WO1992001869A1 - Method and unit for controlling vehicle for loading operation - Google Patents

Abstract

A method and a unit for controlling a vehicle for loading operation which carries a variable capacity hydraulic pump (PV) for operating a loading machine and a torque converter (T) for driving itself. The control unit comprises an engine (E) provided with an electronically controlled governor (10) capable of selecting output characteristics stepwise; means (12), (14), (42) and (43) for setting stepwise the maximum capacity and output torque of the variable-capacity hydraulic pump (PV) for operating the loading machine; means (44), (45) for detecting a pump capacity and hydraulic pressure; switches (42), (43) for selecting output characteristics of the engine; a governor controller (11) for controlling to the output characteristics selected by the selecting switches; and a pump controller (41) for selectively setting the maximum capacity and output torque characteristics of the variable-capacity hydraulic pump (PV) in accordance with the engine output characteristics selected by the selecting switches. Accordingly, even if the hydraulic torque fluctuates at the time of high pressure in the variable-capacity hydraulic pump, the fluctuating range of absorption torque of the torque converter can be controlled, thereby enabling to perform earth-sand scoop-up working with ease and efficiently.

Description

 Description Control device and control method for loading work vehicle Technical field

 The present invention relates to a control device and a control method for a construction vehicle such as a wheel loader that mainly performs a loading operation. Background technology

Fig. 7 shows a working machine control system using a variable displacement hydraulic pump in a conventional wheel loader mainly for loading. Referring to the figure, the engine E is controlled by the governor gV via the linkage £ i by operating the accelerator pedal ap. The output of the engine E is transmitted to the torque converter T and the gear train G. The output transmitted to the gear train G drives the variable displacement hydraulic pump PV. The amount of pressure oil in the variable displacement hydraulic pump PV is controlled by a variable displacement pump control valve pc via a servo cylinder SC. When the packet operation by-lot valve AL is operated, the bucket main operation valve AV is operated, and the bucket A is rotated via the bucket cylinder AC. Tilt backward or dump forward. When the boom operation pilot valve BL is operated, the boom main operation valve BV is operated, and the boom B is rotated through the boom cylinder BC to lift upward. Down or down. PP Is a pilot pump.

FIG. 8 shows a pressure-flow rate characteristic diagram of the variable displacement hydraulic pump in the conventional work machine control system described above. As shown in the figure, by changing the pump flow Q according to the pump discharge hydraulic pressure P corresponding to the maximum hydraulic torque T _X1 or T _X2 , the hydraulic torque at high pressure is increased. Is limited to a necessary and sufficient amount. However, in a vehicle in which the hydraulic pump PV as shown in FIGS. 7 and 8 and the drive train power transmission device (torque converter T) distribute the engine E output. As shown in Fig. 9, the decrease in power consumption due to hydraulic pressure is absorbed by the drive train as shown in Fig. 9, so the drive power increases and the ratio of the drive train output to the work machine output increases. There is a major problem in that vehicles that become larger and dig into soil, etc., impair workability. That is, referring to FIGS. 8 and 9,

(1) hydraulic torque characteristic of the work machine pump - increased when low reduction in T _X1 or et T _X2, the absorption torque moth reverse torque converter T _tx, the pressure et T _{tx 2,} hydraulic The output and drive output distribution are reversed.

(2) When the working machine hydraulic pressure ing the high pressure X, the point, since the hydraulic torque is reduced to the hydraulic torque of the hydraulic torque T _X1, T _X2 or et point Y of X ₂ points T gamma, preparative Torque The absorption torque of the _converter increases from T _tx T tx 2 to T _ty , and the driving force becomes excessive.

The purpose of the present invention is to solve the above-mentioned problems. Disclosure of the invention

 In order to achieve the above object, the present invention provides an engine output characteristic in a loading work vehicle equipped with a variable displacement hydraulic pump for working machine operation and a torque converter for driving a vehicle. An electronically controlled governor that can be selected stepwise is provided, and the maximum capacity and output torque of the variable capacity pump are set in stages. Electromagnetic pilot valve, pump capacity detector, hydraulic pressure Along with the detector, a switch for selecting the output characteristics of the engine and the output characteristics of the variable capacitance pump (hereinafter referred to as the M-mode operation switch) was provided. In addition, an electronic gun controller that controls the engine output characteristics, and a variable pump that selects and sets the maximum capacity of the variable capacity bomb and the output torque characteristics. A controller is provided, and the M mode operation is performed. And Tsu by the selection of the scan I Tsu switch to control the size and distribution of the hydraulic output and the driving output, the improvement of workability.

 The maximum image setting of the electronically controlled governor according to the discharge pressure or output torque of the variable displacement hydraulic pump (hereinafter referred to as the regulation characteristic) Also, by lowering the engine torque setting, the torque fluctuation range of the torque converter can be reduced to reduce the torque fluctuation range. An excessive increase in power was prevented.

In addition, a selection switch (hereinafter referred to as an L-mode operation switch) that can gradually select the setting of the force-off pressure of the discharge flow rate of the variable displacement pump in the above control device. The L-mode operation switch selection stage and the M-mode operation switch selection stage described above provide working machine power and drive power. This is to make it possible to select a power distribution with power in a matrix manner. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a control system diagram of an embodiment of a control system for a loading work vehicle according to the present invention, FIG. 2 is an explanatory diagram of a pressure-flow characteristic curve of a variable displacement pump PV, and FIG. (a), (b), (c) each M, mode and L, the mode combinations, the Micromax _zeta mode and L _z mode combination of M ₃ mode and L ₃ mode 4 (a) and 4 (b) are flow charts of the work implement control method according to the present invention, and FIG. 5 is a flow chart showing the hydraulic torque. 6 (a) and 6 (b) show the power distribution matrix between the working machine oil pressure L and the driving force M, respectively, for the control method for lowering the engine torque setting. The drawings for clarification, FIGS. 7, 8, and 9 are explanatory drawings of conventional ones. BEST MODE FOR CARRYING OUT THE INVENTION

 Next, an embodiment according to the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of a control system for a loading work vehicle according to the present invention, which is the same as that of the conventional control system described with reference to FIG. The code is attached. An electronically controlled governor 10 whose output characteristics can be selected stepwise is mounted on the engine E, and an electronic governor controller 11 is provided. For the input signal of (4) Control the electronically controlled governor 10 accordingly.

(1) Engine rotation speed N _{E due} to rotation sensor 12 provided in gear unit G

 (2) Receives the control information of the variable-capacity pump PV from the variable-pump controller 41 as an input signal and receives the variable information from the electronic governor controller 11 as a variable. (Send information to the pump outlet)

 (3) Depression angle signal A from electronic pedal 14

 (4) M-mode operation switch 42 M-mode selection signal from 2 Variable pump controller 41 1 is an electronic governor controller

11 At the same time as sending and receiving signals between 1 and 5, according to the following input signals (5) to (8), transmit the signals to the electromagnetic pilot valve 46 to switch the valve 46 .

 (5) M mode selection signal from M mode operation switch 4 2 (6) L mode selection signal from L mode operation switch 4 3

(7) Installed in the discharge oil passage of the variable displacement pump PV to detect discharge pressure Oil pressure signal from the pressure detector 44

 (8) Pressure oil discharge amount signal from the pump displacement detector 45 that detects the pump displacement of the variable displacement pump PV

 Next, the operation will be described.

(A) Fig. 2 shows an embodiment of the pressure-flow characteristic curve of the variable capacity pump PV. By operating the M mode operation switch 42, the M Multiple M modes, such as 1 mode, M2 mode, and M3 mode, can be set in stages, and the electronically controlled governor 10 adjusts them accordingly. The torque characteristics of engine E are shown in Figs. 3 (a), (b) and (c) as M1 and Μ By setting as shown by the engine torque curve in the 2 and M3 modes, and by operating the L mode operation switch 43, the working machine Hydraulic pressure can be set stepwise to multiple L modes such as L1, L2, and L3 modes.

Thus, for example, when each of the M1 mode and the L1 mode, the M2 mode and the L2 mode, and the M3 mode and the L3 mode are combined, the maximum torque is obtained. click point B,, B 2, B 3, its oil pressure torque is Ri Do and _{T B 1, T B2, T} B3 , respectively, the absorption preparative torque point bets torque co members data at that time the respective 3 B, B ₂ ′, Β ₃ ′ in FIGS. (A), (b), (c) _show the magnitude relationship of hydraulic _torque Τ _{Β 1} > Τ _Β2 > Τ _Β3 and the driving force ( Match the magnitude relationship of torque converter absorption torque (torque at points Β and ')> (torque at point' ₂ ')> (torque at point' ₃ ') Is possible.

(Β) When the discharge pressure of the variable displacement pump ΡV is high (in this embodiment, PA or higher), the hydraulic torque does not become proportional to the oil pressure as shown in Fig. 2. In order to reduce the fluctuation of the absorption torque of the torque converter, the electronically controlled governor 10 is used as shown in Fig. 3 (a), (b) and (c). The maximum speed of engine E (regulation of the all-speed gunnon) is set to N _{C 1} ,

Change from N C2, N _{C3 to} N _{C 1} ′, N C2 ′, N C3 ′, respectively. For example, in the embodiments shown in Figs. 2 and 3 (a), (b) and (c), the highest engine _{torque is obtained} before and after the hydraulic torque T _A1 , T _AZ and T _A3 of the hydraulic PA. When the hydraulic _torque T _A1 , _{Α Α2} , T _A3 , the absorption _{torque of the torque converter} is Α, ', Α ₂ ', Α ₃ '. Also, the same hydraulic preparative Torque point of FIG. 2 A _4, A 5, Α ₆ and beta _4, beta 5, in the beta _6, FIG. 3, respectively Re its (a), (b), ( a 4 in _{c) ', a 5',} a 6 ' and _{Β 4', Β 5 ',} Β 6' that have varying absorption torque of the torque co members data in the. In this way, even when the hydraulic torque fluctuates when the discharge pressure of the variable-capacity hydraulic pump 第 V is high, the results are shown in Figs. 3 (a), (b) and (c). _{As in 4} ', 吸収 5', and の₆ ', the fluctuation range of the absorption torque of the torque converter can be reduced, and the driving force when the soil is digged in is excessive. It can prevent the increase.

 Next, an embodiment of this control method will be described with reference to flowcharts shown in FIGS. 4 (a) and 4 (b).

Fig. 4 (a) shows that when the pump pressure is cut off when the working machine oil pressure is P _Al (or P _A2 , P _A3 ) or higher, the hydraulic torque is T _A , (or T _A2 , T _A3 ) shows the control flow of the electronically controlled governor 10 when the engine maximum rotation set is reduced when it is below. Fig. 4 (b) shows the hydraulic pressure of the work equipment. If the pump torque is cut off above P _B1 (or P _B2 , P B3) and the hydraulic torque falls below T _B1 (or T _B2 , T _B3 ), This is a control flow of the electronically controlled governor 10 for controlling the target engine speed according to the following.

 In addition, the same effect can be obtained even if the engine torque is reduced according to the magnitude of the hydraulic torque of the variable displacement pump PV.

This will be described with reference to FIG. Above the pump discharge pressure P _A shown in Fig. 2 above, the pump hydraulic torque is lower than T _A1 . If you drop Ri, for example, a hydraulic torque of B ₄ points of FIG. 2

In TB4 (= TA4), the point A can be moved to the point B if the engine torque is reduced by k (TA1-T).

 (C) In this way, fluctuations in the torque absorbed by the torque converter when the work equipment hydraulic pressure is high are reduced, and the hydraulic torque and drive torque in the engine output selection stage are reduced. Fig. 6 (a) shows that the relationship between the magnitudes of the pressures is matched, and that the cutoff pressure of the discharge flow rate of the variable displacement pump PV can be selected stepwise. Thus, the working machine oil pressures LI, L2, L3, which are determined by the working machine pressure selection stage, and the driving forces Ml, M2, which are balanced by the engine output selection stage, Selection of power distribution with M3 becomes possible in a matrix manner. Fig. 6 (b) is a drawing explaining the effects of the working machine oil pressure L and the driving force M in the working machine system. Industrial applicability

 Since the present invention is constructed as described above, even if the hydraulic torque fluctuates when the variable capacity hydraulic pump is at a high pressure, the torque converter can suppress the fluctuation range of the absorption torque. As a result, it is possible to prevent an excessive increase in the driving force at the time of digging in the soil, so that the digging work can be carried out easily and efficiently.

 In addition, since the power distribution of the working machine power and the driving force can be selected in a matrix, it is possible to easily respond to a variety of work forms. You.

Claims

The scope of the claims (1) An engine equipped with an electronically controlled governor that can select output characteristics step by step in a loading work vehicle equipped with a variable displacement hydraulic pump for operating the work equipment and a torque converter for moving the vehicle Means for setting the maximum capacity and output torque of the variable displacement hydraulic pump for working machine operation in a stepwise manner; means for detecting the pump capacity and the oil pressure; and an engine. A governor controller for controlling an output characteristic selected by the selection switch; and a selection control by the selection switch. Control of a loaded vehicle characterized by the provision of a pump controller for selecting and setting the maximum capacity of a variable displacement hydraulic pump and the output torque characteristics in accordance with the engine output characteristics specified. apparatus.  (2) In the control device according to the first aspect of the present invention, in accordance with the discharge pressure or the output torque of the variable displacement hydraulic pump, the maximum rotation of the electronically controlled governor can be set (regular displacement). A method of controlling the engine of a loaded vehicle and the variable capacity hydraulic bob, characterized by lowering the engine torque setting. (3) In the control device according to claim 1, the setting is such that the setting of the force-off pressure of the discharge flow rate of the variable displacement hydraulic pump can be selected stepwise. A switch is provided, and a variable displacement hydraulic switch is provided by the selection stage of the cut-off pressure selection switch and the selection stage of the maximum capacity and output torque selection switch. Discharge flow rate of pump A method for controlling a variable displacement hydraulic pump, characterized in that it is controlled in such a way as to be fixed.