JP5896041B2 - Hydraulic circuit and cargo handling vehicle - Google Patents

Hydraulic circuit and cargo handling vehicle Download PDF

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Publication number
JP5896041B2
JP5896041B2 JP2014552813A JP2014552813A JP5896041B2 JP 5896041 B2 JP5896041 B2 JP 5896041B2 JP 2014552813 A JP2014552813 A JP 2014552813A JP 2014552813 A JP2014552813 A JP 2014552813A JP 5896041 B2 JP5896041 B2 JP 5896041B2
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pump
valve
flow rate
hydraulic
cargo handling
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JPWO2014097423A1 (en
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信雄 向井
信雄 向井
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Shimadzu Corp
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Shimadzu Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
    • B62D5/065—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle characterised by specially adapted means for varying pressurised fluid supply based on need, e.g. on-demand, variable assist
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
    • B62D5/07—Supply of pressurised fluid for steering also supplying other consumers ; control thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F9/00—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes
    • B66F9/06—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks
    • B66F9/075—Constructional features or details
    • B66F9/20—Means for actuating or controlling masts, platforms, or forks
    • B66F9/22—Hydraulic devices or systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/17—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors using two or more pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/20576—Systems with pumps with multiple pumps
    • F15B2211/20584—Combinations of pumps with high and low capacity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40523—Flow control characterised by the type of flow control means or valve with flow dividers
    • F15B2211/4053—Flow control characterised by the type of flow control means or valve with flow dividers using valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/41—Flow control characterised by the positions of the valve element
    • F15B2211/411—Flow control characterised by the positions of the valve element the positions being discrete
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/415—Flow control characterised by the connections of the flow control means in the circuit
    • F15B2211/41509—Flow control characterised by the connections of the flow control means in the circuit being connected to a pressure source and a directional control valve
    • F15B2211/41518—Flow control characterised by the connections of the flow control means in the circuit being connected to a pressure source and a directional control valve being connected to multiple pressure sources
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/78—Control of multiple output members
    • F15B2211/781—Control of multiple output members one or more output members having priority

Description

本発明は、主として荷役装置を備えたフォークリフト等の産業車両、特に荷役車両に用いられる液圧回路、及びこのような液圧回路を備えた荷役車両に関する。   The present invention relates to an industrial vehicle such as a forklift mainly equipped with a cargo handling device, in particular, a hydraulic circuit used for a cargo handling vehicle, and a cargo handling vehicle equipped with such a hydraulic circuit.

従来より、荷役装置を備えたフォークリフト等の産業車両、特に荷役車両において、図４に示すように、液圧供給源である液圧ポンプａ２と、液圧ポンプａ２からの作動液を優先的にステアリングａ５に供給するとともに余剰の作動液を荷役用アクチュエータａ８に供給するための分流弁ａ４と、この分流弁ａ４と荷役用アクチュエータａ８との間に設けられる流量調整弁ａ６と、作動液を貯蔵するためのタンクａ７から前記液圧ポンプａ２、前記分流弁ａ４及び前記流量調整弁ａ６を経て前記荷役用アクチュエータａ８までを接続する通路ａ９とを備えた液圧回路ａ１が広く用いられている。   Conventionally, in an industrial vehicle such as a forklift equipped with a cargo handling device, particularly a cargo handling vehicle, as shown in FIG. 4, the hydraulic pump a2 that is a hydraulic pressure supply source and the hydraulic fluid from the hydraulic pump a2 are given priority. A diversion valve a4 for supplying surplus hydraulic fluid to the steering actuator a8 while supplying the steering a5, a flow rate adjusting valve a6 provided between the diversion valve a4 and the cargo handling actuator a8, and the hydraulic fluid are stored. For this purpose, a hydraulic circuit a1 including a passage a9 connecting the tank a7 to the cargo handling actuator a8 through the hydraulic pump a2, the diversion valve a4 and the flow rate adjusting valve a6 is widely used.

ところで、液圧ポンプからの作動液の流量は液圧ポンプの回転速度に比例する。また、荷役操作を行わない場合には、余剰の作動液は流量調整弁を経てタンクに戻される。このとき、液圧ポンプを１つのみ有する液圧回路を用いた場合、図５に示すように、ポンプから吐出される作動液の全量がステアリングに供給される液圧で分流弁ａ４内を流通することとなる。すなわち、荷役操作を行わない場合には、図５の斜線に示す領域に相当する量の作動液が不必要に分流弁ａ４内を流通し、圧力損失に伴う動力損失が大きくなる。すなわちエネルギーの無駄が大きくなる。   By the way, the flow rate of the hydraulic fluid from the hydraulic pump is proportional to the rotational speed of the hydraulic pump. Further, when the cargo handling operation is not performed, the surplus hydraulic fluid is returned to the tank through the flow rate adjustment valve. At this time, when a hydraulic circuit having only one hydraulic pump is used, as shown in FIG. 5, the entire amount of hydraulic fluid discharged from the pump is circulated through the diverter valve a4 with the hydraulic pressure supplied to the steering. Will be. That is, when the cargo handling operation is not performed, the amount of hydraulic fluid corresponding to the area shown by the oblique lines in FIG. 5 flows unnecessarily through the diversion valve a4, and the power loss accompanying the pressure loss increases. That is, energy is wasted.

このような無駄を削減するための構成として、複数の液圧ポンプ、例えば図６に示すように第１の液圧ポンプｂ２と第２の液圧ポンプｂ３とを有し、以下のような構成を有する液圧回路ｂ１が考えられている。この液圧回路ｂ１は、液圧供給源である前記第１の液圧ポンプｂ２及び第２の液圧ポンプｂ３と、これら液圧ポンプｂ２、ｂ３からの作動液を優先的にステアリングｂ５に供給するとともに余剰の作動液を荷役用アクチュエータｂ８に供給するための分流弁ｂ４と、この分流弁ｂ４と荷役用アクチュエータｂ８との間に設けられる流量調整弁ｂ６と、作動液を貯蔵するためのタンクｂ７から前記第１の液圧ポンプｂ２、前記分流弁ｂ４及び前記流量調整弁ｂ６を経て前記荷役用アクチュエータｂ８までを接続する主通路ｂ９と、前記主通路ｂ９の前記タンクｂ７と前記第１の液圧ポンプｂ２との間から分岐し前記第２の液圧ポンプｂ３を経て前記分流弁ｂ４と前記流量調節弁ｂ６の間で再び主通路ｂ９に合流する副通路ｂ１０とを具備する。このような液圧回路ｂ１では、第１及び第２の液圧ポンプｂ２、ｂ３が最低回転数ｎminで回転している場合にステアリングｂ５に最低限必要な量の作動液を供給できるようにすべく第１の液圧ポンプｂ２の容量を設定し、分流弁ｂ４内を通過する液量を前段で述べた構成のものと比較して削減することはできる。As a configuration for reducing such waste, there are a plurality of hydraulic pumps, for example, a first hydraulic pump b2 and a second hydraulic pump b3 as shown in FIG. A hydraulic circuit b1 having the following is considered. The hydraulic circuit b1 preferentially supplies the first hydraulic pump b2 and the second hydraulic pump b3, which are hydraulic supply sources, and the hydraulic fluid from the hydraulic pumps b2 and b3 to the steering b5. And a flow dividing valve b4 for supplying surplus hydraulic fluid to the cargo handling actuator b8, a flow rate adjusting valve b6 provided between the flow dividing valve b4 and the cargo handling actuator b8, and a tank for storing the hydraulic fluid a main passage b9 that connects the first hydraulic pump b2, the flow dividing valve b4 and the flow rate adjusting valve b6 to the cargo handling actuator b8, the tank b7 of the main passage b9, and the first passage b9. A sub-passage b10 that branches from the fluid pressure pump b2 and passes through the second fluid pressure pump b3 and joins the main passage b9 again between the flow dividing valve b4 and the flow rate control valve b6 is provided. In such a hydraulic circuit b1, when the first and second hydraulic pumps b2 and b3 are rotating at the minimum number of rotations n min , a minimum amount of hydraulic fluid can be supplied to the steering b5. The capacity of the first hydraulic pump b2 can be set as much as possible, and the amount of liquid passing through the flow dividing valve b4 can be reduced as compared with the configuration described in the previous stage.

しかし、このような構成であっても、回転速度が高い場合には前記第１の液圧ポンプｂ２から吐出され分流弁ｂ４を通過する作動液の量は大きく、前述した荷役操作を行わない場合には図５の斜線に示す領域に相当する量の作動液が不必要に分流弁ｂ４内を流通し、圧力損失に伴う動力損失は依然として大きく、エネルギーの無駄が大きくなる。   However, even in such a configuration, when the rotational speed is high, the amount of hydraulic fluid discharged from the first hydraulic pump b2 and passing through the flow dividing valve b4 is large, and the above-described cargo handling operation is not performed. 5, the amount of hydraulic fluid corresponding to the area shown by the oblique lines in FIG. 5 circulates unnecessarily through the diverter valve b4, and the power loss accompanying the pressure loss is still large, resulting in a waste of energy.

特開２０１０−７６９３７号公報JP 2010-76937 A

本発明は以上の点に着目し、荷役装置を備えたフォークリフト等の産業車両、特に荷役車両に用いられる液圧回路において、荷役作業を行わない場合の圧力損失に伴う動力損失の大幅な削減を図ることを目的とする。   The present invention pays attention to the above points, and in a hydraulic circuit used for an industrial vehicle such as a forklift equipped with a cargo handling device, particularly a cargo handling vehicle, the power loss accompanying the pressure loss when the cargo handling operation is not performed is greatly reduced. The purpose is to plan.

以上の課題を解決すべく、本発明に係る液圧回路は、以下に述べるような構成を有する。すなわち本発明に係る液圧回路は、液圧供給源である複数の液圧ポンプと、これら液圧ポンプからの作動液を優先的にステアリングに供給するとともに余剰の作動液を荷役用アクチュエータに供給するための分流弁と、この分流弁と荷役用アクチュエータとの間に設けられる流量調整弁とを備えている液圧回路であって、前記複数の液圧ポンプとして、１つのメインポンプ及び少なくとも１つのサブポンプを有し、さらに、前記サブポンプと分流弁との間に設けられ前記メインポンプの吐出流量が所定吐出流量を下回る場合又は前記メインポンプの回転速度が所定回転速度を下回る場合には前記サブポンプからの作動液を分流弁の上流側に導く第１の状態をとるとともに前記メインポンプの吐出流量が所定吐出流量を上回る場合又は前記メインポンプの回転速度が所定回転速度を上回る場合には前記サブポンプからの作動液を分流弁の下流側かつ流量調整弁の上流側で合流するバイパス通路に導く第２の状態をとる切替弁を備えている。   In order to solve the above problems, the hydraulic circuit according to the present invention has a configuration as described below. That is, the hydraulic circuit according to the present invention supplies a plurality of hydraulic pumps, which are hydraulic supply sources, and supplies hydraulic fluid from these hydraulic pumps preferentially to the steering and supplies surplus hydraulic fluid to the cargo handling actuator. And a flow control valve provided between the flow dividing valve and the cargo handling actuator, wherein the plurality of hydraulic pumps include one main pump and at least one hydraulic pump. Two sub-pumps, and further provided when the discharge flow rate of the main pump is less than a predetermined discharge flow rate provided between the sub-pump and the diversion valve, or when the rotation speed of the main pump is lower than the predetermined rotation rate A first state in which the hydraulic fluid from the main pump is led to the upstream side of the flow dividing valve and the discharge flow rate of the main pump exceeds a predetermined discharge flow rate; When the rotational speed of the pump exceeds a predetermined rotational speed, there is provided a switching valve that takes a second state that guides the hydraulic fluid from the sub-pump to a bypass passage that joins downstream of the diverter valve and upstream of the flow regulating valve. Yes.

また、上述した課題を解決すべく、本発明に係る荷役車両は、前段に述べた液圧回路を備えている。   In order to solve the above-described problem, the cargo handling vehicle according to the present invention includes the hydraulic circuit described in the previous section.

このようなものであれば、前記メインポンプからの作動液のみでステアリングに必要な作動液の所定流量を確保できるメインポンプの回転速度を前記所定回転速度に設定し、前記メインポンプの吐出流量が所定吐出流量を下回る場合又は前記メインポンプの回転速度が所定回転速度を下回る場合には切替弁を第１の状態とすることで、前記バイパス通路に接続していない液圧ポンプすなわち前記メインポンプの容量を小さくしても、ステアリングに供給する作動液の流量は確保できる。その一方で、前記メインポンプの容量を小さくできるので、荷役操作が行われず液圧ポンプの回転速度が高い場合には切替弁を第２の状態とすることで、従来のものと比較して分流弁を通過する作動液の量を大幅に削減でき、従って荷役作業を行わない場合の圧力損失に伴う動力損失の大幅な削減を図ることができる。   If it is such, the rotation speed of the main pump which can ensure the predetermined flow volume of the hydraulic fluid required for steering only by the hydraulic fluid from the main pump is set to the predetermined rotation speed, and the discharge flow rate of the main pump is When the flow rate is lower than the predetermined discharge flow rate or when the rotation speed of the main pump is lower than the predetermined rotation speed, the switching valve is set to the first state, so that the hydraulic pump that is not connected to the bypass passage, that is, the main pump Even if the volume is reduced, the flow rate of the hydraulic fluid supplied to the steering can be secured. On the other hand, since the capacity of the main pump can be reduced, when the cargo handling operation is not performed and the rotational speed of the hydraulic pump is high, the switching valve is set to the second state, thereby diverting the flow compared to the conventional one. The amount of hydraulic fluid that passes through the valve can be greatly reduced, and therefore, the power loss accompanying the pressure loss when the cargo handling operation is not performed can be greatly reduced.

本発明によれば、荷役装置を備えたフォークリフト等の産業車両、特に荷役車両に用いられる液圧回路において、荷役作業を行わない場合の圧力損失に伴う動力損失の大幅な削減を図ることができる。   ADVANTAGE OF THE INVENTION According to this invention, in industrial vehicles, such as a forklift provided with a cargo handling apparatus, especially the hydraulic circuit used for a cargo handling vehicle, it can aim at the significant reduction of the power loss accompanying the pressure loss when not performing cargo handling work. .

本発明の一実施形態に係る液圧回路を示す回路図。The circuit diagram which shows the hydraulic circuit which concerns on one Embodiment of this invention. 同実施形態に係る液圧ポンプの回転速度と液圧回路の分流弁を示す作動液の流量との関係を示す図。The figure which shows the relationship between the rotational speed of the hydraulic pump which concerns on the embodiment, and the flow volume of the hydraulic fluid which shows the shunt valve of a hydraulic circuit. 本発明の他の実施形態に係る液圧回路を示す回路図。The circuit diagram which shows the hydraulic circuit which concerns on other embodiment of this invention. 従来の液圧回路を示す回路図。The circuit diagram which shows the conventional hydraulic circuit. 図４に示す液圧回路における液圧ポンプの回転速度と液圧回路の分流弁を示す作動液の流量との関係を示す図。The figure which shows the relationship between the rotational speed of the hydraulic pump in the hydraulic circuit shown in FIG. 4, and the flow volume of the hydraulic fluid which shows the shunt valve of a hydraulic circuit. 従来の液圧回路を示す回路図。The circuit diagram which shows the conventional hydraulic circuit. 図６に示す液圧回路における液圧ポンプの回転速度と液圧回路の分流弁を示す作動液の流量との関係を示す図。The figure which shows the relationship between the rotational speed of the hydraulic pump in the hydraulic circuit shown in FIG. 6, and the flow volume of the hydraulic fluid which shows the shunt valve of a hydraulic circuit.

本発明の一実施形態を図１及び図２を参照しつつ以下に示す。   An embodiment of the present invention will be described below with reference to FIGS.

本実施形態の液圧回路１は、荷役車両に搭載されるものであり、図１に示すように、液圧供給源である２つの液圧ポンプ、すなわちメインポンプ２及びサブポンプ３と、これら液圧ポンプすなわちメインポンプ２及びサブポンプ３からの作動液を優先的にステアリング５に供給するとともに余剰の作動液を荷役用アクチュエータ８に供給するための分流弁４と、この分流弁４と荷役用アクチュエータ８との間に設けられる流量調整弁６と、作動液を貯蔵するためのタンク７から前記メインポンプ２、前記分流弁４及び前記流量調整弁６を経て前記荷役用アクチュエータ８までを接続する主通路９と、前記主通路９の前記タンク７と前記メインポンプ２との間から分岐し前記サブポンプ３を経て前記主通路９の前記メインポンプ２と前記分流弁４との間で再び主通路９に合流する第１の副通路１０と、前記第１の副通路１０の前記サブポンプ３と分流弁４との間から分岐し前記主通路９の前記分流弁４と前記流量調整弁６との間で前記主通路９に合流する第２の副通路１１と、前記第２の副通路１１が前記第１の副通路１０と分岐する箇所に設けられメインポンプ２の回転速度が所定回転速度ｎ1を下回る場合には前記サブポンプ３からの作動液を分流弁４の上流側に導く第１の状態をとるとともにメインポンプ２の回転速度が所定回転速度ｎ1を上回る場合には前記サブポンプ３からの作動液を前記第２の副通路１１に導く第２の状態をとる切替弁１２とを備えている。ここで、前記第２の副通路１１が、請求項中のバイパス通路である。The hydraulic circuit 1 of the present embodiment is mounted on a cargo handling vehicle. As shown in FIG. 1, two hydraulic pumps that are hydraulic supply sources, that is, a main pump 2 and a sub pump 3, and these liquids The flow dividing valve 4 for supplying the hydraulic fluid from the pressure pump, that is, the main pump 2 and the sub pump 3 preferentially to the steering 5 and supplying the excess hydraulic fluid to the cargo handling actuator 8, and the flow dividing valve 4 and the cargo handling actuator A main flow rate control valve 6 provided between the main pump 2, the flow dividing valve 4 and the flow rate adjustment valve 6 to the cargo handling actuator 8 from a tank 7 for storing hydraulic fluid. The main pump 2 and the diversion valve of the main passage 9 branch from the passage 9 and between the tank 7 of the main passage 9 and the main pump 2 and pass through the sub pump 3. Between the first sub-passage 10 that joins the main passage 9 again, and between the sub-pump 3 and the diversion valve 4 in the first sub-passage 10, and the diversion valve 4 in the main passage 9. A second sub-passage 11 that joins the main passage 9 with the flow rate adjusting valve 6 and a portion where the second sub-passage 11 branches from the first sub-passage 10 are provided in the main pump 2. When the rotational speed is lower than the predetermined rotational speed n 1 , the first state in which the hydraulic fluid from the sub pump 3 is guided to the upstream side of the flow dividing valve 4 is taken and the rotational speed of the main pump 2 exceeds the predetermined rotational speed n 1 . In this case, a switching valve 12 is provided which takes a second state for guiding the hydraulic fluid from the sub pump 3 to the second sub passage 11. Here, the second sub-passage 11 is a bypass passage in the claims.

前記メインポンプ２及びサブポンプ３は、ともに図示しない動力源である車両の駆動用エンジン又はモータに接続されており、同一の回転速度で連動して回転する周知の構成の固定容量ポンプである。ここで、これらメインポンプ２及びサブポンプ３の回転速度は、最低回転速度ｎminと最高回転速度ｎmaxとの間である。The main pump 2 and the sub pump 3 are both connected to a vehicle driving engine or motor, which is a power source (not shown), and are fixed capacity pumps having a known configuration that rotate in conjunction with each other at the same rotational speed. Here, the rotation speeds of the main pump 2 and the sub pump 3 are between the minimum rotation speed n min and the maximum rotation speed n max .

前記分流弁４は、フォークリフト等に用いられ、ステアリング５と、荷役用アクチュエータ８とに作動液を供給する優先弁機構として周知のものと同様の構成を有する。すなわち、この分流弁４は、前記メインポンプ２及びサブポンプ３から吐出された高圧作動液の導入口たる入力ポート４ａと、ステアリング５の作動に必要な作動液を優先してステアリング５に向けて吐出する優先流出力口４ｂと、余剰の作動液を荷役用アクチュエータ８に向けて吐出する余剰流出力口４ｃとを具備する。前記余剰流出力口４ｃから吐出された作動液は、前記流量調整弁６を経て荷役用アクチュエータ８に導かれる。   The diversion valve 4 is used for a forklift or the like, and has the same configuration as a well-known priority valve mechanism that supplies hydraulic fluid to the steering 5 and the cargo handling actuator 8. That is, the diversion valve 4 gives priority to the input port 4a serving as an inlet for the high-pressure hydraulic fluid discharged from the main pump 2 and the sub pump 3 and the hydraulic fluid necessary for the operation of the steering 5 and discharges it toward the steering 5. And a surplus flow output port 4c that discharges surplus hydraulic fluid toward the cargo handling actuator 8. The hydraulic fluid discharged from the surplus flow output port 4 c is guided to the cargo handling actuator 8 through the flow rate adjusting valve 6.

前記流量調整弁６は、図示しない操作レバーが受け付けた操作を受けて開度を変更することにより、荷役用アクチュエータ８に導かれる作動液の量を調節する機能を有する。   The flow rate adjusting valve 6 has a function of adjusting the amount of hydraulic fluid guided to the cargo handling actuator 8 by changing the opening degree in response to an operation received by an operation lever (not shown).

そして、前記切替弁１２は、上述したように、前記サブポンプ３と分流弁４との間に設けられ、メインポンプ２の回転速度が所定回転速度ｎ1を下回る場合、すなわちメインポンプ２からの吐出流量がステアリング５を作動させるために必要な最低限の流量である所定吐出流量ｆminを下回る場合には前記サブポンプ３からの作動液を第１の副通路１０を経て分流弁４の上流側に導く第１の状態をとり、メインポンプ２の回転速度が所定回転速度ｎ1を上回る場合には前記サブポンプ３からの作動液を第２の副通路１１を経て分流弁４の下流側かつ流量調整弁６の上流側に導く第２の状態をとる。ここで、メインポンプ２からの作動液の吐出流量は、メインポンプ２の回転速度に略比例する。すなわち、前記所定回転速度ｎ1では、メインポンプ２から吐出される作動液の流量が、前記所定吐出流量ｆminと略等しくなる。そして、この切替弁１２は、第１の状態をとるように付勢するための付勢手段であるコイルばね１２ａと、電力が供給された際に前記コイルばね１２ａの付勢力に抗して第２の状態とするためのソレノイド１２ｂとを内蔵しており、このソレノイド１２ｂは後述する図示しない制御装置に接続されている。この制御装置は、ＣＰＵ、記憶装置、入出力インタフェースを備えたマイクロコンピュータシステムと、エンジン又はモータの回転速度を検知する回転数センサとを接続して形成したものであり、前記回転数センサの出力信号が示す回転速度が前記所定回転速度ｎ1を上回った場合には前記ソレノイド１２ｂに通電し、切替弁１２を第２の状態とする制御を行う。Then, the switching valve 12, as described above, is provided between the diverter valve 4 and the subordinate fuel pump 3, when the rotational speed of the main pump 2 is below a predetermined rotational speed n 1, i.e. discharge from the main pump 2 When the flow rate is lower than the predetermined discharge flow rate f min that is the minimum flow rate required to operate the steering 5, the hydraulic fluid from the sub pump 3 passes through the first sub passage 10 to the upstream side of the flow dividing valve 4. In the first state of guiding, when the rotational speed of the main pump 2 exceeds the predetermined rotational speed n 1 , the hydraulic fluid from the sub-pump 3 passes through the second sub-passage 11 downstream of the flow dividing valve 4 and the flow rate is adjusted. A second state of leading to the upstream side of the valve 6 is taken. Here, the discharge flow rate of the hydraulic fluid from the main pump 2 is substantially proportional to the rotational speed of the main pump 2. That is, at the predetermined rotational speed n 1 , the flow rate of the hydraulic fluid discharged from the main pump 2 becomes substantially equal to the predetermined discharge flow rate f min . The switching valve 12 includes a coil spring 12a that is an urging means for urging to take the first state and a urging force of the coil spring 12a when electric power is supplied. 2 is built in, and this solenoid 12b is connected to a control device (not shown) to be described later. This control device is formed by connecting a microcomputer system having a CPU, a storage device, and an input / output interface and a rotation speed sensor for detecting the rotation speed of the engine or motor, and outputs the rotation speed sensor. When the rotation speed indicated by the signal exceeds the predetermined rotation speed n 1 , the solenoid 12b is energized and the switching valve 12 is controlled to be in the second state.

ここで、メインポンプ２の回転速度と分流弁４を通過する流量との関係について図２を参照しつつ述べると、回転速度が前記所定回転速度ｎ1を下回る際には、上述したように切替弁１２は第１の状態をとるので、メインポンプ２及びサブポンプ３から吐出される作動液はいずれも分流弁４を通過する。従って、分流弁４を通過する流量は図２の実線Ｄ１＋Ｄ２に示すようなものとなる。一方、回転速度が前記所定回転速度ｎ1を上回る際には、上述したように切替弁１２は第２の状態をとるので、メインポンプ２から吐出される作動液のみが分流弁４を通過する。従って、分流弁４を通過する流量は図２の破線Ｄ１に示すようなものとなる。その際にメインポンプ２から吐出される作動液の流量はステアリング５を作動させるために必要な最低限の流量すなわち前記所定吐出流量ｆminを上回っている。Here, the relationship between the rotational speed of the main pump 2 and the flow rate passing through the flow dividing valve 4 will be described with reference to FIG. 2. When the rotational speed falls below the predetermined rotational speed n 1 , switching is performed as described above. Since the valve 12 is in the first state, the hydraulic fluid discharged from the main pump 2 and the sub pump 3 passes through the flow dividing valve 4. Accordingly, the flow rate passing through the diversion valve 4 is as shown by the solid line D1 + D2 in FIG. On the other hand, when the rotational speed exceeds the predetermined rotational speed n 1 , the switching valve 12 takes the second state as described above, so that only the hydraulic fluid discharged from the main pump 2 passes through the flow dividing valve 4. . Accordingly, the flow rate passing through the diversion valve 4 is as shown by the broken line D1 in FIG. At this time, the flow rate of the hydraulic fluid discharged from the main pump 2 exceeds the minimum flow rate necessary for operating the steering 5, that is, the predetermined discharge flow rate f min .

すなわち本実施形態によれば、図４及び図５を参照しつつ説明した１つの液圧ポンプａ２のみを利用する従来の液圧回路ａ１と比較して、回転数が高い領域においては、分流弁４を通過する作動液の流量を大幅に削減できる。より具体的には、荷役操作を行わない場合に分流弁４を不必要に流通する作動液の量は図２の斜線に示す領域に相当する量であり、回転速度が前記所定回転速度ｎ1を上回る領域すなわちメインポンプ２から吐出される作動液の流量が、前記所定吐出流量ｆminを上回る領域では、図２において前記図２の実線Ｄ１＋Ｄ２の延長部分と前記破線Ｄ１との間の領域Ｘに相当する量だけ、分流弁４を不必要に流通する作動液の量を削減できる。また、図６及び図７を参照しつつ説明した従来の液圧回路１と比較しても、最低回転数ｎmin近傍ではメインポンプ２及びサブポンプ３を利用するので、メインポンプ２からの作動液のみでステアリング５を作動させるために必要な最低限の流量ｆminを確保する必要がなく、メインポンプ２の容量を小さくできることから、回転数が高い領域において分流弁４を通過する作動液の流量を大幅に削減できる。すなわち、従来の液圧回路１と比較して、分流弁４を通過する作動液の流量を大幅に削減することにより作動液が分流弁４を通過する圧力損失に伴う動力損失を抑制できる。そして、この動力損失によるエネルギーの無駄も大幅に削減できる。In other words, according to the present embodiment, in the region where the rotational speed is high as compared with the conventional hydraulic circuit a1 that uses only one hydraulic pump a2 described with reference to FIGS. The flow rate of the hydraulic fluid passing through 4 can be greatly reduced. More specifically, when the cargo handling operation is not performed, the amount of the hydraulic fluid that circulates unnecessarily through the flow dividing valve 4 is an amount corresponding to the area shown by the oblique lines in FIG. 2, and the rotational speed is the predetermined rotational speed n 1. 2, that is, in a region where the flow rate of the hydraulic fluid discharged from the main pump 2 exceeds the predetermined discharge flow rate f min , a region X between the extended portion of the solid line D1 + D2 in FIG. 2 and the broken line D1 in FIG. Thus, the amount of hydraulic fluid that flows unnecessarily through the flow dividing valve 4 can be reduced by an amount corresponding to. Compared with the conventional hydraulic circuit 1 described with reference to FIGS. 6 and 7, since the main pump 2 and the sub pump 3 are used in the vicinity of the minimum rotation speed n min , the hydraulic fluid from the main pump 2 is used. Therefore, it is not necessary to secure the minimum flow rate f min necessary for operating the steering 5 alone, and the capacity of the main pump 2 can be reduced. Therefore, the flow rate of the working fluid that passes through the flow dividing valve 4 in the high rotation speed region Can be greatly reduced. That is, as compared with the conventional hydraulic circuit 1, the power loss due to the pressure loss at which the hydraulic fluid passes through the diverter valve 4 can be suppressed by significantly reducing the flow rate of the hydraulic fluid that passes through the diverter valve 4. And energy waste due to this power loss can be greatly reduced.

なお、本発明は上述した実施例に限らない。   In addition, this invention is not restricted to the Example mentioned above.

例えば、図３に示すように、バイパス通路すなわち第２の副流路１１中に、サブポンプ３を通過した作動液をタンク通路１４を経てタンク７に導く第１の状態とサブポンプ３を通過した作動液を流量調整弁６の上流側に導く第２の状態とをとることが可能な第２の切替弁１３を設けてもよい。この第２の切替弁１３は、第１の状態をとるように付勢するための付勢手段であるコイルばね１３ａと、電力が供給された際に前記コイルばね１３ａの付勢力に抗して第２の状態とするためのソレノイド１３ｂとを内蔵しており、このソレノイドは後述する制御装置に接続されている。この制御装置は、ＣＰＵ、記憶装置、入出力インタフェースを備えたマイクロコンピュータシステムと、エンジン又はモータの回転速度を検知する図示しない回転数センサとを接続して形成したものであり、荷役作業が行われている場合には前記ソレノイド１３ｂに通電し、切替弁１３を第２の状態とする制御を行う。なお、図３に示す液圧回路１は、その他の点では図１及び図２に示す液圧回路１と同様の構成を有するので、対応する箇所には同一の名称及び符号を付し、詳細な説明は省略している。   For example, as shown in FIG. 3, the first state in which the working fluid that has passed through the sub pump 3 is guided to the tank 7 through the tank passage 14 in the bypass passage, that is, the second sub passage 11, and the operation that has passed through the sub pump 3. You may provide the 2nd switching valve 13 which can take the 2nd state which guide | induces a liquid to the upstream of the flow regulating valve 6. FIG. The second switching valve 13 has a coil spring 13a which is a biasing means for biasing to take the first state, and a biasing force of the coil spring 13a when electric power is supplied. The solenoid 13b for making it a 2nd state is built in, and this solenoid is connected to the control apparatus mentioned later. This control device is formed by connecting a microcomputer system having a CPU, a storage device, and an input / output interface, and a rotation speed sensor (not shown) that detects the rotation speed of the engine or motor, and performs a cargo handling operation. If it is not, the solenoid 13b is energized to control the switching valve 13 in the second state. Since the hydraulic circuit 1 shown in FIG. 3 has the same configuration as the hydraulic circuit 1 shown in FIGS. 1 and 2 in other points, the corresponding parts are denoted by the same names and symbols, and the details are as follows. Detailed explanations are omitted.

このような構成であれば、荷役作業が行われていない場合にはサブポンプ３を通過した作動液を無負荷でタンク７に導くことができるので、作動液が流量調整弁６を通過する圧力損失に伴う動力損失をも抑制できる。そして、この動力損失によるエネルギーの無駄をさらに削減できる。   With such a configuration, when the cargo handling operation is not performed, the hydraulic fluid that has passed through the sub pump 3 can be guided to the tank 7 with no load, and therefore the pressure loss at which the hydraulic fluid passes through the flow rate adjustment valve 6. It is also possible to suppress power loss associated with. And waste of energy due to this power loss can be further reduced.

また、複数のサブポンプを有する液圧回路に本発明を適用してもよい。   Further, the present invention may be applied to a hydraulic circuit having a plurality of sub pumps.

加えて、上述した実施形態では、メインポンプ及びサブポンプとして固定容量ポンプを利用し、回転速度と吐出流量とが略比例することに着目し、回転速度が所定回転速度を下回る場合に切替弁が前記サブポンプからの作動液を分流弁の上流側に導く第１の状態をとるようにしているとともに、回転速度が所定回転速度を上回る場合に切替弁が前記サブポンプからの作動液をバイパス通路に導く第２の状態をとるようにしているが、メインポンプからの作動液の吐出流量を流量センサ等の流量検知手段を用いて直接検知し、検知した作動液の吐出流量が所定吐出流量を下回る場合に切替弁が前記サブポンプからの作動液を分流弁の上流側に導く第１の状態をとるようにするとともに、検知した作動液の吐出流量が所定吐出流量を上回る場合に切替弁が前記サブポンプからの作動液をバイパス通路に導く第２の状態をとるようにする構成を採用してもよい。   In addition, in the above-described embodiment, a fixed displacement pump is used as the main pump and the sub pump, and attention is paid to the fact that the rotational speed and the discharge flow rate are substantially proportional. When the rotational speed is lower than the predetermined rotational speed, the switching valve is The first state is such that the hydraulic fluid from the sub pump is guided to the upstream side of the flow dividing valve, and the switching valve guides the hydraulic fluid from the sub pump to the bypass passage when the rotational speed exceeds a predetermined rotational speed. When the discharge flow rate of the hydraulic fluid from the main pump is directly detected using flow rate detection means such as a flow rate sensor, and the detected discharge flow rate of the hydraulic fluid is lower than the predetermined discharge flow rate When the switching valve is in a first state in which the hydraulic fluid from the sub-pump is guided to the upstream side of the flow dividing valve, and the detected hydraulic fluid discharge flow rate exceeds a predetermined discharge flow rate Kawaben may be adopted a configuration in which to take a second state to direct the hydraulic fluid from the sub pump to the bypass passage.

その他、本発明の趣旨を損ねない範囲で種々に変更してよい。   In addition, various changes may be made without departing from the spirit of the present invention.

本発明の構成を採用すれば、荷役装置を備えたフォークリフト等の産業車両、特に荷役車両に用いられる液圧回路において、荷役作業を行わない場合の圧力損失に伴う動力損失の大幅な削減を図ることができる。   By adopting the configuration of the present invention, in a hydraulic circuit used in an industrial vehicle such as a forklift equipped with a cargo handling device, in particular, a cargo handling vehicle, the power loss accompanying the pressure loss when the cargo handling operation is not performed is greatly reduced. be able to.

１…液圧回路
２…メインポンプ（液圧ポンプ）
３…サブポンプ（液圧ポンプ）
４…分流弁
６…流量調整弁
１１…バイパス通路（第２の副通路）
１２…切替弁1 ... Hydraulic circuit 2 ... Main pump (Hydraulic pump)
3. Sub pump (hydraulic pump)
4 ... Branch valve 6 ... Flow control valve 11 ... Bypass passage (second auxiliary passage)
12 ... Switching valve

Claims (2)

液圧供給源である複数の液圧ポンプと、これら液圧ポンプからの作動液を優先的にステアリングに供給するとともに余剰の作動液を荷役用アクチュエータに供給するための分流弁と、この分流弁と荷役用アクチュエータとの間に設けられる流量調整弁とを備えている液圧回路であって、前記複数の液圧ポンプとして、１つのメインポンプ及び少なくとも１つのサブポンプを有し、さらに、前記サブポンプと分流弁との間に設けられ前記メインポンプの吐出流量が所定吐出流量を下回る場合又は前記メインポンプの回転速度が所定回転速度を下回る場合には前記サブポンプからの作動液を分流弁の上流側に導く第１の状態をとるとともに前記メインポンプの吐出流量が所定吐出流量を上回る場合又は前記メインポンプの回転速度が所定回転速度を上回る場合には前記サブポンプからの作動液を分流弁の下流側かつ流量調整弁の上流側で合流するバイパス通路に導く第２の状態をとる切替弁を備えていることを特徴とする液圧回路。 A plurality of hydraulic pumps that are hydraulic pressure supply sources, a diverter valve for preferentially supplying hydraulic fluid from these hydraulic pumps to the steering and supplying excess hydraulic fluid to the cargo handling actuator, and the diverter valve And a flow control valve provided between the cargo handling actuator, the hydraulic pump having one main pump and at least one sub-pump as the plurality of hydraulic pumps, and the sub-pump When the discharge flow rate of the main pump is lower than a predetermined discharge flow rate or when the rotation speed of the main pump is lower than the predetermined rotation speed, the hydraulic fluid from the sub pump is upstream of the flow distribution valve. And when the discharge flow rate of the main pump exceeds a predetermined discharge flow rate or the rotation speed of the main pump is a predetermined rotation speed A fluid pressure circuit comprising a switching valve that takes a second state to guide the hydraulic fluid from the sub-pump to a bypass passage that joins the downstream side of the flow dividing valve and the upstream side of the flow rate adjusting valve when exceeding . 液圧供給源である複数の液圧ポンプと、これら液圧ポンプからの作動液を優先的にステアリングに供給するとともに余剰の作動液を荷役用アクチュエータに供給するための分流弁と、この分流弁と荷役用アクチュエータとの間に設けられる流量調整弁とを備えている液圧回路を搭載した荷役車両であって、前記複数の液圧ポンプとして、１つのメインポンプ及び少なくとも１つのサブポンプを有し、さらに、前記サブポンプと分流弁との間に設けられ前記メインポンプの吐出流量が所定吐出流量を下回る場合又は前記メインポンプの回転速度が所定回転速度を下回る場合には前記サブポンプからの作動液を分流弁の上流側に導く第１の状態をとるとともに前記メインポンプの吐出流量が所定吐出流量を上回る場合又は前記メインポンプの回転速度が所定回転速度を上回る場合には前記サブポンプからの作動液を分流弁の下流側かつ流量調整弁の上流側で合流するバイパス通路に導く第２の状態をとる切替弁を備えていることを特徴とする荷役車両。 A plurality of hydraulic pumps that are hydraulic pressure supply sources, a diverter valve for preferentially supplying hydraulic fluid from these hydraulic pumps to the steering and supplying excess hydraulic fluid to the cargo handling actuator, and the diverter valve A cargo handling vehicle equipped with a hydraulic pressure circuit having a flow rate adjustment valve provided between the cargo handling actuator and the cargo handling actuator, wherein the plurality of hydraulic pressure pumps include one main pump and at least one sub pump. Furthermore, when the discharge flow rate of the main pump provided between the sub pump and the diversion valve is lower than a predetermined discharge flow rate or when the rotation speed of the main pump is lower than the predetermined rotation speed, the working fluid from the sub pump is discharged. When the first state leading to the upstream side of the flow dividing valve is taken and the discharge flow rate of the main pump exceeds a predetermined discharge flow rate, or the rotation of the main pump A switching valve that takes a second state in which the hydraulic fluid from the sub-pump is led to a bypass passage that joins the downstream side of the flow dividing valve and the upstream side of the flow rate adjusting valve when the degree of rotation exceeds a predetermined rotational speed. A characteristic cargo handling vehicle.
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JPWO2014097423A1 (en) 2017-01-12
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