JP2011084368A - Cargo handling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cargo handling device regenerating suitable power, while avoiding complication of a structure. <P>SOLUTION: This cargo handling device 1 returns a working liquid to a tank 8 by making the working liquid flow to a power regenerative external exclusive passage 4 by closing a solenoid valve 33 and opening an external regenerative valve 6 in lift-down operation in a load of mounting a cargo N of predetermined weight or more, and returns the working liquid to the tank 8 by making the working liquid flow inside a control valve 3 with a lift-lock mechanism by opening the solenoid valve 33 and closing the external regenerative valve 6 in the lift-down operation in a low load when the cargo N is not the predetermined weight or more. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cargo handling apparatus using a hydraulic circuit that can be suitably applied to various industrial vehicles including a forklift.

  Conventionally, in a hydraulic device using a control valve such as a forklift, a hydraulic circuit that can regenerate power by using a lift-down operation at the time of loading with a load has been proposed. As an example, a hydraulic circuit 101 using a control valve 103 having a built-in switching valve 131 as shown in FIG.

  The hydraulic circuit 101 is an electric motor MG having a power source as a battery V, and a hydraulic pump 109 is driven by the electric motor MG, whereby the hydraulic fluid in the tank 108 is lifted via a filter f1 and a control valve 103 to a lift cylinder 102. To be able to supply. The switching valve 131 has a switching function for operating the operation lever 131a from the neutral state shown in the figure so that lift-up can be performed at the right-hand position. The switching valve 131 has an operation sensor 131b that can detect the position of the operation lever 131a.

  In the conventional hydraulic circuit 101 shown in the figure, at the time of lift down, the hydraulic fluid from the lift cylinder 102 does not flow to the control valve 103 but flows to the tank 108 through the external return flow path 104 and the filter f2. It has become. The external return flow path 104 is provided with an electromagnetic solenoid valve 106. The controller 107 issues a signal to the solenoid valve 106 so that the opening amount is in accordance with the output of the operation sensor 131b, whereby the hydraulic fluid is guided to the regenerative flow path 104, and the regenerative motor 105 is operated to drive power. Is regenerated. Specifically, the motor MG is driven by the rotation of the regenerative motor 105 to function as a generator.

  In addition to the hydraulic circuit 101 described above, as described in Patent Document 2, a structure for power regeneration is provided in an integrated control valve, so that a return flow from the control valve to the tank is achieved. A configuration is also disclosed in which the path can be switched between a regeneration flow path and a direct connection flow path.

JP 2007-254058 A JP 2007-137598 A

  However, in the configuration shown in FIG. 2, when the weight of the load N is small, the pressure is small in the first place. Therefore, if the resistance of the regenerative motor 105 is subtracted, the pressure for flowing the hydraulic fluid is further reduced. Power regeneration is not possible.

  On the other hand, since the thing of patent document 2 incorporates the structure which switches the flow of a hydraulic fluid for regeneration in the integrated control valve, complication of the structure of control valve itself cannot be avoided. In addition, since the number of valves through which the hydraulic fluid passes and the number of branches in the flow path increase, this may become a resistance and may limit the lift-down speed and the regeneration efficiency.

  In addition, a so-called lift lock mechanism that prohibits lowering of the lift cylinder when the user is not on the forklift at an accurate position is known as a function desired for the forklift at present. In other words, in a normal forklift, replacing the conventional control valve with a control valve with a lift lock mechanism gives the lift lock mechanism, and effectively lifts the possibility of the lift falling unexpectedly against the user's intention. Can be eliminated. Of course, such a power regeneration hydraulic circuit is expected to be equipped with such a lift lock mechanism.

  The present invention focuses on the above points, and an object of the present invention is to provide a cargo handling apparatus capable of regenerating suitable power while avoiding an increase in the number of parts and a complicated structure.

  In order to achieve such an object, the present invention takes the following measures.

  That is, the cargo handling device according to the present invention includes a lift cylinder that expands and contracts and lifts a load, a tank that stores hydraulic fluid, a control valve that controls supply and discharge of the hydraulic fluid to and from the lift cylinder, and the lift cylinder And a power regeneration passage that communicates with the tank through a flow path connecting the control valve and the control valve, and is operated by receiving hydraulic fluid from the lift cylinder when the lift cylinder is shortened. A hydraulic motor, a flow path connecting the lift cylinder and the control valve, and a power regeneration passage are provided to be connected to the power regeneration passage and closed to block the open state from allowing the flow from the lift cylinder to the hydraulic motor in the previous period. An external valve switchable to a state, a flow path between the lift cylinder and the control valve, or the lift cylinder A pressure sensor that is provided in a flow path between the external valve and detects a pressure in the flow path, an operation sensor that detects an operation of an operation member that performs an elevating operation, and a signal from the pressure sensor and the operation sensor And a controller for controlling the control valve and the external valve.

  In this configuration, when the load applied to the lift cylinder during the lowering operation is greater than or equal to a predetermined value, the flow of hydraulic fluid from the lift cylinder to the control valve is blocked by the lift lock valve. It will flow only to the valve. Then, the hydraulic fluid passes through the external valve, rotates the hydraulic motor, and returns to the tank. Therefore, if an electric motor (generator) is connected to the hydraulic motor in advance and the electric motor (generator) is controlled in accordance with the lowering operation, the power can be regenerated while being lowered at a desired speed. Of course, another device can be connected instead of the electric motor (generator), and the device can be driven by a hydraulic motor. On the other hand, when the load is not equal to or greater than the predetermined value, the flow from the lift cylinder to the hydraulic motor is blocked by the external valve, so that the hydraulic fluid flowing out from the lift cylinder is returned to the tank through the control valve. At this time, the flow rate is adjusted by the switching valve of the control valve, and it drops at a speed corresponding thereto.

  Predetermined values in this configuration are the values of the load that provides the desired efficiency when performing power regeneration using a hydraulic motor, the minimum value of the load that can perform power regeneration, and the load that provides the required lowering speed. What is necessary is just to set to a value etc. If the predetermined value is a load value at which a desired efficiency can be obtained, the efficiency will increase if the load is large. Therefore, the hydraulic fluid from the lift cylinder is hydraulic fluid only when the power regeneration can be performed with an efficiency exceeding the desired efficiency. Can be rotated, and highly efficient power regeneration can be realized. Moreover, if the predetermined value is the minimum value of the load capable of power regeneration, power regeneration can be realized over a wider load range. Furthermore, if the predetermined value is a load value at which a required descending speed can be obtained, power regeneration can be realized without sacrificing work efficiency.

  In the present invention, the lift lock valve does not have to be a single one, and may be constituted by a plurality of valves including valves that can be switched by a controller.

  According to the present invention, by combining the lift lock valve and the external valve that the control valve has, the hydraulic fluid can be operated by flowing the hydraulic fluid through the power regeneration passage only when the load is large. Therefore, power regeneration can be performed using a hydraulic motor. On the other hand, when the load is small, the working fluid can be allowed to flow inside the control valve without flowing the working fluid through the power regeneration passage. As a result, it is possible to avoid operating the hydraulic motor even though the regenerative effect cannot be expected, and to sufficiently ensure the descending speed. Further, since the lift lock valve is built in the control valve, the circuit configuration other than the control valve can be simplified and the number of parts for piping can be reduced, and the labor of piping work can be reduced.

The circuit diagram concerning one embodiment of the present invention. The circuit diagram which concerns on a prior art.

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

  As shown in FIG. 1, the cargo handling apparatus 1 according to this embodiment is applied to, for example, a battery-type forklift, and the hydraulic pump 9 is driven by an electric motor MG having a battery V as a power source. Yes. In this embodiment, the lift is operated by a lift cylinder 2 for raising and lowering the load N and a tilt cylinder (not shown) for tilting the mast, and is sucked from the tank 8 through the filter f1 when the hydraulic pump 9 is operated. The hydraulic fluid can be supplied to the lift cylinder 2 and a tilt cylinder (not shown) via the control valve 3 with a lift lock mechanism. In the present embodiment, components related to the lift cylinder 2 will be mainly described, and a description of a configuration for operating the tilt cylinder including the tilt switching valve 35 will be omitted for convenience.

  In addition to the above-described hydraulic pump 9, lift cylinder 2, and control valve 3 with a lift lock mechanism, the cargo handling apparatus 1 includes an external dedicated passage 4 for power regeneration, a hydraulic motor 5 for power regeneration, and an external regeneration valve. 6 and a controller 7.

  The power regeneration motor 5 has a suction port connected to the power regeneration external dedicated passage 4, a discharge port connected to the tank 8 by another passage, and a rotating shaft connected to the motor MG via a one-way clutch. It is connected. That is, when the hydraulic pump 9 is driven, the power regeneration hydraulic motor 5 is not driven by the electric motor MG. However, when the power regeneration hydraulic motor 5 drives the electric motor MG, the hydraulic pump 9 is also driven. Driven. As a result, the hydraulic pump 9 can be driven by the electric motor MG, while it can be regenerated (power generation) by the electric motor MG by the power transmitted from the power regeneration hydraulic motor 5, and the power regeneration hydraulic motor 5 can be regenerated. It is also possible to drive or assist the hydraulic pump 9.

  The control valve 3 with a lift lock mechanism is a multiple manual switching valve, and is installed between the hydraulic pump 9 and the lift cylinder 2. A series of them is a so-called lift section for raising and lowering the lift cylinder 2, and mainly includes a lift switching valve 31, a lift lock valve 32, a solenoid valve 33, and an emergency valve 34.

An operation lever is connected to the switching valve of each section, and an operation lever 31 a is connected to the lift switching valve 31. The position of the lift switching valve 31 is switched according to the operation direction of the operation lever 31a, and the opening amount of the lift switching valve 31 is adjusted according to the operation amount. Further, the lift switching valve 31 is connected by the lift cylinder 2 and the lift passage 36, and is connected by the tank 8 and the tank passage 38.
The lift switching valve 31 has a switching function that allows the lift-up position to be the right-hand position where the operation lever 31a is operated from the neutral position shown in the figure, and the lift-down position to be performed at the left-hand position. Return to position. That is, the lift switching valve 31 allows the flow from the hydraulic pump 9 to the lift cylinder 2 by communicating the passage connecting the hydraulic pump 9 and the lift switching valve 31 with the lift passage 36 at the right-hand position. In the left-hand position, the lift passage 36 and a later-described lift lock valve pilot passage 37 and a tank passage 38 are communicated to allow the flow from the lift cylinder 2 to the tank 8. In the neutral position, both the flow from the hydraulic pump 9 to the lift cylinder 2 and the flow from the lift cylinder 2 to the tank 8 are interrupted. The lift switching valve 31 is further provided with an operation sensor 31b. A specific operation position of the operation lever 31a is detected by the operation sensor 31b, and a position signal is input to the controller 7.

  The lift lock valve 32 is installed on a lift passage 36 that connects the lift switching valve 31 and the lift cylinder 2 in the control valve 3 with a lift lock mechanism, and includes a poppet 32b and a spring 32c. When the lift switching valve 31 is not in operation, the poppet 32b is biased by the spring 32c to close the lift passage 36.

  The pilot passage 37 for lift lock valve is a passage for pilot flow for opening the poppet 32b, and one is connected to the lift passage 36 via a control orifice 32a provided in the poppet 32b. The other is connected to a lift switching valve 31 and is provided with a solenoid valve 33 that can be switched between an open state allowing the flow of hydraulic fluid and a closed state blocking it.

  The emergency valve 34 is installed on a passage connecting the lift lock valve pilot passage 37 and the tank passage 38, and this passage is normally closed by the emergency valve 34.

  The power regeneration external dedicated passage 4 is a passage that branches from the lift passage 36 outside the control valve 3 with a lift lock mechanism and is connected to the power regeneration hydraulic motor 5, and is in an open state that allows the flow of hydraulic fluid on the way. An external regenerative valve 6 is provided that can be switched to a closed state that shuts off and that can be set by an electrical signal in the open state.

  The external regeneration valve 6 is provided upstream of the power regeneration hydraulic motor 5, that is, at a position closer to the branch point between the lift passage 36 and the power regeneration external dedicated passage 4. The amount of hydraulic fluid flowing into 5 can be adjusted. As shown in FIG. 1, the external regeneration valve 6 is provided on the power regeneration external dedicated passage 4, but the flow is switched to a branch point between the lift passage 36 and the power regeneration external dedicated passage 4. Since there is no function of blocking or blocking, the lift passage 36 is substantially connected. Further, the pressure in the lift passage 36 is detected by the pressure sensor 7 b, and the signal is input to the controller 7.

  Based on the output signal of the operation sensor 31b, the controller 7 determines whether the operation direction of the operation lever 31a is the lift-up direction or the lift-down direction, grasps the operation amount, and uses the output signal of the pressure sensor 7b to determine the lift cylinder. It is determined whether the load applied to 2 is greater than or equal to a predetermined value. Here, the predetermined value may be set so as to ensure the required regeneration efficiency based on the weight of the mast or the load N, the current value at the time of regeneration in the electric motor MG described later, and the like. The controller 7 also receives an output signal of an operator position sensor (not shown) for confirming that the operator is in a normal position for driving, and comprehensively determines the output results. Thus, the solenoid valve 33 and the external regeneration valve 6 are controlled to open and close, and the electric motor MG is controlled to achieve proper operation.

  The specific operation for each operation in the present embodiment is as follows.

  During the lift-up operation in which the lift switching valve 31 is in the right-hand position, the controller 7 drives the electric motor MG, and the hydraulic fluid that has flowed out of the hydraulic pump 9 pushes the poppet 32b against the spring 32c. The liquid flows into the lift cylinder 2 via the lift passage 36. At this time, the controller 7 closes the external regeneration valve 6 to prevent the hydraulic fluid from flowing out to the power regeneration external dedicated passage 4. Accordingly, the load N can be raised at a speed corresponding to the operation amount of the operation lever 31a.

  When the lift switching valve 31 is in the left-down position and the load is equal to or greater than a predetermined value, the controller 7 closes the solenoid valve 33 and opens the external regeneration valve 6. In this case, since the flow from the lift passage 36 to the tank passage 38 through the lift switching valve 31 is blocked by the poppet 32b and the solenoid valve 33, all the hydraulic fluid flowing out from the lift cylinder 2 is an external regeneration valve. After passing through 6, the hydraulic motor 5 for power regeneration is rotated. Power can be regenerated by transmitting the rotation to the electric motor MG connected to the rotating shaft and functioning as a generator. That is, electric power can be generated by the electric motor MG and the battery V can be charged. If the operation levers of the other sections are not operated at the same time, the external regeneration valve 6 is quickly fully opened, and the power regeneration hydraulic motor 5 of the power regeneration motor 5 is connected via the electric motor MG according to the operation amount of the operation lever 31a. If the rotational speed is controlled, the regenerative efficiency can be improved and the load can be lowered at an appropriate speed. On the other hand, if the operation levers of the other sections are also operated, the opening amount of the external regeneration valve 6 can be controlled according to the operation amount of the operation lever 31a to lower the load at an appropriate speed. At this time, when the hydraulic pump 9 can be sufficiently driven by the power regeneration hydraulic motor 5, the hydraulic fluid can be supplied through the other sections without driving the electric motor MG. If it is insufficient, it is necessary to drive the hydraulic pump 9 with the electric motor MG. However, the power consumption of the electric motor MG can be suppressed by the amount of power assisted from the hydraulic motor 5 for power regeneration.

  When the lift switching valve 31 is in the lift-down operation at the left row position and the load is not equal to or greater than the predetermined value, the controller 7 opens the solenoid valve 33 and closes the external regeneration valve 6. In this case, since the lift lock valve pilot passage 37 is connected to the tank passage 38 via the lift switching valve 31, the hydraulic fluid in the lift passage 36 flows through the control orifice 32a of the poppet 32b. Because of this flow, a differential pressure that opens the poppet 32b against the bias of the spring 32c is generated and the poppet 32b opens, so that the lift passage 36 and the lift switching valve 31 communicate with each other, and the operation that has flowed out of the lift cylinder 2 Since all of the liquid passes through the lift switching valve 31 and the tank passage 38 and is returned to the tank 8, the load N can be quickly lowered at a speed corresponding to the operation amount of the operation lever 31a.

  When the operator is not in a normal position for driving, the controller 7 stops the electric motor MG and closes both the solenoid valve 33 and the external regeneration valve 6. As a result, the supply of hydraulic fluid from the hydraulic pump 9 is cut off, while the passage leading from the lift passage 36 to the tank passage 38 and the power regeneration external dedicated passage 4 are all independent of the operation position of the operation lever 31a. Closed. For this reason, the operation of the lift cylinder 2 is forbidden so-called lift lock.

  In the present embodiment, the emergency valve 34 is opened and the working fluid is allowed to flow into the tank passage 38 so that the lift-down can be performed without operating the operation lever 31a.

  With the configuration as described above, the cargo handling device 1 according to the present embodiment is arranged with a special function for power regeneration by using the control valve 3 with a lift lock mechanism having high versatility as it is. By effectively avoiding the application of a special structure, it is possible to achieve reliable power regeneration while maintaining a mode that is easy to apply widely. Specifically, in this embodiment, the flow of hydraulic fluid during the lift-down operation is switched by controlling the solenoid valve 33 and the external regeneration valve 6, but the solenoid valve 33 is part of the lift lock mechanism. Since it is built in the control valve 3 with a lift lock mechanism, the circuit configuration is simplified as compared with the case where the same function is realized outside the control valve, so that the number of piping parts is reduced. In the present embodiment, power regeneration is performed when the lift-down operation is performed and the load is equal to or greater than a predetermined value. Therefore, the effect of power regeneration is reliably obtained, and the operating time is extended by charging the battery V. be able to. Even during the lift-down operation, if the load is not equal to or greater than the predetermined value, the hydraulic fluid returns to the tank 8 through the lift switching valve 31 without performing power regeneration, so that the power regeneration hydraulic motor 5 has a resistance. In other words, a sufficient speed cannot be obtained, and work efficiency is not lowered.

  In particular, according to the present embodiment, the function of prohibiting the lowering operation of the lift cylinder 2 depending on the boarding position of the operator, that is, the lift lock mechanism is realized, so that the safety of the lift lock mechanism is effectively obtained together with the function of power regeneration. An operator who is already used to other forklifts that already have a lift lock mechanism can operate and operate the forklifts to which the present invention is applied in the same manner without any discomfort.

  Although the embodiment of the present invention has been described above, the specific configuration of each unit is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment, the electromagnetic solenoid valve is applied alone as the external regeneration valve. However, for example, the circuit configuration is such that the flow path can be switched when the hydraulic fluid from the lift cylinder exceeds the set pressure. It may be applied. In addition, specific modes such as a hydraulic pump, a hydraulic motor, an electric motor, and a battery are not limited to those in the above embodiment, and various modes including the existing ones can be applied. .

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Cargo handling device 2 ... Lift cylinder 3 ... Control valve 4 with a lift lock mechanism ... External exclusive passage 5 for power regeneration ... Hydraulic pressure motor 6 for power regeneration ... External regeneration valve 7 ... Controller 7b ... Pressure sensor 8 ... Tank 9 ... Hydraulic pressure pump 31 ... lift switching valve 31a ... operating lever 31b ... displacement sensor 32 ... lift lock valve 32a ... control orifice 32b ... poppet 32c ... spring 33 ... solenoid valve 34 ... emergency valve 35 ... tilt switching valve 36 ... lift Passage 37 ... Lift lock valve pilot passage 38 ... Tank passage N ... Luggage

Claims (1)

A lift cylinder that expands and contracts to raise and lower the load,
A tank for storing hydraulic fluid;
A control valve for controlling supply and discharge of the hydraulic fluid to and from the lift cylinder;
A power regeneration passage for communicating a flow path connecting the lift cylinder and the control valve with the tank;
A hydraulic motor that is provided in the power regeneration passage and operates by receiving hydraulic fluid from the lift cylinder when the lift cylinder is shortened;
Connected to the flow path connecting the lift cylinder and the control valve and the power regeneration passage, it is possible to switch between the open state that allows the flow from the lift cylinder to the hydraulic motor in the previous period and the closed state that blocks it. An external valve,
A pressure sensor that is provided in a flow path between the lift cylinder and the control valve or a flow path between the lift cylinder and the external valve, and detects a pressure in the flow path;
An operation sensor for detecting the operation of the operation member that performs the lifting operation;
A controller for controlling the control valve and the external valve based on signals from the pressure sensor and the operation sensor;
The control valve is provided in a switching valve that switches the flow direction of the hydraulic fluid and adjusts the flow rate, and a flow path that connects the switching valve and the lift cylinder, and opens and shuts off to allow bidirectional flow. It has a built-in lift lock valve that can be switched to the closed state,
When the controller determines that the operation is a lowering operation based on a signal from the operation sensor, the controller determines whether a load applied to the lift cylinder is greater than or equal to a predetermined value based on the signal from the pressure sensor, and If the value is greater than or equal to the value, the lift lock valve is closed and the external valve is opened. If the value is not greater than the predetermined value, the lift lock valve is opened and the external valve is closed. A cargo handling device characterized by that.

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