work system supply oil passage f. A relief valve 66 that is connected downstream of the control valve 65 and sets the circuit pressure of the working system supply oil passage f is provided in the bypass oil passage h.
The operation lever 61 of the work operation device 15 can be tilted from the neutral position in an oblique direction between front and rear, left and right, front and rear, left and right. By operating the operation lever 61 to tilt, the operation lever 61 of the work operation device 15 can be tilted. Each pilot valve 57, 58, 59, 60 is operated, and a pilot pressure proportional to the operation amount from the neutral position of the operation lever 61 is output from the operated pilot valve 57, 58, 59, 60. It is configured.

Further, when the operation lever 61 is tilted rearward (in the direction of the arrow B1 in FIG. 2), the boom raising pilot valve 57 is operated to output pilot pressure from the pilot valve 57, and the pilot pressure is applied to the boom. When the control valve 63 is operated by operating on one pressure receiving portion of the control valve 63, the lift cylinder 26 is extended, and the boom 22 is raised at a speed proportional to the tilting amount of the operation lever 61.
When the operation lever 61 is tilted forward (in the direction of arrow B2 in FIG. 2), the boom lowering pilot valve 58 is operated to output pilot pressure from the pilot valve 58, and the pilot pressure is controlled by the boom control valve 63. When the control valve 63 is operated by acting on the other pressure receiving portion, the lift cylinder 26 is reduced, and the boom 22 is lowered at a speed proportional to the tilting amount of the operation lever 61.

When the operation lever 61 is tilted to the right (in the direction of arrow B3 in FIG. 2), the bucket dump pilot valve 59 is operated to output pilot pressure from the pilot valve 59, and the pilot pressure is used for the bucket. When the control valve 64 is operated by operating on one pressure receiving portion of the control valve 64, the tilt cylinder 28 extends, and the bucket 23 performs a dumping operation at a speed proportional to the tilting amount of the operation lever 61.
Further, when the operation lever 61 is tilted to the left (in the direction of arrow B4 in FIG. 2), the bucket squeeze pilot valve 60 is operated to output pilot pressure from the pilot valve 60, and the pilot pressure is controlled by the bucket control. When the control valve 64 is operated by acting on the other pressure receiving portion of the valve 64, the tilt cylinder 28 is contracted, and the bucket 23 is squeezed at a speed proportional to the tilting amount of the operation lever 61.

Further, when the operation lever 61 is tilted in an oblique direction, a combined operation of the raising or lowering operation of the boom 22 and the squeeze or dumping operation of the bucket 23 can be performed.
In the hydraulic system according to the present embodiment, a lock cylinder 67 that locks or unlocks a lock member for locking the bucket 23 to the mounting bracket 27, and an electromagnetic two-position switching that operates the lock cylinder 67. A lock valve 68 and a lock release valve 69 are provided.
When the lock valve 68 is excited, the lock cylinder 67 is extended and the lock member is locked, and when the lock release valve 69 is excited, the lock cylinder 67 is contracted and the lock member is unlocked.

One end side of the first and second hydraulic fluid passages i, j is connected to the SP control valve 65, and a joint with a check valve for connecting a hydraulic hose is connected to the other end side of each hydraulic flow passage i, j. The joint devices 71 and 72 having a pair of 71a and 72a are connected, and the hydraulic actuator 34 of the attachment is connected to one or the other joint 71a or 72a of each joint device 71 or 72 via the hydraulic hoses 73 and 74. Thereby, the attachment can be operated by the SP control valve 65 (the hydraulic actuator 34 of the attachment can be controlled).
One joint 71a, 72a of each joint device 71, 72 is for connecting a large-diameter hydraulic hose, and the other joint 71a, 72a is for connecting a small-diameter hydraulic hose. When attaching an attachment (for example, a hydraulically driven mower, a hydraulic breaker, a forest mower, etc.) having a hydraulic actuator 34 that requires a large amount of hydraulic fluid, connect the hydraulic hoses 73 and 74 to a large hydraulic hose connection. 71a and 72a are connected.

The SP control valve 65 is connected to the bypass oil passage h through a drain oil passage k, the first hydraulic fluid flow passage i is connected to the bypass oil passage h through a first escape passage m, The second hydraulic oil flow passage j is connected to the bypass oil passage h through a second relief passage n, and relief valves 76 and 77 are provided in the first and second relief passages m and n, respectively.
The SP control valve 65 is configured to be switchable between a neutral position 65a, a first position 65b, and a second position 65c by pilot pressure, and is returned to the neutral position 65a by a spring.

  When the SP control valve 65 is switched to the first position 65b, hydraulic fluid from the first pump P1 is supplied from the first hydraulic fluid passage i to the hydraulic actuator 34 of the attachment and from the hydraulic actuator 34 of the attachment. When the return oil is flowed from the second hydraulic oil flow passage j to the oil discharge passage k and switched to the second position 65c, the operation from the first pump P1 is performed from the second hydraulic oil flow passage j to the hydraulic actuator 34 of the attachment. Oil is supplied and returned oil from the hydraulic actuator 34 of the attachment is caused to flow from the first hydraulic oil flow passage i to the oil discharge passage k.

Therefore, when one of the pair of hydraulic fluid passages i and j is the hydraulic fluid supply side that supplies hydraulic fluid to the hydraulic actuator 34, the other is the hydraulic fluid return side that circulates the return oil from the hydraulic actuator 34. It will be.
The SP control valve 65 is a valve that can take an arbitrary opening degree (the flow rate can be continuously controlled) according to the magnitude of the pilot pressure acting on the pressure receiving portions 78a and 78b. The flow rate of the hydraulic fluid supplied to the hydraulic actuator 34 from the first hydraulic fluid flow passage i or the second hydraulic fluid flow passage j is controlled by the pilot pressure acting on the pressure receiving portion 78a on the side or the pressure receiving portion 78b on the other side. .

The SP control valve 65 can be operated by a pair of spare operation valves 79 and 80 (which are referred to as SP operation valves) constituted by a proportional electromagnetic pilot valve, and these SP operation valves 79 and 80 are used for the work. The slider 15 can be operated by a slide button 81 (operating means) that is provided on the top side of the operating lever 61 of the operating device 15 and is slidable in the left-right direction. Slide operation is possible.
The SP control valve 65 may be operated by a manual pilot valve that is directly operated manually.

One SP operation valve 79 is connected to a pressure receiving portion 78a on one side of the SP control valve 65 via a first pilot oil passage q, and the other SP operation valve 80 is used for SP via a second pilot oil passage s. It is connected to the pressure receiving part 78b on the other side of the control valve 65.
The pair of SP operation valves 79 and 80 can be supplied with pressure oil from the second pump P2 through a pilot pressure supply oil passage t.
When the slide button 81 is slid left or right, an operation signal corresponding to the operation amount is input to the ECU 82 (control computer, control unit), and a command signal corresponding to the operation amount of the slide button 81 is sent from the ECU 82 to one SP. The solenoid valve 79a is output to the operation valve 79 and the solenoid 79a of the SP operation valve 79 is excited. As a result, a pilot pressure proportional to the operation amount of the slide button 81 is output from one SP operation valve 79. The SP control valve 65 is operated to the first position 65 b in proportion to the operation amount of the slide button 81 by acting on the pressure receiving portion 78 a on one side of the SP control valve 65 via the oil path q.

  When the slide button 81 is slid left and right, an operation signal corresponding to the operation amount is input to the ECU 82 (control computer), and a command signal is output from the ECU 82 to the other SP operation valve 80 so that the SP operation valve. The solenoid 80a of 80 is excited, whereby a pilot pressure proportional to the operation amount of the slide button 81 is output from the other SP operation valve 80, and the pilot pressure is supplied to the SP control valve 65 via the second pilot oil passage s. The SP control valve 65 is operated to the second position 65c in proportion to the operation amount of the slide button 81 by acting on the pressure receiving portion 78b on the other side.

As described above, the hydraulic oil supplied from the first pump P1 to the hydraulic actuator 34 is configured to be controlled in flow rate by the SP control valve 65 in proportion to the operation amount of the slide button 81.
One end side of the increase oil passage u is connected to the third pump P3, the other end side of the increase oil passage u is connected to the first hydraulic oil flow passage i, and a high flow is supplied to the increase oil passage u. A valve 83 is provided.
The high flow valve 83 is composed of a pilot-type two-position switching valve, and flows the discharge oil from the third pump P3 to the drain oil passage g (does not flow to the first hydraulic oil flow passage i); The discharge oil from the third pump P3 can be switched to an increase position 83b for flowing the first hydraulic oil flow passage i, and when the pilot pressure is not applied to the pressure receiving portion 83c, the spring is switched to the non-increase position 83a. The pilot pressure acting on the pressure receiving portion 83c is switched to the increasing position 83b.

The high flow valve 83 is a valve that can take an arbitrary opening degree (the flow rate can be controlled continuously) depending on the magnitude of the pilot pressure acting on the pressure receiving portion 83c, and the pressure receiving portion 83c. Is operated in proportion to the magnitude of the pilot pressure acting on the oil pressure, so that the flow rate of the hydraulic oil flowing from the third pump P3 to the first hydraulic oil flow passage i can be controlled.
One end side of the interlocking oil passage w is connected to the pressure receiving portion 83c of the high flow valve 83, and the other end side of the interlocking oil passage w is connected to the first pilot oil passage q. There is provided a high flow switching valve 84 comprising an electromagnetic two-position switching valve which can be switched between an operating position 84a where the pilot pressure is applied to the pressure receiving portion 83c of the valve 83 and a non-operating position 84b where the pilot pressure is not applied to the pressure receiving portion. It has been.

In the state where the solenoid 84c is demagnetized, the high flow switching valve 84 is switched to the non-operating position 84b by a spring, and the solenoid 84c is excited by a command signal transmitted by the pushing operation of the increase switch 85 (operation means). Switch to position 84a.
Therefore, when attaching an attachment having the hydraulic actuator 34 that requires an increase in hydraulic oil, the high flow switching valve 84 is switched to the operating position 84a, and an attachment having the hydraulic actuator 34 that does not require an increase in hydraulic oil is attached. In this case, the high flow switching valve 84 is set to the non-operation position 84b.

In the case of the above configuration, when attaching an attachment having a hydraulic actuator 34 that requires a large flow rate of hydraulic oil such as a hydraulically driven mower or a hydraulic breaker, the high flow switching valve 84 is operated by pressing the increase switch 85. Switch to the action position 84a.
In this state, when the slide button 81 is slid left or right, one SP operation valve 79 is operated, and a pilot pressure proportional to the operation amount of the slide button 81 is output from the one SP operation valve 79, and the pilot The pressure acts on the pressure receiving portion 78a on one side of the SP control valve 65 via the first pilot oil passage q, and the SP control valve 65 moves to the first position 65b in proportion to the operation amount of the slide button 81. When operated, the flow rate of hydraulic fluid controlled by the SP control valve 65 flows into the first hydraulic fluid flow passage i.

At this time, the pilot pressure output from one SP operation valve 79 also acts on the pressure receiving portion 83c of the high flow valve 83 via the interlocking oil passage w, and the high flow valve 83 is proportional to the operation amount of the slide button 81. The hydraulic oil having a flow rate controlled by the high flow valve 83 is operated to the increase position 83b (the amount of hydraulic oil proportional to the operation amount of the slide button 81) is first operated from the sub pump P3 via the increase oil passage u. It flows to the oil flow passage i.
As a result, the hydraulic fluid at the flow rate controlled by the high flow valve 83 is increased to the hydraulic fluid at the flow rate controlled by the SP control valve 65, and the hydraulically driven mower or hydraulic breaker is passed through the first hydraulic fluid flow passage i. Is supplied to the hydraulic actuator 34 of the attachment, and the hydraulic actuator 34 is rotated forward so that the attachment performs a work operation.

When the slide switch 81 is operated such that the increase switch 85 is pushed and the pilot pressure is applied to the pressure receiving portion 78a on one side of the SP control valve 65, an excitation signal is transmitted and the high flow switching valve is operated. 84 may be switched to the operation position 84a.
In the hydraulic system having the above-described configuration, one SP operation valve 79 is controlled by a command signal from the ECU 82, and the high flow valve 83 and the SP control are controlled by a pilot pressure controlled by the one SP operation valve 79. The valve 65 is controlled (the high flow valve 83 and the SP control valve 65 are controlled via one SP operation valve 79 by a command signal from the ECU 82), but is not limited to this. For example, both the SP control valve 65 and the high flow valve 83 are constituted by electromagnetic proportional valves, and the SP control valve 65 and the high flow valve 83 are directly controlled by the high flow valve 83 by a command signal from the ECU 82. Alternatively, the flow rate of the hydraulic oil may be controlled to be proportional to the flow rate of the hydraulic oil controlled by the control valve 65.

When the slide button 81 is slid left or right and the SP control valve 65 is operated by the other SP operation valve 80, pilot pressure does not act on the pressure receiving portion of the high flow valve 83. Although the amount of hydraulic oil supplied is not increased, there is no problem because work tools such as a hydraulically driven mower and a hydraulic breaker perform normal work operations by rotating in one direction.
The high flow switching valve 84 is an ON-OFF valve that selects whether or not the pilot pressure is applied to the pressure receiving portion 83c of the high flow valve 83. Therefore, the increase switch 85 is pressed and the slide button 81 is operated to the left or right. When the high flow switching valve 84 is switched to the operating position 84a in conjunction with the pressure oil from the second pump P2 to act on the pressure receiving portion 83c of the high flow valve 83, the discharged oil from the third pump P3 Will flow through the first hydraulic fluid passage i, but in this case, even when the SP control valve 65 is not operated much (when the SP control valve 65 is not opened much). Since a large amount of hydraulic fluid suddenly flows into the first hydraulic fluid flow passage i, there is a shock when the SP control valve 65 is operated, and the SP control valve 65 is operated too little. When it is not, since the flow rate of the return oil flowing from the second hydraulic oil flow passage j on the return side to the bypass oil passage h through the drain oil passage k is small, the flow amount is increased to the first hydraulic oil flow passage i. The hydraulic fluid flows from the first escape passage m to the bypass oil passage h through the relief valve 76, and the relief valve 76 remains open.

  On the other hand, in the above-described embodiment, the pilot pressure acting on the pressure receiving portion 83c of the high flow valve 83 is configured to be proportional to the pilot pressure acting on the pressure receiving portion 78a on one side of the SP control valve 65. Therefore, when the SP control valve 65 is not operated to the first position 65b, there is no shock because the flow rate of the hydraulic oil from the third pump P3 increased through the high flow valve 83 is small ( The hydraulic fluid supplied to the hydraulic actuator 34 when the hydraulic actuator 34 is driven by increasing the flow rate of the hydraulic fluid supplied from the first pump P1 to the hydraulic actuator 34 by the third pump. Therefore, the relief valve 76 is not left open.

FIG. 7 shows another embodiment of the hydraulic system, in which the high flow switching valve 84 is constituted by a proportional electromagnetic pilot valve, and the pilot pressure from the second pump P2 controlled by the high flow switching valve 84 is supplied to the high flow valve 83. By acting on the pressure receiving part 83c, the high flow valve 83 is operated to control the flow rate of the hydraulic oil supplied to the first hydraulic oil supply path i via the increased oil path u.
In this embodiment, when the increase switch 85 is pushed and the slide button 81 is operated in the direction of operating one SP operation valve 79, a command signal is transmitted from the ECU, and the slide button 81 is operated. The pilot pressure proportional to the operation amount is applied to the pressure receiving portion 83 c of the high flow valve 83.

Therefore, even in the hydraulic system of this embodiment, when the pilot pressure is applied to the pressure receiving portion 78a on one side of the SP control valve 65 by operating the slide button 81, it acts on the pressure receiving portion 83c of the high flow valve 83. The pilot pressure is proportional to the pilot pressure acting on the pressure receiving portion 78a of the SP control valve 65, and the same effect as the hydraulic system of the above-described embodiment can be obtained.
About another structure, it is comprised similarly to the said embodiment.

It is a circuit diagram of the principal part of the hydraulic system concerning the present invention. It is a circuit diagram of the hydraulic system of a working system. It is a whole circuit diagram of the hydraulic system of a working machine. FIG. 3 is a circuit diagram of a traveling hydraulic system. It is the whole working machine side view. It is side surface sectional drawing of the working machine of the state which raised the cabin. It is a circuit diagram of the hydraulic system which concerns on other embodiment.

Explanation of symbols

34 Hydraulic actuator 65 Control valve (Control valve for SP)
78a Pressure receiving part of control valve for SP 79 Operation valve (SP operation valve)
81 Operation means (slide button)
83 High flow valve 83c High pressure valve pressure receiving portion 84 High flow switching valve 84a Operating position 84b Non-operating position P1 Main pump (first pump)
P3 Sub pump (third pump)
i Hydraulic fluid passage (first hydraulic fluid passage)
j Hydraulic fluid passage (second hydraulic fluid passage)
u Increasing oil passage w Interlocking oil passage

Claims (7)

From the main pump (P1) for supplying the hydraulic oil to the hydraulic actuator (34), the sub pump (P3) for increasing the flow rate of the hydraulic oil supplied to the hydraulic actuator (34), and the main pump (P1) A control valve (65) for controlling the flow rate of hydraulic oil supplied to the hydraulic actuator (34), and a hydraulic oil flow passage (i) for supplying hydraulic oil from the control valve (65) to the hydraulic actuator (34). An increase oil passage (u) for supplying hydraulic oil from the sub pump (P3), and a sub pump (P3) provided in the increase oil passage (u) and supplied to the hydraulic oil flow passage (i). A high flow valve (83) for controlling the flow rate of the hydraulic oil of
The hydraulic system for a working machine, wherein the flow rate of hydraulic fluid controlled by the high flow valve (83) is proportional to the flow rate of hydraulic fluid controlled by the control valve (65).   The high flow valve (83) and the control valve (65) are set so that the flow rate of the hydraulic oil controlled by the high flow valve (83) is proportional to the flow rate of the hydraulic oil controlled by the control valve (65). 2. The oil path system for a working machine according to claim 1, wherein the oil path system is controlled by a command signal from the control unit (82). From the main pump (P1) for supplying the hydraulic oil to the hydraulic actuator (34), the sub pump (P3) for increasing the flow rate of the hydraulic oil supplied to the hydraulic actuator (34), and the main pump (P1) A pilot-type control valve (65) for controlling the flow rate of hydraulic fluid supplied to the hydraulic actuator (34), and a pilot pressure proportional to the operation amount of the operation means (81) is received by the pressure-receiving portion ( 78a), the operation valve (79) for operating the control valve (65) and the hydraulic oil passage (i) for supplying the hydraulic oil from the control valve (65) to the hydraulic actuator (34). An increase oil passage (u) for supplying hydraulic oil from the sub-pump (P3), and a pilot-type high flow valve (83) provided in the increase oil passage (u),
The high flow valve (83) has a flow rate of hydraulic oil from the sub pump (P3) supplied to the hydraulic oil flow passage (i) by a pilot pressure acting on the pressure receiving portion (83c) of the high flow valve (83). Configured to be controlled,
When the operating means (81) is operated, the pilot pressure is applied to the pressure receiving portion (83c) of the high flow valve (83), and the pressure receiving portion (83c) of the high flow valve (83) is applied. A hydraulic system for a working machine, wherein the pilot pressure is proportional to a pilot pressure acting on a pressure receiving portion (78a) of the control valve (65).   The interlocking oil passage (w) is provided to allow the pilot pressure acting on the pressure receiving portion (78a) of the control valve (65) to act on the pressure receiving portion (83c) of the high flow valve (83). Hydraulic system for the working machine described.   An operating position (84a) where a pilot pressure is applied to the pressure receiving portion (83c) of the high flow valve (83) and a non-operating position (84b) where no pilot pressure is applied to the pressure receiving portion (83c) in the interlocking oil passage (w). The hydraulic system for a working machine according to claim 4, further comprising a high flow switching valve (84) that can be switched between.   The hydraulic system for a working machine according to any one of claims 3 to 5, wherein the operation valve (79) is a proportional electromagnetic pilot valve.   A pair of hydraulic fluid passages (i, j) are provided, and the pair of hydraulic fluid passages (i, j) is provided when one of the hydraulic fluid passages (i, j) is on the hydraulic fluid supply side for supplying hydraulic fluid to the hydraulic actuator (34). Is the hydraulic oil return side for circulating the return oil from the hydraulic actuator (34), and the increasing oil passage (u) transfers the hydraulic oil from the sub pump (P3) to one hydraulic oil flow passage (i). The hydraulic system for a working machine according to any one of claims 1 to 6, wherein the hydraulic system is a supply device.

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