JP2010223390A - Hydraulic pump control device for construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the breakage of a driving shaft without suppressing the pump capacities of hydraulic pumps in the state of constructing two hydraulic pumps to be connected in parallel to one driving shaft. <P>SOLUTION: The left travel pump 12 and the dozer pump 13 are constructed to be connected in parallel to a common intermediate shaft. In this state, a proportional electromagnetic type variable relief valve 37 is provided as a relief valve for the dozer pump. During simultaneous operation of travel and dozer actuation, a controller 30 controls the set pressure of the variable relief valve 37 depending on the output torque of the left travel pump 12 to restrict the output torque of the dozer pump 13. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a hydraulic pump control device that controls output torque of a hydraulic pump as a hydraulic source of a hydraulic actuator in a construction machine such as a hydraulic excavator.

  The background art will be described using an excavator as an example. Here, a small excavator having no cabin is illustrated.

  In this excavator, as shown in FIG. 9, an upper swing body 2 is mounted on a lower traveling body 1 so as to be rotatable around a vertical axis. A boom 3, an arm 4, a bucket 5, and these drives are mounted on the upper swing body 2. A work attachment 9 having cylinders 6, 7, and 8 for each boom, arm, and bucket is attached.

  A dozer 10 is attached to the lower traveling body 1. The dozer 10 is driven up and down by a dozer cylinder, and performs a leveling operation for flattening the ground while traveling in a grounded state, a soil carrying operation for carrying the soil by pushing it, and the like.

  Here, if a hydraulic pump that is a supply source of pressure oil to the dozer cylinder is shared with a traveling hydraulic pump (hereinafter referred to as a traveling pump), the dozer 10 can be used during a dozer operation (simultaneous operation of traveling and dozer operation). This is not preferable because the amount of oil supplied to the traveling hydraulic motor changes each time the vehicle is moved up and down, and the traveling speed changes.

  For this reason, it is customary to use a pump (hereinafter referred to as a dozer pump) separate from the traveling pump for the dozer cylinder. In this case, in order to reduce the cost, an inexpensive gear pump is used as a traveling pump, unlike the main pump.

  FIG. 10 shows the hydraulic circuit of the dozer and the traveling system.

  11 is a hydraulic pump for right travel (hereinafter referred to as a right travel pump), 12 is a hydraulic pump for left travel (hereinafter referred to as a left travel pump), 13 is a dozer pump, each of which has a separate relief valve (set pressure is set). The maximum discharge pressure (maximum pump pressure) is regulated by the fixed fixed relief valves 14, 15 and 16.

  17 is a right travel remote control valve as a right travel operation means, 18 is a left travel remote control valve as a left travel operation means, 19 is a dozer remote control valve as a dozer operation means, and each of the remote control valves 17 to 19 runs right and left. The dozer control valves 20, 21, 22 are switched and actuated to control the operations of the right and left traveling motors 23, 24 and the dozer cylinder 25.

  For both traveling pumps 11 and 12, variable displacement pumps are used in which the tilt is changed by pump regulators 26 and 27 and the pump flow rate is changed, and the operation amounts (pilot pressures Pir and Pil) of both traveling remote control valves 16 and 17 are used. ) Is detected by the pilot pressure sensors 28 and 29 and input to the controller 30.

  Then, a signal corresponding to the operation amount is sent from the controller 30 to the pump regulators 26 and 27, whereby the pump tilt changes and the pump flow rate changes. That is, so-called positive control is performed in which the pump flow rate changes in accordance with the travel operation amount. In FIG. 10, T is a tank.

  The above technique is disclosed in Patent Document 1.

  FIG. 11 schematically shows a connection structure of the pumps 11 to 13 to the engine 31 as a power source.

  The input shaft 33 of the right traveling pump 11 is connected to the output shaft 32 of the engine 31, and the input shafts 35 and 36 of the left traveling pump 12 and the dozer pump 13 are splined or geared to the intermediate shaft 34 connected to the input shaft 33. They are connected in parallel to each other by coupling.

  Thus, the rotational force of the engine 31 is transmitted from the intermediate shaft 34 to the left traveling and dozer pumps 12 and 13 via the right traveling pump 11.

JP 2001-262630 A

  According to the configuration in which the left running and dozer pumps 12 and 13 are connected in parallel to the intermediate shaft 34, which is a common drive shaft, as described above, both pumps 12 and 12 are used during dozer operation, that is, during simultaneous operation of running and dozer operation. A total value of 13 output torques acts on the intermediate shaft 34.

  For this reason, when the output torque (pump pressure × pump flow rate) of both pumps 12 and 13 is increased and both the left travel and dozer relief valves 15 and 16 are simultaneously relieved or close to the situation, the intermediate shaft 34 May be damaged.

  Conventionally, as a countermeasure against this point, the maximum value of the total output torque is suppressed by reducing the capacity of the dozer pump 13 to prevent the intermediate shaft 34 from being damaged.

  However, since the pump flow rate of the dozer pump 13 is reduced as a negative effect, the speed at which the dozer is raised slows down and hinders the dozer work, and the life of the dozer cylinder 25 is shortened due to the occurrence of cavitation. It was.

  Therefore, the present invention is based on the premise that the first and second hydraulic pumps (left traveling and dozer hydraulic pumps in the above example) are connected in parallel to one drive shaft (same intermediate shaft). The present invention provides a hydraulic pump control device for a construction machine that can prevent a drive shaft from being damaged without reducing the pump capacity.

  According to the first aspect of the present invention, the first hydraulic pump serving as the hydraulic source of the first hydraulic actuator and the second hydraulic pump serving as the hydraulic source of the second hydraulic actuator are connected in parallel to one drive shaft, while the first hydraulic pump In a hydraulic pump control device for a construction machine in which the discharge pressure of one hydraulic pump is regulated by the first relief valve and the discharge pressure of the second hydraulic pump is regulated by the second relief valve, the second relief valve is used as the second relief valve. While a variable relief valve whose set pressure changes according to an input signal is used, data detection means for detecting data for obtaining the output torque of the first hydraulic pump, and control means for controlling the set pressure of the variable relief valve are provided. This control means prevents the drive shaft from being damaged by the load torque of the drive shaft during simultaneous operation of both the hydraulic actuators. It is one that is configured to control the set pressure of the variable relief valve to be equal to or less than a set value defined in.

  According to a second aspect of the present invention, in the configuration of the first aspect, as the first hydraulic pump, a variable displacement hydraulic pump in which a pump flow rate is changed according to an operation amount of an operation unit that operates a first hydraulic actuator, A fixed displacement hydraulic pump is used as the second hydraulic pump, and a proportional electromagnetic relief valve in which the set pressure continuously changes based on a signal from the control means is used as the variable relief valve. The detecting means detects the pump flow rate and the pump pressure of the first hydraulic pump, and the control means is stored in a map stored about the relationship between the output torque of the first hydraulic pump and the set pressure of the variable relief valve. Based on the detected pump flow rate and pump pressure, the set pressure of the variable relief valve is controlled in accordance with the output torque of the first hydraulic pump. Those composed urchin.

  According to a third aspect of the present invention, in the configuration of the first aspect, as the first hydraulic pump, a variable displacement hydraulic pump in which a pump flow rate is changed in accordance with an operation amount of an operation unit that operates a first hydraulic actuator, A fixed displacement hydraulic pump is used as the second hydraulic pump, and a proportional electromagnetic relief valve in which the set pressure continuously changes based on a signal from the control means is used as the variable relief valve. The detection means detects the pump pressure of the first hydraulic pump, and the control means detects the detection based on a map stored for the relationship between the pump pressure of the first hydraulic pump and the set pressure of the variable relief valve. The set pressure of the variable relief valve is controlled according to the pump pressure that is applied.

  According to a fourth aspect of the present invention, in the configuration of the second or third aspect, in place of the proportional electromagnetic relief valve as the variable relief valve, a set pressure is a two-stage setting based on a signal from the control means. And the control means is configured to set the relief valve to a low pressure when the output torque or pump pressure of the second hydraulic pump exceeds a stored threshold value. It has been done.

  The invention according to claim 5 is the construction according to any one of claims 1 to 4, wherein the lower traveling body is driven to travel by the left and right traveling motors, and the upper revolving body is rotatably mounted on the lower traveling body. A dozer which is provided on the lower traveling body and is driven up and down by a dozer cylinder, wherein the first hydraulic pump is a hydraulic power source for one of the left and right traveling motors, and the second hydraulic pump is a hydraulic power source for the dozer cylinder. The control means used is configured to control the set pressure of the variable relief valve when the both travel motors and the dozer cylinder are operated simultaneously.

  According to the present invention, on the premise that both the first and second hydraulic pumps are connected in parallel to one drive shaft, the variable relief valve is used as the relief valve of the second hydraulic pump (pump for dozer in claim 5). When the first hydraulic actuator (either the left or right traveling motor in claim 5) and the second hydraulic actuator (the dozer cylinder) are simultaneously operated by the control means, the total output torque of both hydraulic pumps is Since it is configured to control the set pressure of the variable relief valve so that the load torque of a certain drive shaft is less than or equal to the set value determined to protect the drive shaft, the drive shaft can be reliably prevented from being damaged. Can do.

  In addition, since the pump pressure of the second hydraulic pump is changed by changing the set pressure of the variable relief valve and the output torque of the pump is controlled, a hydraulic pump with a large capacity is used as the pump pressure. be able to.

  Therefore, for example, in the invention of claim 5 in which the first hydraulic pump is used for excavator travel and the second hydraulic pump is used for the dozer, a large flow rate can be secured for the dozer cylinder in a range where the load torque is small. For this reason, it is possible to ensure an appropriate speed when raising the dozer and to prevent cavitation.

  In this case, in a state where the load torque is increased and the output torque of the second hydraulic pump (dozer pump) is limited, only the raising speed of the dozer is reduced, and the pressure and flow rate of the first hydraulic pump for traveling are Since it does not change and the traveling operation can be ensured as usual, the influence on the dozer work can be reduced as compared with the case where the output torque of the first hydraulic pump is reduced.

  According to the second and third aspects of the invention, the proportional electromagnetic relief valve is used as the variable relief valve, and the output torque or pump pressure of the first hydraulic pump and the set pressure of the relief valve stored in the control means as a map are stored. Since the set pressure of the variable relief valve is controlled in accordance with the output torque or pump pressure of the second hydraulic pump based on the relationship, the torque control of the second hydraulic pump can be performed smoothly without waste.

  On the other hand, according to the invention of claim 4, in which a two-stage relief valve is used as the variable relief valve, the relief valve is inexpensive, so that the cost is low.

1 is a hydraulic circuit diagram showing a first embodiment of the present invention. It is a control block diagram of the embodiment. It is a figure which shows the relationship between the output torque of the left traveling pump in this embodiment, and the setting pressure of a variable relief valve. It is a flowchart for demonstrating the effect | action of the embodiment. It is a figure which shows the relationship between the pump pressure of the left traveling pump in 2nd Embodiment of this invention, and the setting pressure of a variable relief valve. It is a flowchart for demonstrating the effect | action of 2nd Embodiment. It is a hydraulic circuit diagram which shows 3rd Embodiment of this invention. It is a figure which shows the relationship between the output torque of the left traveling pump in 3rd Embodiment, and the setting pressure of a variable relief valve. It is a schematic side view of the shovel which is an example to which the present invention is applied. FIG. 2 is a hydraulic circuit diagram of a travel motor and a dozer cylinder in an excavator. It is a figure which shows typically the connection structure of each hydraulic pump in an excavator.

  In the following embodiments, the present invention is applied to excavator traveling and dozer circuits in accordance with the description of the background art.

  In the hydraulic circuit (FIGS. 1 and 7) in the following embodiments, the following points are the same as those of the conventional hydraulic circuit shown in FIG.

  (I) Variable displacement type right traveling pump 11 and left traveling pump (first hydraulic pump in claims) 12 and fixed displacement type dozer pump (usually a gear pump; second hydraulic pump in claims) 13 And the maximum pump pressure is regulated by separate relief valves.

  (Ii) Among these, the fixed relief valves 14 and 15 having a constant set pressure are used for the traveling pumps 11 and 12.

  (Iii) The control valves 20 to 22 are switched and operated by the right and left traveling and dozer remote control valves 17 to 19 to control the operations of the right and left traveling motors 23 and 24 and the dozer cylinder 25.

  (Iv) As the travel pumps 11 and 12, variable displacement pumps whose inclination is changed by the pump regulators 26 and 27 and the pump flow rate is changed are used, the operation amount of the travel remote control valves 17 and 18 (pilot pressure Pir) , Pil) is detected by the pressure sensors 28, 29 and input to the controller 30.

  (V) A so-called positive control in which the pump flow rate is changed according to the travel operation amount by sending a signal according to the operation amount from the controller 30 to the pump regulators 26 and 27 is performed.

  In the following embodiment, the pump connection structure shown in FIG. 11, that is, the input shaft 33 of the right traveling pump 11 is connected to the output shaft 32 of the engine 31 and the intermediate shaft 34 connected to the input shaft 33. The input shafts 35 and 36 of the left traveling pump 12 and the dozer pump 13 are connected to each other in parallel by spline coupling or gear coupling (the drive shaft of the claims), and the rotational force of the engine 31 is intermediated via the right traveling pump 11. It is assumed that the shaft 34 travels to the left and is transmitted to the dozer pumps 12 and 13.

1st Embodiment (refer FIGS. 1-4)
In the first embodiment, as the relief valve 37 for the dozer pump 13, a proportional electromagnetic variable relief valve in which the set pressure continuously changes in response to a signal from the controller 38 is used.

  Further, as data detection means for detecting data for obtaining the output torque of the left traveling pump 12, in addition to the left traveling pilot pressure sensor 29 for obtaining the flow rate of the pump 12, the pump pressure of the pump 12 is detected. A pump pressure sensor 39 is provided.

  On the other hand, a pilot pressure sensor 40 for detecting a dozer operation (pilot pressure Pid) is provided, and each sensor signal is input to the controller 38.

  The controller 38 performs the following operations.

  I. As shown in the control block diagram of FIG. 2, it is determined whether or not the traveling and dozer operation are simultaneously performed based on the right and left traveling pilot pressures Pir and Pil and the dozer pilot pressure Pid.

  II. At the same time, the pump flow rate of the left travel pump 12 is obtained based on the left travel pilot pressure Pil (left travel operation amount), and the output of the left travel pump 12 is calculated from the pump flow rate and the detected left travel pump pressure Pl. Find the torque.

  III. As shown in FIG. 3, the relationship between the output torque of the left traveling pump 12 and the set pressure of the variable relief valve 37 is stored as a map, and based on this map, the variable relief valve 37 has an output torque corresponding to the output torque of the left traveling pump 12. Controls the set pressure (dozer pump pressure).

  The operation of this point will be described with reference to the flowchart of FIG.

  It is determined whether or not there is a dozer operation in step S1 and whether or not there is a traveling operation in step S2. If both are YES (during simultaneous operation), the left traveling is performed based on the left traveling operation amount (pilot pressure Pil). The flow rate of the pump 12 is calculated (step S3).

  In step S4, the pump pressure of the left traveling pump 12 is read. In step S5, the output torque of the left traveling pump 12 is calculated from the pump pressure and the pump flow rate.

  In the subsequent step S6, the set pressure of the variable relief valve 37 is obtained based on the map of FIG. 3, and a relief pressure command is output to the variable relief valve 37 toward this set pressure.

  As a result, the maximum pump pressure of the dozer pump 13 decreases as the output torque of the left traveling pump 12 increases, and the output torque of the pump 13 is limited.

  Here, since the dozer pump 13 is a fixed displacement type, the pump flow rate is constant, and the upper limit value of the output torque T2 of the pump 13 is limited by limiting the maximum pump pressure as described above.

  Accordingly, the total value of the output torque of the dozer pump 13 and the output torque of the left traveling pump 12 (the load torque acting on the intermediate shaft 34 which is a common drive shaft) is set to prevent the intermediate shaft 34 from being damaged. In other words, so that the output torque of the dozer pump 13 is equal to or less than the value obtained by subtracting the output torque of the left traveling pump 12 from the set value, the left traveling pump output torque and the variable relief valve in FIG. By determining the relationship of the set pressure 37, it is possible to reliably prevent the intermediate shaft 34 from being damaged.

  Moreover, since the pump pressure of the dozer pump 13 is changed by changing the set pressure of the variable relief valve 37 and the output torque of the pump 13 is controlled, a large-capacity dozer pump 13 can be used.

  Therefore, in the embodiment, a large flow rate can be secured for the dozer cylinder 25 in a range where the load torque is small. For this reason, it is possible to ensure an appropriate speed when raising the dozer and to prevent cavitation.

  Further, in a state where the load torque is increased and the output torque of the dozer pump 13 is limited, the pressure and flow rate of the left traveling pump 12 are not changed only by decreasing the raising speed of the dozer 10 in FIG. Since this can be ensured, the influence on the dozer operation can be reduced as compared with the case where the pressure of the left traveling pump 12 is reduced.

Second embodiment (see FIGS. 5 and 6)
In the following embodiments, only differences from the first embodiment will be described.

  Since the hydraulic circuit configuration and the control block configuration are the same as those in FIGS.

  In the first embodiment, the output torque of the left traveling pump 12 is obtained, and the set pressure of the variable relief valve 37 is changed according to the output torque based on the map of FIG. 5, the relationship between the pump pressure of the left traveling pump 12 and the set pressure of the variable relief valve 37 is stored in the controller 38 as a map of FIG. 5, and the set pressure is changed based on the detected pump pressure. ing.

  The operation of this point will be described with reference to the flowchart of FIG.

  Steps S11 and S12 are the same as steps S1 and S2 in the first embodiment (FIG. 4). If it is determined that the operation is simultaneous, the pump pressure of the left traveling pump 12 is read in step S13, and in step S14. The set pressure of the variable relief valve 37 is calculated based on the map of FIG. 5, and the set pressure is commanded to the variable relief valve 37 in step S15.

  Also according to the second embodiment, basically the same effect as the first embodiment can be obtained.

  In addition, since the step of calculating the output torque of the left traveling pump 12 can be omitted, the program of the controller 38 is simplified.

Third embodiment (see FIGS. 7 and 8)
In the third embodiment, a two-stage relief valve is used as the variable relief valve 41.

  The variable (two-stage) relief valve 41 includes a hydraulic pilot-type relief valve main body 42 in which the set pressure changes in two steps of high pressure / low pressure according to the pilot pressure, and a pilot hydraulic pressure source 44 with respect to the relief valve main body 42. The electromagnetic switching valve 43 that supplies / shuts off the pilot pressure is controlled by the controller 38.

  That is, in the torque control system of the first embodiment or the pressure control system of the second embodiment, when the output torque or pump pressure of the left traveling pump 12 exceeds the stored threshold value X of FIG. The setting pressure of the stage relief valve 41 is configured to be switched from a high pressure to a low pressure.

  According to the third embodiment, since the set pressure changes only in two stages of high pressure / low pressure, the work amount of the dozer pump 13 is wasted compared to both the first and second embodiments, but the variable relief valve 41. Is inexpensive and has the advantage of low cost.

  In the above embodiment, the left traveling pump 12 and the dozer pump 13 are assumed to be connected in parallel to the intermediate shaft 34 in FIG. 11, but the right traveling pump 11 and the dozer pump 13 are connected to the intermediate shaft 34 in parallel. A configuration may be assumed.

  In addition, the present invention is not limited to a pump drive system having a connection structure in which two hydraulic pumps are connected in parallel to a common drive shaft, or other excavators or crushers configured based on an excavator. Can be widely applied to construction machinery.

DESCRIPTION OF SYMBOLS 1 Lower traveling body 2 Upper revolving body 10 Dozer 11 Right traveling pump 12 Left traveling pump (first hydraulic pump)
13 Dozer pump (second hydraulic pump)
DESCRIPTION OF SYMBOLS 15 Relief valve for left travel pumps 24 Left travel motor 25 Dozer cylinder 29 Left travel pilot pressure sensor as data detection means 34 Intermediate shaft which is a common drive shaft 37 Variable relief valve 38 Controller (control means)
39 Pump pressure sensor as data detection means 40 Pilot pressure sensor 41 Two-stage relief valve

Claims (5)

  A first hydraulic pump that is a hydraulic source of the first hydraulic actuator and a second hydraulic pump that is a hydraulic source of the second hydraulic actuator are connected in parallel to one drive shaft, while the discharge pressure of the first hydraulic pump is In the hydraulic pump control device for a construction machine in which the discharge pressure of the second hydraulic pump is regulated by the second relief valve by the first relief valve, the set pressure changes as an input signal from the outside as the second relief valve. While a variable relief valve is used, it comprises data detection means for detecting data for obtaining the output torque of the first hydraulic pump, and control means for controlling the set pressure of the variable relief valve. When the hydraulic actuators are operated simultaneously, the load torque of the drive shaft is set to prevent damage to the drive shaft Hydraulic pump control system for a construction machine characterized in that it is configured to control the set pressure of the variable relief valve to be equal to or less than.   As the first hydraulic pump, a variable displacement hydraulic pump whose pump flow rate changes in accordance with an operation amount of an operating means for operating a first hydraulic actuator, a fixed displacement hydraulic pump as the second hydraulic pump, and the variable As the relief valve, a proportional electromagnetic relief valve whose set pressure continuously changes continuously based on a signal from the control means is used, respectively, while the data detection means includes a pump flow rate and a pump of the first hydraulic pump. And the control means obtains the pressure from the detected pump flow rate and pump pressure based on a stored map of the relationship between the output torque of the first hydraulic pump and the set pressure of the variable relief valve. 2. The configuration according to claim 1, wherein the set pressure of the variable relief valve is controlled in accordance with an output torque of the first hydraulic pump. Hydraulic pump control system for a construction machine.   As the first hydraulic pump, a variable displacement hydraulic pump whose pump flow rate changes in accordance with an operation amount of an operating means for operating a first hydraulic actuator, a fixed displacement hydraulic pump as the second hydraulic pump, and the variable As the relief valve, a proportional electromagnetic relief valve whose set pressure continuously changes continuously based on a signal from the control means is used, while the data detection means detects the pump pressure of the first hydraulic pump. The control means sets the set pressure of the variable relief valve according to the detected pump pressure based on a map stored about the relationship between the pump pressure of the first hydraulic pump and the set pressure of the variable relief valve. The hydraulic pump control device for a construction machine according to claim 1, wherein the hydraulic pump control device is configured to control.   As the variable relief valve, instead of the proportional electromagnetic relief valve, a two-stage relief valve in which the set pressure changes in two stages of high pressure and low pressure based on a signal from the control means is used. The construction machine according to claim 2 or 3, wherein the relief valve is set to a low pressure when the output torque or pump pressure of the second hydraulic pump exceeds a stored threshold value. Hydraulic pump control device.   A lower traveling body that is driven by left and right traveling motors, an upper revolving body that is rotatably mounted on the lower traveling body, and a dozer that is provided on the lower traveling body and is driven up and down by a dozer cylinder; The first hydraulic pump is used as a hydraulic power source for one of the left and right traveling motors, the second hydraulic pump is used as a hydraulic power source for the dozer cylinder, and the control means is used during simultaneous operation of the both traveling motors and the dozer cylinder. The hydraulic pump control device for a construction machine according to any one of claims 1 to 4, wherein the set pressure of the variable relief valve is controlled.

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