JP3627570B2 - Control device for work machine in forklift truck - Google Patents

Description

【００２８】
これにより、前述した第一の実施の形態と同様、リフトシリンダ５に供給される作動油が大幅に増加するのを防止することができ、リフトシリンダ５における急作動及びフォーク７の急上昇の発生をなくすことができると共に、リフトシリンダ５の負荷に応じて出力する指令信号Ｓｒを変更することで、フォーク７上に積載する荷物の重量によってリフトシリンダ５の作動状態が変化するのを防止することもできる。
【００２９】
次に、本発明によるフォークリフトトラックにおける作業機の制御装置の第二の実施の形態について説明する。
作業機の制御装置としては、前述した第一の実施の形態と同様であるが、制御コントローラ１６におけるリフト用比例電磁弁１４に出力する指令信号Ｓｒの算出において、第一の実施の形態と異なる。すなわち、リフト用比例電磁弁１４に出力するリフトレバー１７の操作量に基づいた指令信号Ｓｒを、リフトレバー１７の操作量に基づいたポンプモータ１３に出力する駆動信号Ｄｒとチルトレバー１８の操作量に基づいたポンプモータ１３に出力する駆動信号Ｄｔとの差に応じて減少して算出し、これをリフト用比例電磁弁１４に出力する。
【００３０】
この制御コントローラ１６におけるリフト用比例電磁弁１４へ出力する指令信号Ｓｒの算出について具体的に述べると、まず、リフトレバー１７の操作量より、予め設定した図４に示すリフトレバーの操作量に対するリフト用比例電磁弁へ出力する指令信号である電流値を示したリフト用演算マップを用いて指令信号Ｓｒ１を算出する。このリフト用演算マップには一つの関数線を備え、この関数線はリフトレバー１７を単独で用いた際の通常値である。そして、リフトレバー１７の操作量より算出したポンプモータ１３に出力する駆動信号Ｄｒとチルトレバー１８の操作量より算出したポンプモータ１３に出力する駆動信号Ｄｔとを対比して、この差（Ｄｔ−Ｄｒ）を求めて、この求めた差より減少値ｄを算出する。この減少値ｄの算出は、図５に示す減少値演算マップを用いる。ただし、減少値ｄの算出は、チルトレバー１８の操作量より算出した駆動信号Ｄｔがリフトレバー１７の操作量より算出した駆動信号Ｄｒより大きい時（Ｄｔ＞Ｄｒ）のみである。そして、前述のリフト用演算マップを用いて算出した指令信号Ｓｒ１から減少値ｄを減算して（Ｓｒ１−ｄ）、リフト用比例電磁弁１４に出力する最終的な指令信号Ｓｒを算出する。
【００３１】
このようにリフトレバー１７とチルトレバー１８の同時操作の際、制御コントローラ１６においては、リフト用比例電磁弁１４へ出力する指令信号Ｓｒを、リフトレバー１７の操作量に基づいたポンプモータ１３に出力する駆動信号Ｄｒとチルトレバー１８の操作量に基づいたポンプモータ１３に出力する駆動信号Ｄｔとの差に応じて減少して算出し、これを出力することで、前述した第一の実施の形態と同様、仮にチルトレバー１８の操作量によりポンプモータ１３に大きい値の駆動信号Ｄが出力され、油圧ポンプ１２によって回路内に多量の作動油が流れても、リフト用比例電磁弁１４においてはリフトレバー１７の操作量に基づいた駆動信号Ｄｒとチルトレバー１８の操作量に基づいた駆動信号Ｄｔとの差に応じて減少した指令信号Ｓｒによりバルブ開度が通常の値（リフトレバー１７を単独使用した場合の値）より小さくなり、これにより、リフトシリンダ５に供給される作動油が大幅に増加するのを防止することができ、リフトシリンダ５における急作動及びフォーク７の急上昇の発生をなくすことができる。しかも、リフトレバー１７の操作量に基づいた駆動信号Ｄｒとチルトレバー１８の操作量に基づいた駆動信号Ｄｔとの差が小さくなると、これに対応して減少値ｄも小さくなり、差がなくなると、減少値ｄも０となることで、リフトレバー１７を単独使用した場合の通常の値とすることができ、これにより、リフトレバー１７やチルトレバー１８の操作量が変化するごとにリフト用比例電磁弁１４へ出力する指令信号Ｓｒにおける減少値ｄを変更することで、常に最適でかつきめの細かな制御を行うことができる。
【００３２】
また、本発明によるフォークリフトトラックにおける作業機の制御装置の第二の実施の形態の変形例について説明する。
前述した第二の実施の形態とほぼ同様となるが、リフトシリンダ５の負荷を検出する負荷検出手段としての圧力センサを備えて、この圧力センサによりリフトシリンダ５の負荷を検出することで、フォーク７上に積載する荷物の重量を検出する。
【００３３】
そして、前記コントローラでは、前述した第二の実施の形態と同様、ポンプモータ１３に駆動信号Ｄを出力すると共に、チルト用比例電磁弁１５に指令信号Ｓｔを出力し、さらに、リフト用比例電磁弁１４にチルトレバー１８の操作量に応じて減少した指令信号Ｓｒを出力するが、この時のリフト用比例電磁弁１４に出力する指令信号Ｓｒの算出において、圧力センサで検出したリフトシリンダ５の負荷に応じて指令信号Ｓｒを変更する。
【００３４】
つまり、前記コントローラにおいては、リフトレバー１７の操作量より算出したポンプモータ１３に出力する駆動信号Ｄｒとチルトレバー１８の操作量より算出したポンプモータ１３に出力する駆動信号Ｄｔとを対比して、この差（Ｄｔ−Ｄｒ）を求めて、この求めた差より減少値ｄを算出するが、この減少値ｄの算出においては、図６に示す減少値演算マップを用いる。この減少値演算マップはリフトシリンダ５の負荷に応じて変化する、すなわちその傾きが変わるようになる関数線を備え、負荷に応じて関数線の傾きが変わることで、この関数線を用いてリフトレバー１７の操作量よりリフト用比例電磁弁１４へ出力する指令信号Ｓｒを算出する。
【００３５】
これにより、前述した第二の実施の形態と同様、リフトシリンダ５に供給される作動油が大幅に増加するのを防止することができ、リフトシリンダ５における急作動及びフォーク７の急上昇の発生をなくすことができると共に、リフトシリンダ５の負荷に応じて出力する指令信号Ｓｒを変更することで、フォーク７上に積載する荷物の重量によってリフトシリンダ５の作動状態が変化するのを防止することもできる。
【００３６】
なお、前述した第一、第二の実施の形態において、作業機アクチュエータ及び作業機レバーとして、チルトシリンダ３及びチルトレバー１８を用いた場合について述べているが、これに限定されるものではなく、他のアタッチメント用シリンダ及びその操作レバー等でも良い。
【００３７】
また、前述した第一、第二の実施の形態において、作業機アクチュエータであるチルトシリンダ３に作動油を供給するようになる流量規制手段として比例電磁弁を用いていたが、これに限定されるものではなく、例えば、手動操作弁等を用いても良い。
【００３８】
また、前述した第一、第二の実施の形態及びそれぞれの変形例では、リフトシリンダと作業機アクチュエータの一つであるチルトシリンダの二つを同時に操作する場合において説明していたが、三つ以上の複数のものを同時に操作する場合でも同様に行うことができ、これにより同様の効果を得ることもできる。
【００３９】
【発明の効果】
リフトレバーと作業機レバーを同時に操作の際、作業機レバーの操作量によりポンプモータに大きい値の駆動信号が出力され、油圧ポンプによって回路内に多量の作動油が流れても、リフト用比例電磁弁において作業機レバーの操作量に応じて減少した指令信号によりバルブ開度を通常の値より小さくして、リフトシリンダに多量の作動油が供給されるのを防止する。これにより、リフトシリンダにおける急作動及びフォークの急上昇の発生をなくすことができ、リフトレバーと作業機レバーの同時操作作業の際のフォーク上に積んだ荷物の崩れといった問題を低減し、安全性や操作性の大幅な向上を図ることができる。
【００４０】
また、リフトレバーと作業機レバーを同時に操作の際、作業機レバーの操作量によりポンプモータに大きい値の駆動信号が出力され、油圧ポンプによって回路内に多量の作動油が流れても、リフト用比例電磁弁においてリフトレバーの操作量に基づいたポンプモータに出力する駆動信号と作業機レバーの操作量に基づいたポンプモータに出力する駆動信号との差に応じて減少した指令信号によりバルブ開度を通常の値より小さくして、リフトシリンダに多量の作動油が供給されるのを防止する。これにより、やはり、リフトシリンダにおける急作動及びフォークの急上昇の発生をなくすことができ、リフトレバーと作業機レバーの同時操作作業の際のフォーク上に積んだ荷物の崩れといった問題を低減し、安全性や操作性の大幅な向上を図ることができる。
【００４１】
さらに、フォーク上に積載する荷物の重量によってリフトシリンダの作動状態が変化するのを防止することもでき、フォーク上の荷物の有無による操作フィーリングが異なるのを防止することができる。
【図面の簡単な説明】
【図１】フォークリフトトラックの概略説明図である。
【図２】フォークリフトトラックにおける作業機の制御装置の構成図である。
【図３】制御コントローラにおいて記憶するリフト用演算マップの図表である。
【図４】制御コントローラにおいて記憶する他のリフト用演算マップの図表である。
【図５】制御コントローラにおいて記憶する減少値演算マップの図表である。
【図６】制御コントローラにおいて記憶する他の減少値演算マップの図表である。
【符号の説明】
１…車体、２…作業機、３…チルトシリンダ、３ａ…ボトム、３ｂ…ロッド、４…マスト、５…リフトシリンダ、５ａ…ボトム、６…リフトブラケット、７…フォーク、１１…油圧タンク、１２…油圧ポンプ、１３…ポンプモータ、１４…リフト用比例電磁弁、１５…チルト用比例電磁弁、１６…制御コントローラ、１７…リフトレバー、１８…チルトレバー。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a work machine in a forklift truck, and more particularly to a control device that controls a lift cylinder and a work machine actuator in the work machine.
[0002]
[Prior art]
Conventionally, in a forklift truck, as shown in FIG. 1, a work machine 2 is provided at a front portion of a vehicle body 1. As the work machine 2, a tilt cylinder which is a kind of work machine actuator is provided at a front portion of the vehicle body 1. 3 includes a mast 4 that can be tilted back and forth, and a lift bracket 6 that can be moved up and down by a lift cylinder 5 and a chain along the mast 4. The lift bracket 6 includes a fork 7.
[0003]
As shown in FIG. 2, the control device for the working machine includes a hydraulic pump 12 that discharges hydraulic oil from the hydraulic tank 11 and a pump motor 13 that drives the hydraulic pump 12. A lift proportional solenoid valve 14 is provided that regulates the flow rate of the discharged hydraulic oil and supplies the desired flow rate to the lift cylinder 5, and the flow rate of the hydraulic oil discharged from the hydraulic pump 12 is regulated to set the desired flow rate to the tilt cylinder. 3 is provided with a proportional solenoid valve 15 for tilt to be supplied to 3.
[0004]
The lift proportional solenoid valve 14 is moved by the solenoid a and the solenoid b to move the spool at the rising position U, the stop position N, and the lowering position D, and is operated by changing the direction in which the hydraulic oil flows and changing the valve opening degree. By changing the oil flow rate, the lift cylinder 5 is raised, stopped, and lowered. Further, the proportional solenoid valve 15 for tilt is moved at the forward tilt position F, the stop position N, and the rear tilt position B by moving the spool by the solenoid a and the solenoid b. By changing the flow rate of hydraulic oil by the change, the tilt cylinder 3 is tilted forward, stopped, and tilted backward.
[0005]
The solenoids a and b of the proportional solenoid valve 14 for lift and the solenoids a and b of the proportional solenoid valve 15 for tilt are connected to the controller 16, and a command signal is received from the controller 16. It is controlled. The controller 16 is connected to a lift lever 17 that moves the lift bracket 6 and the fork 7 up and down and a tilt lever 18 that tilts the mast 4 back and forth by an operator in the cab of the vehicle body 1. Each operation amount is input from the lift lever 17 and the tilt lever 18, thereby outputting a drive signal to the pump motor 13 to control the drive of the pump motor 13, and proportional to the lift based on these operation amounts. Command signals are output to the solenoids a and b of the solenoid valve 14 and the solenoids a and b of the proportional solenoid valve 15 for tilting, and desired valve opening is performed in each of the proportional solenoid valve 14 for lift and the proportional solenoid valve 15 for tilt. Control to a degree.
[0006]
That is, when the operator operates the lift lever 17, the lift bracket 6 and the fork 7 are moved up and down, and when the operator operates the tilt lever 18, the mast 4 is tilted back and forth.
[0007]
[Problems to be solved by the invention]
In a conventional control device for a work machine in a forklift truck, the lift lever and the tilt lever are operated simultaneously to operate the lift cylinder and the tilt cylinder via the lift proportional solenoid valve and the tilt proportional solenoid valve. When the controller and the mast are tilted back and forth at the same time, the controller usually calculates the drive signal output to the pump motor based on the operation amount of the lift lever and tilt lever, and pumps a drive signal with a larger value in both of them. Output to the motor. As a result, when a simultaneous operation is performed, a large-value drive signal is output to the pump motor, so that the fork can be lifted and the mast can be tilted back and forth at the same time.
[0008]
In such a conventional control device for a work machine in a forklift truck, since a large value drive signal is output to the pump motor when simultaneously operated, a large amount of hydraulic oil is generated in the circuit by the hydraulic pump driven by the pump motor. Began to flow. For this reason, for example, the tilt cylinder is operated by operating the tilt lever, and when the tilt cylinder reaches the stroke end, the pressure rises to the relief valve set pressure in the circuit. By supplying a large amount of hydraulic oil (high pressure) to the valve, even if the valve opening of the proportional solenoid valve for lift is the valve opening based on the operation amount of the lift lever, a large amount of hydraulic oil is There was a risk that the fork would suddenly rise due to sudden movement in the lift cylinder. For this reason, there was a problem that the luggage loaded on the fork collapsed.
This invention makes it the subject to eliminate these problems.
[0009]
[Means for Solving the Problems]
The first invention includes a hydraulic pump that discharges hydraulic oil and a pump motor that drives the hydraulic pump, and regulates the flow rate of hydraulic oil discharged from the hydraulic pump to provide a desired flow rate to a lift cylinder in the work machine. Proportional solenoid valve for lift to be supplied, the drive signal is output to the pump motor to control the drive of the pump motor, and the command signal based on the operation amount of the lift lever is output to the proportional solenoid valve for lift In the control device for a work machine in a forklift truck provided with a controller for controlling the operation of the proportional solenoid valve, the controller detects that the lift lever and the work machine lever are operated simultaneously. A drive signal output to the pump motor 13 is calculated from the operation amount of the lift lever 17 and a drive signal output to the pump motor 13 is calculated from the operation amount of the work implement lever. While outputting a signal to the pump motor 13, A control device for a work implement in a forklift truck that outputs a command signal based on an operation amount of a lift lever that is output to a proportional solenoid valve for lift, in accordance with an operation amount of the work implement lever.
[0010]
The second invention comprises a hydraulic pump that discharges hydraulic oil and a pump motor that drives the hydraulic pump, and regulates the flow rate of hydraulic oil discharged from the hydraulic pump to provide a desired flow rate to a lift cylinder in the work machine. Proportional solenoid valve for lift to be supplied, the drive signal is output to the pump motor to control the drive of the pump motor, and the command signal based on the operation amount of the lift lever is output to the proportional solenoid valve for lift In the control device for a work machine in a forklift truck provided with a controller for controlling the operation of the proportional solenoid valve, the controller detects that the lift lever and the work machine lever are operated simultaneously. A drive signal output to the pump motor 13 is calculated from the operation amount of the lift lever 17 and a drive signal output to the pump motor 13 is calculated from the operation amount of the work implement lever. While outputting a signal to the pump motor 13, A command signal based on the lift lever operation amount output to the lift proportional solenoid valve is output to the pump motor based on the drive signal output to the pump motor based on the lift lever operation amount and the work device lever operation amount. This is a control device for a work machine in a forklift truck that outputs a reduced signal according to a difference from a drive signal.
[0011]
According to a third invention, in the first or second invention, there is provided load detecting means for detecting a load of the lift cylinder, and the controller controls the lift lever operation amount to be reduced and output to the lift proportional solenoid valve. A control device for a work machine in a forklift truck that changes a command signal based on the load detected by a load detection means.
[0012]
[Action]
According to the first invention, when the lift lever and the work implement lever are operated simultaneously, a large drive signal is output to the pump motor according to the operation amount of the work implement lever, and a large amount of hydraulic oil is generated in the circuit by the hydraulic pump. Even if it flows, the valve opening is made smaller than the normal value by the command signal that is decreased according to the operation amount of the work implement lever in the lift proportional solenoid valve, and a large amount of hydraulic oil is prevented from being supplied to the lift cylinder. To do.
[0013]
According to the second aspect of the invention, when the lift lever and the work implement lever are operated simultaneously, a large drive signal is output to the pump motor according to the operation amount of the work implement lever, and a large amount of hydraulic oil is generated in the circuit by the hydraulic pump. Even if it flows, it decreases in accordance with the difference between the drive signal output to the pump motor based on the operation amount of the lift lever and the drive signal output to the pump motor based on the operation amount of the work implement lever in the proportional solenoid valve for lift. The valve opening is made smaller than the normal value by the command signal to prevent a large amount of hydraulic oil from being supplied to the lift cylinder.
[0014]
According to the third aspect of the invention, by changing the command signal output according to the load of the lift cylinder, the operating state of the lift cylinder is prevented from changing depending on the weight of the load loaded on the fork.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of a control device for a work machine in a forklift truck according to the present invention will be described.
As shown in FIG. 1, the forklift truck includes a work machine 2 at the front portion of the vehicle body 1 as shown in FIG. 1. The work machine 2 is a kind of work machine actuator at the front portion of the vehicle body 1. A mast 4 that can be tilted forward and backward by the tilt cylinder 3 is provided, a lift bracket 5 that can be moved up and down by a chain is provided along the mast 4, and a fork 7 is provided on the lift bracket 6. .
[0016]
As shown in FIG. 2, the control device for the working machine includes a hydraulic pump 12 that discharges hydraulic oil from the hydraulic tank 11 and a pump motor 13 that drives the hydraulic pump 12. A lift proportional solenoid valve 14 is provided that regulates the flow rate of the discharged hydraulic oil and supplies the desired flow rate to the lift cylinder 5, and the flow rate of the hydraulic oil discharged from the hydraulic pump 12 is regulated to set the desired flow rate to the tilt cylinder. 3 is provided with a proportional solenoid valve 15 for tilting which is a proportional solenoid valve for working machine actuators to be supplied to the working machine actuator 3.
[0017]
The proportional solenoid valve 14 for lift moves the spool by the solenoid a and the solenoid b, and cuts off the flow of the working oil and the rising position U where the working oil is supplied to the bottom 5a side of the lift cylinder 5. From the stop position N, the bottom 5a side of the lift cylinder 5 is moved to a lowered position D where the hydraulic oil flows into the hydraulic tank 11, and the flow direction of the hydraulic oil and the flow rate of the hydraulic oil by changing the valve opening are changed. Then, the lift cylinder 5 is raised, stopped, and lowered.
[0018]
Further, the tilt proportional solenoid valve 15 moves the spool by the solenoid a and the solenoid b to supply the hydraulic oil to the bottom 3a side (rear side) of the tilt cylinder 3 and the flow of the hydraulic oil. Is moved at a stop position N at which the hydraulic oil is shut off, and at a rearward tilt position B at which the hydraulic oil is supplied to the rod 3b side (front side) of the tilt cylinder 3, and the direction in which the hydraulic oil flows and the valve opening change The tilting cylinder 3 is tilted forward, stopped, and tilted backward by changing the flow rate of hydraulic oil.
[0019]
The solenoids a and b of the proportional solenoid valve 14 for lift and the solenoids a and b of the proportional solenoid valve 15 for tilt are connected to the controller 16, and a command signal is received from the controller 16. It is controlled. The controller 16 includes a CPU, a RAM, a ROM, a clock, various interfaces, and the like, and a lift that moves the lift bracket 6 and the fork 7 up and down by an operator provided in the cab of the vehicle body 1. The lever 17 is connected to a tilt lever 18 that is a working machine lever that tilts the mast 4 back and forth, and each operation amount is input from the lift lever 17 and the tilt lever 18, thereby outputting a drive signal to the pump motor 13. Then, the drive of the pump motor 13 is controlled, and command signals are output to the solenoids a and b of the lift proportional solenoid valve 14 and the solenoids a and b of the tilt proportional solenoid valve 15 based on these operation amounts. Then, the lift proportional solenoid valve 14 and the tilt proportional solenoid valve 15 are controlled so as to have desired valve openings.
[0020]
That is, when the operator operates the lift lever 17, the lift bracket 6 and the fork 7 are moved up and down, and when the operator operates the tilt lever 18, the mast 4 is tilted back and forth.
[0021]
In the control device for a working machine thus configured, when the controller 16 detects that the lift lever 17 and the tilt lever 18 are operated simultaneously, that is, when a signal is input from the lift lever 17 and the tilt lever 18, The drive signal Dr to be output to the pump motor 13 is calculated from the operation amount of the lift lever 17, and the drive signal Dt to be output to the pump motor 13 is calculated from the operation amount of the tilt lever 18, and the drive signals Dr and Dt of both are calculated. A comparatively large drive signal D is output to the pump motor 13. On the other hand, a command signal St based on this operation amount is calculated from the operation amount of the tilt lever 18 and this command signal St is output to the proportional solenoid valve 15 for tilt. Further, the command signal Sr based on the operation amount of the lift lever 17 is calculated in accordance with the operation amount of the tilt lever 18 and is output to the proportional solenoid valve 14 for lift.
[0022]
The calculation of the command signal decreased in accordance with the operation amount of the tilt lever 18 output to the lift proportional solenoid valve 14 in the controller 16 will be specifically described. The command signal Sr is calculated using a lift calculation map indicating a current value which is a command signal output to the lift proportional solenoid valve with respect to the operation amount. As shown in FIG. 3, the lift calculation map includes a plurality of function lines. For example, from the first function line A, which is a normal value when the lift lever 17 is used alone, from the first function line A There are three function lines, a second function line B having a slightly lower value and a third function line C having a value significantly lower than the first function line A, and the amount of operation of the tilt lever 18 from among these three function lines. A desired function line is selected according to the above. This is because the first function line A is selected when the operation amount of the tilt lever 18 is small or little, and the second function line B is selected when the operation amount of the tilt lever 18 is normal. When the amount is large, the third function line C is selected. A command signal Sr output to the lift proportional solenoid valve 14 is calculated from the operation amount of the lift lever 17 using the function line thus selected. Note that the function lines in the lift calculation map are not limited to the above-described three, and the command signal Sr may be calculated more finely by using as many as five or six.
[0023]
As described above, when the lift lever 17 and the tilt lever 18 are operated simultaneously, the controller 16 calculates the command signal Sr to be output to the lift proportional solenoid valve 14 in accordance with the operation amount of the tilt lever 18, By outputting this, even if a large drive signal D is output to the pump motor 13 due to the operation amount of the tilt lever 18, even if a large amount of hydraulic fluid flows in the circuit by the hydraulic pump 12, the proportional solenoid valve for lift is used. 14, the command signal Sr decreased in accordance with the operation amount of the tilt lever 18, so that the valve opening becomes smaller than a normal value (value when the lift lever 17 is used alone), and is supplied to the lift cylinder 5. It is possible to prevent a significant increase in operating oil. Therefore, for example, when the tilt cylinder 3 is operated by operating the tilt lever 18 and the tilt cylinder 3 reaches the stroke end, the pressure rises to the relief valve set pressure in the circuit. At this time, if the lift lever 17 is operated, a large amount of hydraulic fluid (high pressure) is supplied to the lift proportional solenoid valve 14, but here the valve opening becomes smaller than normal (when the lift lever 17 is used alone). Thus, a large amount of hydraulic oil does not flow into the lift cylinder 5, and the sudden operation of the lift cylinder 5 and the sudden rise of the fork 7 can be eliminated.
[0024]
A modification of the first embodiment of the control device for the work machine in the forklift truck according to the present invention will be described.
Although it is almost the same as the first embodiment described above, a fork is provided by providing a pressure sensor as a load detecting means for detecting the load of the lift cylinder 5 and detecting the load of the lift cylinder 5 by this pressure sensor. 7 Detect the weight of the load loaded on top.
[0025]
The controller outputs a drive signal D to the pump motor 13 as well as a command signal St to the tilt proportional solenoid valve 15 as in the first embodiment, and further, a lift proportional solenoid valve. The command signal Sr decreased according to the amount of operation of the tilt lever 18 is output to 14. The load of the lift cylinder 5 detected by the pressure sensor in calculating the command signal Sr output to the lift proportional solenoid valve 14 at this time is output. The command signal Sr is changed according to the above.
[0026]
In other words, the controller calculates the command signal Sr to be output to the lift proportional solenoid valve 14 using the lift calculation map shown in FIG. 3, and the desired signal is selected from the three function lines in the lift calculation map. When selecting the function line, the function line is selected according to the operation amount of the tilt lever 18 and the load of the lift cylinder 5. For example, as shown in Table 1 below, when the operation amount of the tilt lever 18 is small and the load is large, the first function line A is selected, and the operation amount of the tilt lever 18 is normal and the load is small. In the middle case, the second function line B is selected, and when the operation amount of the tilt lever 18 is large and there is no load, the third function line C is selected. The command signal Sr output to the lift proportional solenoid valve 14 is calculated from the operation amount of the lift lever 17 using the function line thus selected.
[0027]
[Table 1]

[0028]
As a result, as in the first embodiment described above, it is possible to prevent the hydraulic oil supplied to the lift cylinder 5 from significantly increasing, and the sudden operation of the lift cylinder 5 and the sudden rise of the fork 7 can be prevented. In addition, it is possible to prevent the operating state of the lift cylinder 5 from changing due to the weight of the load loaded on the fork 7 by changing the command signal Sr output according to the load of the lift cylinder 5. it can.
[0029]
Next, a second embodiment of the control device for the work machine in the forklift truck according to the present invention will be described.
The work machine control device is the same as that of the first embodiment described above, but differs from the first embodiment in the calculation of the command signal Sr output to the proportional solenoid valve 14 for lift in the controller 16. . That is, the command signal Sr based on the operation amount of the lift lever 17 output to the proportional solenoid valve for lift 14, the drive signal Dr output to the pump motor 13 based on the operation amount of the lift lever 17, and the operation amount of the tilt lever 18. Based on the difference, the calculation is performed in accordance with the difference from the drive signal Dt output to the pump motor 13, and this is output to the proportional solenoid valve 14 for lift.
[0030]
The calculation of the command signal Sr to be output to the lift proportional solenoid valve 14 in the controller 16 will be specifically described. First, the lift from the operation amount of the lift lever 17 to the preset operation amount of the lift lever shown in FIG. A command signal Sr1 is calculated using a lift calculation map indicating a current value as a command signal output to the proportional solenoid valve. This lift calculation map has one function line, which is a normal value when the lift lever 17 is used alone. Then, the drive signal Dr output to the pump motor 13 calculated from the operation amount of the lift lever 17 and the drive signal Dt output to the pump motor 13 calculated from the operation amount of the tilt lever 18 are compared, and this difference (Dt− Dr) is obtained, and a decrease value d is calculated from the obtained difference. The decrease value d is calculated using a decrease value calculation map shown in FIG. However, the decrease value d is calculated only when the drive signal Dt calculated from the operation amount of the tilt lever 18 is larger than the drive signal Dr calculated from the operation amount of the lift lever 17 (Dt> Dr). Then, the decrement value d is subtracted from the command signal Sr1 calculated using the above-described lift calculation map (Sr1-d), and the final command signal Sr output to the lift proportional solenoid valve 14 is calculated.
[0031]
As described above, when the lift lever 17 and the tilt lever 18 are operated simultaneously, the controller 16 outputs the command signal Sr output to the lift proportional solenoid valve 14 to the pump motor 13 based on the operation amount of the lift lever 17. In accordance with the difference between the drive signal Dr to be driven and the drive signal Dt to be output to the pump motor 13 based on the operation amount of the tilt lever 18, it is calculated by decreasing, and this is output, whereby the first embodiment described above. Similarly to the above, even if a large amount of drive signal D is output to the pump motor 13 by the operation amount of the tilt lever 18 and a large amount of hydraulic oil flows in the circuit by the hydraulic pump 12, the lift proportional solenoid valve 14 lifts. The command signal S decreased according to the difference between the drive signal Dr based on the operation amount of the lever 17 and the drive signal Dt based on the operation amount of the tilt lever 18. As a result, the valve opening becomes smaller than a normal value (a value when the lift lever 17 is used alone), and it is possible to prevent the hydraulic oil supplied to the lift cylinder 5 from greatly increasing. The sudden operation of the cylinder 5 and the sudden rise of the fork 7 can be eliminated. In addition, when the difference between the drive signal Dr based on the operation amount of the lift lever 17 and the drive signal Dt based on the operation amount of the tilt lever 18 is reduced, the decrease value d is correspondingly reduced and the difference is eliminated. Since the decrease value d is also 0, it can be set to a normal value when the lift lever 17 is used alone. Thus, every time the operation amount of the lift lever 17 or the tilt lever 18 is changed, the lift proportionality is increased. By changing the decrease value d in the command signal Sr output to the solenoid valve 14, it is possible to always perform optimum and fine control.
[0032]
A modification of the second embodiment of the control device for the work machine in the forklift truck according to the present invention will be described.
Although it is almost the same as the second embodiment described above, a fork sensor is provided as a load detecting means for detecting the load of the lift cylinder 5 and the load of the lift cylinder 5 is detected by this pressure sensor. 7 Detect the weight of the load loaded on top.
[0033]
The controller outputs a drive signal D to the pump motor 13 and a command signal St to the tilt proportional solenoid valve 15 as in the second embodiment described above, and further, a lift proportional solenoid valve. The command signal Sr decreased according to the amount of operation of the tilt lever 18 is output to 14. The load of the lift cylinder 5 detected by the pressure sensor in calculating the command signal Sr output to the lift proportional solenoid valve 14 at this time is output. The command signal Sr is changed according to the above.
[0034]
That is, in the controller, the drive signal Dr output to the pump motor 13 calculated from the operation amount of the lift lever 17 and the drive signal Dt output to the pump motor 13 calculated from the operation amount of the tilt lever 18 are compared. The difference (Dt−Dr) is obtained, and a decrease value d is calculated from the obtained difference. In calculating the decrease value d, a decrease value calculation map shown in FIG. 6 is used. This reduction value calculation map has a function line that changes according to the load of the lift cylinder 5, that is, its inclination changes, and the inclination of the function line changes according to the load. A command signal Sr to be output to the lift proportional solenoid valve 14 is calculated from the operation amount of the lever 17.
[0035]
As a result, as in the second embodiment described above, it is possible to prevent the hydraulic oil supplied to the lift cylinder 5 from greatly increasing, and the sudden operation of the lift cylinder 5 and the sudden rise of the fork 7 can be prevented. In addition, it is possible to prevent the operating state of the lift cylinder 5 from changing due to the weight of the load loaded on the fork 7 by changing the command signal Sr output according to the load of the lift cylinder 5. it can.
[0036]
In the first and second embodiments described above, the case where the tilt cylinder 3 and the tilt lever 18 are used as the work implement actuator and the work implement lever is described. However, the present invention is not limited to this. Other attachment cylinders and their operation levers may be used.
[0037]
Further, in the first and second embodiments described above, the proportional solenoid valve is used as the flow rate regulating means that supplies hydraulic oil to the tilt cylinder 3 that is the work machine actuator. However, the present invention is not limited to this. For example, a manually operated valve or the like may be used.
[0038]
In the first and second embodiments and the respective modifications described above, the description has been given of the case where two of the lift cylinder and the tilt cylinder which is one of the work machine actuators are operated simultaneously. Even when a plurality of the above items are operated at the same time, the same operation can be performed, and the same effect can be obtained.
[0039]
【The invention's effect】
When operating the lift lever and work implement lever simultaneously, even if a large amount of drive signal is output to the pump motor due to the amount of operation of the work implement lever, even if a large amount of hydraulic fluid flows in the circuit by the hydraulic pump, The valve opening is made smaller than the normal value by a command signal that is reduced in accordance with the operation amount of the work implement lever in the valve to prevent a large amount of hydraulic oil from being supplied to the lift cylinder. As a result, the sudden operation of the lift cylinder and the sudden rise of the fork can be eliminated, and the problem of collapse of the load loaded on the fork during simultaneous operation of the lift lever and the work implement lever can be reduced. The operability can be greatly improved.
[0040]
When operating the lift lever and work implement lever at the same time, even if a large amount of drive signal is output to the pump motor due to the amount of operation of the work implement lever, even if a large amount of hydraulic fluid flows in the circuit by the hydraulic pump, In the proportional solenoid valve, the valve opening is determined by a command signal that is reduced according to the difference between the drive signal output to the pump motor based on the operation amount of the lift lever and the drive signal output to the pump motor based on the operation amount of the work implement lever. Is made smaller than the normal value to prevent a large amount of hydraulic oil from being supplied to the lift cylinder. As a result, the sudden operation of the lift cylinder and the sudden rise of the fork can be eliminated, and the problem of collapse of the load loaded on the fork during simultaneous operation of the lift lever and the work implement lever can be reduced. And operability can be greatly improved.
[0041]
Furthermore, it is possible to prevent the operating state of the lift cylinder from changing depending on the weight of the load loaded on the fork, and to prevent the operation feeling depending on the presence / absence of the load on the fork from being different.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of a forklift truck.
FIG. 2 is a configuration diagram of a control device for a work machine in a forklift truck.
FIG. 3 is a chart of a lift calculation map stored in the controller.
FIG. 4 is a chart of another lift calculation map stored in the controller.
FIG. 5 is a chart of a decrease value calculation map stored in the controller.
FIG. 6 is a chart of another reduction value calculation map stored in the controller.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Vehicle body, 2 ... Working machine, 3 ... Tilt cylinder, 3a ... Bottom, 3b ... Rod, 4 ... Mast, 5 ... Lift cylinder, 5a ... Bottom, 6 ... Lift bracket, 7 ... Fork, 11 ... Hydraulic tank, 12 DESCRIPTION OF SYMBOLS: Hydraulic pump, 13 ... Pump motor, 14 ... Proportional solenoid valve for lift, 15 ... Proportional solenoid valve for tilt, 16 ... Control controller, 17 ... Lift lever, 18 ... Tilt lever.

Claims (3)

A hydraulic pump 12 that discharges hydraulic oil and a pump motor 13 that drives the hydraulic pump 12 are provided. The flow rate of hydraulic oil discharged from the hydraulic pump 12 is regulated and a desired flow rate is supplied to the lift cylinder 5 in the work machine. The lift proportional solenoid valve 14 is provided, a drive signal is output to the pump motor 13 to control the drive of the pump motor 13, and a command signal based on the operation amount of the lift lever 17 is output to the lift proportional solenoid valve 14 In the control device for the work machine in the forklift truck provided with the controller 16 for controlling the operation of the lift proportional solenoid valve 14,
When the controller 16 detects that the lift lever 17 and the work implement lever are operated at the same time , the drive signal output to the pump motor 13 based on the operation amount of the lift lever 17 and the pump motor 13 based on the operation amount of the work implement lever. Based on the operation amount of the lift lever 17 that is output to the proportional solenoid valve for lift 14 and outputs a drive signal having a large value to the pump motor 13 by comparing the drive signals to be output. A control device for a work machine in a forklift truck, wherein the command signal is reduced and output according to an operation amount of the work machine lever. A hydraulic pump 12 that discharges hydraulic oil and a pump motor 13 that drives the hydraulic pump 12 are provided. The flow rate of hydraulic oil discharged from the hydraulic pump 12 is regulated and a desired flow rate is supplied to the lift cylinder 5 in the work machine. The lift proportional solenoid valve 14 is provided, a drive signal is output to the pump motor 13 to control the drive of the pump motor 13, and a command signal based on the operation amount of the lift lever 17 is output to the lift proportional solenoid valve 14 In the control device for the work machine in the forklift truck provided with the controller 16 for controlling the operation of the lift proportional solenoid valve 14,
When the controller 16 detects that the lift lever 17 and the work implement lever are operated at the same time , the drive signal output to the pump motor 13 based on the operation amount of the lift lever 17 and the pump motor 13 based on the operation amount of the work implement lever. Based on the operation amount of the lift lever 17 that is output to the proportional solenoid valve for lift 14 and outputs a drive signal having a large value to the pump motor 13 by comparing the drive signals to be output. The command signal is reduced and output according to the difference between the drive signal output to the pump motor 13 based on the operation amount of the lift lever 17 and the drive signal output to the pump motor 13 based on the operation amount of the work implement lever. A control device for a work machine in a forklift truck. The controller 16 includes load detection means for detecting the load of the lift cylinder 5, and the controller 16 outputs a command signal based on the operation amount of the lift lever 17 that is reduced and output to the lift proportional solenoid valve 14 to the load detection means. 3. The work machine control device for a forklift truck according to claim 1 or 2, wherein the control device is changed according to the detected load.

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