JP2017002947A - Air bleeding device of construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air bleeding device of a construction machine, which can easily discharge air remaining in a pilot pressure oil supply pipe line.SOLUTION: An air bleeding device of a hydraulic excavator 1 of the present invention comprises an on-off valve 25 which is formed branching from a pilot pressure oil supply pipe line 16, opens when pressure in the pilot pressure oil supply pipe line 16 is below a predetermined pressure P1, and closes when the pressure in the pilot pressure oil supply pipe line 16 is the predetermined pressure P1 or more, a drain pipe line 18 leading the hydraulic oil passed through the on-off valve 25 to a hydraulic oil tank 17, and a pressure regulation part 19 regulating the pressure in the pilot pressure oil supply pipe line 16. The pressure regulation part 19 sets the pressure in the pilot pressure oil supply pipe line 16 to be larger than pressure in the hydraulic oil tank 17 and less than the predetermined pressure P1 to discharge air in the pilot pressure oil supply pipe line 16.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an air bleeder for a construction machine that discharges air remaining in a pilot pressure oil supply pipe that is a flow path of pilot pressure oil discharged from a pilot pump.

  In general, a construction machine such as a hydraulic excavator includes an engine, a hydraulic pump driven by the engine, a control valve for controlling a flow of pressure oil discharged from the hydraulic pump, and a pilot pressure at a working portion of the control valve. A pilot pump that supplies oil and switches the position of the control valve, a pilot pressure oil supply line that guides the pilot pressure oil discharged from the pilot pump to the control valve, a hydraulic pump and a pilot pump, and hydraulic fluid And a hydraulic oil tank for storage.

  In the construction machine configured as described above, when air remains in the pilot pressure oil supply line, the pilot pressure oil is discharged into the pilot pressure oil supply line by the pilot pump to operate the control valve. Then, the pressure in the pilot pressure oil supply pipeline is compressed, so that a pressure increase delay occurs in the pilot pressure oil common pipeline. Therefore, there has been a problem that the operability of the construction machine is deteriorated due to the operation of the control valve being delayed as compared with the case where no air remains in the pilot pressure oil supply pipeline. Therefore, conventionally, an air bleeding device that discharges air in the pilot pressure oil supply pipeline has been applied to construction machines.

  As one of the prior arts of this type of air bleeder, it is provided with an orifice provided at a position branched from a pilot pressure oil supply pipe, and a drain pipe by an external pipe connected to the orifice. The air in the pilot pressure oil supply line is discharged to the drain line together with a part of the pilot pressure oil by the air being pushed out from the orifice by the pilot pressure oil supplied under pressure to the oil supply line. An apparatus is known (see, for example, Patent Document 1).

  In this prior art air venting device, a portion of the pilot pressure oil is always discharged to the drain line while the pilot pressure oil is being supplied to the pilot pressure oil supply line. This reduces the energy efficiency of devices such as control valves that are operated by. Therefore, a tank capable of storing hydraulic oil, a hydraulic pump disposed above the tank, a suction pipe for sucking the hydraulic oil by connecting the suction port of the hydraulic pump and the inside of the tank, There has been proposed an air bleeding device for a hydraulic circuit including a discharge pipe connected to a discharge port of a hydraulic pump (see, for example, Patent Document 2).

  FIG. 6 is a diagram showing a configuration of the air venting device of the hydraulic circuit, and FIG. 7 is a diagram showing a configuration of a main part of the air venting device of the hydraulic circuit.

  As shown in FIGS. 6 and 7, the conventional air venting device 100 of the hydraulic circuit disclosed in Patent Document 2 is an air that protrudes upward and opens in the vicinity of the discharge port of the hydraulic pump P in the discharge pipe DP. It is attached to the punching device attachment port DPa. The air vent device 100 includes a main body 110 formed in a cylindrical shape, an air vent hole 110a formed in the upper end of the main body 110, and a ball (open / close valve) 120 disposed in the ball holding space 110c of the main body 110. The spring pin 130 is inserted into the ball holding hole 110b of the main body 110. The spring pin 130 is formed with a slit 130a extending vertically. An air vent pipe RP that guides air remaining in the suction pipe SP and the hydraulic pump P from the air vent hole 110a to the hydraulic oil tank T is connected between the upper end of the air vent device 100 and the tank T.

  In the air bleeder 100 configured as described above, the ball 120 is placed on the spring pin 130 by its own weight before the drive of the hydraulic pump P is started, so that the main body passes through the slit 130a of the spring pin 130. The opening at the lower end surface of 110 and the opening at the upper end surface communicate with each other, and the on-off valve is open. Therefore, the air in the suction pipe SP and the hydraulic pump P passes through the space S1 above the hydraulic oil accumulated in the discharge pipe DP and is discharged from the air bleeding device 100 through the air bleeding pipe RP.

  On the other hand, after the drive of the hydraulic pump P is started, the air in the hydraulic pump P enters the discharge pipe DP and is discharged from the open / close valve to the tank T through the air vent pipe RP in the same manner as described above. . As the hydraulic pump P continues to be driven, the ball holding hole 110b of the air bleeder 100 is filled with hydraulic oil, and the ball 120 raised by the hydraulic oil closes the air vent hole 110a at the upper end of the main body 110. Therefore, it is possible to avoid the hydraulic oil discharged from the hydraulic pump P from flowing out from the air vent device 100. Therefore, if the conventional air bleeding device 100 is applied to a construction machine, it is considered that the pilot pressure oil flowing through the pilot pressure oil supply conduit can be prevented from being discharged together with the air.

JP-A-8-159334 Japanese Patent Laid-Open No. 10-318203

  However, when the hydraulic circuit air venting device 100 disclosed in Patent Document 2 is applied to a construction machine, and the air venting device 100 is attached to a pilot pressure oil supply pipe instead of the discharge pipe DP, If the driving of the pilot pump is not started, the pressures of the pilot pressure oil supply line and the hydraulic oil tank are in an equilibrium state. For this reason, even if the on-off valve is in an open state, air remaining in the pilot pressure oil supply line is unlikely to be discharged from the air vent device 100 to the hydraulic oil tank. There is a concern that a sufficient air venting effect by the venting device 100 cannot be obtained.

  The present invention has been made in view of such a state of the art, and an object of the present invention is to provide an air bleeding device for a construction machine that can easily discharge air remaining in a pilot pressure oil supply pipe. is there.

  In order to achieve the above object, an air bleeding device for a construction machine according to the present invention includes an engine, a hydraulic pump driven by the engine, and a control valve for controlling a flow of pressure oil discharged from the hydraulic pump. A pilot pump for supplying pilot pressure oil to the operating portion of the control valve and switching the position of the control valve; and a pilot pressure oil supply pipe for guiding the pilot pressure oil discharged from the pilot pump to the operating portion of the control valve Air for a construction machine that is provided in a construction machine including a passage, a hydraulic oil tank that is connected to the hydraulic pump and the pilot pump and stores hydraulic oil, and that discharges air remaining in the pilot pressure oil supply pipe The venting device is formed by branching from the pilot pressure oil supply pipe, and is opened when the pressure in the pilot pressure oil supply pipe is less than a predetermined pressure. An open / close valve that closes when the pressure in the pilot pressure oil supply line is equal to or higher than a predetermined pressure, a drain line that guides the hydraulic oil that has passed through the open / close valve to the hydraulic oil tank, and the pilot pressure oil supply A pressure adjusting unit that adjusts the pressure in the pipe, and the pressure adjusting unit makes the pressure in the pilot pressure oil supply pipe larger than the pressure in the hydraulic oil tank and less than the predetermined pressure. It is set, and the air in the pilot pressure oil supply line is discharged.

  In the present invention configured as described above, an open / close valve and a drain pipe for connecting air remaining in the pilot pressure oil supply pipe to the hydraulic oil tank are connected between the pilot pressure oil supply pipe and the hydraulic oil tank. ing. Therefore, if the pressure in the pilot pressure oil supply line is set below a predetermined pressure by the pressure adjusting unit after the pilot pump is started, the on-off valve at a position branched from the pilot pressure oil supply line Becomes an open state, and the pressure of the pilot pressure oil supply line and the hydraulic oil tank is in an equilibrium state. At this time, the pressure adjusting unit adjusts the pressure in the pilot pressure oil supply line by setting the pressure in the pilot oil supply line to be larger than the pressure in the hydraulic oil tank and less than a predetermined pressure, thereby adjusting the air in the pilot pressure oil supply line. Is pushed out to the drain line through the open / close valve by the pilot pressure oil discharged from the pilot pump, so that the air remaining in the pilot pressure oil supply line can be easily discharged.

  Moreover, the air venting device for a construction machine according to the present invention is characterized in that, in the above-described invention, the predetermined pressure is set to a value smaller than a lower limit pressure of a normal control pressure range of the control valve. With this configuration, the pressure in the pilot pressure oil supply pipe is larger than the lower limit pressure in the normal control pressure region of the control valve in order to operate the control valve while the construction machine is working. The on-off valve can be kept closed, and the pilot pressure oil guided to the control valve during work can be prevented from flowing out to the drain line through the on-off valve.

  In the air venting device for a construction machine according to the present invention, in the invention, the on-off valve is configured such that the pressure in the pilot pressure oil supply line is larger than the pressure in the hydraulic oil tank by the pressure adjusting unit. When the pressure is set below the predetermined pressure, the pilot pressure oil moves downward due to its own weight, and when the pressure in the pilot pressure oil supply line is set to be equal to or higher than the predetermined pressure by the pressure adjusting unit, the pilot pressure oil It comprises a ball member that moves upward due to the pressure in the supply pipe, and a cylindrical accommodation chamber that accommodates the ball member and guides the ball member along the vertical direction. Provided at the upper end connected to the road, provided at the drain line side opening formed so that the ball member moved upward is seated, and at the lower end connected to the pilot pressure oil supply line side It is characterized by having said ball member is pilot pressure hydraulic fluid supply pipe roadside opening formed eccentrically from the cylindrical axis so as not seated radially moved downward.

  In the present invention configured as described above, when the pressure in the pilot pressure oil supply pipe is set to be larger than the pressure in the hydraulic oil tank and less than a predetermined pressure by the pressure adjusting unit, the ball member is moved by its own weight. It moves downward while being guided by the storage chamber, and comes into contact with the lower end of the storage chamber. At this time, the pilot pressure oil supply line side opening at the lower end of the storage chamber is formed to be eccentric from the cylindrical axis of the storage chamber in the radial direction so that the ball member does not seat. The opening is not blocked and the on-off valve can be kept open.

  On the other hand, when the pressure in the pilot pressure oil supply pipe is set to a predetermined pressure or higher by the pressure adjusting unit, the ball member moves upward while being guided to the storage chamber by the pressure in the pilot pressure oil supply pipe. , Abuts the upper end of the storage chamber. At this time, since the ball member is seated in the drain line side opening at the upper end of the storage chamber, the drain line side opening is blocked by the ball member, so that the on-off valve can be kept closed.

  As described above, since the ball member in the accommodation chamber moves in the vertical direction in accordance with the pressure in the pilot pressure oil supply line set by the pressure adjusting unit, the open / close state of the on-off valve can be appropriately controlled. The discharge of air in the pressure oil supply line and the suppression of the outflow of pilot pressure oil from the pilot pressure oil supply line can be performed in a well-balanced manner.

  Further, in the air venting device for a construction machine according to the present invention, in the above invention, the pressure adjusting unit is operated to instruct an adjustment of the pressure in the pilot pressure oil supply pipe, and the operation is performed in accordance with the operation amount. Pilot pressure oil provided in an operation section for outputting a command current, and a pipe line between the pilot pump and the on-off valve, and the command current output from the operation section being input and discharged from the pilot pump And a pressure reducing valve that reduces the pressure in the pilot pressure oil supply line to a pressure corresponding to the command current, and discharges air in the pilot pressure oil supply line by the operation unit. When a predetermined operation is performed, the pressure reducing valve inputs a command current corresponding to the operation amount of the predetermined operation of the operation unit and throttles the pilot pressure oil discharged from the pilot pump. By, it is characterized by reducing the pressure of the pilot pressure oil supply conduit greater than the pressure of the working oil tank, and a pressure below the predetermined pressure.

  According to the present invention configured as described above, the pressure in the pilot pressure oil supply line is adjusted by the pressure reducing valve in the hydraulic oil tank by performing a predetermined operation using the operation unit in advance before the work by the construction machine is performed. Therefore, it is possible to quickly set the pressure to a pressure lower than the predetermined pressure and lower than the predetermined pressure, so that the air bleeding operation of the pilot pressure oil supply pipe can be completed at an early stage.

  Further, in the air venting device for a construction machine according to the present invention, in the above invention, the pressure adjusting unit is operated to instruct an adjustment of the pressure in the pilot pressure oil supply pipe, and the operation is performed in accordance with the operation amount. An operation unit that supplies hydraulic oil at a pressure, and a pipe line between the pilot pump and the on-off valve, operates under the pressure of the hydraulic oil supplied from the operation unit, and discharges from the pilot pump. A pressure reducing valve for reducing the pressure in the pilot pressure oil supply line to a pressure corresponding to the pressure of the hydraulic oil supplied from the operation unit When a predetermined operation for discharging the air in the pilot pressure oil supply pipeline is performed, the pressure reducing valve receives the pressure of the hydraulic oil supplied by the predetermined operation of the operation unit and receives the pilot pressure. The pressure in the pilot pressure oil supply line is reduced to a pressure greater than the pressure in the hydraulic oil tank and less than the predetermined pressure by restricting the pilot pressure oil discharged from the pump. Yes.

  According to the present invention configured as described above, the pressure in the pilot pressure oil supply line is adjusted by the pressure reducing valve in the hydraulic oil tank by performing a predetermined operation using the operation unit in advance before the work by the construction machine is performed. Therefore, it is possible to quickly set the pressure to a pressure lower than the predetermined pressure and lower than the predetermined pressure, so that the air bleeding operation of the pilot pressure oil supply pipe can be completed at an early stage. In particular, when a pressure reducing valve that operates by receiving the pressure of hydraulic oil supplied from the operation unit in a construction machine, that is, when a pilot operated pressure reducing valve is mounted, by using this pilot operated pressure reducing valve, The present invention can be applied without newly adding a pressure reducing valve.

  According to the air bleeder for a construction machine of the present invention, even if the pressures of the pilot pressure oil supply line and the hydraulic oil tank are in an equilibrium state, the pressure regulator adjusts the pressure in the pilot pressure oil supply line. By setting the pressure in the pilot pressure oil to be larger than the pressure in the tank and less than the predetermined pressure, air in the pilot pressure oil supply line is pushed out from the on-off valve to the drain line by the pilot pressure oil. The air remaining in can be easily discharged. Thereby, since sufficient air bleeding effect can be obtained with respect to the pilot pressure oil supply pipeline, the operability of the construction machine can be improved as compared with the conventional art.

It is a figure which shows the structure of the hydraulic shovel mentioned as an example of the construction machine with which 1st Embodiment of the air bleeding apparatus which concerns on this invention is applied. It is a figure which shows the structure of the hydraulic circuit which concerns on 1st Embodiment of this invention. It is a figure which shows the structure of the valve | bulb which concerns on 1st Embodiment of this invention, and an on-off valve. It is a figure explaining the relationship between the pressure P in the pilot pressure oil supply pipe line and spool control amount Q which concern on 1st Embodiment of this invention. It is a figure which shows the structure of the hydraulic circuit which concerns on 2nd Embodiment of this invention. It is a figure explaining the structure of an example of the conventional air bleeding apparatus. It is a figure explaining the structure of the principal part of FIG.

  EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the air bleeding apparatus of the construction machine which concerns on this invention is demonstrated based on figures.

[First Embodiment]
The first embodiment of the air bleeding device according to the present invention is applied to a construction machine, for example, a hydraulic excavator 1 shown in FIG. The hydraulic excavator 1 is disposed above the traveling body 2, the revolving body 3 having a revolving frame 3a, and attached to the front of the revolving body 3. And a front work machine 4 that performs the above operations.

  The revolving unit 3 is arranged on the front side, the cab 5 on which an operator who operates the front work machine 4 gets on, the counter weight 6 arranged on the rear side and keeping the balance of the vehicle body so that the vehicle body does not tilt, An engine room 7 provided between the cab 5 and the counterweight 6 and a vehicle body cover 8 provided on the upper part of the engine room 7 are provided.

  The front work machine 4 includes a boom 4A whose base end is pivotally attached to the revolving frame 3a and pivots in the vertical direction, an arm 4B pivotally attached to the tip of the boom 4A, and the arm 4B. The bucket 4C is rotatably attached to the tip of the bucket. The front work machine 4 connects the revolving body 3 and the boom 4A, connects the boom cylinder 4a that rotates the boom 4A by extending and contracting, the boom 4A and the arm 4B, and extends and contracts the arm 4B. The arm cylinder 4b that rotates the bucket 4C and the bucket cylinder 4c that connects the arm 4B and the bucket 4C and rotates the bucket 4C by expanding and contracting are provided.

  Further, as shown in FIG. 2, the swing body 3 includes an engine 7a housed in the engine room 7, a controller (not shown) for controlling the operation of the vehicle body, a boom cylinder 4a and an arm using the engine 7a as a power source. The hydraulic circuit 10 for driving hydraulic actuators, such as the cylinder 4b and the bucket cylinder 4c, is provided.

  The hydraulic circuit 10 is rotated by the driving force of the engine 7a and discharges hydraulic oil as pressure oil to the boom cylinder 4a, the arm cylinder 4b, and the bucket cylinder 4c, and the boom cylinder 4a, The arm cylinder 4b, the bucket cylinder 4c, and the control valve (valve 12) for controlling the flow of pressure oil discharged to the tilting piston for controlling the discharge flow rate of the hydraulic pump 11, that is, the flow rate and direction of the pressure oil are provided. doing.

  In the first embodiment of the present invention, the control of the flow of pressure oil to the tilting piston (not shown), the arm cylinder 4b, and the bucket cylinder 4c is performed similarly to the control of the flow of pressure oil to the boom cylinder 4a. Therefore, in the following description of the hydraulic circuit 10, the configuration and operation related to the control of the flow of pressure oil to the boom cylinder 4a will be described in detail, and the configuration and operation related to the control of the tilting piston, the arm cylinder 4b, and the bucket cylinder 4c will be described. Is omitted. FIG. 2 shows a valve 12 for the boom cylinder 4a for controlling the flow rate and direction of the pressure oil discharged to the boom cylinder 4a. The valves 12 for the other tilt piston, arm cylinder 4b and bucket cylinder 4c are shown. Illustration of the valve 12 is omitted.

  The valve 12 supplies, for example, pressure oil to the boom cylinder 4a, a first drive position for extending the boom cylinder 4a, and a neutral position for blocking the flow of pressure oil to the boom cylinder 4a and stopping the expansion and contraction operation of the boom cylinder 4a. , And a spool valve that returns pressure oil from the boom cylinder 4a and switches to one of the second drive positions for shortening the boom cylinder 4a.

  Specifically, the valve 12 includes a casing 12A that forms an outer shell, a spool 12B that is housed in the casing 12A and reciprocates in the axial direction, and a spring 12C that urges the spool 12B to an initial position. It is comprised from the action part 12D which makes the pilot pressure oil discharged from the below-mentioned pilot pump 15 act on the spool 12B. Therefore, the spool 12B in the valve 12 receives the pressure of the pilot pressure oil from the action portion 12D, and moves in the axial direction against the elastic force of the spring 12C, so that the position of the valve 12 is switched.

  Further, the hydraulic circuit 10 supplies pilot pressure oil to the action portion 12D of the valve 12, and switches the position of the valve 12, and the pilot pressure oil discharged from the pilot pump 15 is supplied to the action portion 12D of the valve 12. Connected to the pilot pressure oil supply line 16, the hydraulic pump 11 and the pilot pump 15, the hydraulic oil tank 17 for storing the hydraulic oil sucked into the hydraulic pump 11 and the pilot pump 15, and the valve 12. A drain line 18 that guides the pressure oil returned to the valve 12 to the hydraulic oil tank 17 and a pressure adjusting unit 19 that adjusts the pressure in the pilot pressure oil supply line 16 are provided.

  The pressure adjusting unit 19 includes, for example, an operation unit 21 that performs an operation for instructing the adjustment of the pressure in the pilot pressure oil supply pipeline 16 and outputs a command current corresponding to the operation amount. The operation portion 21 is provided in the cab 5 so as to be rotatable in the front-rear and left-right directions. The operation lever 21A is gripped and operated by the operator to move the front work machine 4 and can be rotated in the cab 5 in the vertical direction. The front work machine 4 is operated by the operation lever 21A when it is in a lock release position that disables the operation of the front work machine 4 by the operation lever 21A and prevents the operator from getting on and off. The gate lock lever 21B enables the operation of the front work machine 4 by the gate lock lever 21B, and safety when the operator gets on and off the cab 5 can be ensured.

  The pressure adjusting unit 19 is provided, for example, between the pilot pump 15 and the valve 12 in the pilot pressure oil supply pipe 16, and receives a command current output from the get lock lever 21B and discharges it from the pilot pump 15. A proportional solenoid valve 22B for a gate lock lever as a pressure reducing valve 22 for reducing the pressure in the pilot pressure oil supply line 16 to a pressure corresponding to the command current by restricting the pilot pressure oil thus produced, and a pilot pressure oil supply pipe Pilot pressure oil provided in the path 16 between the proportional solenoid valve 22B for the gate lock lever and the valve 12 and having passed through the proportional solenoid valve 22B for the gate lock lever by inputting the command current output from the operation lever 21A. By reducing the pressure in the pilot pressure oil supply line 16 to a pressure corresponding to the command current. It is composed of a control lever for the proportional solenoid valve 22A of and.

  The relationship between the operation amount of the gate lock lever 21B and the command current output from the gate lock lever 21B is that when the gate lock lever 21B is in the lock position, the command current output from the gate lock lever 21B is 0. The command current output from the gate lock lever 21B is set to a maximum value when the lock lever 21B is in the unlock position. The relationship between the command current input to the proportional solenoid valve 22B for gate lock lever and the pressure in the pilot pressure oil supply conduit 16 is such that the command current input to the proportional solenoid valve 22B for gate lock lever increases. It is set to a proportional relationship in which the pressure in the pilot pressure oil supply pipeline 16 increases.

  Therefore, if the gate lock lever 21B is in the locked position, no command current is output from the get lock lever 21B, so that the proportional solenoid valve 22B for the gate lock lever is completely closed and the pilot discharged from the pilot pump 15 Cut off the flow of pressure oil. On the other hand, if the gate lock lever 21B is in the unlocked position, the proportional solenoid valve 22B for the gate lock lever is fully opened when the command current output from the get lock lever 21B is input, and is discharged from the pilot pump 15. The pilot oil that has been made flows directly to the proportional solenoid valve 22A for the operating lever on the downstream side.

  The relationship between the operation amount of the operation lever 21A and the command current output from the operation lever 21A is set such that the command current output from the operation lever 21A increases as the operation amount of the operation lever 21A increases. Further, the relationship between the command current input to the control lever proportional solenoid valve 22A and the pressure in the pilot pressure oil supply pipe 16 is such that the pilot pressure increases as the command current input to the control lever proportional solenoid valve 22A increases. It is set to a proportional relationship in which the pressure in the oil supply line 16 increases.

  Therefore, when the operation lever 21A is not operated and is in the neutral position, the operation lever proportional solenoid valve 22A receives the command current output from the operation lever 21A, and the pilot that has passed through the gate lock lever proportional solenoid valve 22B. By squeezing the pressure oil, the pressure in the pilot pressure oil supply pipe 16 is reduced to be less than a predetermined pressure P1 (see FIG. 4) described later. On the other hand, when the operation lever 21A is operated in the forward or backward direction, the operation lever proportional solenoid valve 22A passes the gate lock lever proportional solenoid valve 22B when the command current output from the operation lever 21A is input. By reducing the pilot pressure oil, the pressure in the pilot pressure oil supply line 16 is reduced to a pressure corresponding to the command current. That is, when the operation amount of the operation lever 21A increases, the command current input to the operation lever proportional solenoid valve 22A increases, so the pressure in the pilot pressure oil supply line 16 also increases.

  Here, when the excavator 1 is assembled before shipment or maintenance work is performed to disassemble and maintain the vehicle body, the pilot pressure oil supply pipe 16 is not filled with the pilot pressure oil, and the pilot pressure oil is not filled. Since air remains in the pressure oil supply line 16, this air needs to be discharged from the pilot pressure oil supply line 16.

  Therefore, in the first embodiment of the present invention, the hydraulic circuit 10 is formed by branching from the pilot pressure oil supply pipeline 16, and the pressure in the pilot pressure oil supply pipeline 16 is less than the predetermined pressure P1 described above. There is an on-off valve 25 that is sometimes opened and closed when the pressure in the pilot pressure oil supply line 16 is equal to or higher than a predetermined pressure P1, and the pressure regulator 19 adjusts the pressure in the pilot pressure oil supply line 16 to the operating oil. The air in the pilot pressure oil supply line 16 is discharged by setting it to be larger than the pressure in the tank 17 and less than a predetermined pressure P1.

  Specifically, the on-off valve 25 is, for example, integrally provided in the valve 12 and has a ball check valve structure that connects the branch point of the pilot pressure oil supply pipe 16 and the drain pipe 18 along the vertical direction. It is composed of As shown in FIG. 3, the on-off valve 25 is configured such that the pressure in the pilot pressure oil supply line 16 is greater than the pressure in the hydraulic oil tank 17, that is, the maximum value of the internal pressure in the hydraulic oil tank 17 by the pressure adjusting unit 19. When the pressure is set lower than the predetermined pressure P1, the pilot pressure oil moves downward due to its own weight, and when the pressure in the pilot pressure oil supply line 16 is set to be equal to or higher than the predetermined pressure P1 by the pressure adjusting unit 19. A ball member 26 that moves upward due to the pressure in the supply pipe 16, a cylindrical accommodation chamber 27 that accommodates the ball member 26 and guides the ball member 26 along the vertical direction, and an upper portion of the accommodation chamber 27 And a branch plug 29 that is formed below the housing chamber 27 and communicates with a branch point of the pilot pressure oil supply conduit 16. It is made up of. An opening / closing lid 30 that opens and closes when a tool such as a hexagon wrench is inserted into the casing 12A is provided on the upper portion of the casing 12A of the valve 12.

  The storage chamber 27 is formed by processing the inside of the casing 12 </ b> A of the valve 12, and the weight of the ball member 26 and the gap between the ball member 26 and the inner wall of the storage chamber 27 are within the pilot pressure oil supply pipe 16. Is set in advance so that the ball member 26 receives the pilot pressure oil flowing into the storage chamber 27 from the branch hole 29 and moves upward when the pressure is set to a predetermined pressure P1 or higher.

  The seat plug 28 has a hollow portion 28 </ b> A having a sufficient opening area as a pipe line formed along the axial direction, and is composed of a taper screw for pipe communicating from the storage chamber 27 to the drain pipe line 18. Is processed into a shape to which a tool inserted into the casing 12A from the opening / closing lid 30 is engaged. Further, a male screw (not shown) outside the seat plug 28 is screwed into a female screw (not shown) formed in the upper portion of the accommodating chamber 27 in the casing 12A, so that the seat plug 28 is in the casing 12A. It is fixed above the inner storage chamber 27.

  The storage chamber 27 is provided at the upper end connected to the drain line 18 and is formed in a circular shape having an inner diameter smaller than the outer diameter of the ball member 26 so that the ball member 26 moved upward is seated. The drain line side opening 27A and the lower end connected to the pilot pressure oil supply line 16 side are formed eccentrically from the cylindrical shaft in the radial direction so that the ball member 26 moved downward is not seated. And a hole-shaped pilot pressure oil supply line side opening 27B. The pilot pressure oil supply pipe side opening 27 </ b> B is connected to the upper end of the branch hole 29.

  Then, when the air in the pilot pressure oil supply pipe 16 is discharged, the above-mentioned predetermined pressure P1, which serves as a reference for the pressure set by the pressure adjusting unit 19, is, for example, as shown in FIG. It is set to a value smaller than the lower limit pressure Pmin of the control pressure range. The normal control pressure range of the valve 12 is a minimum pressure Pmin at which the spool 12B overcomes the elastic force of the spring 12C and starts to move, and a maximum pressure Pmax at which the spool 12B is pushed back by the elastic force of the spring 12C. This is a pressure region indicating a range. That is, when the pressure in the pilot pressure oil supply line 16 is the lower limit pressure Pmin of the normal control pressure range of the valve 12, the control amount Q of the spool 12B becomes the minimum value Qmin, and the pressure in the pilot pressure oil supply line 16 is When the upper limit pressure Pmax of the normal control pressure range of the valve 12 is reached, the control amount Q of the spool 12B becomes the maximum value Qmax.

  Next, the operation of the on-off valve 25 in the air venting operation in the pilot pressure oil supply pipeline 16 will be described in detail.

  When the excavator 1 is assembled before shipping, or when maintenance work is performed to disassemble and maintain the vehicle body, an operator who performs air venting gets on the cab 5 and the gate lock lever of the pressure adjusting unit 19 When 21B is operated to the unlocked position, the proportional solenoid valve 22B for the gate lock lever is completely opened by inputting the command current output from the get lock lever 21B.

  Next, when the operator holds the operation lever 21A in the neutral position, the operation lever proportional solenoid valve 22A inputs a minimum command current corresponding to the operation amount at the neutral position of the operation lever 21A from the pilot pump 15. By reducing the discharged pilot pressure oil, the pressure P1 in the pilot pressure oil supply line 16 is larger than the pressure in the hydraulic oil tank 17 and smaller than the lower limit pressure Pmin in the normal control pressure region of the valve 12. Reduce to less than.

  When the pressure in the pilot pressure oil supply pipe 16 decreases to less than the pressure P1, the ball member 26 is not pushed up by the pilot pressure oil in the on-off valve 25, and moves downward while being guided by the own weight to the storage chamber 27. 27 abuts on the lower end of At this time, since the pilot pressure oil supply line side opening 27B of the storage chamber 27 is eccentric in the radial direction from the cylindrical axis of the storage chamber 27, the ball member 26 is seated on the pilot pressure oil supply line side opening 27B. The pilot pressure oil supply pipe side opening 27B is not blocked by the ball member 26. Thereby, the state which opened the on-off valve 25 can be maintained.

  Since the pressure in the pilot pressure oil supply pipe 16 is larger than the pressure in the hydraulic oil tank 17, the air remaining in the pilot pressure oil supply pipe 16 is transferred to the branch hole 29 of the on-off valve 25, the storage chamber. 27, together with the pilot pressure oil, can be discharged to the hydraulic oil tank 17 through the hollow portion 28 </ b> A of the seat plug 28 and the drain line 18.

  Next, the operation of the on-off valve 25 in work such as excavation using the front work machine 4 will be described in detail.

  After all the air in the pilot pressure oil supply pipe 16 is discharged to the hydraulic oil tank 17, an operator who performs excavation or the like gets into the cab 5, and the gate lock lever 21B of the pressure adjusting unit 19 is unlocked. When operated, the proportional solenoid valve 22B for the gate lock lever is completely opened by inputting the command current output from the get lock lever 21B.

  Next, when the operator operates the operation lever 21A to the front position or the rear position, the operation lever proportional solenoid valve 22A inputs a command current corresponding to the operation amount of the front position or the rear position of the operation lever 21A, and the pilot pump By reducing the pilot pressure oil discharged from 15, the pressure in the pilot pressure oil supply line 16 is reduced to a pressure corresponding to the command current. As a result, the pressure in the pilot pressure oil supply line 16 becomes larger than the lower limit pressure Pmin in the normal control pressure range of the valve 12, so that the ball member 26 is connected to the pressure in the pilot pressure oil supply line 16 in the on-off valve 25. Thus, it moves upward while being guided by the storage chamber 27 and comes into contact with the upper end of the storage chamber 27.

  At this time, since the ball member 26 is seated in the drain pipe side opening 27A at the upper end of the storage chamber 27, the drain pipe side opening 27A is blocked by the ball member 26, so that the on-off valve 25 is kept closed. be able to. Accordingly, there is no pressure increase delay caused by the air in the pilot pressure oil supply line 16 while the operator operates the operation lever 21A to perform excavation or the like, so that the valve 12 can be smoothly operated. Operation can be realized. Thereby, excellent operability can be obtained.

  According to the first embodiment of the present invention configured as described above, the pilot pressure oil supply line 16 is operated even if the air removal operation of the pilot pressure oil supply line 16 is performed and the on-off valve 25 is opened. As a result, the pressure in the hydraulic oil tank 17 is not balanced, and the air in the pilot pressure oil supply line 16 can be pushed out from the on-off valve 25 to the drain line 18 by the pilot pressure oil. Thereby, the air remaining in the pilot pressure oil supply pipeline 16 can be easily discharged.

  In particular, the first embodiment of the present invention is applied to the hydraulic excavator 1, and the rotational speed of the engine 7a that drives the hydraulic pump 11 and the pilot pump 15 is an idle operation that is operated at the minimum rotational speed. In addition, pilot pressure oil of about 1/3 to 1/2 of the rated rotational speed is discharged from the pilot pump 15. In the first embodiment of the present invention, in consideration of the performance of the engine 7a mounted on the hydraulic excavator 1, the pressure in the pilot pressure oil supply line 16 is accurately adjusted by the pressure adjusting unit 19. Even if the pilot pressure oil is discharged from the pilot pump 15 vigorously, the air pressure remains excessively in the state where the air remains in the pilot pressure oil supply line 16 and the on-off valve 25 is not closed, and the pilot pressure oil is supplied. The air in the pipe line 16 can be reliably discharged. As described above, a sufficient air bleeding effect can be obtained with respect to the pilot pressure oil supply pipeline 16, so that the operability of the hydraulic excavator 1 can be improved.

  In the first embodiment of the present invention, the pressure in the pilot pressure oil supply line 16 that is the starting point for closing the on-off valve 25 is set to a value P1 that is smaller than the lower limit pressure Pmin in the normal control pressure range of the valve 12. Therefore, while the operator in the cab 5 operates the operation lever 21A and performs work such as excavation, the pressure in the pilot pressure oil supply line 16 is within the range of the normal control pressure range of the valve 12. The opening / closing valve 25 can be kept closed. Thereby, since it is possible to suppress the pilot pressure oil from flowing out to the drain line 18 through the on-off valve 25 during the operation, it is possible to improve the energy efficiency of equipment such as the valve 12 that is operated by the pilot pressure oil. The workability of 1 can be improved.

  In the first embodiment of the present invention, the on-off valve 25 is a ball check valve that opens and closes when the ball member 26 in the storage chamber 27 moves in the vertical direction according to the pressure in the pilot pressure oil supply pipe 16. Since it is comprised from a structure, the open / close state of the on-off valve 25 can be appropriately controlled by the gate lock lever 21B and the operation lever 21A. As a result, the discharge of air in the pilot pressure oil supply pipe 16 and the suppression of the outflow of pilot pressure oil from the pilot pressure oil supply pipe 16 can be performed in a well-balanced manner.

  Further, since the on-off valve 25 is integrally provided inside the valve 12, the on-off valve 25 is positioned on the terminal side of the pilot pressure oil flow path that flows through the pilot pressure oil supply conduit 16. Therefore, the air remaining in the entire area of the pilot pressure oil supply line 16 can be pushed out to the drain line 18 through the on-off valve 25 by the pilot pressure oil, so that the air in the pilot pressure oil supply line 16 is effectively discharged. can do.

  Further, according to the first embodiment of the present invention, when the excavator 1 is assembled before shipping, or when a maintenance operation for disassembling and maintaining the vehicle body is performed, an operator who performs the air bleeding operation is provided with a gate lock lever. By operating 21B to the unlocked position and holding the operating lever 21A in the neutral position, the pressure in the pilot pressure oil supply line 16 is actuated by the proportional solenoid valve 22B for the gate lock lever and the proportional solenoid valve 22A for the operating lever. It can be quickly set to a value less than the value P1 that is larger than the pressure in the oil tank 17 and smaller than the lower limit pressure in the normal control pressure range of the valve 12. Thereby, since the air bleeding operation of the pilot pressure oil supply pipe 16 can be completed at an early stage, the operator can start work such as excavation immediately after getting into the cab 5.

  Further, the proportional solenoid valve 22B for the gate lock lever and the proportional solenoid valve 22A for the operation lever operate by inputting the command current output from the gate lock lever 21B and the operation lever 21A, and thus the gate lock lever 21B and the operation lever 21A. With this operation, the pressure in the pilot pressure oil supply pipe 16 can be accurately controlled. Thereby, the reliability with respect to the pressure control of the pilot pressure oil supply pipeline 16 by the pressure adjusting unit 19 can be enhanced.

  In the first embodiment of the present invention, since the seat plug 28 is a pipe taper screw, the seat plug 28 is accommodated in the housing chamber 27 in the casing 12A using a tool inserted into the casing 12A of the valve 12 from the opening / closing lid 30. It can be easily attached above. Further, since the amount of movement of the ball member 26 in the accommodation chamber 27 in the vertical direction is determined by the assembly position of the seat plug 28 in the casing 12A, the seat plug 28 is attached to the portion in the casing 12A where the seat plug 28 is attached. It is possible to easily position the seat plug 28 with respect to the accommodating portion 27 only by managing the position size of the reference diameter.

  That is, since the position of the reference diameter is fixed because the seat plug 28 is a pipe taper screw, the seat plug 28 is positioned by tightening the seat plug 28 into a portion where the seat plug 28 is attached in the casing 12A. Just good. In addition, when the seat plug 28 is rotated once around the axis, the seat plug 28 advances one pitch in the axial direction. Therefore, even when the seat plug 28 is strongly tightened in the casing 12A, the position of the seat plug 28 can be easily adjusted, and the vertical position of the ball member 26 can be adjusted. A sufficient movable area in the direction can be secured.

[Second Embodiment]
FIG. 5 is a diagram showing a configuration of a hydraulic circuit according to the second embodiment of the present invention.

  As shown in FIG. 2, the operation unit 21 of the pressure adjusting unit 19 according to the first embodiment of the present invention includes the gate lock lever 21 </ b> B and the operation lever 21 </ b> A that output a command current according to the operation amount. On the other hand, as shown in FIG. 5, the operation unit 41 of the pressure adjusting unit 39 according to the second embodiment of the present invention includes a gate lock lever 41 </ b> B and an operation lever 41 </ b> A that supply hydraulic oil having a pressure corresponding to the operation amount. It is configured. Specifically, the gate lock lever 41 </ b> B and the operation lever 41 </ b> A are connected to the upstream side of the pilot pressure oil flow in the pilot pressure oil supply line 16, for example, and are pilots that flow through the pilot pressure oil supply line 16. The pressure oil is depressurized according to the operation amount, and the depressurized hydraulic oil is supplied.

  Further, the pressure reducing valve 22 of the pressure adjusting unit 19 according to the first embodiment of the present invention is composed of the proportional solenoid valve 22B for the gate lock lever and the proportional solenoid valve 22A for the operation lever. The pressure reducing valve 42 of the pressure adjusting unit 39 according to the second embodiment operates by receiving the pressure of the hydraulic oil supplied from the gate lock lever 41B, and throttles the pilot pressure oil discharged from the pilot pump 15 to thereby reduce the pilot pressure. A pilot-actuated pressure reducing valve 42B for the gate lock lever that reduces the pressure in the oil supply line 16 to a pressure corresponding to the pressure of the hydraulic oil supplied from the gate lock lever 41B, and the hydraulic oil supplied from the operation lever 41A The pressure in the pilot pressure oil supply line 16 is reduced by operating the pressure and squeezing the pilot pressure oil discharged from the pilot pump 15. Is composed of a control lever for pilot operated pressure reducing valve 42A to reduce the pressure corresponding to the pressure of the working oil supplied from the over 41A. The other configurations of the second embodiment are the same as those of the first embodiment, and the same reference numerals are given to portions that overlap or correspond to those of the first embodiment.

  According to the second embodiment of the present invention configured as described above, the same operational effects as the first embodiment described above can be obtained, and the pressure of the hydraulic oil supplied from the gate lock lever 41B and the operation lever 41A can be received. The pilot operated pressure reducing valve 42B for the gate lock lever and the pilot operated pressure reducing valve 42A for the operating lever operate in the same manner as the proportional solenoid valve 22B for the gate lock lever and the proportional solenoid valve 22A for the operating lever according to the first embodiment. The pressure in the pilot pressure oil supply pipe 16 can be adjusted accurately.

  Therefore, the second embodiment of the present invention is also applied to a hydraulic excavator configured to control the switching of the position of the valve 12 using the pilot operated pressure reducing valve 42B for the gate lock lever and the pilot operated pressure reducing valve 42A for the operation lever. Therefore, it is not necessary to newly add the proportional solenoid valve 22B for the gate lock lever and the proportional solenoid valve 22A for the operation lever according to the first embodiment, and an apparatus with excellent convenience can be provided.

  In the first embodiment of the present invention described above, the proportional solenoid valve 22B for the gate lock lever and the proportional solenoid valve 22A for the operation lever are used as the pressure reducing valve 22 of the pressure adjusting unit 19, and in the second embodiment of the present invention, The description has been given of the case where the pilot-actuated pressure reducing valve 42B for the gate lock lever and the pilot-actuated pressure reducing valve 42A for the operation lever are used as the pressure reducing valve 42 of the pressure adjusting unit 39. It is not limited to a proportional solenoid valve and a pilot-actuated pressure reducing valve, but may be another type of pressure reducing valve.

  In the first and second embodiments of the present invention, the pilot pressure oil supply line side opening 27B is provided at the lower end of the storage chamber 27 connected to the pilot pressure oil supply line 16 side, and has moved downward. Although the case where the ball member 26 is formed eccentrically from the cylindrical shaft of the storage chamber 27 in the radial direction has been described so as not to be seated, the present invention is not limited to this, and the pilot pressure oil supply line side opening 27B is, for example, a long If the ball member 26 moved downward is not seated by being formed into a shape such as a hole, it may not be eccentric from the cylindrical axis of the storage chamber 27 in the radial direction.

1 Excavator (construction machine)
4 Front working machine 4A Boom 4a Boom cylinder 4B Arm 4b Arm cylinder 4C Bucket 4c Bucket cylinder 7a Engine 10 Hydraulic circuit 11 Hydraulic pump 12 Valve (control valve)
12A Casing 12B Spool 12C Spring 12D Action part 15 Pilot pump 16 Pilot pressure oil supply line 17 Hydraulic oil tank 18 Drain line 19, 39 Pressure adjustment part 21, 41 Operation part
21A, 41A Operation lever 21B, 41B Gate lock lever 22, 42 Pressure reducing valve 22A Proportional solenoid valve for operation lever 22B Proportional solenoid valve for gate lock lever 25 Open / close valve 26 Ball member 27 Storage chamber 27A Drain pipe side opening 27B Pilot pressure oil Supply pipe side opening 28 Seat plug 28A Hollow portion 29 Branch hole 30 Opening / closing lid 42A Pilot operated pressure reducing valve for operation lever 42B Pilot operated pressure reducing valve for gate lock lever

Claims (5)

An engine, a hydraulic pump driven by the engine, a control valve for controlling a flow of pressure oil discharged from the hydraulic pump, and pilot pressure oil is supplied to an operation portion of the control valve, and the position of the control valve A pilot pump for switching the pilot pressure, a pilot pressure oil supply line for guiding the pilot pressure oil discharged from the pilot pump to the action part of the control valve, and an operation connected to the hydraulic pump and the pilot pump to store the hydraulic oil Provided in construction machines with oil tanks,
In the air bleeder of a construction machine that discharges air remaining in the pilot pressure oil supply pipeline,
It is formed by branching from the pilot pressure oil supply pipeline, and is opened when the pressure in the pilot pressure oil supply pipeline is less than a predetermined pressure, and the pressure in the pilot pressure oil supply pipeline is equal to or higher than a predetermined pressure. An on-off valve that closes when
A drain line for guiding the hydraulic oil that has passed through the on-off valve to the hydraulic oil tank;
A pressure adjusting unit for adjusting the pressure in the pilot pressure oil supply pipeline,
The pressure adjusting unit discharges air in the pilot pressure oil supply line by setting the pressure in the pilot pressure oil supply line to be larger than the pressure in the hydraulic oil tank and less than the predetermined pressure. An air venting device for a construction machine. The air bleeder for a construction machine according to claim 1,
The air venting device for a construction machine, wherein the predetermined pressure is set to a value smaller than a lower limit pressure in a normal control pressure range of the control valve. The air venting device for a construction machine according to claim 2,
The on-off valve is
When the pressure in the pilot pressure oil supply line is set to be greater than the pressure in the hydraulic oil tank and less than the predetermined pressure by the pressure adjusting unit, the pressure adjusting unit moves downward due to its own weight, and the pressure adjusting unit A ball member that moves upward by the pressure in the pilot pressure oil supply line when the pressure in the pilot pressure oil supply line is set to be equal to or higher than the predetermined pressure by
The ball member is accommodated, and includes a cylindrical accommodation chamber that guides the ball member along the vertical direction,
This containment room
A drain line side opening provided at an upper end connected to the drain line and formed so that the ball member moved upward is seated;
A pilot pressure oil supply line side opening provided at a lower end connected to the pilot pressure oil supply line side and formed eccentrically from the cylindrical shaft in the radial direction so that the ball member moved downward is not seated; An air venting device for a construction machine, comprising: In the bleeder of the construction machine according to any one of claims 1 to 3,
The pressure adjusting unit is
An operation for instructing adjustment of the pressure in the pilot pressure oil supply pipeline is performed, and an operation unit that outputs a command current according to the operation amount;
The pilot pressure oil is provided in a pipe line between the pilot pump and the on-off valve, and the pilot pressure oil discharged from the pilot pump is throttled by inputting the command current output from the operation unit. A pressure reducing valve that reduces the pressure in the supply line to a pressure corresponding to the command current,
When a predetermined operation for discharging air in the pilot pressure oil supply pipeline is performed by the operation unit, the pressure reducing valve inputs a command current corresponding to an operation amount of the predetermined operation of the operation unit. By reducing the pilot pressure oil discharged from the pilot pump, the pressure in the pilot pressure oil supply line is reduced to a pressure greater than the pressure in the hydraulic oil tank and less than the predetermined pressure. An air venting device for construction machinery. In the bleeder of the construction machine according to any one of claims 1 to 3,
The pressure adjusting unit is
An operation for instructing the adjustment of the pressure in the pilot pressure oil supply pipeline is performed, and an operation unit for supplying hydraulic oil having a pressure corresponding to the operation amount;
Provided in a pipe line between the pilot pump and the on-off valve, operates under the pressure of hydraulic oil supplied from the operation unit, and throttles the pilot pressure oil discharged from the pilot pump, A pressure reducing valve that reduces the pressure in the pilot pressure oil supply line to a pressure corresponding to the pressure of the hydraulic oil supplied from the operation unit,
When a predetermined operation for discharging the air in the pilot pressure oil supply pipeline is performed by the operation unit, the pressure reducing valve receives the pressure of the hydraulic oil supplied by the predetermined operation of the operation unit. By reducing the pilot pressure oil discharged from the pilot pump, the pressure in the pilot pressure oil supply line is reduced to a pressure larger than the pressure in the hydraulic oil tank and less than the predetermined pressure. A bleeder for construction machinery.