JP2011127569A - Assisted regeneration device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an assisted regeneration device reducing a drag loss of a regeneration motor or an assist pump. <P>SOLUTION: The assisted regeneration device 10 includes a motor generator 4 rotatively operating with electric energy, the regeneration motor 2 rotatively driving the motor generator 4 with the energy of working fluid in regeneration, and the assist pump 3 rotatively driven by the motor generator 4 to discharge the working fluid in assistance. The regeneration motor 2 includes a supply means supplying the working fluid between a cylinder block 42 and a port plate 47 and is configured to set the inclination angle of a swash plate 46 of the regeneration motor 2 at almost zero in assistance and to supply pressurized hydraulic oil between the swash plate 46 and the port plate 47 of the regeneration motor 2 in assistance. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an assist regeneration device that regenerates the energy of a working fluid in conjunction with a regeneration motor and an assist pump.

  As an assist regeneration device used for hydraulic work equipment such as a hydraulic excavator, there is one disclosed in Patent Document 1.

  This is because the working machine system actuator, the traveling system actuator, the first pump and the second pump that selectively supply hydraulic oil to the working machine system or the traveling system actuator, and the inertial energy to the working machine system actuator. And a variable capacity regenerative motor connected to the return path when potential energy is applied, and rotating together with the regenerative motor and operating oil in one or both of the first pump and the second pump. A variable capacity type assist pump that joins the motor, a motor generator that rotates together with the regenerative motor and the assist pump, and a power storage unit that stores electric power generated by the motor generator.

  Thereby, since the auxiliary pump is rotated by inertial energy or potential energy acting on the actuator of the work machine system, the load of the drive source can be reduced and the energy efficiency can be increased.

JP 2007-327527 A

  However, in the assist regeneration device described above, since the regeneration motor and the assist pump rotate together with the motor generator, the regeneration motor also rotates together when the motor generator assists the rotation of the assist pump. At this time, the displacement volume of the regenerative motor is controlled to be zero so that the hydraulic oil does not circulate through the regenerative motor. However, there is a problem in that a drag loss of the regenerative motor occurs even if the displacement volume is zero.

  In addition, when the regenerative motor regenerates the motor generator, the assist pump also rotates together. At this time, the displacement of the assist pump is controlled to be zero so that the assist pump does not discharge the hydraulic oil. However, there is a problem that drag loss of the assist pump occurs even if the displacement of the assist pump is zero.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an assist regeneration device that reduces drag loss of a regeneration motor or an assist pump.

  The present invention includes a motor generator that is rotated by electric energy, a regenerative motor that rotates the motor generator by the energy of the working fluid during regeneration, and an assist pump that is driven by the motor generator to discharge the working fluid during assist. An assist regenerative device, wherein the regenerative motor slidably contacts a cylinder block that is rotatably supported, a plurality of pistons accommodated in the cylinder block, a swash plate that reciprocates the pistons, and an end surface of the cylinder block. And a supply means for supplying a pressurized working fluid between the cylinder block and the port plate, and the inclination angle of the swash plate is made larger than zero during regeneration, while the inclination angle of the swash plate is made substantially zero during assistance. The cylinder block and port block are switched by the supply means. And a control means for increasing the pressure of the hydraulic fluid directed between the over bets were intended to comprise a.

  According to the present invention, when the motor generator assists the rotational drive of the assist pump, the regenerative motor rotates together with the assist pump. However, the inclination angle of the swash plate is switched to substantially zero, and the cylinder block and the port plate are A pressurized working fluid is supplied between them, and the cylinder block rotates in a state where the cylinder block is suspended and supported by the port plate via the working fluid. As a result, the regenerative motor reduces drag loss that occurs in the sliding portion between the cylinder block and the port plate during assist, and increases the operating efficiency of the assist regenerator.

The schematic side view of the excavation attachment of the hydraulic shovel which shows embodiment of this invention. The hydraulic circuit diagram of a fluid pressure control device. The schematic sectional drawing of an assist regeneration device similarly. The schematic sectional drawing of the assist regeneration apparatus which shows other embodiment.

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

(First embodiment)
FIG. 1 is a schematic side view showing a configuration of a excavation attachment 100 of a hydraulic excavator.

  The excavation attachment 100 includes a boom 101, an arm 102, and a bucket 103 for performing excavation work and the like, and these are driven by a boom cylinder 104, an arm cylinder 105, and a bucket cylinder 106, which are actuators. Each of the boom cylinder 104, the arm cylinder 105, and the bucket cylinder 106 is a hydraulic cylinder.

  The boom cylinder 104 has a piston rod 107 connected to the boom 101, and the boom 101 is driven by the movement and expansion / contraction of the piston rod 107.

  FIG. 2 is a schematic configuration diagram of a fluid pressure control device that controls the operation of the hydraulic excavator. In the present embodiment, an extension / contraction operation of a boom cylinder 104 that drives a boom (load) 101 of a hydraulic excavator will be described.

  The boom cylinder 104 is partitioned by the piston 108 into a rod side pressure chamber 104a and a bottom side pressure chamber 104b.

  The main pump 118 and the pilot pump 109 which are hydraulic sources are driven by an engine (not shown) mounted on the hydraulic excavator, and discharge hydraulic oil (working fluid). The engine is operated at a predetermined rotational speed and load with good operating efficiency.

  The hydraulic oil discharged from the main pump 118 is supplied to the rod side pressure chamber 104a or the bottom side pressure chamber 104b of the boom cylinder 104 via the main control valve 110. The main pump 118 and the main control valve 110 are connected by a main passage 111. Connected to the main passage 111 is a sub-passage 31 that guides hydraulic oil discharged from an assist pump 3 of the assist regeneration device 10 described later.

  The main control valve 110 and the rod side pressure chamber 104 a of the boom cylinder 104 are connected by a first passage 112. The main control valve 110 and the bottom pressure chamber 104b of the boom cylinder 104 are connected by a second passage 113. The return path 21 branches from the second path 113, and this return path 21 is connected to the regenerative motor 2 of the assist regenerative device 10. Hydraulic oil that flows out from the bottom-side pressure chamber 104 b when the boom cylinder 104 is contracted is supplied to the regenerative motor 2 through the second passage 113 and the return passage 21.

  The main control valve 110 performs switching operation by selectively introducing the discharge pressure of the pilot pump 109 as pilot pressure to the pilot chambers 110a and 110b via the electromagnetic switching valve 115. The switching of the pilot pressure by the electromagnetic switching valve 115 is performed by the controller 114 controlling the electromagnetic switching valve 115 based on a lever operation by a crew of the hydraulic excavator.

  The main control valve 110 has a contracted position a that contracts the boom cylinder 104, an extended position b that extends the boom cylinder 104, and a stop position c that holds the load of the boom cylinder 104.

  When the pilot pressure guided to the pilot chamber 110a is increased, the main control valve 110 is switched to the contracted position a, the hydraulic oil is supplied from the main pump 118 to the rod side pressure chamber 104a through the first passage 112, and the bottom The hydraulic oil in the side pressure chamber 104 b is returned to the tank T through the second passage 113. As a result, the piston 108 in the boom cylinder 104 moves downward in FIG. 2, the boom cylinder 104 contracts, and the boom 101 descends in the direction of the arrow 121 shown in FIG.

  On the other hand, when the pilot pressure guided to the pilot chamber 110b is increased, the main control valve 110 is switched to the extension position b, and hydraulic oil is supplied from the main pump 118 to the bottom pressure chamber 104b via the second passage 113. In addition, the hydraulic oil in the rod side pressure chamber 104 a is returned to the tank T through the first passage 112. As a result, the piston 108 in the boom cylinder 104 moves upward in FIG. 2, the boom cylinder 104 extends, and the boom 101 rises in the direction of the arrow 122 shown in FIG.

  When drain pressure is introduced as pilot pressure to both the pilot chambers 110a and 110b, the main control valve 110 is switched to the stop position c, the supply and discharge of hydraulic oil to the boom cylinder 104 is shut off, and the movement of the boom 101 Is stopped.

  In this way, the boom cylinder 104 that drives the boom 101 is subjected to a force for contracting the boom cylinder 104 by the weight of the boom 101 and the like. In the boom cylinder 104, the bottom side pressure chamber 104b is a load side pressure chamber in which the load pressure acts.

  The fluid pressure control device includes an assist regeneration device 10 that collects hydraulic energy of hydraulic oil flowing out of the boom cylinder 104 and assists the driving of the boom cylinder 104.

  The assist regenerative device 10 is provided with a regenerative motor 2, an assist pump 3, and a motor generator 4 on the same shaft, and these rotate in conjunction with each other at the same speed.

  The assist regeneration device 10 is not limited to this, and the regenerative motor 2, the assist pump 3, and the motor generator 4 may be configured to rotate at different speeds via a power transmission mechanism including gears and the like.

  The regenerative motor 2 and the assist pump 3 are of the variable capacity type in which the displacement volume can be changed by the capacity switching actuators 2a and 3a.

  A battery 5 is connected to the motor generator 4 via an inverter 6. The motor generator 4 is rotated by electric energy, and performs power generation that generates a rotational force by electric power and power generation that generates electric power by the rotational operation.

  The assist regenerative device 10 is used for recovering the hydraulic energy of hydraulic oil flowing out from the bottom-side pressure chamber 104b as electrical energy as necessary when the boom cylinder 104 is contracted, and when the boom cylinder 104 is extended. In response, assist that provides assisting force is performed.

  Hereinafter, the operation of the assist regeneration device 10 will be described in detail. In the following description, a decrease in load means a change in the direction in which the volume of the load side pressure chamber decreases, and an increase in load means a change in the direction in which the volume of the load side pressure chamber increases. Point to. Therefore, in the case of the boom cylinder 104, the decrease in load means that the boom cylinder 104 contracts and the boom 101 descends, and the increase in load means that the boom cylinder 104 extends and the boom 101 rises. Point to.

  First, regeneration by the assist regeneration device 10 performed as necessary when the load is lowered will be described.

  When a lever operation for contracting the boom cylinder 104 is performed by the crew of the excavator, the controller 114 switches the main control valve 110 to the contracted position a. As a result, the hydraulic oil discharged from the main pump 118 is supplied to the rod-side pressure chamber 104a, and the hydraulic oil in the bottom-side pressure chamber 104b is returned to the tank T through the second passage 113 and the throttle 110c.

  When the boom cylinder 104 is contracted in this way, the controller 114 determines, for example, that the charge amount of the battery 5 is smaller than the full charge amount, and performs regeneration by the assist regeneration device 10.

  As a control means, the controller 114 switches the capacity of the regenerative motor 2 largely via the capacity switching actuator 2a when it is determined that it is during regeneration. As a result, part of the hydraulic oil flowing out from the bottom pressure chamber 104b is supplied to the regenerative motor 2 via the return passage 21, and the regenerative motor 2 is rotated by the hydraulic oil. Driven by rotation. The electric power generated by the motor generator 4 is sent to the battery 5 via the inverter 6 and stored in the battery 5. Thus, the assist regeneration device 10 recovers the pressure energy of the hydraulic oil flowing out from the bottom side pressure chamber 104b as electric energy.

  During this regeneration, the controller 114 switches the capacity of the assist pump 3 to substantially zero via the capacity switching actuator 3a. As a result, the displacement of the assist pump 3 becomes substantially zero and the hydraulic oil is not discharged, and the driving loss of the assist pump 3 during regeneration is reduced.

  On the other hand, the controller 114 switches the capacity of the regenerative motor 2 to substantially zero when, for example, it is determined that the battery charge amount has reached the full charge amount and regeneration is not necessary. Thereby, the displacement volume of the regenerative motor 2 becomes substantially zero and the hydraulic oil does not circulate, and all the hydraulic oil flowing out from the bottom side pressure chamber 104b is returned to the tank T through the second passage 113 and the throttle 110c, There is no regeneration.

  Next, the assist by the assist regeneration device 10 performed as necessary when the load increases will be described.

  When a lever operation for extending the boom cylinder 104 is performed by a crew member of the hydraulic excavator, the controller 114 switches the main control valve 110 to the extended position b. As a result, the hydraulic oil discharged from the main pump 118 is supplied to the bottom side pressure chamber 104b, and the hydraulic oil in the rod side pressure chamber 104a is returned to the tank T through the first passage 112.

  Here, the controller 114 assists when the flow rate of the hydraulic oil supplied to the bottom side pressure chamber 104b is insufficient with only the discharge flow rate of the main pump 118 by the driving force of the engine, such as when the boom cylinder 104 is desired to be quickly extended. And assist by the assist regeneration device 10 is performed.

  When the controller 114 determines that it is an assist time, the controller 114 greatly switches the displacement of the assist pump 3 via the capacity switching actuator 3a, and supplies the electric power of the battery 5 to the motor generator 4 via the inverter 6, The assist pump 3 is rotationally driven by the motor generator 4. As a result, the hydraulic oil discharged from the assist pump 3 passes through the sub passage 31 and joins the flow of hydraulic oil in the main passage 111 and is sent to the bottom pressure chamber 104b, and has an auxiliary force for extending the boom cylinder 104. Give.

  At the time of this assist, the controller 114 switches and holds the displacement volume of the regenerative motor 2 to substantially zero. Thereby, the flow of the hydraulic oil circulating through the regenerative motor 2 is stopped, and the driving loss of the regenerative motor 2 during assist is reduced.

  FIG. 3 is a schematic cross-sectional view showing the structure of the assist regeneration device 10. This will be described below.

  The regenerative motor 2 and the assist pump 3 each use a swash plate type variable displacement type piston pump motor and have the same structure. The regenerative motor 2 is a larger piston pump motor than the assist pump 3.

  The regenerative motor 2 and the assist pump 3 include a cylinder block 42 connected to the rotation shaft 41, a plurality of pistons 45 accommodated in a cylinder 43 of the cylinder block 42, a swash plate 46 that reciprocates the piston 45, And a port plate 47 with which the end face of the cylinder block 42 comes into sliding contact.

  When the cylinder block 42 rotates together with the rotary shaft 41, each piston 45 reciprocates between the swash plate 46 and expands / contracts the volume chamber 44 of each cylinder 43.

  The port plate 47 includes a pair of ports 48 and 49 communicating with the volume chamber 44, and hydraulic oil is supplied to and discharged from the volume chamber 44 through the ports 48 and 49.

  The cylinder block 42 is pressed against the port plate 47 by a biasing force of a spring (not shown). The sliding portion between the cylinder block 42 and the port plate 47 constitutes a mechanical seal that suppresses leakage of hydraulic fluid flowing through the ports 48 and 49.

  The swash plate 46 is supported to be tiltable via a bearing (not shown) and is moved by the capacity switching actuators 2a and 3a (see FIG. 2).

  During regeneration, the regeneration motor 2 is switched to a predetermined value in which the inclination angle of the swash plate 46 is larger than zero by the capacity switching actuator 2a. As a result, the pressurized hydraulic fluid guided from the return passage 21 flows into the volume chamber 44 through the port 48 of the port plate 47, and the piston 45 reciprocates the cylinder 43 to rotate the cylinder block 42. At this time, the hydraulic oil flowing out from the volume chamber 44 flows out into the tank T through the port 49 of the port plate 47.

  At the time of assist, the regenerative motor 2 maintains the inclination angle of the swash plate 46 at substantially zero. As a result, the stroke (displacement volume) of the piston 45 becomes substantially zero, and the flow of hydraulic oil circulating through the regenerative motor 2 stops. Thereby, the drive loss of the regenerative motor 2 at the time of assist is suppressed.

  At the time of assist, the assist pump 3 is switched to a predetermined value in which the inclination angle of the swash plate 46 is larger than zero by the capacity switching actuator 3a. Thereby, as the cylinder block 42 rotates, the piston 45 reciprocates the cylinder 43, and the hydraulic oil from the tank T is sucked into the volume chamber 44 through the port 49 of the port plate 47. The hydraulic fluid discharged from the hydraulic fluid merges with the hydraulic fluid flowing through the main passage 111 through the port 48 and the sub passage 31 of the port plate 47, and the boom cylinder 104 is extended.

  During regeneration, the assist pump 3 maintains the inclination angle of the swash plate 46 at substantially zero. As a result, the stroke of the piston 45 that reciprocates in the cylinder 43 becomes substantially zero, and the above-described flow of hydraulic oil stops. Thereby, the drive loss of the assist pump 3 at the time of regeneration is suppressed.

  However, in the regenerative motor 10, even when the regenerative motor 2 and the assist pump 3 are operated so that the inclination angle of the swash plate 46 is maintained at substantially zero, the cylinder block 42 is moved by the urging force of a spring (not shown). When the structure is pressed against 47, there arises a problem that the operating efficiency of the assist regeneration device 10 is lowered due to drag loss (friction resistance) generated in the sliding portion between the cylinder block 42 and the port plate 47.

  In response to this, the assist regeneration device 10 of the present invention is configured to supply pressurized hydraulic oil between the cylinder block 42 and the port plate 47 during the rotation operation in which the inclination angle of the swash plate 46 is maintained at substantially zero, By dragging and supporting the end surface of the rotating cylinder block 42 via hydraulic oil, drag loss generated in the sliding portion between the cylinder block 42 and the port plate 47 is reduced.

  The regenerative motor 2 and the assist pump 3 serve as a supply means for supplying pressurized hydraulic fluid between the cylinder block 42 and the port plate 47, as shown in FIG. 3, and an annular supply groove 59 opened at the end face of the cylinder block 42. Is formed around the ports 48 and 49, and supply passages 51 and 52 are connected to the supply groove 59, and an electromagnetic switching for selectively communicating the pilot pump (external hydraulic power source) 109 and the tank T to the supply passages 51 and 52. Valves 53 and 54 are provided.

  However, the present invention is not limited to this, and the supply grooves formed around the ports 48 and 49 may be formed on the end surface of the port plate 47. Further, the supply groove may not be annular as long as it has a structure that reduces drag loss.

  The electromagnetic switching valves 53 and 54 connect the pilot pump 109 to the supply passages 51 and 52 and connect the tank T to the supply position a for guiding the pressurized hydraulic oil discharged from the pilot pump 109, and reduce the drain pressure. And a drain position b for guiding.

  In addition, as a supply means for supplying pressurized hydraulic fluid between the cylinder block 42 and the port plate 47 of the regenerative motor 2 and the assist pump 3, the electromagnetic switching valves 53 and 54 are not used and the cylinder block 42 and the port plate 47 are not connected. It is good also as a structure which increases / decreases the pressure of the working fluid led to.

  Next, control of the regenerative motor 2 performed by the controller 114 will be described.

  The controller 114 controls to switch the electromagnetic switching valve 53 to the supply position a while switching the tilt angle of the swash plate 46 of the regenerative motor 2 to substantially zero at the time of assist when the regenerative motor 2 does not generate power. The pressurized hydraulic fluid is supplied between the second cylinder block 42 and the port plate 47.

  The controller 114 constitutes control means for increasing the pressure of the working fluid guided between the cylinder block 42 and the port plate 47 of the regenerative motor 2 by the supply means during assist.

  Thus, the regenerative motor 2 is supplied with pressurized hydraulic fluid between the cylinder block 42 and the port plate 47 of the regenerative motor 2 during the rotation operation of the cylinder block 42 in which the inclination angle of the swash plate 46 is held substantially zero. As a result, the rotating cylinder block 42 is floated and supported by the port plate 47 via the hydraulic oil, and drag loss generated in the sliding portion between the cylinder block 42 and the port plate 47 is reduced, and the operating efficiency of the assist regeneration device 10 at the time of assisting is reduced. Can be enhanced.

  On the other hand, the controller 114 switches the inclination angle of the swash plate 46 of the regenerative motor 2 to a predetermined value larger than zero during regenerative power generation of the regenerative motor 2 and switches the electromagnetic switching valve 53 to the drain position b to regenerate the motor 2. Control for guiding the drain pressure between the cylinder block 42 and the port plate 47 is performed.

  In this way, when the regenerative motor 2 generates power, the cylinder block 42 is rotated and the drain pressure is guided between the cylinder block 42 and the port plate 47, thereby reducing the sliding gap between the cylinder block 42 and the port plate 47. As the pistons 45 reciprocate, leakage of hydraulic oil flowing through the ports 48 and 49 is suppressed, and the operation efficiency of the regenerative motor 2 is maintained.

  Next, control of the assist pump 3 performed by the controller 114 will be described.

  The controller 114 performs control for switching the tilt angle of the swash plate 46 of the assist pump 3 to substantially zero and switching the electromagnetic switching valve 54 to the supply position a during regeneration when the assist pump 3 does not discharge the hydraulic oil. Pressurized hydraulic oil is supplied between the cylinder block 42 and the port plate 47.

  The controller 114 constitutes control means for increasing the pressure of the working fluid guided between the cylinder block 42 and the port plate 47 of the assist pump 3 by the supply means during regeneration.

  Thus, the assist pump 3 is supplied with pressurized hydraulic fluid between the cylinder block 42 of the assist pump 3 and the port plate 47 when the cylinder block 42 is rotated so that the inclination angle of the swash plate 46 is maintained at substantially zero. As a result, the rotating cylinder block 42 is floated and supported by the port plate 47 via the hydraulic oil, and drag loss generated in the sliding portion between the cylinder block 42 and the port plate 47 is reduced, and the operation efficiency of the assist regeneration device 10 during regeneration is reduced. Can be enhanced.

  On the other hand, the controller 114 switches the tilt angle of the swash plate 46 of the assist pump 3 to a predetermined value larger than zero and assists the assist pump 3 by switching the electromagnetic switching valve 54 to the drain position b when assisting the hydraulic pump to discharge the hydraulic oil. 3 to control the drain pressure between the cylinder block 42 and the port plate 47. If both the electromagnetic switching valves 53 and 54 are set to the drain position b, the regenerative motor 2 can provide assist force to the assist pump 3 if the tilt angle of the swash plate of the assist pump 3 and the regenerative motor 2 is controlled as in the conventional case. It is also possible to perform an assist to be given.

  Thus, when the assist pump 3 rotates the cylinder block 42 that discharges the hydraulic oil, the drain pressure is guided between the cylinder block 42 and the port plate 47, thereby reducing the sliding gap between the cylinder block 42 and the port plate 47. As the pistons 45 reciprocate, the leakage of hydraulic oil flowing through the ports 48 and 49 is suppressed, and the operational efficiency of the assist pump 3 is maintained.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. This embodiment is different from the first embodiment in supply means for supplying pressurized hydraulic oil between the cylinder block 42 and the port plate 47. Hereinafter, the difference will be mainly described. In the embodiment described below, the same reference numerals are used for portions that perform the same functions as those of the first embodiment described above, and repeated descriptions are omitted as appropriate.

  FIG. 4 is a schematic configuration diagram of the assist regeneration device 10 according to the present embodiment.

  The regenerative motor 2 according to the present embodiment has a supply passage 51 connected between the cylinder block 42 and the port plate 47 as supply means for supplying pressurized hydraulic oil between the cylinder block 42 and the port plate 47, and this supply An electromagnetic switching valve 53 for selectively communicating the sub-passage 31 for guiding the hydraulic oil discharged from the assist pump 3 and the tank T to the passage 51 is provided.

  The electromagnetic switching valve 53 is connected to the supply passage 51 by connecting the sub passage 31 to supply the pressurized hydraulic fluid discharged from the assist pump 3, and the tank T is connected to the drain position b to guide the drain pressure. And have.

  The controller 114 controls to switch the electromagnetic switching valve 53 to the supply position a while switching the angle of inclination of the swash plate 46 of the regenerative motor 2 to substantially zero during assist when the regenerative motor 2 does not generate power.

  Thus, the regenerative motor 2 is supplied with pressurized hydraulic fluid between the cylinder block 42 and the port plate 47 of the regenerative motor 2 during the rotation operation of the cylinder block 42 in which the inclination angle of the swash plate 46 is held substantially zero. As a result, the rotating cylinder block 42 is floated and supported by the port plate 47 via the hydraulic oil, and drag loss generated in the sliding portion between the cylinder block 42 and the port plate 47 is reduced, and the operating efficiency of the assist regeneration device 10 at the time of assisting is reduced. Can be enhanced.

  On the other hand, the controller 114 switches the inclination angle of the swash plate 46 of the regenerative motor 2 to a predetermined value larger than zero during regenerative power generation of the regenerative motor 2 and switches the electromagnetic switching valve 53 to the drain position b to regenerate the motor 2. Control for guiding the drain pressure between the cylinder block 42 and the port plate 47 is performed.

  In this way, when the regenerative motor 2 generates power, the cylinder block 42 is rotated and the drain pressure is guided between the cylinder block 42 and the port plate 47, thereby reducing the sliding gap between the cylinder block 42 and the port plate 47. As the pistons 45 reciprocate, leakage of hydraulic oil flowing through the ports 48 and 49 is suppressed, and the operation efficiency of the regenerative motor 2 is maintained.

  In the assist pump 3 according to the present embodiment, a supply passage 52 is connected between the cylinder block 42 and the port plate 47 as supply means for supplying pressurized hydraulic oil between the cylinder block 42 and the port plate 47. 52 is provided with an electromagnetic switching valve 54 that selectively connects the tank T with the return passage 21 that guides the hydraulic oil flowing out from the bottom pressure chamber 104b to the regenerative motor 2.

  The electromagnetic switching valve 54 connects the return passage 21 to the supply passage 52 to supply the pressurized hydraulic fluid flowing out from the bottom pressure chamber 104b, and the drain position to connect the tank T and guide the drain pressure. b.

  The controller 114 performs control to switch the tilt angle of the swash plate 46 of the assist pump 3 to substantially zero and switch the electromagnetic switching valve 54 to the supply position a during regeneration when the assist pump 3 does not discharge the hydraulic oil.

  Thus, the assist pump 3 is supplied with pressurized hydraulic fluid between the cylinder block 42 of the assist pump 3 and the port plate 47 when the cylinder block 42 is rotated so that the inclination angle of the swash plate 46 is maintained at substantially zero. As a result, the rotating cylinder block 42 is floated and supported by the port plate 47 via the hydraulic oil, and drag loss generated in the sliding portion between the cylinder block 42 and the port plate 47 is reduced, and the operation efficiency of the assist regeneration device 10 during regeneration is reduced. Can be enhanced.

  On the other hand, the controller 114 switches the tilt angle of the swash plate 46 of the assist pump 3 to a predetermined value larger than zero and assists the assist pump 3 by switching the electromagnetic switching valve 54 to the drain position b when assisting the hydraulic pump to discharge the hydraulic oil. 3 to control the drain pressure between the cylinder block 42 and the port plate 47.

  Thus, when the assist pump 3 rotates the cylinder block 42 that discharges the hydraulic oil, the drain pressure is guided between the cylinder block 42 and the port plate 47, thereby reducing the sliding gap between the cylinder block 42 and the port plate 47. As the pistons 45 reciprocate, the leakage of hydraulic oil flowing through the ports 48 and 49 is suppressed, and the operational efficiency of the assist pump 3 is maintained.

  As described above, in the present embodiment, since the sub passage 31 and the return passage 21 are connected to the supply passages 51 and 52, respectively, there is no need to connect an external hydraulic source to the supply passages 51 and 52, and the hydraulic circuit The configuration can be simplified.

  Note that the present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  For example, as supply means for supplying pressurized hydraulic oil between the cylinder block 42 of the regenerative motor 2 and the assist pump 3 and the port plate 47, means (for example, an orifice) for restricting the flow of hydraulic oil is provided in the supply passages 51 and 52. Thus, the hydraulic pressure supplied between the cylinder block 42 and the port plate 47 may be appropriately adjusted.

  In each of the above embodiments, the assist regeneration device 10 is applied to the fluid pressure control device that drives only the boom cylinder 104 in order to facilitate understanding of the invention. However, the boom cylinder 104, the arm cylinder 105, and the bucket cylinder 106 are used. The present invention may be applied to a fluid pressure control device that drives a plurality of actuators.

  Furthermore, in each of the above-described embodiments, the hydraulic cylinder has been described as an example of the actuator. However, the present invention is not limited to this, and a traveling motor or a swing motor of a construction machine such as a hydraulic excavator or a work machine may be used.

  Moreover, you may use working fluid, such as a water-soluble alternative liquid, for example instead of oil as working oil.

2 Regenerative motor 3 Assist pump 4 Motor generator 10 Assist regenerative device 21 Return path
31 Sub passage 41 Rotating shaft 42 Cylinder block 43 Cylinder
44 Volume chamber 45 Piston
46 Swash plate 47 Port plate 114 Controller

Claims (4)

A motor generator that rotates by electric energy;
A regenerative motor that rotationally drives the motor generator by the energy of the working fluid during regeneration;
An assist regenerative device comprising an assist pump that is rotationally driven by the motor generator at the time of assist and discharges the working fluid,
The regenerative motor is
A cylinder block rotatably supported;
A plurality of pistons housed in the cylinder block;
A swash plate that reciprocates this piston,
A port plate that slidably contacts the cylinder block to supply and discharge the working fluid;
Supply means for supplying pressurized working fluid between the cylinder block and the port plate;
While the tilt angle of the swash plate is made larger than zero during regeneration, the tilt angle of the swash plate is switched to substantially zero during assist, and the pressure of the working fluid guided between the cylinder block and the port plate is increased by the supply means. And an assist regenerative device comprising a control means. As the supply means of the regenerative motor,
A supply passage connected between the cylinder block and the port plate;
The assist regeneration device according to claim 1, wherein the working fluid discharged from the assist pump is guided to the supply passage. The assist pump is
A cylinder block rotatably supported;
A plurality of pistons housed in the cylinder block;
A swash plate that reciprocates this piston,
A port plate that slidably contacts the cylinder block to supply and discharge the working fluid;
Supply means for supplying pressurized working fluid between the cylinder block and the port plate;
The tilt angle of the swash plate of the assist pump is made larger than zero during assist, while the tilt angle of the swash plate of the assist pump is switched to substantially zero during regeneration, and the cylinder block and the port are supplied by the supply means of the assist pump. The assist regeneration device according to claim 1, further comprising: a control unit that increases a pressure of the working fluid guided between the plates. As the supply means of the assist pump,
A supply passage connected between the cylinder block and the port plate;
The assist regeneration device according to claim 3, wherein a working fluid guided to the regeneration motor is supplied to the supply passage.

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