JP4783393B2 - Hydraulic control equipment for construction machinery - Google Patents

Description

  The present invention relates to a hydraulic control device for a construction machine, and in particular, a construction machine including a controller for continuously controlling the operation of a throttle switching control valve for controlling hydraulic oil supplied from a hydraulic pump to a hydraulic actuator. The present invention relates to a hydraulic control device.

  Conventionally, in a hydraulic control device for construction machinery such as a hydraulic excavator, a tandem circuit that sequentially supplies hydraulic oil discharged from a pump to a plurality of throttle switching control valves, and a plurality of throttle switching of hydraulic oil discharged from the pump. 2. Description of the Related Art A hydraulic control device having a parallel circuit that independently supplies a control valve is known (see, for example, Patent Document 1).

  FIG. 2 shows an example of a hydraulic excavator as a construction machine. In FIG. 2, the hydraulic excavator 1 is provided with a lower traveling body 2 so that an upper swinging body 4 can swing via a swinging mechanism 3, and a front work machine 5 is mounted on the upper swinging body 4. The front work machine 5 has a base end portion of a boom 6 pivotally attached to the upper swing body 4 and a base end portion of an arm 7 rotatably connected to a tip end portion of the boom 6. A bucket 8 is rotatably connected to the tip of the arm 7. The boom 6 is rotated by the boom cylinder 9, the arm 7 is rotated by the arm cylinder 10, and the bucket 8 is rotated by the bucket cylinder 11.

  FIG. 4 shows an example of a drive control circuit in a conventional hydraulic excavator. In FIG. 4, a hydraulic pump 23 that discharges hydraulic oil is attached to a drive shaft 22 of an engine 21 mounted on the hydraulic excavator 1. Further, downstream of the hydraulic pump 23, throttle switching control valves 28a and 28b for controlling hydraulic oil supplied from the hydraulic pump 23 to left and right traveling motors (hydraulic motors) 24 and 24 as hydraulic actuators, respectively, There are provided throttle switching control valves 28c, 28d and 28e for controlling hydraulic oil supplied from the hydraulic pump 23 to the boom cylinder 9, arm cylinder 10 and bucket cylinder 11 as hydraulic actuators.

  The throttle switching control valves 28a, 28b, 28c, 28d, and 28e connect a center bypass passage 29a in series with the hydraulic pump 23, and the hydraulic oil discharged from the hydraulic pump 23 is throttle switched control valves 28a to 28e. The pump ports are connected in parallel by a parallel passage 30a to the tandem circuit 29 and the hydraulic pump 23 which are sequentially supplied to the hydraulic pump 23, and the hydraulic oil discharged from the hydraulic pump 23 is independently supplied to the throttle switching control valves 28a to 28e. The parallel circuit 30 is connected. In the parallel circuit 30, check valves 31a, 31c, 31d and 31e are provided between the throttle switching control valves 28a, 28c to 28e and the hydraulic pump 23, respectively.

  Further, in this drive control circuit, pilot pressure sensors 34a, 34b, 34c, 34d, 34e are provided in the pilot lines 33a, 33b, 33c, 33d, 33e of the throttle switching control valves 28a-28e, and the pilot pressures are respectively provided. That is, the operation amounts of traveling, boom raising, bucket excavation, and arm pulling are detected by these pilot pressure sensors 34a to 34e and sent to the controller 35 as control means.

Reference numerals 36a and 36b in FIG. 4 are remote control valves for the travel motors 9 and 9. When the remote control valves 36a and 36b are operated, a signal from the controller 35 is sent to the throttle switch control valve 28a for the travel motor. , 28b, and the throttle switching control valves 28a, 28b are controlled in accordance with the operation amount of the remote control valves 36a, 36B and the pilot pressures from the pilot pressure sensors 34a, 34b, respectively. Reference numerals 36c, 36d, and 36e are boom, bucket, and arm remote control valves, respectively, and signals from the controller 35 are sent to the boom, bucket, and arm through the operations of the remote control valves 36c to 36e. The throttle switching control valves 28c to 28e are respectively input to the throttle switching control valves 28c to 28e, and the throttle switching control valves 28c to 28e are controlled in accordance with the operation amounts of the remote control valves 36c to 36e and the pilot pressures from the pilot pressure sensors 34c to 34e.

  The controller 35 is operated by the hydraulic pump 23 on the basis of a map prepared beforehand, for example, a characteristic map as shown in FIG. 3, for the operation amount of the remote control valves 36a to 36e and the pilot pressure from each pilot pressure sensor 34a to 34e. The oil discharge amount and the operation of the throttle switching control valves 28c to 28e are respectively controlled.

  FIG. 3 shows the relationship between the hydraulic control amount and the operation amount (stroke) of the actuator (cylinders 15, 17, 19). A diagram PT in FIG. 3 shows a change in the flow rate of the hydraulic oil discharged from the hydraulic pump 23 to escape to the tank T by the throttle switching control valves 28c to 28e and bleed off. That is, in the diagram PT, the escape amount is increased in the initial stroke section S of each cylinder 15, 17, 19, and the amount of hydraulic oil from the hydraulic pump 23 entering each cylinder 15, 17, 19 is reduced. Reduce excess pressure. In addition, the amount of oil (pressure oil) released to the tank T is sequentially reduced after passing the initial stroke section S until reaching the upper limit of the control region indicated by the line L in FIG.

  The diagram PC in FIG. 3 is discharged from the hydraulic pump 23 and sent to the cylinders 15, 17, 19 during the meter-in stroke in which the hydraulic oil discharged from the hydraulic pump 23 is sent to the cylinders 15, 17, 19. The state which is controlling the flow volume of hydraulic oil is shown. The diagram PC shows that the amount of oil (pressure oil) entering each of the cylinders 15, 17 and 19 increases as the escape amount shown by the diagram PT decreases.

  The line CT in FIG. 3 shows the flow rate at which the hydraulic oil returns from the cylinders 15, 17, 19 to the tank T during the meter-out stroke in which the hydraulic oil in the cylinders 15, 17, 19 escapes to the tank T. (Pressure oil) changes. The diagram CT shows that the oil amount (pressure oil) in each cylinder 15, 17, 19 decreases as the stroke amount of each cylinder 15, 17, 19 decreases.

By the way, in such a drive control circuit of a hydraulic excavator, in the meter-in stroke in which the hydraulic oil discharged from the hydraulic pump 23 is sent to the cylinders 15, 17, 19, the operation to supply the cylinders 15, 17, 19 is performed. The oil amount only needs to be controlled until the operation amount (stroke amount) of each cylinder 15, 17, 19 reaches the upper limit L of the control region. That is, after the upper limit L of the control range is exceeded, the operation of the cylinders 15, 17, and 19 is not greatly affected even if hydraulic oil is freely added to the cylinders 15, 17, and 19.
Japanese Patent No. 3545626

  However, in the conventional hydraulic excavator control circuit, the hydraulic oil supplied from the hydraulic pump 23 is passed through the throttle switching control valves 28c to 28e even after the upper limit of the control range is exceeded and the control range is exceeded. , 17 and 19. For this reason, there has been a problem that pressure loss is caused by supplying hydraulic oil through the throttle switching control valve outside the control range.

Therefore, a technical problem to be solved in order to reduce the pressure loss outside the control region arises, and the present invention aims to solve this problem.

  The present invention has been proposed to achieve the above object, and the invention according to claim 1 is directed to a pump that discharges hydraulic oil, a plurality of hydraulic actuators that are operated by the hydraulic oil, and a plurality of hydraulic actuators that operate from the pump. A plurality of throttle switching control valves that respectively control the hydraulic oil supplied to the hydraulic actuator, a tandem circuit that sequentially supplies the hydraulic oil discharged from the pump to the plurality of throttle switching control valves, and a discharge from the pump. In a hydraulic control device for a construction machine, comprising: a parallel circuit that independently supplies the hydraulic oil to a plurality of throttle switching control valves; and a controller that continuously controls the operation of the throttle switching control valve. And a controller that directly supplies the hydraulic actuator without passing through the throttle switching control valve. When the upper limit of the control range for controlling the operation of the hydraulic actuator according to the map is exceeded, the bypass unit is operated while maintaining the control within the control range, and the hydraulic oil outside the control range exceeding the upper limit of the control range is removed. Provided is a hydraulic control device for a construction machine configured to supply the hydraulic actuator.

  According to this configuration, when pressure oil is supplied to the actuator, the predetermined pressure oil is maintained until reaching the upper limit of the control range controlled by the controller, and after exceeding the upper limit of the control range, While maintaining the control in the control region, the hydraulic oil supplied from the hydraulic pump can be supplied directly to the actuator through the bypass unit without passing through the switching control valve.

  According to a second aspect of the present invention, there is provided a hydraulic control device for a construction machine, wherein the bypass section is constituted by a bypass valve that can be controlled by the controller.

  According to this configuration, when outside the control range, the hydraulic oil supplied from the hydraulic pump is directly supplied to the actuator through the bypass valve.

  According to the first aspect of the present invention, after the controller deviates from the upper limit of the control range controlled by the controller, the hydraulic oil supplied from the hydraulic pump is directly supplied to the actuator through the bypass unit while maintaining the control in the control range. Therefore, pressure loss outside the control range can be reduced. Further, the throttle switching control valve can be shared, and the throttle switching control valve can be modularized.

  Since the invention according to claim 2 has a structure in which the hydraulic oil supplied from the hydraulic pump is directly supplied to the actuator through a bypass valve having high versatility, etc. when the control range is exceeded, the invention according to claim 1 is obtained. In addition to the effects, the structure can be simplified.

In order to achieve the purpose of reducing pressure loss outside the control range, a pump that discharges hydraulic oil, a plurality of hydraulic actuators that are operated by the hydraulic oil, and a plurality of hydraulic actuators that are supplied from the pump to the hydraulic actuators A plurality of throttle switching control valves for controlling the hydraulic oil, a tandem circuit for sequentially supplying the hydraulic oil discharged from the pump to the plurality of throttle switching control valves, and a plurality of throttles for the hydraulic oil discharged from the pump In a hydraulic control apparatus for a construction machine, comprising: a parallel circuit that independently supplies a switching control valve; and a controller that continuously controls the operation of the throttle switching control valve. Pressure control oil from the hydraulic oil is supplied to the throttle switching control valve. A bypass unit that enables direct supply to the hydraulic actuator without passing through, and the controller includes the hydraulic actuator. When the upper limit of the control area for controlling the operation of the motor according to the map is exceeded, the bypass unit is operated while maintaining the control within the control area, and the hydraulic oil outside the control area exceeding the upper limit of the control area is Realized by supplying to the hydraulic actuator.

  A hydraulic control device for a hydraulic excavator according to the present invention will be described below with reference to the preferred embodiments shown in FIGS. In FIG. 1, the same members as those of the conventional one shown in FIG.

  FIG. 1 shows an example of a drive control circuit in a hydraulic excavator 1 to which the present invention is applied. In FIG. 1, a hydraulic pump 23 that discharges hydraulic oil is attached to a drive shaft 22 of an engine 21 mounted on the hydraulic excavator 1. Further, downstream of the hydraulic pump 23, throttle switching control valves 28a and 28b for controlling hydraulic oil supplied from the hydraulic pump 23 to left and right traveling motors (hydraulic motors) 24 and 24 as hydraulic actuators, respectively, There are provided throttle switching control valves 28c, 28d and 28e for controlling hydraulic oil supplied from the hydraulic pump 23 to the boom cylinder 9, arm cylinder 10 and bucket cylinder 11 as hydraulic actuators.

  The throttle switching control valves 28a, 28b, 28c, 28d, and 28e connect a center bypass passage 29a in series with the hydraulic pump 23, and the hydraulic oil discharged from the hydraulic pump 23 is throttle switched control valves 28a to 28e. The pump ports are connected in parallel by a parallel passage 30a to the tandem circuit 29 and the hydraulic pump 23 which are sequentially supplied to the hydraulic pump 23, and the hydraulic oil discharged from the hydraulic pump 23 is independently supplied to the throttle switching control valves 28a to 28e. The parallel circuit 30 is connected. In the parallel circuit 30, check valves 31a, 31c, 31d and 31e are provided between the throttle switching control valves 28a, 28c to 28e and the hydraulic pump 23, respectively. Further, bypass valves 32, 32, and 32 are provided between the throttle switching control valves 28c to 28e and the hydraulic pump 23 via the check valves 31c, 31d, and 31e, respectively.

  In the drive control circuit of this embodiment, pilot pressure sensors 34a, 34b, 34c, 34d, 34e are provided on the pilot lines 33a, 33b, 33c, 33d, 33e of the throttle switching control valves 28a-28e, respectively. Pilot pressures, that is, operating amounts of traveling, boom raising, bucket excavation, and arm pulling are detected by these pilot pressure sensors 34a to 34e and sent to a controller 35 as control means.

  Reference numerals 36a and 36b in FIG. 2 are remote control valves for the travel motors 9 and 9. When the respective remote control valves 36a and 36b are operated, a signal from the controller 35 is sent to the throttle switch control valve 28a for the travel motor. , 28b, and the throttle switching control valves 28a, 28b are controlled in accordance with the operation amount of the remote control valves 36a, 36B and the pilot pressures from the pilot pressure sensors 34a, 34b, respectively. Reference numerals 36c, 36d, and 36e are boom, bucket, and arm remote control valves, respectively, and signals from the controller 35 are sent to the boom, bucket, and arm through the operations of the remote control valves 36c to 36e. The throttle switching control valves 28c to 28e are respectively input to the throttle switching control valves 28c to 28e, and the throttle switching control valves 28c to 28e are controlled in accordance with the operation amounts of the remote control valves 36c to 36e and the pilot pressures from the pilot pressure sensors 34c to 34e.

  The controller 35 is operated by the hydraulic pump 23 on the basis of a map prepared beforehand, for example, a characteristic map as shown in FIG. 3, for the operation amount of the remote control valves 36a to 36e and the pilot pressure from each pilot pressure sensor 34a to 34e. The oil discharge amount and the operation of the throttle switching control valves 28c to 28e are respectively controlled.

By the way, in the drive control circuit of the hydraulic excavator as shown in this embodiment, the hydraulic pump 2
In the meter-in stroke in which the hydraulic oil discharged from the cylinder 3 is sent to the cylinders 15, 17, 19, the hydraulic oil supplied to the cylinders 15, 17, 19 is the operation amount (stroke) of each cylinder 15, 17, 19. The amount of oil may be controlled only until the amount reaches the upper limit L of the control range. That is, after the upper limit L of the control range is exceeded, the operation of the cylinders 15, 17, and 19 is not greatly affected even if hydraulic oil is freely added to the cylinders 15, 17, and 19.

  Therefore, in the drive control circuit according to the present embodiment, bypass portions including bypass valves 32, 32, and 32 are provided between the cylinders 15, 17, and 19 and the check valves 31c to 31e, respectively, and supplied from the hydraulic pump 23. The hydraulic oil can be supplied directly to the cylinders 15, 17, 19 through the bypass valves 32, 32, 32.

  Further, the controller 35 maintains the pressure oil in the control area according to the map shown in FIG. 3 until the upper limit L of the control area is reached, and after having exceeded the upper limit L of the control area, While maintaining the pressure oil in the control area, the hydraulic oil outside the control area sent from the hydraulic pump 23 (the hydraulic oil in the hatched portion indicated by symbol B in FIG. 3) is supplied to each cylinder 15, 17, 19 has a function that allows the bypass valves 32, 32, and 32 to be opened and supplied directly without passing through the throttle switching control valves 28c to 28e. That is, when the operation amount (stroke) of each of the cylinders 15, 17, and 19 exceeds the upper limit L of the control region, the controller 35 causes the controller 35 to bypass the bypass valve 32 while it is out of the upper limit L of the control region. , 32 and 32 are opened, and hydraulic oil outside the control range supplied from the hydraulic pump 23 is supplied directly to the cylinders 15, 17 and 19 through the bypass valves 32, 32 and 32.

  Therefore, in the drive control circuit of the present embodiment, when the pressure oil is supplied to each of the cylinders 15, 17, 19 as actuators, the predetermined pressure oil as shown in FIG. 3 is maintained within the upper limit L of the control region, After deviating beyond the upper limit L of the control area, the hydraulic oil supplied from the hydraulic pump 23, that is, the hydraulic oil outside the control area indicated by symbol B in FIG. 3 is maintained while maintaining the pressure oil in the control area. Since it is directly supplied to the cylinders 15, 17, and 19 through the bypass valves 32, 32, and 32 so as not to pass through the throttle switching control valve, it is possible to reduce pressure loss in a region outside the control region. . Further, when different control is required for each of the cylinders 15, 17, and 19, the hydraulic oil outside the control region outside the control region can be directly supplied to the cylinders that need to be corrected. Can be shared, and the throttle control valve can be modularized.

  In addition, in the structure of the said Example, although the hydraulic fluid after having gone out of a control range was disclosed to the cylinders 15, 17, and 19 via the bypass valves 32, 32, 32, the bypass valves 32, 32 were disclosed. , 32 may be directly supplied to the cylinders 15, 17, 19 without going through them.

  The present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

1 is a side view of a hydraulic excavator to which the present invention is applied. The drive control circuit diagram of a hydraulic excavator same as the above. The figure which shows the relationship between the amount of bleed-off and the control operation amount of an actuator. The drive control circuit diagram of the conventional hydraulic shovel.

Explanation of symbols

9 Boom cylinder (actuator)
10 Arm cylinder (actuator)
11 Bucket cylinder (actuator)
21 Engine 22 Drive shaft 23 Hydraulic pump 24 Travel motor (hydraulic motor)
28a, 28b Throttle switching control valves 28c to 28e Throttle switching control valve 29a Center bypass passage 29 Tandem circuit 30a Parallel passage 30 Parallel circuit 32 Bypass valve 35 Controllers 36a to 36e Remote control valve S Pilot pressure section T in operation initial stage T Tank L Restriction area Upper limit B Pressure oil outside control range outside control range

Claims (2)

A pump that discharges hydraulic oil, a plurality of hydraulic actuators that are operated by the hydraulic oil, a plurality of throttle switching control valves that respectively control hydraulic oil that is supplied from the pump to the hydraulic actuators, and a pump that discharges from the pump A tandem circuit for sequentially supplying the hydraulic oil to the plurality of throttle switching control valves, a parallel circuit for independently supplying the hydraulic oil discharged from the pump to the plurality of throttle switching control valves, and operation of the throttle switching control valve A hydraulic control device for a construction machine comprising a controller for continuously controlling
A bypass unit that enables the pressure oil from the pump to be directly supplied to the hydraulic actuator without passing through the throttle switching control valve;
The controller operates the bypass unit while maintaining the control in the control range when the control range for controlling the operation of the hydraulic actuator according to the map is exceeded, and the controller is outside the control range exceeding the upper limit of the control range. A hydraulic control device for a construction machine, wherein the hydraulic oil is supplied to the hydraulic actuator.   The hydraulic control device for a construction machine according to claim 1, wherein the bypass section is configured by a bypass valve that can be controlled by the controller.

Images