JP4773989B2 - Torque control device for 3-pump system for construction machinery - Google Patents

Description

  The present invention relates to a torque control device for a three-pump system for construction machinery, and in particular, includes at least three variable displacement hydraulic pumps driven by one prime mover (engine), and the absorption torque of these three hydraulic pumps is The present invention relates to a torque control device for a three-pump system for a construction machine such as a hydraulic excavator that is controlled so as not to exceed an output torque of an engine.

  As a hydraulic drive device for a construction machine such as a hydraulic excavator, there is a three-pump system that includes three hydraulic pumps driven by a single engine and that drives a plurality of hydraulic actuators by pressure oil discharged from these three hydraulic pumps. One known example is described in Patent Document 1. The three-pump system described in Patent Literature 1 controls the maximum absorption of the first and second hydraulic pumps by controlling the capacities of the first and second hydraulic pumps based on the discharge pressures of the first and second hydraulic pumps. A first regulator that controls the absorption torque of the first and second hydraulic pumps so that the torque does not exceed an assigned maximum absorption torque of the first and second hydraulic pumps, and a third hydraulic pump based on the discharge pressure of the third hydraulic pump And a second regulator for controlling the absorption torque of the third hydraulic pump so that the maximum absorption torque of the third hydraulic pump does not exceed the allocated maximum absorption torque of the third hydraulic pump. The first regulator has spring means acting in the capacity increasing direction of the first and second hydraulic pumps, and the control characteristics (torque control characteristics) of the maximum absorption torque of the first and second hydraulic pumps are set by the spring means. is doing. The first regulator has a pressure receiving portion that acts in the capacity decreasing direction of the first and second hydraulic pumps, and guides the discharge pressure of the third hydraulic pump to the pressure receiving portion via the pressure reducing valve, and then guides it to the pressure receiving portion. Control is performed so that the pressure applied does not exceed a predetermined pressure set in the pressure reducing valve. As a result, when the discharge pressure of the third hydraulic pump increases, the maximum absorption torque (assigned maximum absorption torque) of the first and second hydraulic pumps is reduced until the discharge pressure of the third hydraulic pump reaches a predetermined pressure. Then, the total absorption torque of the first, second and third hydraulic pumps is controlled. Here, the predetermined pressure set in the pressure reducing valve is the minimum discharge pressure (absorption by the second regulator) in the discharge pressure range of the third hydraulic pump in which absorption torque control (also referred to as input torque limit control) by the second regulator is performed. The maximum discharge pressure in the discharge pressure range of the third hydraulic pump in which torque control is not performed).

JP 2002-242904 A

  In the conventional three-pump system as described in Patent Document 1, when the discharge pressure of the third hydraulic pump is low, the absorption torque that is not used in the third hydraulic pump can be used on the first and second hydraulic pump sides. Thus, the output torque of the engine can be used effectively. However, since the torque control characteristic set by the spring means does not coincide with the constant torque curve, the allocated maximum absorption torque of the first and second hydraulic pumps is not fully utilized, and the engine output torque is effectively used. There was room for further improvement from the viewpoint.

  That is, in the first regulator, the control characteristics of the maximum absorption torque of the first and second hydraulic pumps are set by the spring means. This torque control characteristic is a characteristic represented by a polygonal line in the pump pressure-pump capacity diagram, and does not coincide with a constant torque curve represented by a hyperbola. Further, when the assigned maximum absorption torque of the first and second hydraulic pumps decreases due to the increase in the discharge pressure of the third pump, the broken line representing the torque control characteristic in the pump pressure-pump capacity diagram shows the pump capacity. Therefore, the difference value with respect to the constant torque curve also changes. Therefore, when the absorption torques of the first and second hydraulic pumps are controlled based on the torque control characteristic set by the spring means, the allocated maximum absorption torque cannot be used for the difference value with respect to the constant torque curve.

  It is an object of the present invention to efficiently allocate the maximum absorption torque allocated to the first and second hydraulic pumps in a three-pump system that increases or decreases the maximum absorption torque allocated to the first and second hydraulic pumps according to the discharge pressure of the third hydraulic pump. It is an object of the present invention to provide a torque control device for a three-pump system for a construction machine that can be used well and can achieve further effective use of engine output torque.

  (1) In order to achieve the above object, the present invention provides a prime mover, variable displacement first and second hydraulic pumps driven by the prime mover, and variable displacement third hydraulic pressure driven by the prime mover. By controlling the capacities of the first and second hydraulic pumps based on the discharge pressures of the pump and the first and second hydraulic pumps, the maximum absorption torque of the first and second hydraulic pumps can be set to the first and second hydraulic pumps. A first regulator that controls the absorption torque of the first and second hydraulic pumps so as not to exceed an allocated maximum absorption torque of the second hydraulic pump; and a capacity of the third hydraulic pump based on a discharge pressure of the third hydraulic pump And a second regulator for controlling the absorption torque of the third hydraulic pump by controlling the first hydraulic pump, and the first regulator sets torque control characteristics of the first and second hydraulic pumps. In the torque control device for a three-pump system for construction machinery having a spring means, a first pressure sensor for detecting a discharge pressure of the first hydraulic pump, a second pressure sensor for detecting a discharge pressure of the second hydraulic pump, A third pressure sensor for detecting a discharge pressure of the third hydraulic pump; and when the discharge pressure of the third hydraulic pump is equal to or lower than a predetermined pressure, the first and the second hydraulic pumps increase as the discharge pressure of the third hydraulic pump increases. Based on the first control means for controlling the first regulator to reduce the assigned maximum absorption torque of the second hydraulic pump, and the discharge pressures of the first to third hydraulic pumps detected by the first to third pressure sensors. The torque control characteristics of the first and second hydraulic pumps are adjusted so that the maximum absorption torque of the first and second hydraulic pumps approaches the assigned maximum absorption torque. It obtains a first torque correction value for correcting the absorption torque obtained Ri assumed and a second control means for controlling the first regulator on the basis of the first torque correction value.

  Thus, when the assigned maximum absorption torque of the first and second hydraulic pumps is controlled by the first control means, the first torque correction value is obtained by the second control means, and the first torque correction value is calculated based on the first torque correction value. By controlling the regulator, the difference in torque control characteristics with respect to the constant torque curve of the assigned maximum absorption torque of the first and second hydraulic pumps is corrected. Therefore, the assigned maximum absorption torque of the first and second hydraulic pumps is efficiently used. The engine output torque can be utilized more effectively.

  (2) In the above (1), preferably, the second control means is configured such that the discharge pressure and the first torque of the first and second hydraulic pumps corresponding to a plurality of discharge pressure ranges of the third hydraulic pump. A plurality of torque correction tables in which a relationship with a correction value is set, and one of the plurality of torque correction tables is selected according to a discharge pressure of the third hydraulic pump detected by the third pressure sensor; The first torque correction value is obtained with reference to the discharge pressures of the first and second hydraulic pumps detected by the first and second pressure sensors in the selected torque correction table.

  (3) In the above (1) or (2), preferably, the speed of the prime mover is controlled based on command means for commanding the target speed of the prime mover and the target speed commanded by the command means. And a motor control device, wherein the second control means calculates a reference torque for the first to third hydraulic pumps based on a target rotational speed commanded by the command means, and the first torque is calculated based on the first torque. A target absorption torque for controlling the absorption torque of the first and second hydraulic pumps is obtained by adding a torque correction value, and the first regulator is controlled so as to obtain this target absorption torque.

  (4) In the above (1) or (2), preferably, the first regulator arranges the spring means so as to act in a capacity increasing direction of the first and second hydraulic pumps, and the first regulator The first and second hydraulic pumps have a plurality of pressure receiving portions that act in a capacity decreasing direction, and the first control unit is configured to perform the third hydraulic pressure when the discharge pressure of the third hydraulic pump is equal to or lower than the predetermined pressure. A pressure reducing valve for outputting the discharge pressure of the pump as it is and reducing the discharge pressure of the third hydraulic pump to the predetermined pressure when the discharge pressure of the third hydraulic pump exceeds the predetermined pressure; A second control unit configured to calculate a target absorption torque for controlling the absorption torque of the first and second hydraulic pumps based on the first torque correction value; and to convert the target absorption torque into a hydraulic signal. Electromagnetic ratio A discharge pressure of the first and second hydraulic pumps to at least one of the plurality of pressure receiving portions of the first regulator, and another one of the plurality of pressure receiving portions to the first control Configured as a part of the means, the output pressure of the pressure reducing valve is guided to the pressure receiving part, and another one of the plurality of pressure receiving parts is configured as a part of the second control means, and the pressure receiving part includes the Leads the output pressure of the proportional solenoid valve.

  (5) In the above (1) or (2), preferably, the commanding means for commanding the target rotational speed of the prime mover, and the rotational speed of the prime mover based on the target rotational speed commanded by the commanding means. A motor controller for controlling the engine; and a rotational speed sensor for detecting an actual rotational speed of the motor, wherein the second control unit is configured to control the first to third based on the target rotational speed commanded by the command unit. A reference torque for the hydraulic pump is calculated, and a second torque correction value for speed sensing control is calculated from a deviation between the target rotational speed commanded by the command means and the actual rotational speed of the prime mover detected by the rotational speed sensor. And a target absorption torque for controlling the absorption torque of the first and second hydraulic pumps by adding the second torque correction value and the first torque correction value to the reference torque. Look, for controlling the first regulator to the target absorption torque is obtained.

  According to the present invention, in the three-pump system that increases or decreases the allocated maximum absorption torque of the first and second hydraulic pumps according to the discharge pressure of the third hydraulic pump, the allocated maximum absorption torque of the first and second hydraulic pumps is efficiently used. It can be used well, and the engine output torque can be used more effectively.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing the whole of a three-pump system for a construction machine provided with a torque control device according to an embodiment of the present invention. This embodiment is intended for a hydraulic excavator as a construction machine.

  In FIG. 1, a three-pump system for a construction machine according to the present embodiment includes a prime mover 1, a variable displacement first hydraulic pump 2, a second hydraulic pump 3, and a third hydraulic pump 4 driven by the prime mover 1. Three main pumps, a fixed displacement pilot pump 5 driven by the prime mover 1, a control valve unit 6 connected to the first, second and third hydraulic pumps 2, 3 and 4, and a control valve unit A plurality of hydraulic actuators 7, 8, 9, 10, 11, 12,.

  The control valve unit 6 has three valve groups 6a, 6b and 6c corresponding to the first, second and third hydraulic pumps 2, 3 and 4, and each of the three valve groups 6a, 6b and 6c is plural. Are supplied from the first, second and third hydraulic pumps 2, 3, 4 to the plurality of hydraulic actuators 7, 8, 9, 10, 11, 12,. The oil flow (direction and flow rate) is controlled. The flow control valves of the three valve groups 6a, 6b and 6c are known center bypass types, and the corresponding hydraulic actuator operating means (operating lever device) is not operated, and the flow control valves are in the neutral position. In some cases, the discharge lines 2a, 3a, 4a of the first, second and third hydraulic pumps 2, 3, 4 are communicated with the tank. At this time, the discharge pressures of the first, second and third hydraulic pumps 2, 3 and 4 are reduced to the tank pressure.

  The plurality of hydraulic actuators 7, 8, 9, 10, 11, 12,... Include, for example, a swing motor of an excavator, an arm cylinder, a left and right traveling motor, a bucket cylinder, and a boom cylinder. For example, the hydraulic actuator 7 is a swing motor. The hydraulic actuator 8 is an arm cylinder, the hydraulic actuator 9 is a left traveling motor, the hydraulic actuator 10 is a right traveling motor, the hydraulic actuator 11 is a bucket cylinder, and the hydraulic actuator 12 is a boom cylinder.

  Main relief valves 15, 16, 17 are provided in the discharge lines 2 a, 3 a, 4 a of the first, second and third hydraulic pumps 2, 3, 4, and a pilot relief valve 18 is provided in the discharge line 5 a of the pilot pump 5. Is provided. The main relief valves 15, 16, and 17 regulate the discharge pressure of the first, second, and third hydraulic pumps 2, 3, and 4, and set the maximum pressure of the main circuit. The pilot relief valve 18 regulates the maximum discharge pressure of the pilot pump 5 and sets the pressure of the pilot hydraulic source.

  The prime mover 1 is a diesel engine, and the diesel engine (hereinafter simply referred to as an engine) 1 is provided with a dial type rotation speed command operation device 21 and an engine control device 22. The rotational speed command operating device 21 is command means for commanding the target rotational speed of the engine 1, and the engine control device 22 includes a controller 23, a governor motor 24, and a fuel injection device (governor) 25. The controller 23 receives a command signal from the rotation speed command operating device 21, performs a predetermined calculation process, and outputs a drive signal to the governor control motor 24. The governor control motor 24 rotates in accordance with the drive signal, and controls the fuel injection amount of the fuel injection device 25 so that the target rotational speed commanded by the rotational speed command operating device 21 is obtained.

  The torque control device according to the present embodiment is provided in such a three-pump system, and controls the capacity of the first and second hydraulic pumps 2 and 3 (the displacement volume or the inclination of the swash plate). The first regulator 31 that controls the absorption torque (consumed torque) of the first and second hydraulic pumps 2 and 3 and the capacity of the third hydraulic pump 4 (the displacement volume or the tilt of the swash plate) are controlled. When the second regulator 32 that controls the absorption torque (consumption torque) of the third hydraulic pump 4 and the discharge pressure of the third hydraulic pump 4 are below a predetermined pressure (P2 in FIG. 3) set by the spring 33a, When the discharge pressure of the third hydraulic pump 4 is output as it is and the discharge pressure of the third hydraulic pump 4 exceeds a predetermined pressure (P2 in FIG. 3) set by the spring 33a, the discharge pressure of the third hydraulic pump 4 is set to the predetermined pressure. A pressure reducing valve 33 for reducing the pressure to output, pressure sensors 34a, 34b, 34c for detecting the discharge pressures of the first to third hydraulic pumps 2, 3, 4 respectively, an electromagnetic proportional valve 35, and the controller 23 And.

  The first regulator 31 includes springs 31a and 31b that act in the direction of increasing the capacity of the first and second hydraulic pumps 2 and 3, and four pressure receiving parts that act in the direction of decreasing the capacity of the first and second hydraulic pumps 2 and 3. 31c, 31d, 31e, 31f. The discharge pressures of the first and second hydraulic pumps 2 and 3 are introduced into the pressure receiving portions 31c and 31d through the pilot lines 37 and 38, and the output pressure (control pressure) of the electromagnetic proportional valve 35 is oil in the pressure receiving portion 31e. The pressure is introduced through the passage 39a, and the output pressure of the pressure reducing valve 33 is introduced into the pressure receiving portion 31f through the oil passage 39b. The springs 31 a and 31 b and the pressure receiving portions 31 e and 31 f have a function of setting the maximum absorption torque of the first and second hydraulic pumps 2 and 3. With such a configuration, the first regulator 31 has a maximum absorption torque (assignment) set by the control pressure that the absorption torque of the first and second hydraulic pumps 2 and 3 is guided to the springs 31a and 31b and the pressure receiving portions 31e and 31f. The capacities of the first and second hydraulic pumps 2 and 3 are controlled so as not to exceed the maximum absorption torque.

  The springs 31a and 31b have a function of setting torque control characteristics of the first and second hydraulic pumps 2 and 3, and the pressure reducing valve 33 and the pressure receiving portion 31f are configured so that the discharge pressure of the third hydraulic pump 4 is the pressure reducing valve 33. The maximum absorption torque (assigned maximum absorption torque) of the first and second hydraulic pumps 2 and 3 as the discharge pressure of the third hydraulic pump 4 rises when the pressure is below the predetermined pressure (P2 in FIG. 3) The pressure regulator 31e has a function of correcting the difference between the torque control characteristic set by the springs 31a and 31b and a constant torque curve (torque correction control). ing.

  The second regulator 32 includes a spring 32a that acts in the direction of increasing the capacity of the third hydraulic pump 4, and a pressure receiving portion 32b that acts in the direction of decreasing capacity of the third hydraulic pump 4, and the pressure receiving portion 31b includes a third hydraulic pressure. The discharge pressure of the pump 4 is introduced through the pilot line 40. The spring 32 a has a function of setting the maximum absorption torque (assigned maximum absorption torque) of the third hydraulic pump 4. With such a configuration, the second regulator 32 controls the capacity of the third hydraulic pump 4 so that the absorption torque of the third hydraulic pump 4 does not exceed the maximum absorption torque set by the spring 32a.

  The pressure sensors 34 a, 34 b, 34 c output detection signals corresponding to the discharge pressures of the first to third hydraulic pumps 2, 3, 4, respectively, and these detection signals are input to the controller 23. The controller 23 performs predetermined arithmetic processing and outputs a drive signal to the electromagnetic proportional valve 35. The electromagnetic proportional valve 35 generates a control pressure corresponding to the drive signal from the controller 23 using the discharge pressure of the pilot pump 5 as a base pressure, and this control pressure is sent to the pressure receiving portion 31e of the first regulator 31 via the signal line 39. Led. Thereby, the 1st regulator 31 adjusts the maximum absorption torque of a 1st and 2nd hydraulic pump according to the control pressure guide | induced to the pressure receiving part 31e.

  FIG. 2 shows the discharge pressure (average value) of the first and second hydraulic pumps 2 and 3 by the first regulator 31 and the capacity of the first and second hydraulic pumps 2 and 3 when the torque correction control of the present invention is not performed. It is a figure which shows the relationship with (the displacement volume or inclination of a swash plate).

  In FIG. 2, broken lines A, B, and C are torque control characteristics set by the springs 31a and 31b, and a broken line A indicates that the hydraulic actuator related to the third hydraulic pump 4, for example, the hydraulic actuator 12 is not operating. When the discharge pressure of the third hydraulic pump 4 is reduced to the minimum pressure P0 (see FIG. 3), the broken line B indicates that the discharge pressure of the third hydraulic pump 4 is the minimum pressure P0 (see FIG. 3). Absorption torque control start pressure by the second regulator 32 (minimum discharge pressure of the third hydraulic pump 4 for which the absorption torque control by the second regulator 32 is implemented) P2 (see FIG. 3) and an intermediate pressure P1 (see FIG. 3) ) And the broken line C are those when the discharge pressure of the third hydraulic pump 4 is at P2.

  When the discharge pressure of the third hydraulic pump 4 is at the minimum pressure P0, the capacities of the first and second hydraulic pumps change as follows based on the torque control characteristic of the broken line A (hereinafter referred to as characteristic line A as appropriate). To do.

  When the average value of the discharge pressures of the first and second hydraulic pumps 2 and 3 is within the range of P0 to P1A, the absorption torque control is not performed, and the capacity of the first and second hydraulic pumps 2 and 3 is the maximum capacity. It is on the characteristic line L1 and is the maximum (constant). At this time, the absorption torque of the first and second hydraulic pumps 2 and 3 increases as their discharge pressures increase. When the average value of the discharge pressures of the first and second hydraulic pumps 2 and 3 exceeds P1A, the absorption torque control is performed, and the capacities of the first and second hydraulic pumps 2 and 3 decrease along the characteristic line A. As a result, the absorption torque of the first and second hydraulic pumps 2 and 3 is controlled so as not to exceed the prescribed torque Ta (the maximum absorption torque assigned to the first and second hydraulic pumps 2 and 3) represented by the constant torque curve TA. The In this case, the pressure P1A is the start pressure of the absorption torque control by the first regulator 31, and P1A to Pmax are the discharge pressure ranges of the first and second hydraulic pumps 2 and 3 in which the absorption torque control by the first regulator 31 is performed. It is. Pmax is the maximum value of the average value of the discharge pressures of the first and second hydraulic pumps 2 and 3, and is a value corresponding to the relief set pressure of the main relief valves 15 and 16. When the discharge pressures of the first and second hydraulic pumps 2 and 3 increase to Pmax, the main relief valves 15 and 16 are operated, and further increase in pump discharge pressure is limited.

  Here, the output pressure of the pressure reducing valve 33 is introduced into the pressure receiving portion 31f of the first regulator 31 through the oil passage 39b. The pressure reducing valve 33 outputs the discharge pressure of the third hydraulic pump 4 as it is until the discharge pressure of the third hydraulic pump 4 reaches a predetermined pressure set by the spring 33a. When the pressure exceeds the predetermined pressure, the discharge pressure of the third hydraulic pump 4 is reduced to the predetermined pressure and output. The output pressure of the pressure reducing valve 33 is introduced in a direction to reduce the set value of the maximum absorption torque of the first and second hydraulic pumps 2 and 3 in the pressure receiving portion 31f. As a result, when the discharge pressure of the third hydraulic pump 4 increases, the absorption torque control characteristic line shifts in the horizontal axis direction as indicated by the broken lines A, B, and C, and the first regulator 31 starts the absorption torque control accordingly. The pressure changes (decreases) from P1A to P1B and P1C, and the discharge pressure range in which the absorption torque control by the first regulator 31 is performed changes from P1A to Pmax to P1A to Pmax and P1A to Pmax. Accordingly, the assigned maximum absorption torque of the first and second hydraulic pumps 2 and 3 decreases from Ta to Tb and Tc.

  In the pressure reducing valve 33, the predetermined pressure set by the spring 33a is set to coincide with P2, which is the minimum discharge pressure of the third hydraulic pump 4 for which the absorption torque control by the second regulator 32 is performed.

  FIG. 3 is a diagram showing the relationship between the discharge pressure of the third hydraulic pump 4 by the second regulator 32 and the capacity of the third hydraulic pump 4 (displacement volume or swash plate tilt). In FIG. 3, a solid line D is a torque control characteristic set by the spring 32a.

  When the discharge pressure of the third hydraulic pump 4 is within the range of P0 to P2, the absorption torque control is not performed, and the capacity of the third hydraulic pump 4 is on the maximum capacity characteristic line L2 and is maximum (constant). . At this time, the absorption torque of the third hydraulic pump 4 increases as the discharge pressure increases. When the discharge pressure of the third hydraulic pump 4 exceeds P2, absorption torque control is performed, and the capacity of the third hydraulic pump 4 decreases along the characteristic line of the solid line D. Thus, the absorption torque of the third hydraulic pump 4 is controlled so as not to exceed the specified torque Td (the maximum absorption torque assigned to the third hydraulic pump) represented by the constant torque curve TD. In this case, the pressure P2 is the starting pressure of the absorption torque control by the second regulator 32, and P2 to Pmax are the discharge pressure range of the third hydraulic pump 4 in which the absorption torque control by the second regulator 32 is performed. Pmax is the maximum value of the discharge pressure of the third hydraulic pump 4 and is a value corresponding to the relief set pressure of the main relief valve 17. When the discharge pressure of the third hydraulic pump 4 rises to Pmax, the main relief valve 17 is activated, and further increase in the pump discharge pressure is restricted.

  FIG. 4 is a functional block diagram showing processing functions related to the torque control device of the controller 23. The controller 23 includes a pump base torque calculator 42, an average pump discharge pressure calculator 43a, a correction torque selector 43b, a first correction torque calculator 44a, a second correction torque calculator 44b, and a third correction torque calculator. 44c, the 1st addition part 45 and the 2nd addition part 46, the solenoid valve output pressure calculating part 47, and the solenoid valve drive current calculating part 48 are provided.

  The pump base torque calculation unit 42 calculates the total maximum absorption torque that can be used by the three pumps of the first, second, and third hydraulic pumps 2, 3, and 4 as the pump base torque (reference torque) Tr. The target rotational speed command signal is input from the rotational speed command operating device 21 and is referred to a table stored in the memory, and the pump base torque Tr corresponding to the target rotational speed is calculated. The relationship between the target rotational speed and the pump base torque Tr is set in the memory table so that the pump base torque Tr decreases as the target rotational speed decreases.

  Here, the absorption torque of the third hydraulic pump 4 when the discharge pressure of the third hydraulic pump 4 is at P1 is Tb2, and the absorption torque of the third hydraulic pump 4 when the discharge pressure of the third hydraulic pump 4 is at P2. Is Tc2, the pump base torque (reference torque) Tr has the following relationship with respect to the specified torques Ta, Tb, Tc and the absorption torques Tb2, Tc2.

Tr = Ta
= Tb + Tb2
= Tc + Tc2
FIG. 5 is a diagram showing the relationship between the engine output torque Te and the pump base torque (pump maximum absorption torque) Tr. The output torque Te of the engine 1 decreases as the engine speed decreases. The pump maximum absorption torque Tr needs to be within the range of the output torque Te of the engine 1. Therefore, the pump maximum absorption torque Tr also decreases as the target rotational speed decreases.

  The average pump discharge pressure calculation unit 43a receives discharge pressure detection signals of the first and second hydraulic pumps 2 and 3 from the pressure sensors 34a and 34b, and averages the discharge pressures of the first and second hydraulic pumps 2 and 3. Calculate the value.

  The correction torque selector 43b selects one of the first to third correction torque calculators 44a, 44b, 44c according to the discharge pressure of the third hydraulic pump (hereinafter referred to as Pp3), and the selected correction torque An average value of the discharge pressures of the first and second hydraulic pumps 2 and 3 calculated by the average pump discharge pressure calculation unit 43a (hereinafter referred to as an average discharge pressure, which is appropriately denoted by Pp12) is output to the calculation unit. The correction torque selector 43b selects one of the first to third correction torque calculators 44a, 44b, 44c as follows according to the discharge pressure Pp3 of the third hydraulic pump.

(1) P0 ≦ Pp3 ≦ P01 → select first correction torque calculator 44a (2) P01 <Pp3 ≦ P12 → select second correction torque calculator 44b (3) P12 <Pp3 → third correction torque calculator 44c Here, P01 is an arbitrary pressure in the range of P0 <P01 <P1, and P12 is an arbitrary pressure in the range of P1 <P12 <P2.

  When the discharge pressure Pp3 of the third hydraulic pump 4 is in the range of P0 ≦ Pp3 ≦ P01, the first correction torque calculator 44a is a broken line A with respect to the specified torque Ta represented by the constant torque curve TA shown in FIG. The difference value of the absorption torque based on the torque control characteristic is calculated as a torque correction value.

  That is, the first correction torque calculation unit 44a inputs the average discharge pressure Pp12 of the first and second hydraulic pumps 2 and 3, and refers to the first torque correction table T1 stored in the memory, and calculates the average thereof. A first torque correction value Tm1 corresponding to the discharge pressure Pp12 is calculated. In the first torque correction table T1, the following relationship between the average discharge pressure Pp12 and the first torque correction value Tm1 is set.

  6A is a diagram showing the relationship between the prescribed torque Ta represented by the constant torque curve TA shown in FIG. 2 and the absorption torque based on the torque control characteristic of the broken line A. FIG.

  As shown in FIG. 6A, when the average discharge pressure Pp12 of the first and second hydraulic pumps 2 and 3 is in the range of P0 to P1A, the maximum absorption torque of the first and second hydraulic pumps 2 and 3 is As the average discharge pressure Pp12 increases, it increases proportionally (straight line E1). When the average discharge pressure Pp12 of the first and second hydraulic pumps 2 and 3 exceeds P1A, the absorption torque control based on the broken line A in FIG. 2 is performed, and the maximum absorption torque of the first and second hydraulic pumps 2 and 3 is shown in FIG. Control is performed based on the torque control characteristic represented by the two broken lines A (curve E2).

  In the first regulator 31, the torque control characteristic represented by the polygonal line A in FIG. 2 is set by the springs 31a and 31b, and the polygonal line A of this torque control characteristic does not coincide with the constant torque curve TA represented by the hyperbola. . For this reason, there is a region indicated by a hatched portion E3 between the absorption torque of the curve E2 corresponding to the broken line A and the absorption torque Ta of the constant torque curve TA, and the region of the hatched portion E3 is the first and second hydraulic pumps. Reference numerals 2 and 3 denote torque portions that have not been used up and are areas that can be corrected.

  FIG. 6B is a diagram showing the relationship between the average discharge pressure Pp12 and the absorption torque at the shaded portion E3 in FIG. 6A, and the curve M1 corresponds to the curve E2 in FIG. 6A. In the first torque correction table T1, a curve M1 shown in FIG. 6B is set as a relationship between the average discharge pressure Pp12 and the first torque correction value Tm1.

  When the discharge pressure Pp3 of the third hydraulic pump 4 is in the range of P01 <Pp3 ≦ P12, the second correction torque calculator 44b is a broken line B with respect to the specified torque Tb represented by the constant torque curve TB shown in FIG. The difference value of the absorption torque based on the torque control characteristic is calculated as a torque correction value.

  That is, the second correction torque calculation unit 44b inputs the average discharge pressure Pp12 of the first and second hydraulic pumps 2 and 3, and refers to the second torque correction table T2 stored in the memory, and calculates the average thereof. A second torque correction value Tm2 corresponding to the discharge pressure Pp12 is calculated. In the second torque correction table T2, the following relationship between the average discharge pressure Pp12 and the second torque correction value Tm2 is set.

  FIG. 7A is a diagram showing the relationship between the prescribed torque Tb represented by the constant torque curve TB shown in FIG. 2 and the absorption torque based on the torque control characteristic of the broken line B. FIG.

  As shown in FIG. 7A, when the average discharge pressure Pp12 of the first and second hydraulic pumps 2 and 3 is in the range of P0 to P1B, the maximum absorption torque of the first and second hydraulic pumps 2 and 3 is As the average discharge pressure Pp12 increases, it increases proportionally (straight line F1). When the average discharge pressure Pp12 of the first and second hydraulic pumps 2 and 3 exceeds P1B, the absorption torque control based on the broken line B in FIG. 2 is performed, and the maximum absorption torque of the first and second hydraulic pumps 2 and 3 is as shown in FIG. Is controlled based on the torque control characteristic represented by the polygonal line B (curve F2).

  In the first regulator 31, as in the case of the broken line A in FIG. 2, the broken line B of the torque control characteristic does not coincide with the constant torque curve TB represented by the hyperbola, and the absorption torque and torque of the curve F2 corresponding to the broken line B There is a correctable region between the absorption torque Tb of the constant curve TB and indicated by the hatched portion F3, where the first and second hydraulic pumps 2 and 3 are not used up.

  In FIG. 2, a broken line B of the torque control characteristic set when the discharge pressure Pp3 of the third hydraulic pump 4 is P1 is set when the discharge pressure Pp3 of the third hydraulic pump 4 is P0. While the curve A of the torque control characteristic is shifted in the horizontal axis direction, the curves TA and TB of the maximum absorption torques Ta and Tb are hyperbolic curves, and when the maximum absorption torque changes from Ta to Tb, The positional relationship with respect to the axis and the horizontal axis changes equally. For this reason, the difference between the constant torque curves TA and TB changes when the polygonal line A is set and when the polygonal line B is set. That is, the curve F2 in FIG. 7A does not match the curve E2 in FIG. 6A, and the hatched portion F3 does not match the hatched portion E3.

  FIG. 7B is a diagram showing the relationship between the average discharge pressure Pp12 and the absorption torque at the shaded portion F3 in FIG. 7A, and the curve M2 corresponds to the curve F2 in FIG. 7A. In the second torque correction table T2, a curve M2 shown in FIG. 7B is set as the relationship between the average discharge pressure Pp12 and the second torque correction value Tm2.

  When the discharge pressure Pp3 of the third hydraulic pump 4 is in the range of P13 <Pp3, the third correction torque calculator 44c is a torque of the broken line C with respect to the specified torque Tc represented by the constant torque curve TC shown in FIG. The absorption torque difference value based on the control characteristics is calculated as a torque correction value.

  That is, the third correction torque calculation unit 44c inputs the average discharge pressure Pp12 of the first and second hydraulic pumps 2 and 3, and refers to the third torque correction table T3 stored in the memory to calculate the average thereof. A third torque correction value Tm3 corresponding to the discharge pressure Pp12 is calculated. In the third torque correction table T3, the following relationship between the average discharge pressure Pp12 and the third torque correction value Tm3 is set.

  FIG. 8A is a diagram showing the relationship between the prescribed torque Tc represented by the constant torque curve TC shown in FIG. 2 and the absorption torque based on the torque control characteristic of the broken line C.

  As shown in FIG. 8A, when the average discharge pressure Pp12 of the first and second hydraulic pumps 2 and 3 is in the range of P0 to P1C, the maximum absorption torque of the first and second hydraulic pumps 2 and 3 is As the average discharge pressure Pp12 increases, it increases proportionally (straight line G1). When the average discharge pressure Pp12 of the first and second hydraulic pumps 2 and 3 exceeds P1C, the absorption torque control based on the broken line C in FIG. 2 is performed, and the maximum absorption torque of the first and second hydraulic pumps 2 and 3 is as shown in FIG. Is controlled based on the torque control characteristic represented by the polygonal line C (curve G2).

  In the first regulator 31, the torque control characteristic represented by the broken line C in FIG. 2 is set by the springs 31a and 31b, and the broken line C of this torque control characteristic does not coincide with the constant torque curve TC represented by the hyperbola. . Therefore, there is a region indicated by a hatched portion G3 between the absorption torque of the curve G2 corresponding to the broken line C and the absorption torque Tb of the constant torque curve TC, and the region of the hatched portion G3 is the first and second hydraulic pumps. Reference numerals 2 and 3 denote torque portions that have not been used up and are areas that can be corrected.

  In FIG. 2, a broken line C of the torque control characteristic set when the discharge pressure Pp3 of the third hydraulic pump 4 is P2 is set when the discharge pressure Pp3 of the third hydraulic pump 4 is P1. While the curve B of the torque control characteristic is further shifted in the horizontal axis direction, the curves TB and TC of the maximum absorption torques Tb and Tc are hyperbolic curves. 6 (a) and FIG. 7 (a) do not coincide with the curves E2 and F2, and the shaded portion G3 does not coincide with the shaded portions E3 and F3 of FIG. 6 (a) and FIG. 7 (a).

  FIG. 8B is a diagram showing the relationship between the average discharge pressure Pp12 and the absorption torque at the shaded portion G3 in FIG. 8A, and the curve M3 corresponds to the curve G2 in FIG. 8A. In the third torque correction table T3, a curve M3 shown in FIG. 8B is set as a relationship between the average discharge pressure Pp12 and the third torque correction value Tm3.

  The first addition unit 45 adds the calculation values of the first to third correction torque calculation units 44a, 44b, and 44c, thereby obtaining the torque correction value calculated by the correction torque calculation unit selected by the correction torque selection unit 43b. Output as a correction value Tm.

The second addition unit 46 adds the torque correction value Tm output from the first addition unit 45 to the pump base torque Tr calculated by the pump base torque calculation unit 42 and absorbs the first and second hydraulic pumps 2 and 3. A target absorption torque Tn for controlling the torque is calculated. In other words,
Tn = Tr + Tm
The solenoid valve output pressure calculation unit 47 calculates a control pressure for setting the target torque Tn as the maximum absorption torque of the first and second hydraulic pumps 2 and 3 in the first regulator 31, and the second addition The target absorption torque Tn obtained by the unit 46 is referred to a table stored in the memory, and the output pressure Pc of the electromagnetic proportional valve 35 corresponding to the target absorption torque Tn is calculated. In the memory table, the relationship between the target absorption torque Tn and the output pressure Pc is set so that the output pressure Pc decreases as the target absorption torque Tn increases.

  The solenoid valve drive current calculator 48 calculates the drive current Ic of the solenoid proportional valve 35 for obtaining the output pressure Pc of the solenoid proportional valve 35 obtained by the solenoid valve output pressure calculator 47, and the solenoid valve output pressure. The output pressure Pc of the electromagnetic proportional valve 35 obtained by the calculation unit 47 is referred to a table stored in the memory, and the drive current Ic of the electromagnetic proportional valve 35 corresponding to the output pressure Pc is calculated. In the memory table, the relationship between the output pressure Pc and the drive current Ic is set so that the drive current Ic increases as the output pressure Pc increases. This drive current Ic is amplified by an amplifier (not shown) and output to the electromagnetic proportional valve 35.

  In the above, the pressure reducing valve 33 and the pressure receiving portion 31f of the first regulator 31 are configured such that when the discharge pressure of the third hydraulic pump 4 rises when the discharge pressure of the third hydraulic pump 4 is equal to or lower than the predetermined pressure P2, The first control means for controlling the first regulator 31 so as to reduce the assigned maximum absorption torque of the second hydraulic pumps 2 and 3 is configured. The controller 23, the electromagnetic proportional valve 35, and the pressure receiving portion 31e of the first regulator 31 are pressure sensors. Maximum absorption torques of the first and second hydraulic pumps 2 and 3 based on the discharge pressures of the first to third hydraulic pumps 2, 3 and 4 detected by 34a, 34b and 34c (first to third pressure sensors). Is a first torque correction value for correcting the absorption torque obtained by the torque control characteristics of the first and second hydraulic pumps 2 and 3 so as to approach the assigned maximum absorption torque. Because, constituting the second control means for controlling the first regulator 31 on the basis of the first torque correction value.

  Next, the operation of the present embodiment configured as described above will be described.

  When one of the hydraulic actuators related to the first and second hydraulic pumps 2 and 3, for example, the hydraulic actuator 7 is operated, the pressure oil from the first hydraulic pump 2 is included in the valve group 6 a of the control valve unit 6. It is supplied to the hydraulic actuator 7 via the corresponding flow control valve. At this time, the discharge pressure of the first hydraulic pump 2 increases due to the load pressure of the hydraulic actuator 7, and the discharge pressure of the first hydraulic pump 2 is guided to the pressure receiving portion 31c of the first regulator 31, and the first and second hydraulic pressures are supplied. When the average discharge pressure of the pump 2 exceeds a predetermined value, the maximum absorption torque of the first and second hydraulic pumps 2 is controlled so that the capacity of the first hydraulic pump 2 is reduced. It is controlled not to exceed the assigned maximum absorption torque.

  When the hydraulic actuator related to the third hydraulic pump 4, for example, the hydraulic actuator 12 is operated, the discharge pressure of the third hydraulic pump is guided to the pressure receiving portion 31 f of the first regulator 31 via the pressure reducing valve 33. When the discharge pressure of the third hydraulic pump 4 is below the predetermined pressure P2 set in the pressure reducing valve 33, the maximum absorption of the first and second hydraulic pumps 2 and 3 as the discharge pressure of the third hydraulic pump 4 increases. The first regulator 31 is controlled to reduce the torque (assigned maximum absorption torque). As a result, when the discharge pressure of the third hydraulic pump 4 is lower than the predetermined pressure P2, the absorption torque that is not used by the third hydraulic pump 4 can be used by the first and second hydraulic pumps 2 and 3. Therefore, the output torque of the engine 1 can be used effectively.

  Further, when the first regulator 31 controls the absorption torque of the first and second hydraulic pumps 2 and 3 as described above, the controller 23 detects the first to third hydraulic pumps 2 detected by the pressure sensors 34a, 34b and 34c. The electromagnetic proportional valve 35 is controlled based on the discharge pressure of ˜4, and the first regulator 31 is controlled by guiding the output pressure of the electromagnetic proportional valve 35 to the pressure receiving portion 31 e of the first regulator 31. 2 The assigned maximum absorption torque of the hydraulic pumps 2 and 3 can be used efficiently.

  That is, when the discharge pressure Pp3 of the third hydraulic pump 4 is within the range of P0 ≦ Pp3 ≦ P01, the correction torque selection unit 43b of the controller 23 selects the first correction torque calculation unit 44a and calculates the first correction torque calculation. In the unit 44a, the first torque correction table T1 is referred to the average discharge pressure Pp12 of the first and second hydraulic pumps 2 and 3, and the first torque correction value Tm1 corresponding to the average discharge pressure Pp12 is calculated. The second addition unit 46 of the controller 23 calculates a value obtained by adding the first torque correction value Tm1 to the pump base torque Tr as the target absorption torque Tn, and drives the electromagnetic proportional valve 35 based on the target absorption torque Tn. Then, a control pressure corresponding to the pressure receiving portion 31e of the first regulator 31 is introduced. This control pressure acts against the urging force of the springs 31a and 31b of the first regulator 31, and the absorption torque of the first and second hydraulic pumps 2 and 3 is equal to the absorption torque of the hatched portion E3 in FIG. Control to increase. Thereby, the maximum absorption torque (for example, the maximum absorption torque based on the torque control characteristic of the broken line A in FIG. 2) of the first and second hydraulic pumps 2 and 3 is assigned the maximum absorption torque (for example, the prescribed torque of the constant torque curve TA in FIG. 2). Ta) is corrected to approach, and the assigned maximum absorption torque of the first and second hydraulic pumps 2 and 3 can be used efficiently.

  When the discharge pressure Pp3 of the third hydraulic pump 4 is within the range of P01 <Pp3 ≦ P12, the correction torque selection unit 43b of the controller 23 selects the second correction torque calculation unit 44b and the second correction torque calculation unit 44b. Then, the average discharge pressure Pp12 of the first and second hydraulic pumps 2 and 3 is referred to the second torque correction table T2, and the second torque correction value Tm2 corresponding to the average discharge pressure Pp12 is calculated. The second addition unit 46 of the controller 23 calculates a value obtained by adding the second torque correction value Tm2 to the pump base torque Tr as the target absorption torque Tn, and drives the electromagnetic proportional valve 35 based on the target absorption torque Tn. Then, a control pressure corresponding to the pressure receiving portion 31e of the first regulator 31 is introduced. This control pressure acts opposite to the biasing force of the springs 31a and 31b of the first regulator 31, and the absorption torque of the first and second hydraulic pumps 2 and 3 is equal to the absorption torque of the hatched portion F3 in FIG. Control to increase. Thereby, the maximum absorption torque (for example, the maximum absorption torque based on the torque control characteristic of the broken line B in FIG. 2) of the first and second hydraulic pumps 2 and 3 is assigned the maximum absorption torque (for example, the specified torque of the constant torque curve TB in FIG. 2). It is corrected to approach Tb), and the assigned maximum absorption torque of the first and second hydraulic pumps 2 and 3 can be used efficiently.

  When the discharge pressure Pp3 of the third hydraulic pump 4 is within the range of P13 <Pp3, the correction torque selection unit 43b of the controller 23 selects the third correction torque calculation unit 44c, and the third correction torque calculation unit 44c The average discharge pressure Pp12 of the first and second hydraulic pumps 2 and 3 is referred to the third torque correction table T3, and a third torque correction value Tm3 corresponding to the average discharge pressure Pp12 is calculated. The second addition unit 46 of the controller 23 calculates a value obtained by adding the third torque correction value Tm3 to the pump base torque Tr as the target absorption torque Tn, and drives the electromagnetic proportional valve 35 based on the target absorption torque Tn. Then, a control pressure corresponding to the pressure receiving portion 31e of the first regulator 31 is introduced. This control pressure acts opposite to the biasing force of the springs 31a and 31b of the first regulator 31, and the absorption torque of the first and second hydraulic pumps 2 and 3 is equal to the absorption torque of the hatched portion G3 in FIG. Control to increase. Thereby, the maximum absorption torque (for example, the maximum absorption torque based on the torque control characteristic of the broken line C in FIG. 2) of the first and second hydraulic pumps 2 and 3 is assigned the maximum absorption torque (for example, the prescribed torque of the constant torque curve TC in FIG. 2). Tc) is corrected so that the assigned maximum absorption torque of the first and second hydraulic pumps 2 and 3 can be used efficiently.

  As described above, according to the present embodiment, in the three-pump system that increases or decreases the allocated maximum absorption torque of the first and second hydraulic pumps 2 and 3 according to the discharge pressure of the third hydraulic pump 4, the first and second The allocated maximum absorption torque of the two hydraulic pumps 2 and 3 can be used efficiently, and the output torque of the engine 1 can be used more effectively.

  A second embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a block diagram showing the entire construction machine three-pump system provided with the torque control device according to the present embodiment, and FIG. 10 is a functional block diagram showing processing functions related to the torque control device of the controller. is there. In the figure, the same components as those shown in FIGS. 1 and 4 are denoted by the same reference numerals. The present embodiment uses the torque control function in the first embodiment, and adds a so-called speed sensing control function to the torque control function.

  9, in addition to the controller 23B, the first regulator 31, the second regulator 32, the pressure sensors 34a, 34b, and 34c, the pressure reducing valve 33, and the electromagnetic proportional valve 35, the torque control device according to the present embodiment further includes: A rotation speed sensor 51 for detecting the rotation speed of the engine 1 is provided.

  10, the controller 23B according to the present embodiment includes the components shown in FIG. 4 (pump base torque calculation unit 42, total pump discharge pressure calculation unit 43a, correction torque selection unit 43b, first correction torque calculation unit 44a. In addition to the second correction torque calculation unit 44b, the third correction torque calculation unit 44c, the first addition unit 45, the second addition unit 46, the electromagnetic valve output pressure calculation unit 47, the electromagnetic valve drive current calculation unit 48), subtraction A unit 52, a gain multiplication unit 53, and a third addition unit 54 are further provided.

  The subtraction unit 52 subtracts the target rotational speed from the actual rotational speed of the engine 1 detected by the rotational speed sensor 51, and calculates the rotational speed deviation ΔN.

  The gain multiplying unit 53 multiplies the rotational speed deviation ΔN calculated by the subtracting unit 52 by a correction torque gain (speed sensing control gain) KT for speed sensing control to calculate a torque correction value ΔN for speed sensing control.

The second addition unit 46 adds the torque correction value Tm output from the first addition unit 45 to the pump base torque Tr calculated by the pump base torque calculation unit 42 and absorbs the first and second hydraulic pumps 2 and 3. A first target absorption torque Tn0 for controlling the torque is calculated. In other words,
Tn0 = Tr + Tm
The third addition unit 54 adds the torque correction value ΔN of the speed sensing control calculated by the gain multiplication unit 53 to the first target absorption torque Tn0 calculated by the second addition unit 46, and calculates the second target absorption torque Tn. .

  The second target absorption torque Tn calculated in this way is converted into a drive signal for the electromagnetic proportional valve 35 by the solenoid valve output pressure calculator 47 and the solenoid valve drive current calculator 48 as in the first embodiment. A control pressure corresponding to the target absorption torque Tn is output from the proportional valve 35 and guided to the pressure receiving portion 31e of the first regulator. The first regulator 31 sets the maximum absorption torque to Tn and controls the absorption torque of the first and second hydraulic pumps 2 and 3 so as not to exceed Tn.

  The effects of torque reduction control and torque increase control by speed sensing control will be described with reference to FIG.

  FIG. 11 is a diagram showing the relationship between engine output torque, pump absorption torque, and speed sensing control. In the figure, a straight line DR is a characteristic line of a regulation region in which the fuel injection amount is controlled by the fuel injection device 25 when the target engine rotational speed is at the rated rotational speed Nrated, and the point P is the maximum in the regulation region. This is the fuel injection point. In the illustrated example, the fuel injection device 25 has a droop characteristic that controls the engine speed to increase as the engine load decreases from the maximum fuel injection point P. A straight line G is a characteristic line of the speed sensing control gain KT in the gain multiplication unit 53 of FIG.

<Decrease torque control>
Assume that the engine 1 and the first to third hydraulic pumps 2 to 4 are operating in a state where the output torque of the engine 1 and the absorption torques of the first to third hydraulic pumps 2 to 4 are balanced at the point M1 in FIG. . When the load (discharge pressure) of the first and second hydraulic pumps 2 and 3 or the third hydraulic pump 4 suddenly increases from this state, the rotational speed of the engine 1 becomes transient due to a delay in control of the fuel injection device 25. descend. In such a case, the subtraction unit 52 of FIG. 10 calculates the rotation speed deviation ΔN as a negative value, the gain multiplication unit 53 also calculates the torque correction value ΔT of the speed sensing control as a negative value, and the addition unit 54 By adding a torque correction value ΔT as a negative value to the first target absorption torque Tn0, a second target absorption torque Tn that is smaller than the first target absorption torque Tn0 by the absolute value of the torque correction value ΔT is calculated. As a result, the maximum absorption torque set in the first regulator 31 is reduced by ΔT, and the absorption torques of the first and second hydraulic pumps controlled by the first regulator 31 are similarly reduced (torque reduction control). That is, in FIG. 11, the operating point of the absorption torque control for the first to third hydraulic pumps 2 to 4 is the speed from the balance point M1 of the output torque of the engine 1 and the absorption torque of the first to third hydraulic pumps 2 to 4. It moves to the point M2 along the characteristic line G of the sensing control gain KT. As a result of the decrease in the absorption torque of the first to third hydraulic pumps 2 to 4 as described above, the rotational speed of the engine 1 can be quickly increased to prevent the engine performance from being lowered and the work performance can be improved.

<Increase torque control>
At the point M1 in FIG. 11 where the output torque of the engine 1 and the absorption torque of the first to third hydraulic pumps 2 to 4 are balanced, the subtraction unit 52 in FIG. 10 calculates the rotational speed deviation ΔN as a positive value, and gain The speed correction torque correction value ΔT calculated by the multiplication unit 53 is also calculated as a positive value, and the second target absorption torque Tn calculated by the addition unit 54 is greater than the first target absorption torque Tn0 by the torque correction value ΔT. Increases by the absolute value. As a result, the maximum absorption torque set in the first regulator 31 also increases by ΔT, and the absorption torques of the first and second hydraulic pumps controlled by the first regulator 31 also increase accordingly (increase torque control). . Thus, even when the base pump torque Tr is set with a margin with respect to the engine output torque Te, the maximum absorption torque of the first regulator 31 (absorption of the first and second hydraulic pumps) at the balance point M1 in the steady state. (Torque) can be controlled to be larger than the base pump torque Tr, and the engine output can be effectively used. Moreover, since the operating point of the engine 1 approaches the maximum fuel injection point P, fuel efficiency can be improved.

  Also in the present embodiment configured as described above, the assigned maximum absorption torque of the first and second hydraulic pumps 2 and 3 is increased or decreased according to the discharge pressure of the third hydraulic pump 4 as in the first embodiment. In the three-pump system, the assigned maximum absorption torque of the first and second hydraulic pumps 2 and 3 can be used efficiently, and the output torque of the engine 1 can be used more effectively.

  In the present embodiment, the rotational speed sensor 51 is provided, and the arithmetic functions of the subtraction unit 52, the gain multiplication unit 53, and the addition unit 54 are added to the controller 23B. When the prime mover is overloaded, it is possible to prevent engine performance from being lowered by reducing torque control and improve work performance. When the engine speed deviation ΔN is positive, the engine is controlled by increasing torque. The output can be effectively used and the fuel consumption can be improved.

  Further, in the present embodiment, the same control means (controller 23B) is used to calculate the three pump torque control and the speed sensing control, and both are controlled by one control signal. One set of devices such as the pressure receiving portion 31e of the first regulator 31 to which the control pressure from the electromagnetic proportional valve 35 is guided is required, and speed sensing control can be performed in the three-pump torque control with a simple configuration.

  A third embodiment of the present invention will be described with reference to FIG. FIG. 12 is a diagram showing a regulator portion of the torque control device according to the third embodiment. In the figure, the same components as those shown in FIG. In the present embodiment, the first regulator and the second regulator are provided with a function of controlling the capacity (discharge flow rate) of the first to third hydraulic pumps according to the required flow rate.

  In FIG. 12, the first and second hydraulic pumps 2 and 3 include a first regulator 131, and the third hydraulic pump 4 includes a second regulator 132. The first and second hydraulic pumps 2 and 3 adjust the displacement volume (capacity) by adjusting the tilt angle of the swash plates 2b and 3b, which are displacement displacement variable members, by the first regulator 131, and according to the required flow rate. While controlling the pump discharge flow rate, the pump absorption torque is adjusted. The third hydraulic pump 4 adjusts the displacement volume (capacity) by adjusting the tilt angle of the swash plate 4b, which is a displacement displacement variable member, by the second regulator 131, and controls the pump discharge flow rate according to the required flow rate. Adjust pump absorption torque.

  The first regulator 131 includes a tilt control actuator 112 that operates the swash plates 2 b and 3 b, a torque control servo valve 113 that controls the actuator 112, and a position control valve 114. The tilt control actuator 112 is linked to the swash plates 2b and 3b and has a pump tilt control spool 112a having different pressure receiving areas at the pressure receiving portions provided at both ends, and a small area pressure receiving portion side of the pump tilt control spool 112a. A tilt control increasing torque receiving chamber 112b is provided, and a tilt control decreasing torque receiving chamber 112c is provided on the large area pressure receiving portion side. The tilt control increasing torque receiving chamber 112b is connected to the discharge line 5a of the pilot pump 5 via an oil passage 135, and the tilt control decreasing torque receiving chamber 112c is connected to the discharge passage 5a of the pilot pump 5 with an oil passage 135 and torque control. The servo valve 113 and the position control valve 114 are connected.

  The torque control servo valve 113 includes a torque control spool 113a, springs 113b1 and 113b2 located on one end side of the torque control spool 113a, a PQ control pressure receiving chamber 113c located on the other end side of the torque control spool 113a, and a first torque reduction. A control pressure receiving chamber 113d and a second reduced torque control pressure receiving chamber 113e are provided. The discharge lines 2a and 2b of the first and second hydraulic pumps 2 and 3 are provided with a shuttle valve 136 for detecting the discharge pressure on the high pressure side of the first and second hydraulic pumps 2 and 3, and the PQ control pressure receiving chamber 113c is The first reduced torque control pressure receiving chamber 113d is connected to the electromagnetic proportional valve 35 output port via the oil passage 39, and the second reduced torque control pressure receiving chamber 113e is connected to the output port of the shuttle valve 136 via the signal line 115. The pressure reducing valve 33 is connected to the output port via a control oil passage 39b. As described above, the electromagnetic proportional valve 35 is operated by a drive signal (electric signal) from the controller 23 (FIG. 1), and the pressure reducing valve 33 is a predetermined pressure (discharge pressure of the third hydraulic pump 4 is set by a spring 33a ( When P2) is exceeded, the discharge pressure of the third hydraulic pump 4 is reduced to the predetermined pressure and output.

  The position control valve 114 includes a position control spool 114a, a weak spring 114b for position holding located on one end side of the position control spool 114a, and a control pressure receiving chamber 114c located on the other end side of the position control spool 114a. Yes. A hydraulic signal 116 corresponding to the operation amount (required flow rate) of the operation system related to the first and second hydraulic pumps 2 and 3 is guided to the control pressure receiving chamber 114c. The hydraulic signal 116 can be generated by various known methods. For example, the highest operating pilot pressure among the operating pilot pressures generated by the operating lever device may be selected and used as the hydraulic signal 116. Further, when the flow control valve is a center bypass type valve, a throttle is provided on the downstream side of the center bypass line, the pressure upstream of the throttle is taken out as a negative control pressure, and the negative control pressure is inverted as a hydraulic signal 116. Also good.

  The pump tilt control spool 112a controls the tilt angle (capacity) of the swash plate of the first and second hydraulic pumps 2 and 3 by the pressure balance of the pressure oil in the pressure receiving chambers 112b and 112c. The discharge pressure on the high pressure side of the first and second hydraulic pumps 2 and 3 is guided to the PQ control pressure receiving chamber 113c of the torque control servo valve 113, and the torque control spool 113a moves to the left in the drawing as the pressure increases. . As a result, the discharge oil of the pilot pump 5 flows into the pressure receiving chamber 112c, the pump tilt control spool 112a is moved to the right in the figure, and the swash plates 2b, 3b of the first and second hydraulic pumps 2, 3 are reduced in volume by pushing the pump. Drive in the direction to reduce the pump absorption torque by reducing the pump capacity. As the discharge pressures of the first and second hydraulic pumps 2 and 3 become lower, the reverse operation is performed, and the swash plates 2b and 3b of the first and second hydraulic pumps 2 and 3 are driven in the direction of increasing the displacement of the pump. Then, the pump absorption volume is increased to increase the pump absorption torque.

  The torque control characteristics of the torque control servo valve 113 with respect to the first and second hydraulic pumps 2 and 3 are determined by the pressures led to the springs 113b1 and 113b2 and the first and second reduced torque control pressure receiving chambers 113d and 113e. As described above, the torque control characteristic shifts according to the output pressure 33 (see FIG. 2). Further, by controlling the electromagnetic proportional valve 35 and changing its output pressure, as described above, the hatched portion E3 in FIG. 6 (a), the hatched portion F3 in FIG. 7 (a), and the hatched portion in FIG. 8 (a). Control is performed to increase the absorption torque of the first and second hydraulic pumps 2 and 3 by the absorption torque of the part G3. Thereby, the maximum absorption torque (for example, the maximum absorption torque based on the torque control characteristic of the broken line A in FIG. 2) of the first and second hydraulic pumps 2 and 3 is assigned the maximum absorption torque (for example, the prescribed torque of the constant torque curve TA in FIG. 2). Ta) is corrected to approach, and the assigned maximum absorption torque of the first and second hydraulic pumps 2 and 3 can be used efficiently.

  The second regulator 131 includes a tilt control actuator 212 that operates the swash plate 4 b, a torque control servo valve 213 that controls the actuator 212, and a position control valve 214. The tilt control actuator 212, the torque control servo valve 213, and the position control valve 214 are configured similarly to the tilt control actuator 112, the torque control servo valve 113, and the position control valve 114 of the first regulator 131. Equivalent parts are shown with reference numerals in which numbers in the 10s are changed to numbers in the 200s. However, since the torque control servo valve 113 does not require adjustment of the set torque, there is no equivalent to the first and second reduced torque control pressure receiving chambers 113d and 113e.

  The operation of the second regulator 132 is substantially the same as the operation of the first regulator 131. However, the absorption torque control characteristic is determined by the spring 213b of the torque control servo valve 213 and is constant (see FIG. 3).

  In the present embodiment configured as described above, the first regulator 131 and the second regulator 132 have a function of controlling the capacity (discharge flow rate) of the first to third hydraulic pumps 2 to 4 according to the required flow rate. The same effects as those of the first embodiment can be obtained.

  Although several embodiments of the present invention have been described above, various modifications can be made to these embodiments within the spirit of the present invention.

  For example, in the above embodiment, the first and third torque correction values Tm1 to Tm3 set in the first to third torque correction tables T1 to T3 of the first to third correction torque calculators 44a to 44c are set to the first. However, it may be a function of the sum of the discharge pressures of the first and second hydraulic pumps (total discharge pressure).

  In the above embodiment, when the pressure reducing valve 33 and the pressure receiving portion 31f are provided and the discharge pressure of the third hydraulic pump 4 is equal to or lower than the predetermined pressure (P2 in FIG. 3), the discharge pressure of the third hydraulic pump 4 is The first regulator 31 is controlled so as to reduce the maximum absorption torque (assigned maximum absorption torque) of the first and second hydraulic pumps 2 and 3 as it increases, but the target absorption torque calculated in the controller 23 (or 23B). The same function may be provided by including the information in Tn (or Tn1), controlling the electromagnetic proportional valve, and guiding the output pressure to the pressure receiving portion 31e. For example, in the first embodiment shown in FIG. 4, the absorption torque of the third hydraulic pump is calculated based on the discharge pressure of the third hydraulic pump 4 detected by the pressure sensor 34c in the controller 23, and this absorption torque is calculated. Is subtracted from the pump base torque Tr calculated by the pump base torque calculation unit 42 to obtain the assigned maximum absorption torque of the first and second hydraulic pumps, and the torque correction output from the first addition unit 45 to this assigned maximum absorption torque The target absorption torque Tn for controlling the absorption torque of the first and second hydraulic pumps 2 and 3 is calculated by adding the value Tm. Accordingly, the same control can be performed without providing the pressure reducing valve 33 and the pressure receiving portion 31f, and the circuit configuration can be simplified.

  Furthermore, in the above embodiment, the controller 23 (or 23B) divides the discharge pressure of the third hydraulic pump 4 into three pressure ranges, and three correction torque calculation units 44a, 44b, 44c are provided correspondingly. However, the number of divisions of the discharge pressure of the third hydraulic pump 4 and the number of correction torque calculation units are not limited to three, and may be two or four or more. When the number of divisions of the discharge pressure of the third hydraulic pump 4 and the number of correction torque calculation units are two, the absorption torque of the difference between the constant torque curve and the torque control characteristic is compared to the three cases of the above embodiment. Although the accuracy of correction for using is reduced, the utilization efficiency of the assigned maximum absorption torque is improved as compared with the conventional technique that does nothing. When the number of divisions of the discharge pressure of the third hydraulic pump 4 and the number of correction torque calculation units are four or more, the correction accuracy for using the absorption torque of the difference between the constant torque curve and the torque control characteristic is further improved. Thus, the allocated maximum absorption torque can be used more efficiently.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the whole 3 pump system for construction machines provided with the torque control apparatus concerning the 1st Embodiment of this invention. Relationship between discharge pressure (average value) of first and second hydraulic pumps by first regulator and capacity (displacement volume or tilt of swash plate) of first and second hydraulic pumps when control of the present invention is not performed FIG. It is a figure which shows the relationship between the discharge pressure of the 3rd hydraulic pump by a 2nd regulator, and the capacity | capacitance (a displacement or inclination of a swash plate) of a 3rd hydraulic pump. It is a functional block diagram which shows the processing function regarding the torque control apparatus of a controller. It is a figure which shows the relationship between an engine output torque and a pump base torque (reference torque). It is a figure for demonstrating the relationship between the total discharge pressure set to a 1st torque correction table, and a 1st torque correction value, Fig.6 (a) is represented by the torque fixed curve TA shown in FIG. FIG. 6B is a diagram showing the relationship between the prescribed torque Ta and the absorption torque based on the torque control characteristic of the broken line A, and FIG. 6B is a diagram showing the relationship between the average discharge pressure Pp12 at the hatched portion E3 in FIG. It is. It is a figure for demonstrating the relationship between the total discharge pressure set to a 2nd torque correction table, and a 2nd torque correction value, Fig.7 (a) is represented by the constant torque curve TB shown in FIG. FIG. 7B is a diagram showing the relationship between the prescribed torque Tb and the absorption torque based on the torque control characteristic of the broken line B, and FIG. 7B is a diagram showing the relationship between the average discharge pressure Pp12 at the hatched portion F3 in FIG. It is. It is a figure for demonstrating the relationship between the total discharge pressure set to a 3rd torque correction table, and a 3rd torque correction value, and Fig.8 (a) is represented by the torque fixed curve TC shown in FIG. It is a figure which shows the relationship between the regulation torque Tc and the absorption torque based on the torque control characteristic of the broken line C, and is a figure which shows the relationship between the average discharge pressure Pp12 and the absorption torque of the shaded part G3 of Fig.8 (a). It is a block diagram which shows the whole 3 pump system for construction machines provided with the torque control apparatus concerning the 2nd Embodiment of this invention. It is a functional block diagram which shows the processing function regarding the torque control apparatus of the controller in 2nd Embodiment. It is a figure which shows the relationship between engine output torque and pump absorption torque, and speed sensing control. It is a figure which shows the regulator part of the torque control apparatus concerning the 3rd Embodiment of this invention.

Explanation of symbols

1 prime mover (engine)
2 1st hydraulic pump 3 2nd hydraulic pump 4 3rd hydraulic pump 6 Control valve units 6a, 6b, 6c Valve groups 7-12 Multiple hydraulic actuators 15, 16, 17 Main relief valve 18 Pilot relief valve 21 Speed command operation Device 22 Engine control device 23, 23B Controller 24 Governor control motor 25 Fuel injection device 31 First regulator 31a, 31b Spring 31c, 31d, 31e, 31f Pressure receiving portion 32 Second regulator 33 Pressure reducing valve 34a, 34b, 34c Pressure sensor 35 Electromagnetic Proportional valve 42 Pump base torque calculation unit 43a Average pump discharge pressure calculation unit 43b Correction torque selection unit 44a First correction torque calculation unit 44b Second correction torque calculation unit 44c Third correction torque calculation unit 45 First addition unit 46 Second addition Part 47 Solenoid valve output pressure Calculation unit 48 the solenoid valve drive current calculating section 51 speed sensor 52 subtracting unit 53 gain multiplication unit 54 third adding unit 131 first regulator 132 second regulator 112, 212 tilting control actuator 113, 213 Torque control servo valve 113
113b1, 113b2 Spring 113d First reduced torque control pressure receiving chamber 113e Second reduced torque control pressure receiving portions 114, 214 Position control valve

Claims (5)

Prime mover,
Variable displacement first and second hydraulic pumps driven by the prime mover;
A variable displacement third hydraulic pump driven by the prime mover;
By controlling the capacities of the first and second hydraulic pumps based on the discharge pressures of the first and second hydraulic pumps, the maximum absorption torque of the first and second hydraulic pumps becomes the first and second hydraulic pumps. A first regulator for controlling the absorption torque of the first and second hydraulic pumps so as not to exceed an allocated maximum absorption torque of the pump;
A second regulator for controlling the absorption torque of the third hydraulic pump by controlling the capacity of the third hydraulic pump based on the discharge pressure of the third hydraulic pump;
In the torque control device for a three-pump system for construction machinery, the first regulator has spring means for setting torque control characteristics of the first and second hydraulic pumps.
A first pressure sensor for detecting a discharge pressure of the first hydraulic pump;
A second pressure sensor for detecting a discharge pressure of the second hydraulic pump;
A third pressure sensor for detecting a discharge pressure of the third hydraulic pump;
When the discharge pressure of the third hydraulic pump is less than or equal to a predetermined pressure, the first regulator is configured to reduce the assigned maximum absorption torque of the first and second hydraulic pumps as the discharge pressure of the third hydraulic pump increases. First control means for controlling;
Based on the discharge pressures of the first to third hydraulic pumps detected by the first to third pressure sensors, the first and second hydraulic pumps so that the maximum absorption torque approaches the allocated maximum absorption torque. Second control means for determining a first torque correction value for correcting the absorption torque obtained by the torque control characteristics of the first and second hydraulic pumps and controlling the first regulator based on the first torque correction value; A torque control device for a three-pump system for a construction machine. The torque control device for a three-pump system for construction machinery according to claim 1,
The second control means has a plurality of torque corrections that set a relationship between the discharge pressures of the first and second hydraulic pumps and the first torque correction values corresponding to a plurality of discharge pressure ranges of the third hydraulic pump. One of the plurality of torque correction tables is selected according to the discharge pressure of the third hydraulic pump detected by the third pressure sensor, and the first and second torque correction tables are selected in the selected torque correction table. A torque control device for a three-pump system for a construction machine, wherein the first torque correction value is obtained by referring to discharge pressures of the first and second hydraulic pumps detected by a pressure sensor. In the torque control device for a three-pump system for construction machinery according to claim 1 or 2,
Command means for commanding a target rotational speed of the prime mover;
A prime mover control device that controls the number of revolutions of the prime mover based on the target number of revolutions commanded by the command means;
The second control means calculates a reference torque for the first to third hydraulic pumps based on a target rotational speed commanded by the command means, and adds the first torque correction value to the reference torque. Torque control of a three-pump system for construction machinery characterized in that a target absorption torque for controlling the absorption torque of the first and second hydraulic pumps is obtained, and the first regulator is controlled so as to obtain this target absorption torque. apparatus. In the torque control device for a three-pump system for construction machinery according to claim 1 or 2,
The first regulator includes a plurality of pressure receiving portions arranged with the spring means acting in the capacity increasing direction of the first and second hydraulic pumps and acting in the capacity decreasing direction of the first and second hydraulic pumps. Have
The first control means outputs the discharge pressure of the third hydraulic pump as it is when the discharge pressure of the third hydraulic pump is below the predetermined pressure, and the discharge pressure of the third hydraulic pump is the predetermined pressure. A pressure reducing valve for reducing and outputting the discharge pressure of the third hydraulic pump to the predetermined pressure,
The second control means includes calculation means for calculating a target absorption torque for controlling the absorption torque of the first and second hydraulic pumps based on the first torque correction value, and the target absorption torque as a hydraulic signal. An electromagnetic proportional valve to convert,
The discharge pressures of the first and second hydraulic pumps are guided to at least one of the plurality of pressure receiving portions of the first regulator, and the other one of the plurality of pressure receiving portions is configured as a part of the first control means. Then, the output pressure of the pressure reducing valve is guided to the pressure receiving portion, and another one of the plurality of pressure receiving portions is configured as a part of the second control means, and the output pressure of the electromagnetic proportional valve is set in the pressure receiving portion. Torque control device for a three-pump system for construction machinery In the torque control device for a three-pump system for construction machinery according to claim 1 or 2,
Command means for commanding a target rotational speed of the prime mover;
A prime mover control device for controlling the rotational speed of the prime mover based on a target rotational speed commanded by the command means;
A rotation speed sensor for detecting an actual rotation speed of the prime mover;
The second control means calculates a reference torque for the first to third hydraulic pumps based on the target rotational speed commanded by the commanding means, and the target rotational speed commanded by the commanding means and the rotational speed. A second torque correction value for speed sensing control is calculated from a deviation from the actual rotational speed of the prime mover detected by a sensor, and the second torque correction value and the first torque correction value are added to the reference torque to calculate the second torque correction value. Torque control of a three-pump system for construction machinery characterized in that a target absorption torque for controlling the absorption torque of the first and second hydraulic pumps is obtained, and the first regulator is controlled so as to obtain this target absorption torque. apparatus.

Images