JPH11230334A - Vehicle with variable capacity type torque converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle with a variable capacity type torque converter having high degree of freedom in controlling, easy to maintain desired capacity, east to carry out controlling operation, and easy to maintain maximum traction force and vehicle speed constant without discontinuing travelling or operation. SOLUTION: This vehicle with a variable capacity Q type torque converter including a driving system equipped with a changeable capacity type torque converter, an operating system operable on the basis of the operation of an operation lever 12b, and an engine 1 giving power to the torque converter and the operation system, is provided with an automatic returning type thrust-in means 22a, 22b to the operation lever 12b and it includes a control means 18 signally connected to the thrust-in means 22a, 22b and increases the capacity Q of the torque converter correspondingly to either the number of thrust-in times 'n' or the thrust-in time 't' when it receives a thrust-in signal Sa from one of the thrust-in means 22a, while it reduces the capacity Q of the torque converter correspondingly to either the number of thrust-in times 'n' or the thrust-in time 't' when it receives a thrust-in signal Sb from the other thrust-in means 22b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vehicle with a variable capacity torque converter.

[0002]

2. Description of the Related Art As is known, a torque converter has a pump, a turbine, and a stator. The pump is rotated by a rotational torque from a power source, thereby flowing fluid through the turbine to rotate the turbine and rotate an output shaft directly connected to the turbine. The stator is provided on the fixed member via a one-way clutch rotatable only in the same direction as the pump, and returns the fluid from the turbine to the pump. With such a stator, the torque converter causes the torques Tt, Tp, Ts that the turbine, pump, and stator receive from the fluid.
, A torque conversion of “Tt = Tp + Ts” is performed. The pump torque Tp is given by the product of a coefficient k different between different types of torque converters, the square of the pump rotation speed Np, and the fifth power of a representative dimension D such as the converter outer diameter (Tp =
kNp ² D ^5). However, because it is difficult to handle as it is, "Tp
= .Tau.p (Np / 1000) ² ". That is, “kNp ² D ⁵ = τp (Np / 1000) ² ”, which can be further transformed to “τp = k · 1000 ² · D ⁵ ”. If this is compared with “Tp = kNp ² D ⁵ ”, τp Is the pump torque Tp at "Np = 1000 rpm".
In addition, since τp is a comprehensive value of the coefficient k and the representative dimension D, it becomes a constant value for each torque converter. Therefore, τp is used for determining the magnitude of the capacity Q between different types of torque converters. That is, τp is easy to handle in practical use, and therefore, it is usually called especially the primary torque coefficient τp. By the way, since the representative dimension D is a constant value for each torque converter, it becomes “τp」 k ”, but the coefficient k is the speed ratio e (e =
Nt / Np, 0 ≦ e ≦ 1, Nt: turbine speed). Therefore, as shown in FIG. 7 which is a general performance curve diagram of the torque converter, the torque coefficient τp changes according to the speed ratio e. As shown in FIG. 7, the torque ratio λ (= Tt / Tp, λ> 0, Tt: turbine torque) also changes according to the speed ratio e.

In such a torque converter, for example, a clutch is provided between a pump of a fixed displacement torque converter and a power source, and a plurality of pumps of, for example, a fixed displacement torque converter are provided and some of them are connected to a power source. A clutch is provided between each of the power sources, and an actuator for changing the blade angle of the stator is provided. These clutches and actuators are ON / OFF controlled (for example, in the case of a clutch type, ON: a half clutch having a predetermined slip ratio β). Condition, OF
F: a clutch directly connected state), a variable displacement torque converter in which the capacity Q changes by multi-step control or stepless control is known. Such a vehicle with a variable capacity torque converter includes, for example, a wheel loader, a dozer shovel,
A work vehicle such as a motor grader is known (hereinafter, referred to as “example machine”). The example machine has a traveling system driven by an engine serving as a power source and a working system, and is operable for one or both of traveling and work. The variable displacement torque converter is provided in the traveling system. Hereinafter, ON / OFF control, multi-step control, and stepless control of the capacity Q of the torque converter in the example machine will be exemplified.

(1) ON / OFF control is as follows. FIG.
FIG. 5 is a diagram showing a matching performance between the engine and the variable displacement torque converter, in which an engine output curve Hp, an engine torque curve Te, and a pump torque curve Tp of three typical and exemplary torque converters, with the engine speed Ne as the horizontal axis. And the running system torque TeD and the working system torque TeH. FIG. 3A shows the state when the switch is OFF (Np = Ne).
: When the clutch is directly connected), FIG.
: Slip ratio β (= 1−Np / Ne) at the time of half clutch. Each pump torque curve Tp is obtained by the following procedure.
This will be described with reference to FIG. First, a torque coefficient τp of a desired speed ratio e (for example, e = 0.9 to 0.99 (at a light load)) is read from FIG.
= .Tau.p (Np / 1000) ² ", and then the pump rotational speed Np (= Ne). The quadratic curve obtained from the above is the pump torque curve Tp at the speed ratio e (= 0.9 to 0.99). The above is another speed ratio e (e = 0.5 to 0.8 (at a large load), e = 0 in FIG.
(At the time of overload, so-called stall)) to obtain the respective pump torque curves Tp. On the other hand, FIG.
In the group of pump torque curves Tp, although the torque coefficient τp itself does not change at all, the pump rotation speed Np becomes “Np =
(1−β) Ne ”, and since the horizontal axis of FIG. 7B is the engine speed Ne, the pump torque curve Tp with the speed ratio e closer to zero is closer to that of FIG. A larger downward correction is made, which translates into a substantially smaller capacity torque converter. That is, FIG. 11A shows the state when the capacity is large, and FIG.
Is a torque converter for small capacity. Specific operational effects of the ON / OFF control are illustrated in the following (i) to (v).
The engine fuel injection amount increasing / decreasing means such as the accelerator pedal and the throttle lever are assumed to have the maximum depression angle and the maximum tilt angle, and maintain these angles. Note that the engine performance in FIG. 8 is based entirely on the all-speed governor,
The following description also applies to the engine performance based on the maximum / minimum speed governor and the like which may also be used in the example machine.

(I) When the example machine is driven only by the traveling system without using a working system, for example, in a bulldozer or in a snow-plowing operation when removing snow (TeH = 0, TeD = Te)
) And OFF (FIG. 8A). In this case, "TeH
= 0 ”, the torque converter matches at a point a1 if the load is light, a point a2 if the load becomes large, and a3 if the load becomes overloaded.
Absorb. That is, in this case, the torque converter mainly operates in the high engine speed range Ne1 as shown in FIG.
That is, matching is performed in the engine high output range (rated output range) and the engine high torque range. Then, the torque converter outputs a turbine torque Tt (= λTp) obtained by multiplying the pump torque Tp at each of the matching points a1 to a3 by a torque ratio λ (see FIG. 7) at each speed ratio e.

(Ii) However, when the work system is further driven at the time of the OFF state (TeH + TeD = Te), the work system torque TeH causes the point b1 if the torque converter is lightly loaded.
Thus, the matching is performed at the point b2 when the load becomes large, and at the point b3 when the load is further overloaded, and the respective pump torques Tp are absorbed. That is, at this time, the torque converter mainly operates as shown in FIG.
That is, although the engine torque Te is slightly higher, the matching is performed in the middle output range of the engine. Further, the engine speed Ne greatly changes due to the load fluctuation (e = 0 to 1).

(Iii) Then, the torque converter is switched to ON (FIG. 8B) to reduce the capacity. In this case, the torque converter matches at a point c1 at a light load, at a point c2 at a large load, and at a point c3 at an overload, and absorbs the respective pump torques Tp. That is, in this case, as shown in FIG.
The matching is performed in the high engine speed range Ne1, that is, in the high engine output range (rated output range).

(Iv) However, if the working system is stopped again at the time of the above-mentioned ON (TeH = 0, TeD = Te), the torque converter is at a point d1 when the load is light and at a point d2 when the load becomes large.
Then, when the overload is further increased, the matching is performed at the point d3, the respective pump torques Tp are absorbed, and the high engine torque cannot be absorbed. That is, it cannot absorb the high engine output. Therefore, at this time, the switch is turned off, and the above (i)
Return to

(V) In addition to the control examples (i) to (iv) above, in the example machine, the ON / OF operation is performed during the combined operation of traveling and excavation.
The F control is operated continuously, and the running system torque TeD
There is known a so-called inching operation in which the excavation efficiency is increased by suddenly changing (that is, the maximum traction force) an impact force on an excavated object.

(2) The stepless control is as follows. The above (1)
ON / OFF control of direct coupling clutch (OF
F) or whether to use a half clutch with a predetermined slip ratio β (ON)
And there is no control freedom. Therefore, Japanese Patent Application Laid-Open
JP-A-502834 describes a stepless control based on a linear function P1 as shown in FIG. Specifically, the first half of the depression amount θ of the brake pedal of the wheel loader is used for changing the capacity of the torque converter, and the controller previously stores the depression amount θ and the linear function P1 (= −f (θ)) of the clutch pressure P. And the amount of depression of the brake pedal by the operator θ
Then, the clutch pressure P is continuously generated based on the linear function P1.

(3) The multi-stage control is as follows. The above (2)
Japanese Patent Laid-Open Publication No.
196142. This is multi-step control and stepless control based on a plurality of linear functions Pi (P1 to P3), as also shown in FIG. In particular,
Each linear function Pi is mutually the maximum clutch pressure P1max to P3max.
And its inclination are different. Then, on the instrument panel of the wheel loader or the like, two dials and a changeover switch for the operator to select and input any one of the primary functions Pi are provided, and the controller receives the selection from the dial and the changeover switch by the operator (multi-step). Then, the clutch pressure P is generated in a stepless manner based on the linear function Pi previously selected and input in response to the depression amount θ of the brake pedal by the operator.

[0012]

However, the above prior art has the following problems. (1) The ON / OFF control is a two-step control as described above, and there is no control freedom.

(2) The technique disclosed in JP-A-5-502834 and JP-A-9-196142 is brake pedal control. In this case, it is difficult to control not only the capacity of the torque converter but also the brake control as a security element.
When the depression of the brake pedal is stopped, the torque converter reaches the maximum capacity. That is, when a certain capacity Q is to be obtained, the pedal must be depressed, and when a certain constant capacity Q is to be maintained, the pedal depression amount θ must be maintained constant, which imposes a heavy burden on the operator.

(3) Japanese Patent Application Laid-Open No. 9-196142 has no description of what kind of situation the technology is supposed to produce and what effect it produces in that situation, and it is difficult to recall it. Therefore, assuming that the selection operation of the primary function Pi in this technique is frequently performed, in this case, it is necessary to operate two dials and a changeover switch provided on an instrument panel or the like for selection. For this reason, the operator must release his hand from the work equipment lever and the steering wheel, etc. During the selection operation, traveling and work are interrupted,
Poor productivity.

(4) In the techniques disclosed in JP-A-5-502834 and JP-A-9-196142, the variable capacity function of the torque converter and the example machine are not organically coupled. This will be described with reference to FIGS. FIG. 10 is a maximum traction force curve at the first forward speed. In FIG. 10, in the technique disclosed in Japanese Patent Application Laid-Open No. 5-502834, when the capacity Q of the torque converter is changed, the maximum traction force FD changes as indicated by the arrow X (FD1 to FD3). The amount only occurs as a linear function of the brake pedal depression amount θ. On the other hand, the technique disclosed in Japanese Patent Application Laid-Open No. 9-196142 only has a plurality of linear functions which are different from each other and can be selected freely from the above-mentioned Japanese Patent Application Laid-Open No. 5-502834.
However, as shown in FIG. 10, the maximum traction force FD changes freely and largely depending on the vehicle speed V regardless of the capacity Q of the torque converter. In other words, the vehicle speed V changes freely and largely according to the maximum traction force FD. Therefore, the following problem occurs.

First, the maximum traction force FD is not determined. In a wheel loader or a dozer excavator, there are many combined operations of traveling and excavation (tilt) with respect to an excavated object. At this time, FIG.
As shown in (1), it is desirable that the combined vector FDH of the traction force vector FDb based on the traveling and the scraping force vector FHb based on the operation of the bucket or the arm be directed in the direction of easy excavation in the excavated object. However, according to the above prior art, although the maximum tractive force FD changes as shown in FIG. 10 due to the capacity control of the torque converter (FD1 to FD3), each of the maximum tractive forces FD is determined according to the vehicle speed V as described above. And it changes greatly. Of course, the range of change of the vehicle speed V during this combined operation is small, but the maximum traction force FD still changes with the vehicle speed V. Moreover, the above (2)
As described above, maintaining the pedal depression amount θ by a certain amount is a burden on the operator. In other words, the magnitude of the traction force vector FDb is hard to be determined, and therefore the size and direction of the combined vector FDH are also hard to be determined. Further, since the pedal is operated by the pedal, the pedal is easily depressed, and if the traction force vector FDb is given to the excavated object more than necessary, the tire and the crawler belt may be inadvertently slipped.

Second, the vehicle speed V is not determined. In a wheel loader or a dozer shovel, there are many combined operations of traveling and loading / unloading (dumping) with respect to a dump truck or a hopper. At this time, it is necessary to avoid collision with a dump truck or a hopper when approaching. However, according to the above-mentioned prior art, although the maximum vehicle speed Vimax changes (V1max to V3max) as shown in FIG. 10 due to the capacity control of the torque converter, the respective vehicle speeds V are determined according to the maximum traction force FD as described above. And it changes greatly. Therefore, in order to avoid collision with a dump truck, a hopper or the like, the accelerator pedal is usually depressed and the vehicle speed V is reduced. However, when the accelerator pedal is depressed, the engine speed N
e decreases, and the matching point between the torque converter and the engine becomes a low-medium engine output Hp region or a high fuel consumption rate region. In addition, when the accelerator pedal is depressed again, there is a problem that a high output engine must be mounted in order to improve the acceleration acceleration of the engine speed Ne depending on the pump torque curve Tp.

That is, according to the above prior art, the sum vector F
In order to direct the DH in the direction of easy excavation and to extract the optimum vehicle speed V and the maximum traction force FD in a well-organized manner, the skill of an operator who can operate both the accelerator pedal and the brake pedal well. Is required. In short, as described above, in the above-described conventional technology, the variable capacity function of the torque converter and the example machine are not organically coupled.

An object of the present invention is to provide a vehicle with a variable displacement torque converter that can solve some of the above-mentioned problems of the prior art and that takes safety into consideration.

[0020]

In order to achieve the above object, a vehicle with a variable displacement torque converter according to the present invention comprises: a traveling system having a torque converter 2 having a variable capacity Q; In a vehicle with a variable displacement torque converter having a work system operable based on the operation of the operation lever 12b and an engine 1 for supplying power to the work system, (a) an automatic reset type pushing means is provided on the operation lever 12b. In addition to providing 22a and 22b,
(b) Signally connected to the pushing means 22a, 22b,
1) When the push signal Sa is received from the one push means 22a, the capacity Q of the torque converter 2 is increased according to either the number of pushes n or the push time t, and (b2) the push signal Sb from the other push means 22b. The control means 18 reduces the capacity Q of the torque converter 2 in accordance with one of the number of pressings n and the pressing time t when receiving.

According to the first configuration, the following operation and effect can be obtained. (1) The operation lever 12b for operating the operation system is arranged at a position where the operator can easily handle the operation system, and is always gripped during the operation. Pushing means 22 for changing the capacity Q of the torque converter 2 to the operation lever 12b
a and 22b are provided. Moreover, the pushing means 22a, 2
2b is an automatic return type. For this reason, the capacity Q of the torque converter 2 can be quickly, accurately, and easily controlled without releasing the operation lever 12b, and thus without hindering the operation of traveling or work. That is, unlike the prior art, the brake control is not made difficult by using the brake pedal together with the operation every time the operation is performed, and, of course, the operation is not interrupted. No skill is required for operation. (2) The desired capacity Q of the torque converter 2 can be obtained by pushing the pushing means 22a and 22b apart. When the pushing is stopped, the desired capacity Q is maintained. That is, unlike the prior art, the changed capacity Q can be easily maintained. (3) Upon receiving the push signals Sa and Sb from the push means 22a and 22b, the control means 18 increases or decreases the capacity Q of the torque converter 2 according to either the number of pushes n or the push time t. Multi-step control is performed when the capacity Q of the torque converter 2 is increased or decreased according to the number n of times of pressing, while multi-step control and stepless control are performed when the capacity Q of the torque converter 2 is increased or decreased according to the pressing time t. Either one or both are mixed controls, and the control flexibility is high in any case. Therefore, the necessary minimum traction force FD can be finely and easily secured. For example, it is possible to convert a part of the unnecessary tractive force into the working force without converting it into the vehicle speed. In addition, the optimum matching of the torque converter 2 with the engine 1 can be performed in a finely detailed manner.
In addition, optimization and downsizing of the torque converter 2 can be realized. (4) That is, since the capacity control of the torque converter 2 can be performed promptly and finely, it is easy to keep the maximum traction force FD substantially constant even if the vehicle speed V slightly changes. For example, the traction force vector FDb can be made substantially constant during the combined operation of running and excavation (tilt). Therefore, it is easy to direct the combined vector FDH with the scraping force vector FHb by the operation of the bucket or the arm in the direction of easy excavation at the object to be excavated. In other words, careless control of the capacity of the torque converter 2 is eliminated, and inconveniences such as slippage of tires and crawler tracks are eliminated. In other words,
The vehicle speed V can be controlled substantially constant. Therefore, for example, when approaching a dump truck, a hopper, or the like in a combined operation of traveling and loading / unloading (dumping), collision with these can be avoided without depressing the accelerator pedal. Since there is no need to depress the accelerator pedal, the maximum traction force FD can be stabilized without lowering the matching point between the torque converter and the engine. Then, since the accelerator pedal is not depressed, the problem of the acceleration acceleration of the engine speed Ne can be solved. That is, the first configuration organically combines the variable capacity function of the torque converter and the example device.

Second, a traveling system having a torque converter 2 with a variable capacity Q, a work system operable based on the operation of an operation lever 12b, and an engine 1 for supplying power to the torque converter 2 and the work system. (A) a reference torque input means 23 for freely inputting a reference torque Ts on the turbine side of the torque converter 2; and (b) an actual torque T on the turbine side.
a), and (c) the reference torque input means 23 and the actual torque detection means 19 are connected in a signal manner.
s is compared with the actual torque Ta from the actual torque detecting means 19, and the control means 18 controls the capacity Q of the torque converter 2 so that "Ta = Ts" when "Ta>Ts". It is characterized by.

According to the second configuration, the following operation and effect can be obtained. According to the first configuration, as described above, the pushing means 22a and 22b can be quickly and finely operated, and as a result, the vehicle speed V and the maximum traction force FD can be substantially stabilized without depressing the accelerator pedal. However, according to the second configuration, the operator operates the reference torque input means 23
If the reference torque Ts is input in advance from the
8 automatically compares the actual torque Ta from the actual torque detecting means 19 with the reference torque Ts, and when “Ta> Ts”, sets the torque converter 2 so that “Ta = Ts”.
To control the capacity. Therefore, even if the vehicle speed V slightly changes, the traction force vector FDb during the combined operation of traveling and excavation (tilt) can be completely constant, and the combined vector FDH can be easily changed in the direction of easy excavation at the excavated object. It can be oriented to increase productivity. The direction of the scraping force vector FHb by the operation of the bucket or the arm is determined by the operation lever 1.
It can be obtained freely by the operation of 2b. In other words, the optimum direction of the combined vector FDH for each excavated object can be obtained only by operating the operation lever 12b, thereby improving the productivity.

Third, a traveling system including a torque converter 2 having a variable capacity Q, a work system operable based on the operation of an operation lever 12b, and an engine 1 for supplying power to the torque converter 2 and the work system. (A) operating lever 12b
And (b) a reference torque input means 23 for freely inputting a reference torque Ts on the turbine side of the torque converter 2, and (c) an actual torque Ta on the turbine side. The actual torque detecting means 19, (d) the pressing means 22a and 22b, the reference torque input means 23, and the actual torque detecting means 19, and (d1) the pressing signal Sa from one of the pressing means 22a. When the pressure signal Sb is received, the capacity Q of the torque converter 2 is increased in accordance with one of the number of pressings n and the pressing time t. (D2) When receiving the pressing signal Sb from the other pressing means 22b, the number of pressings n and the pressing time t, the capacity Q of the torque converter 2 is reduced. (d3) When the reference torque Ts from the reference torque input means 23 is received, the reference torque Ts Is compared with the actual torque Ta from the actual torque detecting means 19, and (d31) “Ta
<Ts ”, the capacitance Q is fixed, and (d32)“ Ta> T
s ", and control means 18 for controlling the capacity Q of the torque converter 2 such that" Ta = Ts ".

According to the third configuration, the following operation and effect can be obtained. The third configuration has the pushing means 22a and 22b in the first configuration, and the reference torque input means 23 and the actual torque detecting means 19 in the second configuration. Therefore, (1) when the reference torque input means 23 is not used, the operation and effect of the first configuration are produced. (2) When the pushing means 22a and 22b are not used, the operation and effect of the second configuration are produced. (3) Reference torque input means 23 and pushing means 22a,
When using 22b, the capacity Q is fixed when “Ta <Ts”, while “Ta = Ts” when “Ta> Ts”.
Is controlled. Details are as follows. If the capacity Q of the torque converter 2 is fixed by the pushing means 22a and 22b, the actual torque Ta based on the capacity Q changes based on the vehicle speed V. However, in the third configuration, the reference torque Ts is input. In this case, the magnitude relationship between the actual torque Ta and the reference torque Ts is related to the first pattern in which “Ta> Ts” passes through “Ta = Ts” to “Ta <Ts” as the vehicle speed V increases, and the vehicle speed V. From the beginning to the end, there is a second pattern in which “Ta <Ts”. Therefore, the control means 18 ignores the signal Sa (or Sb) from the pushing means 22a, 22b when "Ta>Ts" in the first pattern, and sets the capacity Q of the torque converter 2 so that "Ta = Ts". To change. On the other hand, when “Ta <Ts” in the first and second patterns, the capacity Q of the torque converter 2 is kept as it is (that is, the pushing means 22
a, the capacity Q of the torque converter 2 based on the signal Sa (or Sb) from the 22b is fixed. That is, the reference torque Ts is the upper limit of the actual torque Ta. Therefore, by setting the optimum reference torque Ts in advance for each of the different types of work, unnecessary operations on the pushing means 22a and 22b can be eliminated, and the traction force vector FDb required for the excavated object can be given by the reference torque Ts. Therefore, slippage of tires and crawler tracks can be eliminated. That is, the operation burden on the operator is reduced, and the productivity is also improved. If the reference torque input means 23 is arranged on the operation lever 12b like the pushing means 22a, 22b, there is no problem in handling. Even if the reference torque input means 23 is arranged on the instrument panel as in the related art, the operation on the reference torque input means 23 may be performed for each different operation, so that the running and the work are not interrupted.

Fourth, a traveling system having a torque converter 2 with a variable capacity Q, a work system operable based on the operation of an operation lever 12b, and an engine 1 for supplying power to the torque converter 2 and the work system. (A) reference vehicle speed input means 24 capable of freely inputting reference vehicle speed Vs, (b) actual vehicle speed detection means 21 for detecting actual vehicle speed Va, and (c) reference vehicle speed input. The reference vehicle speed Vs from the reference vehicle speed input unit 24 and the actual vehicle speed Va from the actual vehicle speed detection unit 21 are compared by signal connection to the unit 24 and the actual vehicle speed detection unit 21.
> Vs ", the traction force FD is almost zero (FD ≒ 0)
And a control means 18 for reducing the capacity Q of the torque converter 2 or setting the capacity Q of the torque converter 2 to zero (Q = 0).

According to the fourth configuration, the following operation and effect can be obtained. According to the first configuration, as described above, the pushing means 22a and 22b can be quickly and finely operated, and as a result, the vehicle speed V and the maximum traction force FD can be substantially stabilized without depressing the accelerator pedal. However, according to the fourth configuration, if the operator previously inputs the reference vehicle speed Vs from the reference vehicle speed input means 24, the control means 18 automatically determines the actual vehicle speed Va from the actual vehicle speed detection means 21 and the reference vehicle speed Vs. In comparison, when “Va> Vs”, the capacity Q of the torque converter 2 is reduced or the capacity Q of the torque converter 2 is reduced to zero (Q = 0) so that the traction force FD becomes substantially zero (FD ≒ 0). . That is, since the capacity of the torque converter 2 is controlled when "Va>Vs", the tractive force FD at this time is substantially eliminated. Details are as follows. "Va> Vs
”, The capacity Q of the torque converter 2 is reduced so that the traction force FD becomes substantially zero (FD ≒ 0).
a> Vs ". That is, when the running resistance increases, the vehicle speed is controlled to be "Va = Vs". When the running resistance decreases, "Va>Vs", but the tractive force FD remains almost zero (FD ≒ 0). On the other hand, when “Va> Vs”, the capacity Q of the torque converter 2 is reduced to zero (Q = 0).
Then, constant vehicle speed control of "Va = Vs" is performed. In any case, when “Va> Vs”, the traction force F at that time
All of D can be diverted to working system torque TeH. If it is assumed that the torque converter 2 is not subjected to the capacity control at the time of “Va ≦ Vs”, the maximum traction force FD during this time is generated as a traction force vector FDb, or the force that immediately increases the vehicle speed V to “Va = Vs”. Become. For example, when approaching a dump truck or a hopper during a combined operation of traveling and loading / unloading (dumping), the latter becomes “Va = Vs”, so that the collision with the dump truck or the hopper does not occur and the accelerator pedal is not pressed. Can be approached at "Va = Vs" without decreasing the vehicle speed V by stepping back. In addition, the traction force FD at the time of "Va = Vs" is all converted to the working system torque TeH, which is extremely economical.

Fifth, variable displacement torque converter 2
And a variable displacement torque converter having a transmission 4 capable of changing the rotational torque from the torque converter 2 based on a shift signal from a shift lever 9 and a control means 18 for variably controlling the capacity Q of the torque converter 2. The vehicle has (a) an actual vehicle speed detection means 21 for detecting an actual vehicle speed Va, and (b) a control means 18
Are connected to the shift lever 9 and the actual vehicle speed detecting means 21 in a signal manner, and are connected to each speed stage F of the transmission 4.
1, the maximum vehicle speed Vimax of F2, R1, R2 is stored in advance,
The maximum vehicle speed V1max of the current gear stage F1 is read from the current gear stage F1 from the shift lever 9 and the above-mentioned memory, and is compared with the actual vehicle speed Va from the actual vehicle speed detecting means 21 to obtain "Va>V1ma".
When “x” and when controlling the capacity of the torque converter 2, the control means 18 is a control unit 18 that maximizes the capacity Q of the torque converter 2.

According to the fifth configuration, the following operation and effect can be obtained. The vehicle in the fifth configuration is the same as the first to fourth vehicles.
Unlike the configuration, it is not limited to a work vehicle. That is, in a vehicle with a variable displacement torque converter, for example, if the vehicle is descended over a long distance during the displacement control of the torque converter 2, the vehicle speed V is easily reduced to the maximum vehicle speed Vimax at the variable speed stage because the torque converter 2 has a small displacement. (V> Vimax,
Overrun) Operationally dangerous. In this case, it is desirable to use the engine brake together with the brake and the retarder. Of course, the effectiveness of the engine brake in a vehicle with a torque converter is small, but the braking function is still a security function, so it is desirable to apply the engine brake even a little. The fifth configuration achieves this. That is, when “Va> V1max” and the torque converter 2
By controlling the capacity Q of the torque converter 2 to the maximum when the capacity of the torque converter 2 is controlled, the engine brake can be applied although it is small. In addition, in the fifth configuration, when the vehicle speed control based on the output of the engine 1 is performed after returning to “V <Vimax”, the vehicle speed control can be performed immediately because the capacity Q of the torque converter 2 is already at the maximum at this time (so-called “V <Vimax”). Responsiveness is improved). Note that it is preferable that the criterion at the time of return is not "V <Vimax" but "V <Vimax-α" to prevent hunting.

[0030]

Preferred embodiments of the present invention will be described below with reference to FIGS. Note that the same reference numerals are given to the elements already described in the column of the “prior art”, and the duplicate description will be omitted.

An example machine is the wheel loader shown in FIG.
As shown in FIG. 2, a drive train in the order of the engine 1, the clutch 2a, the fixed capacity torque converter 2b, the transmission 4, the front and rear drive shafts 5F and 5R, the front and rear differentials 6F and 6R, and the front and rear tires 7F and 7R,
A shift lever 9 (see FIG. 2) provided in the cab 8;
It has a traveling system driven by receiving traveling system torque TeD from the engine 1. Also, the example machine has a working machine having a bucket 11 rotatably movable by a bucket hydraulic cylinder 10b at the tip of an arm that can be raised and lowered by an arm hydraulic cylinder 10a (see FIG. 2) at the front, and an operator cab 8
The operating oil for the arm 12a (see FIG. 2) and the operating lever 12b for the bucket (see FIG. 2) and the hydraulic oil pump 13 (see FIG. 2) which is driven by receiving the working system torque TeH are used to discharge oil. Hydraulic circuit 14 that supplies to both cylinders 10a and 10b based on the operation amounts of operation levers 12a and 12b and expands and contracts them to operate the working machine (see FIG. 2).
And a working system comprising: In addition, the example machine has a main switch 25 for starting and stopping the machine.

The arm operating lever 12a has four positions: Up (up), N (neutral), Down (down), and Flow (floating), and the bucket operating lever 12b has Tilt (tilt, excavation), N ( Neutral), Dump (dump, loading / unloading), the shift lever 9 and the transmission 4 are F1 to F3 (forward first to third speeds), N (neutral), R
It has seven positions 1 to R3 (reverse 1st to 3rd) freely switchable. As shown in the maximum tractive force curve of FIG. 3, F1 and R1, F2 and R2, F3 and R3 have the same reduction ratio, respectively, 7 km / h (V1max), 12 km / h (V2max), and 32 km / h (V2max).
It has a maximum vehicle speed Vimax of Km / h (V3max).

The example machine has a capacity control system for the torque converter 2b, as further described in detail in FIG. The torque converter 2b is of a fixed displacement type, and its capacity does not change. However, the torque converter 2b is used in pairs with a clutch 2a, which will be described later in detail, to constitute a substantially variable displacement torque converter. Therefore, hereinafter, when the reference numeral 2 is attached to "torque converter 2", the torque converter is a variable capacity type torque converter.

The clutch 2a is provided on a transmission shaft for transmitting the driving force of the engine 1 to a pump (not shown) of the torque converter 2b. In the half-clutch state, the slip ratio β can be changed freely. The discharge-side maximum pressure Pmax (relief pressure Pmax) of the hydraulic pump 15 is defined by a relief valve 16. The variable pressure reducing valve 1 provided on the upstream side of the relief valve 16
7 is a secondary hydraulic pressure, which is stipulated to be freely changeable. The variable pressure reducing valve 17 has a spring, and when the clutch pressure P is generated based on the urging force of the spring, the clutch 2a is in a directly connected state. (That is, the torque converter 2 has the maximum capacity Qmax.) However, the variable pressure reducing valve 17 is a proportional solenoid valve, and when receiving a current A from a controller 18 including a microcomputer or the like, the stronger the current A, the weaker the urging force of the spring, thereby the clutch pressure is reduced. Decrease P. That is, the current A
Is stronger, the slip ratio β of the clutch 2a (the level in the half-clutch state) increases, and accordingly, the torque converter 2 having the small capacity QS is sequentially provided. Note that the spring force may be increased as the current A becomes stronger, thereby increasing the clutch pressure P (in this case, it is necessary to replace the description in the following description).

Incidentally, an actual torque detector 19 is provided on the rear drive shaft 5R, and the actual torque Ta generated on the rear drive shaft 5R is detected and inputted to the controller 18.

The vehicle body 20 is provided with an actual vehicle speed detector 21 for detecting the actual vehicle speed Va of the example machine and inputting it to the controller 18.

As described above, the controller 18 outputs the current A to the variable pressure reducing valve 17 and simultaneously outputs the current A to the actual torque detector 1.
9 receives the actual torque Ta and the actual vehicle speed detector 21 receives the actual vehicle speed Va. Further, the gear position signals F1, F2, R1, R2 are transmitted from the speed change lever 9 to the increase / decrease button 22a,
It is possible to accept push signals Sa and Sb from 22b, reference torque Ts from reference torque input dial 23, and reference vehicle speed Vs from reference vehicle speed input dial 24. still,
The increase / decrease buttons 22a and 22b are used to operate the bucket operation lever 12.
The two dials 23 and 24 are provided on the instrument panel near the driver's seat in the cab 8.

The gear position signals F1, F2, R1, R2 are as follows. The shift lever 9 has seven positions N, F1 to F as described above.
3, R1 to R3. Although not shown, the controller 1
8 receives a 7 position signal from the shift lever 9 and gives a shift command to the transmission 4 to shift it. Then, the controller 18 controls the gear position signals F1, F among the seven position signals.
The maximum vehicle speed Vimax for each of the variable speed stages i based on the driving force of the engine 1 is stored in advance for 2, R1, and R2, and a process described in detail below is performed. In a structure in which the shift lever 9 is mechanically connected to the transmission 4 by a link mechanism or the like to achieve a shift, the controller 18 controls the shift speed signal F
1, F2, R1, R2 only.

The pressing signals Sa and Sb are as follows. The increase / decrease buttons 22a and 22b are mechanically automatic reset switches, but are functionally self-holding in cooperation with the controller 18. Details are as follows. The increase button 22a is provided to protrude from the side surface of the knob of the bucket operation lever 12b,
The operator presses the middle finger by the abdominal surface of the middle finger, and inputs a pressing signal Sa to the controller 18 during the pressing. When the operator loosens the middle finger or releases the middle finger from the increase button 22a to stop pushing, the increase button 22a automatically returns to the original protruding state, and sets the push signal Sa to zero (Sa = 0). On the other hand, the decrease button 22b is provided on the top surface of the knob and is pushed by the abdominal surface of the thumb, and inputs a pushing signal Sb to the controller 18 during this pushing. When the operator loosens the thumb or releases the thumb from the decrease button 22b to stop pushing, the decrease button 22b automatically returns to the original protruding state, and sets the pushing signal Sb to zero (Sb = 0). In addition, the increase / decrease button 22a,
The installation location of 22b may be reversed, and both may be provided on the left and right of the top surface of the knob. In short, any position can be used as long as the operator can operate quickly without releasing the bucket operating lever 12b.

The reference torque Ts and the reference vehicle speed Vs are as follows. Scales are displayed on the reference torque input dial 23 and the reference vehicle speed input dial 24, and the operator can freely input the desired reference torque Ts and reference vehicle speed Vs in a digital (stepwise) or analog (linear) manner. There is. The reference torque Ts and the reference vehicle speed Vs are input to the controller 18 and stored.

Hereinafter, the capacity control of the torque converter 2 by the controller 18 will be described with reference to FIGS.

(A) First, the control of the capacity of the torque converter 2 by the increase / decrease buttons 22a and 22b will be described. For ease of explanation, the two dials 23 and 24 are not used, and the initial current A to the variable pressure reducing valve 17 is set to zero (A = 0, that is, “P = P” and the torque Converter 2
Is the maximum capacity Qmax). That is, the controller 18 operates the increase / decrease button 2
The duration t from the time when the push signals Sa and Sb are received from the 2a and 22b to the time when it is lost (that is, the press time t from the time when the operator pushes the increase / decrease buttons 22a and 22b to the time when the finger is released or released). The pressing time t is monitored and compared with a first reference time t1 (0.15 sec in the present embodiment) and a second reference time t2 (0.1 sec in the present embodiment) stored in advance.

(A1) When the operator presses the decrease button 22b (n = 1), the controller 18 outputs the current nΔ stored in advance.
A is input to the variable pressure reducing valve 17 (A = ΔA). Then, the operator presses the decrease button 22 during a time period shorter than the first reference time t1.
When b is returned (t <0.15 sec), the controller 18 continues to supply the current ΔA to the variable pressure reducing valve 17 after the pressing time t (A = ΔA). As a result, the clutch pressure P becomes the current Δ
The torque converter 2 is reduced by a small hydraulic pressure ΔP corresponding to A (P−ΔP), and the torque converter 2 is reduced to a small capacity QS1. That is, the decrease button 2
2b is functionally self-holding in cooperation with controller 18, as described above.

(A2) Following the above (a1), when the operator presses the decrease button 22b again (n = 2), the controller 18 further inputs the current ΔA to the variable pressure reducing valve 17 (A = 2ΔA). . Then, when the operator returns the decrease button 22b to the original state again before the first reference time t1 (t <0.
The controller 18 continues to supply the current 2ΔA to the variable pressure reducing valve 17 (A = 2Δ).
A). As a result, the clutch pressure P is further reduced by the small oil pressure ΔP (P−2ΔP), and the torque converter 2 is further reduced in capacity QS2.

As described above, the pressing time t is equal to the first reference time t.
When it is shorter than 1 (t <t1), the controller 18 inputs the current A (= nΔA) obtained by multiplying the current ΔA to the number of times of pressing n to the variable pressure reducing valve 17, and sequentially reduces the capacity Q to a small capacity QSn. .
In the present embodiment, “n = 12” is set as the maximum (“A ≦ 17Δ
A ") and"n> 13 "are set to idle pressing. Note that “A = 11
ΔA ”is a small capacity QS11 at which the maximum traction force FD becomes almost zero.
(FD ≒ 0), “A = 12ΔA” sets the capacity Q to zero (QS12 = 0).

(A3) On the other hand, when the pressing time t is longer than the first reference time t1 (t> t1), the controller 18 executes the following. For example, following the above (a2), when the operator presses the decrease button 22b again (n = 3), the controller 1
In step 8, the current .DELTA.A is further input to the variable pressure reducing valve 17 (A = 3.DELTA.A), but the following is executed because the pushing time t is longer than the first reference time t1 (t> t1). (A31) For example, when “t = 0.62 sec”, the second
Each time the reference time t2 (= 0.1 sec) elapses, the current A (= 9.DELTA.A) obtained by adding the current .DELTA.A six times is used as the variable pressure reducing valve 17.
(A = 9ΔA). (A32) On the other hand, for example, if “t = 2 sec”, “A
.Ltoreq.12.DELTA.A ", the addition of the current .DELTA.A is stopped when" t = 0.9 sec ", and the current A is set to A (= 12.DELTA.A).

In the case of (a3), while the current A is "3ΔA to 12ΔA", the above (a31) and (a3
Rather than adding the current ΔA every second reference time t2 to reduce the capacity Q in multiple steps as in 2), the second reference time t2 is eliminated and the currents 3ΔA to 12ΔA are set as functions of the pushing time t. It may be reduced steplessly.

(A4) The increase button 22a is the decrease button 2
2b, the current A is decreased by ΔA or functionally in the opposite manner, thereby increasing the clutch pressure P by ΔP or functionally, whereby the torque converter 2 previously changed to the small capacity QS is gradually reduced. Alternatively, the capacity is increased functionally.

As can be seen from the above description, the controller 1
Reference numeral 8 denotes a pressing signal S for processing the pressing signals Sa and Sb.
It is necessary to be able to discriminate the difference between a and Sb. The controller 18 of the present embodiment individually configures the input sections of the press signals Sa and Sb, and performs discrimination based on the input sections. Of course, increase / decrease button 22
For example, a voltage difference, a current difference, a pulse difference (a shape difference, a frequency difference, a phase difference, etc.) are given to the push signals Sa, Sb in a, 22b in advance, and the controller 18 discriminates based on such differences. It may be a configuration that does. With this configuration, it is not necessary to individually configure the input sections of the pressing signals Sa and Sb as in the present embodiment.

The functions and effects based on the above (a1) to (a4) are as described in the above-mentioned paragraph number [0021], and therefore, redundant description will be omitted.

(B) Next, the capacity control of the torque converter 2 based on the reference torque Ts will be described. As shown in the control section diagram of FIG. 4, when the controller 18 receives the shift speed signal F1 from the shift lever 9 and receives the reference torque Ts from the reference torque input dial 23, the controller 18 detects the reference torque Ts and the actual torque detector. 19, the capacity of the torque converter 2 is controlled based on comparison with the actual torque Ta. Details will be described with reference to FIG. FIG. 5 is a graph of the maximum tractive force curve when the reference torque is used while changing the scale of F1 of the maximum tractive force curve of FIG. Although the maximum torque Tt (or Ta or the like) and the maximum tractive force FD are strictly different, in the present embodiment, they are regarded as the same as described below. The maximum traction force FD is usually "FD = (ρη / r) Tt
−FR ”, while the torque Tt is“ Tt = (FD + FR)
) / (Ρη / r) ”. ρ is the total reduction ratio from the transmission 4 to the rear tire 7R for each variable speed stage i, η is its transmission efficiency, r is the radius of the rear tire 7R,
Tt is a half of the transmission input torque (half of the turbine torque Tt, which is the reason that the torque detector 19 is not actually mounted on the front drive shaft 5F despite the fact that the example machine is driven by the front wheels), FR is a running resistance composed of a gradient resistance, a wind pressure resistance, a road surface resistance, and the like, and varies depending on a road condition. Therefore, although the maximum traction force curve and the maximum torque curve are strictly different, the limit torque Ts is, for example, as described above, from the actual torque detector 19 provided on the rear drive shaft 5R with the actual torque Ta to be compared with the limit torque Ts. And the reference torque Ts naturally exceeds the running resistance FR, as will be described in detail later. On the other hand, the reference vehicle speed Vs, which will be described in detail later, is also the maximum vehicle speed Vimax at each variable speed stage i. In the present invention, it can be considered that the maximum traction force curve in FIG. 3 is regarded as the maximum torque curve.

(B1) For the sake of simplicity, it is assumed that the increase / decrease buttons 22a and 22b are not initially pressed (A = 0, that is, "P = P", and the torque converter 2 has the maximum capacity Qmax). . First, as shown in FIG. 5, the operator operates the controller 1 through the reference torque input dial 23.
8 is input with the reference torque Ts. Next, when the operator switches the shift lever 9 to the F1 position, the controller 18 compares the actual torque Ta with the reference torque Ts, and determines that "Ta>Ts".
, The current A is generated so as to satisfy “Ta = Ts”, and the capacity Q of the torque converter 2 is controlled. That is, "T
If “a> Ts”, the current A is gradually increased until “Ta = Ts”, while if “Ta <Ts”, “Ta = Ts”
The current A is gradually reduced until In this case, the gradual increase,
The gradually decreasing current is irrelevant to the current ΔA based on the operation of the increase / decrease buttons 22a, 22b (of course, it may be the same, but in this case, the control quality is coarse). In particular,
In FIG. 5, when "V = 0", the controller 18 sets "Q = QS".
6 ”(until matching at point g1).
= V1 ”until“ Q = QS4 ”(until matching at point g2),“ V = V2 ”until“ Q = QS2 ”(until matching at point g3), and“ V ≧ V3 ” The current A is changed while maintaining "Q = Qmax"("V = V3" is matched at the point g4). In the above, the vehicle speed V (= 0 to V3) is exemplified, but these are only for easy explanation. In short, as described above, regardless of the vehicle speed V, if “Ta> Ts”, “Ta> Ts” = Ts ", while the current A is gradually decreased until" Ta = Ts "if" Ta <Ts ".

(B2) When changing the reference torque Ts, the reference torque input dial 23 may be turned. In this case, the reference torque Ts moves up and down in FIG.

The functions and effects based on the above (b1) and (b2) are as described in the above paragraph number [0023], and therefore, redundant description will be omitted. Note that the capacity control based on the reference torque Ts is limited to F1 because of the constant maximum traction force FD.
This is to apply to the combined operation of running and excavation (tilt) that requires (constant actual torque Ta), and this combined operation is usually performed in F1. Of course,
The present invention may be applied to other speed stages such as F2.

(B3) Pressing signals Sa, Sb from the increase / decrease buttons 22a, 22b during the control of (b1), (b2).
Is input, the controller 18 fixes the capacity Q based on the increase / decrease buttons 22a and 22b when "Ta <Ts". On the other hand, when “Ta> Ts”, “Ta = Ts”
The current A is controlled so that

The operation and effect based on the above (b3) are as described in the above paragraph number [0025] (3), and therefore redundant description will be omitted.

(C) Next, the capacity control of the torque converter 2 based on the reference vehicle speed Vs will be described. That is, the controller 18
The reference vehicle speed Vs from the reference vehicle speed input dial 24, the actual vehicle speed Va from the actual vehicle speed detector 21, and the speed change signals F1, F2, R from the shift lever 9 as shown in FIG.
The following processing is performed based on R1 and R2. Details will be described with reference to FIG.

(C1) For the sake of simplicity, it is assumed that initially the increase / decrease buttons 22a and 22b are not depressed (A = 0, that is, "P = P" and the torque converter 2
Is the maximum capacity Qmax). First, the operator inputs the actual vehicle speed Va (= 3 km / h) shown in FIG. 5 to the controller 18 via the reference vehicle speed input dial 24. Next, when the operator switches the shift lever 9 to F1, the controller 18 sets the actual vehicle speed V
a and the reference vehicle speed Vs (“Vs = 4 km / h” in this embodiment), and when “Va> Vs”, the maximum traction force FD
A (= 11Δ) so that is substantially zero (FD ≒ 0).
A) is generated, and the capacity Q of the torque converter 2 is reduced.
Alternatively, a current A (= 12ΔA) that makes the capacity Q of the torque converter 2 zero (Q = 0) is generated. Specifically, FIG.
In the case of the torque converter 2 having the maximum capacity Qmax, for example, if the example machine has sufficient working system torque TeH and the traveling system torque TeD is not necessary, the actual vehicle speed V
a immediately becomes the reference vehicle speed Vs (Va = Vs). Then, the controller 18 immediately generates the current A (= 11ΔA) and reduces the capacity Q of the torque converter 2. As a result, "V
a = Vs "is maintained. When “Va = Vs”, the capacitance Q is the small capacitance QS11 (= 11ΔA).
Depending on the running resistance FR, "Va>Vs" may be satisfied.

(C2) To change the reference vehicle speed Vs, the reference vehicle speed input dial 24 may be turned. In this case, the reference vehicle speed Vs moves left and right in FIG.

The functions and effects based on the above (c1) and (c2) are as described in the above-mentioned paragraph number [0027], and therefore, redundant description will be omitted. The reason why the capacity control based on the reference vehicle speed Vs is limited to F1, F2, R1, and R2 is that a combined operation of traveling and loading / unloading (dumping) is performed on a dump truck, a hopper, or the like that requires a substantially constant vehicle speed Vs. And the combined operation is performed in F1, F2, R
1 or R2, and F3 and R3 are usually dedicated to running. Of course, it may be applied to R3 or F3 or not applied to F2, R1 and R2.

(C3) Pressing signals Sa, Sb from the increase / decrease buttons 22a, 22b during the control of the above (c1), (c2)
Is input, the controller 18 changes the capacity Q of the torque converter 2 based on the push signals Sa and Sb. Then, the changed capacity Q is set as the maximum capacity (c1),
(C2) is controlled. That is, (c1), (c
2) The respective effects based on (a1) to (a4) are superimposed.

(C4) When the reference torque Ts is input from the reference torque input dial 23 during the control of the above (c1) and (c2), the above (c1), (c2), (b1) and (b)
The respective effects based on 2) are superimposed.

(C5) Pressing signals Sa and Sb from the increase / decrease buttons 22a and 22b during the control of the above (c1) and (c2)
Is input and the reference torque Ts is input from the reference torque input dial 23, the above (c1), (c2),
The respective effects based on (a1) to (a4), (b1) and (b2) are superimposed.

(D) Next, the capacity control of the torque converter 2 during overrun will be described. As described above, the controller 18 controls the shift speed signal F among the seven position signals of the shift lever 9.
The maximum vehicle speed Vimax for each speed change stage based on the driving force of the engine 1 is stored in advance for 1, F2, R1, and R2.
The controller 18 controls the actual vehicle speed V when controlling the capacity of the torque converter 2 based on the above (a) to (c5).
a is the maximum vehicle speed V1max (7 km / h) at the speed change signal F1.
Is exceeded (Va> V1max), the current A is set to zero, and the clutch 2a is brought into a directly connected state.

The operation and effect based on the above (d) are as described in the above paragraph number [0029], and therefore, redundant description will be omitted.

The capacity Q of the torque converter 2 and the reference torque input dial 23 by the increase / decrease buttons 22a and 22b
Of the reference torque Ts by the reference torque and the reference vehicle speed Vs by the reference torque input dial 23 are respectively set to 22a and 22a.
The problem can be solved by returning the 2b, 23, 24 to the initial position, but also by turning off the main switch 25 connected to the controller 18 in a signal manner. Of course, instead of the main switch 25 that controls the start and stop of the engine 1, a switch dedicated to cancellation may be provided.

In the following, other embodiments will be described.

(1) Although the example machine in the above embodiment is a wheel loader, a work vehicle such as a dozer shovel or a motor grader may be used. In short, the engine torque T
A work vehicle with a variable displacement torque converter having a traveling system that operates by receiving e through the variable displacement torque converter 2 and a working system that operates by receiving the engine torque Te may be used. Even in this case, the same operation and effect as the above embodiment can be obtained. The control (d) in the above embodiment is not limited to a work vehicle, and can be applied to any vehicle having a variable displacement torque converter.

(2) Actual torque detector 1 in the above embodiment
9 is provided only on the rear drive shaft 5R, but is preferably provided on the front and rear drive shafts 5F, 5R. In this case, the actual torque Ta before and after is added (2Ta), and the control is executed by the added torque 2Ta. This improves control quality.

(3) Increase / decrease button 22a in the above embodiment,
Although 22b is provided on the bucket operating lever 12b, it may be provided on the arm operating lever 12a. Further, they may be provided on both operation levers 12a and 12b. If both operation levers 12a and 12b are single levers that can be operated in multiple directions like a joystick lever, they are provided on this lever. Even in this case, the same operation and effect as the above embodiment can be obtained. It may be provided at or near the steering handle. If necessary, it may be provided on a member that can be always held by the operator.

(4) The variable displacement torque converter 2 in the above embodiment is of the clutch type in which the clutch 2a is provided between the pump of the fixed displacement type torque converter 2b and the engine 1, but as described above, A fixed displacement torque converter 2b having a plurality of pumps and a clutch 2a provided between some of them and the engine 1 may be used.
In this case, some or all of the clutches 2a are controlled. Further, a variable capacity torque converter 2 provided with an actuator for changing the blade angle of the stator may be used. In short, any variable torque converter 2 may be used. Even if it does in this way, the basic effect of the above-mentioned embodiment does not change.

(5) In the above embodiment, the actual torque detector 1
9 and an actual vehicle speed detector 21. Instead of these, detectors for detecting the pump speed Np and the turbine speed Nt of the torque converter 2b are provided, respectively, and the controller 18 as shown in FIG. The torque converter performance curve may be stored in advance and processed as follows. That is, the controller 18 receives the two rotation speeds Np and Nt from each detector and calculates the speed ratio e (= Nt / Np). Then, the torque coefficient τp and the torque ratio λ are extracted from the stored torque converter performance curve of FIG. 7 according to the speed ratio e. And the torque coefficient τ
p and the pump rotation speed Np are set to the above-mentioned “τp (Np / 100
0) ² ] to obtain the pump torque Tp (= τ
p (Np / 1000) ² ). Then, the turbine torque Tt (= λTp) is obtained by multiplying the pump torque Tp by the torque ratio λ. Here, by setting the reference torque Ts input from the reference vehicle speed input dial 24 to a value corresponding to the turbine torque Tt in advance, the processing of the above embodiment can be continued as it is. On the other hand, by setting the reference vehicle speed Vs input from the reference vehicle speed input dial 24 to a value corresponding to the turbine speed Nt in advance, the processing of the above embodiment can be continued as it is.

(6) Push signals Sa and S in the above embodiment
b is used for changing the capacity of the torque converter 2 as described in (a1) to (a4) above.
It can also be used as a reference value input means for the reference torque Ts or the reference vehicle speed Vs instead of the reference numerals 3 and 24. That is, the controller 1
8 is, for example, the number of presses n for the press signal Sa.
And the current-[Delta] A corresponding to one of the pushing time t and the unit increased reference torque + [Delta] Ts and the unit increased reference vehicle speed + V
Remember s. On the other hand, for the pressing signal Sb, a current +
The unit reduction reference torque -ΔTs and the unit reduction reference vehicle speed -ΔVs are stored together with ΔA. The controller 18 receives the push signals Sa and Sb from the increase / decrease buttons 22a and 22b and outputs a current A (= nΔA), and at the same time, increases / decreases the unit actual vehicle speed ± ΔV with respect to the current actual torque Ta and the reference torque Ts.
a and the actual vehicle speed ± ΔVa. In this case, since these act as a set, individual control of the capacity Q of the torque converter 2 by the increase / decrease buttons 22a, 22b, the reference vehicle speed input dial 24, and the reference torque input dial 23 as in the above embodiment. It is effective when not performing.

[Brief description of the drawings]

FIG. 1 is a side view of a wheel loader according to an embodiment.

FIG. 2 is a capacity control block diagram of a variable displacement torque converter according to the embodiment.

FIG. 3 is a graph showing a maximum traction curve of the embodiment.

FIG. 4 is a control division diagram in the embodiment.

FIG. 5 is a maximum traction force curve diagram when a reference torque is used.

FIG. 6 is a maximum traction force curve diagram when a reference vehicle speed is used.

FIG. 7 is a general performance curve diagram of a torque converter.

8A and 8B are diagrams showing matching performance between an engine and a variable displacement torque converter, wherein FIG. 8A shows a case of a maximum displacement and FIG. 8B shows a case of a small displacement.

FIG. 9 is a relationship diagram between a pedal depression amount and a clutch pressure according to a conventional technique.

FIG. 10 is a maximum traction curve of the wheel loader at the first forward speed.

FIG. 11 is a force vector diagram during a composite operation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Variable capacity torque converter, 2a
... clutch, 2b ... fixed displacement torque converter, 4 ...
Transmission: 9: transmission lever, 12b: operation lever, 18: controller (control means), 19: actual torque detector (actual torque detection means), 21: actual vehicle speed detection means, 22a: increase button (automatic return type push-in) Means), 22
b: Decrease button (automatic return type pressing means), 23: Reference torque input means, 24: Reference vehicle speed input means, F1, F2,
R1, R2: speed stage, n: number of pushes, Q: torque converter capacity, Sa, Sb: push signal, t: duration (push time), Ta: actual torque, Ts: reference torque, Va: actual vehicle speed, Vs … Reference vehicle speed, Vimax… Maximum vehicle speed, V1max… Maximum vehicle speed of forward and backward 1st speed.

Claims (5)

[Claims] 1. A torque converter 2 having a variable capacity Q.
(A) a vehicle equipped with a variable displacement torque converter including: a traveling system having: a working system operable based on the operation of an operating lever 12b; and a torque converter 2 and an engine 1 for supplying power to the working system. 12b is provided with automatic return type pushing means 22a, 22b, and (b)
(B1) signally connected to the pushing means 22a, 22b
When the push signal Sa is received from one push means 22a, the capacity Q of the torque converter 2 is increased according to either the number of pushes n or the push time t, and (b2) the push signal Sb is received from the other push means 22b. A vehicle with a variable displacement torque converter, characterized by comprising a control means (18) for decreasing the capacity (Q) of the torque converter (2) in accordance with one of the number of presses (n) and the push time (t). 2. A torque converter 2 having a variable capacity Q.
(A) a vehicle equipped with a variable displacement type torque converter having a traveling system having: a working system operable based on the operation of an operation lever 12b; and a torque converter 2 and an engine 1 for supplying power to the working system. Reference torque input means 23 capable of freely inputting reference torque Ts on the turbine side, (b) actual torque detection means 19 for detecting actual torque Ta on the turbine side, and (c) reference torque input means 23 The reference torque Ts from the reference torque input means 23 and the actual torque Ta from the actual torque detection means 19 are compared in a signal manner to the torque detection means 19, and when "Ta>Ts","Ta = Ts" Control means 1 for controlling the capacity Q of the torque converter 2 such that
8. A vehicle with a variable displacement torque converter, comprising: 3. A torque converter 2 having a variable capacity Q.
(A) a vehicle equipped with a variable displacement torque converter including: a traveling system having: a working system operable based on the operation of an operating lever 12b; and a torque converter 2 and an engine 1 for supplying power to the working system. 12b is provided with automatic return type pushing means 22a, 22b, and (b)
A reference torque input means 23 for freely inputting a reference torque Ts on the turbine side of the torque converter 2, and (c) an actual torque detecting means 19 for detecting the actual torque Ta on the turbine side.
(D) signally connected to the pressing means 22a, 22b, the reference torque input means 23, and the actual torque detecting means 19, and (d1) a pressing signal S from one of the pressing means 22a.
a, the capacity Q of the torque converter 2 is increased in accordance with one of the number of pressings n and the pressing time t,
(d2) When the push signal Sb is received from the other push means 22b, the capacity Q of the torque converter 2 is reduced according to either the number of pushes n or the push time t, and (d3)
Further, when receiving the reference torque Ts from the reference torque input means 23, the reference torque Ts is converted to the actual torque detection means 19.
(D31) “Ta <Ts”
, The capacity Q is fixed, and (d32) the torque converter 2 is set such that “Ta = Ts” when “Ta> Ts”.
And a control means 18 for controlling a capacity Q of the vehicle. 4. A torque converter 2 having a variable capacity Q.
(A) reference vehicle speed in a vehicle equipped with a variable displacement torque converter having a traveling system provided with: a work system operable based on the operation of an operation lever 12b; and a torque converter 2 and an engine 1 for supplying power to the work system. Reference vehicle speed input means 24 capable of inputting Vs, (b) actual vehicle speed detection means 21 for detecting actual vehicle speed Va, and (c) reference vehicle speed input means 24
And the reference vehicle speed Vs from the reference vehicle speed input means 24 and the actual vehicle speed Va from the actual vehicle speed detection means 21 are compared, and "Va>Vs"
, The control means 1 reduces the capacity Q of the torque converter 2 so that the traction force FD becomes substantially zero (FD ≒ 0) or sets the capacity Q of the torque converter 2 to zero (Q = 0).
8. A vehicle with a variable displacement torque converter, comprising: 5. A variable-capacity torque converter 2, and a transmission 4 capable of changing the rotational torque from the torque converter 2 based on a shift signal from a shift lever 9.
A vehicle equipped with a variable displacement torque converter having a control means 18 for variably controlling the capacity Q of the torque converter 2 includes (a) actual vehicle speed detection means 21 for detecting an actual vehicle speed Va, and (b) control means. Reference numeral 18 denotes each speed stage F1, F2, R of the transmission 4 which is connected to the transmission lever 9 and the actual vehicle speed detection means 21 in a signal manner.
1, the maximum vehicle speed Vimax of R2 is stored in advance,
From the current gear position F1 from the current position and the memory.
Is read out and compared with the actual vehicle speed Va from the actual vehicle speed detecting means 21. When "Va>V1max" and when the capacity of the torque converter 2 is controlled, the capacity Q of the torque converter 2 is increased. A vehicle with a variable displacement torque converter, characterized in that the vehicle is a control means 18.