JP3498367B2 - Control device for vehicles equipped with hydraulic transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a vehicle equipped with a fluid transmission, which simultaneously improves operability and fuel efficiency. 2. Description of the Related Art As a vehicle equipped with a fluid transmission of this type,
For example, there is a forklift. In a conventional forklift, an output shaft of an engine and wheels are connected via a stepped transmission having a sliding element, an accelerator pedal is directly connected to a throttle valve of the engine via a wire, and the sliding element is further connected. A clutch pedal (referred to as an inching pedal in an AT vehicle) for operating and connecting / disconnecting wheels to / from the output shaft of the engine is provided, and the vehicle speed and the cargo handling speed are adjusted through these two pedals. Like that. Specifically, when performing normal driving, the vehicle speed is adjusted by the operation amount of the accelerator pedal with the clutch pedal connected, and when performing the cargo handling operation while the vehicle is stopped, the vehicle speed is adjusted by the operation amount of the accelerator pedal with the clutch pedal disengaged. The cargo handling speed is adjusted. However, in these configurations, since the accelerator and the throttle valve are directly connected via a wire,
The actual engine speed is directly controlled by the throttle opening, and is far from the engine speed that satisfies the optimum fuel efficiency condition determined by the engine characteristics with respect to the throttle opening. Therefore, there is a problem that fuel efficiency during traveling is poor. Therefore, in order to improve operability by eliminating the need for clutch pedal operation and to realize an engine speed that satisfies the optimum fuel consumption condition determined by the engine characteristics in accordance with the throttle opening, the accelerator pedal has recently been used. Separate from the throttle valve and set not only the speed ratio of the transmission but also the throttle opening as the control target.The target vehicle speed is set according to the accelerator operation amount, and the target engine speed matching the optimal fuel economy condition is set according to the throttle opening, and the actual vehicle speed is set. And either the speed ratio of the transmission or the throttle opening is controlled by the deviation between the target engine speed and the other, and the other is controlled by the deviation between the actual engine speed and the target engine speed. ing. [0005] However, such a control device has a problem in that a malfunction or a delay in starting easily occurs at the time of starting. The characteristics at the time of start are as follows.
When the throttle opening is controlled by the vehicle speed deviation and the speed ratio is controlled by the engine speed deviation, as shown in FIG. 9, the accelerator pedal ACC is depressed, and (a) the target vehicle speed V ₀ is determined ( b), the vehicle speed deviation occurs and the throttle valve THL opens (c), and the target engine speed SE ₀ and the engine speed SE increase with the increase of the throttle valve THL opening (d), and the resulting engine speed deviation As a result, the speed ratio e changes (e), and the vehicle speed V starts increasing (b). Vehicle speed deviation occurs immediately after depresses the accelerator ACC when moving off, throttle the target engine speed SE ₀ open increases. Since in this state the load on the engine is very small, but the vehicle changes the upper around the speed ratio e to the target engine speed SE ₀ increased engine speed SE immediately starts to move, actually throttle is opened To engine speed S
Since there is a time delay until E rises, it takes time for the actual engine speed SE to exceed the target engine speed SE _0, and the start ratio is delayed because the speed ratio e does not change.
As described above, there is a problem that the behavior at the start is unstable. Although not shown, when the speed ratio is controlled by the vehicle speed deviation and the throttle opening is controlled by the engine speed deviation, the accelerator ACC is not shown.
, The target vehicle speed V ₀ is determined, the vehicle speed deviation occurs, the speed ratio e changes, and the start of the vehicle starts, the engine load increases, and the engine speed SE decreases, causing the engine speed deviation. Throttle valve THL
Opens. Therefore, there is a problem that the engine speed at the time of starting is too low and the engine tends to be stuck. [0007] Further, such a control device has a disadvantage that an overshoot or the like occurs in the vehicle speed. In the former case in which the throttle opening is controlled by the vehicle speed deviation and the speed ratio by the engine speed deviation, respectively, the time point t ₀ at which the vehicle speed V reaches the target vehicle speed V ₀ and the vehicle speed deviation becomes _zero. But, since the engine speed deviation becomes positive, the speed ratio e is still the vehicle speed V changes may exceed the target vehicle speed V _0. As a result, the throttle opening TH
For L also changes continue, until the vehicle speed V converges to the target vehicle speed V ₀ is time consuming. In order to solve these problems, there has been proposed a device in which the speed ratio and the throttle opening are controlled only by the accelerator opening without performing the control based on the throttle opening only at the start. Driving that satisfies the optimal fuel economy conditions is not possible. At the time of start and normal driving, 2
Although a device in which one control means is switched has been devised, the control device becomes more complicated than necessary. In addition, it is not possible to eliminate problems in speed adjustment such as overshoot. SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and is provided with a fluid type transmission capable of improving both operability and optimal fuel economy without complicating a control system. It is an object to provide a control device for a vehicle. [0010] The present invention employs the following configuration in order to achieve the above object. That is, as shown in FIG. 1, the control device for a vehicle equipped with a fluid transmission such as a forklift according to the present invention is a fluid type device that intervenes between an engine a and a wheel b to continuously change a speed ratio e. In a vehicle equipped with a fluid transmission including a transmission c and an accelerator o which is not connected to a throttle valve d of the engine a, an accelerator operation amount detecting means f, a vehicle speed detecting means g, The engine speed detecting means h, the throttle opening detecting means i, the first setting means j for setting the target vehicle speed V ₀ with respect to the accelerator operation amount ACC, and the optimum fuel efficiency condition for the throttle opening THL. A second setting unit k for setting a target engine speed SE ₀ , a first comparing unit m for comparing the actual vehicle speed V with the target vehicle speed V 0 and outputting a deviation ε ₁ , a real engine speed SE and a target Engine A second comparing unit n for comparing the rotation speed SE ₀ with the rotation speed SE ₀ and outputting a deviation ε ₂ , a first control unit p for outputting a speed ratio control signal s (e) based on the deviations ε ₁ and ε ₂ , And a second control means q for outputting a throttle opening control signal s (THL) based on the deviations ε ₁ and ε ₂ . As described above, the speed ratio e and the throttle opening TH are controlled by the two control variables of the vehicle speed V and the engine speed SE.
Since L and L are controlled at the same time, operability can be remarkably improved while realizing optimum fuel efficiency control. That is, when the driver depresses the accelerator o, the accelerator operation amount ACC is inputted from the accelerator operation amount detecting means f to the first setting means j, and the first setting means j corresponds to the operation amount ACC. The set target vehicle speed V ₀ is set. Then, the target vehicle speed V ₀ is input to the first comparison unit m together with the actual vehicle speed V detected by the vehicle speed detection means g, and a deviation ε ₁ = V ₀ between the two from this comparison unit m.
−V is input to the control means p. On the other hand, the throttle opening degree TH is transmitted from the throttle opening degree detecting means i to the second setting means k.
L is input, and the target engine speed SE ₀ corresponding to the throttle opening THL is set by the second setting means k. Then, the target engine speed SE ₀ is
The data is input to the second comparison unit n together with the actual engine speed SE detected by the engine speed detection means h.
, The difference ε ₂ = SE ₀ −SE between them is input to the control means p. First control means p is both deviations epsilon _1, and outputs the speed ratio control signal s (e) controlling the speed ratio e by epsilon _2, the second control unit q is both deviations epsilon _1, epsilon ₂ A throttle opening control signal s (THL) is output to control the throttle opening THL, the vehicle speed V is set to a target vehicle speed V ₀ appropriate for the accelerator operation amount ACC by the driver, and the engine speed SE is set to an optimum fuel efficiency condition. Is controlled to the target engine rotational speed SE ₀ that conforms to Since the speed ratio e and the throttle opening THL are simultaneously controlled by the deviations ε ₁ and ε ₂ , there is no time delay between the operation of the speed ratio e and the operation of the throttle opening THL, realizing optimal fuel economy control. Thus, it is possible to improve operability. No special control is required at the start. The characteristics of the first setting means j, the second setting means k, the first control means p, and the second control means q are flexibly changed according to the operating characteristics of the controlled mechanical system. It is possible to realize more comfortable operating characteristics more easily. An embodiment of the present invention will be described below with reference to FIGS. In this embodiment, the present invention is applied to a forklift. The form in this embodiment
The lift is, as shown in FIG.
A hydraulic transmission (HST) 3 interposed between the engine 1 and the wheels 2 for continuously changing the speed ratio e, and an accelerator 4 disconnected from the throttle valve of the engine 1 And a controller 6 for controlling these. The engine 1 has a throttle valve control actuator 1a, and a throttle drive signal S (T
HL), the actuator 1a drives a throttle valve (not shown) to drive the required throttle opening TH
L is realized. The HST 3 has a configuration in which a variable displacement pump 31 and a variable displacement motor 32 are connected by a hydraulic circuit 33. The pump input shaft 31a is mounted on the engine 1 and the motor output shaft 32a is mounted on the wheels 2 respectively. And engine 1
And the wheel 2 are connected at a speed ratio e. The speed ratio e is set as follows. That is, the capacity of the pump 31 is D _p ,
Assuming that the rotation speed of the pump input shaft 31a is N _p , the capacity of the motor 32 is D _m , the rotation speed of the motor output shaft 32a is N _m, and the maximum displacements D _{p max} and D _{m max} are equal to each other, If the further assumption that there is a leak in the hydraulic circuit _{33, D p × N p =} D m × N m the relationship is satisfied, the speed ratio e _{is, e = N m / N p} = D p / D m It is represented as The speed ratio e is set to the pump capacity _Dp or the motor capacity _Dm.
Can be adjusted steplessly by changing. That is, as shown in FIG. 3, when the pump displacement D _p is changed from 0 to the maximum D _{p max} while the motor displacement D _m is kept at the maximum D _{m max} , the speed ratio e becomes as shown in FIG. 0 ≦ e ≦
Changes in one area, changing toward zero motor capacity D _m from the maximum D _{m max} in further state that the pump displacement D _p was held at the maximum D _{p max} as shown in FIG. 3, FIG. 4 Thus, it has the characteristic that the speed ratio e changes in the range of 1 ≦ e. The variable displacement motor 32 can be replaced with a fixed displacement motor. In this case, the speed ratio e is
It changes only in the region of 0 ≦ e ≦ 1. A fixed pump is connected to the pump input shaft 31a via a gear or the like, and this fixed pump transfers oil to be discharged using a power of the engine 1 to a lift cylinder or a tilt cylinder (not shown), and lifts and lowers a mast or a mast. The tilting is performed. The control in this embodiment is performed as shown in FIG. The thick line is a portion corresponding to the mechanical element, and the thin line is a portion corresponding to the control element of the controller 6. As shown in FIG. 6, the engine 1 rotates at an engine speed SE at a certain throttle opening THL, and outputs an output torque TE determined by the two. HS
T3 converts the engine speed SE into the vehicle speed V at the vehicle speed ratio e, and transmits the resulting load torque TW to the engine 1. The deviation between the output torque TE and the load torque TW is determined by the engine speed S via the inertia s · Ie of the engine 1.
Increase or decrease E. The operating characteristics of these mechanical elements are as follows. In the steady state, the speed ratio e, the throttle opening THL, the engine speed SE, and the vehicle speed V are constant, and the output torque TE and the load torque TW are balanced. When the speed ratio e increases, the vehicle speed V increases accordingly, and at the same time, the load torque TW increases to exceed the output torque TE, and the engine speed SE decreases through the inertia s · Ie. Reducing the speed ratio e causes the reverse process. When the throttle opening THL is increased, as shown in FIG. 6, the output torque TE increases to exceed the load torque TW, the engine speed SE increases through the inertia s · Ie, and the vehicle speed V increases.
Increase. When the throttle opening THL is reduced, the reverse process occurs. In the control device as described above, in this embodiment, in order to control the speed ratio e of the HST 3 and the throttle opening THL of the engine 1, an accelerator operation amount detector 51, a vehicle speed detector 52, Engine speed detector 5
3 and a throttle opening degree detector 54 are provided. These output signals are sent to a controller 6 serving as a first setting unit, a second setting unit, a first comparison unit, a second comparison unit, a first control unit, and a second control unit. Is entered. The accelerator operation amount detector 51 is, for example, a potentiometer attached to the rotation axis of the accelerator 4, and converts the accelerator operation amount ACC into an electric signal and outputs the electric signal to the controller 6. I have. The vehicle speed detector 52, for example an axle i.e. a encoders provided attached to the motor output shaft 32a or the like, and outputs to the controller 6 converts the vehicle speed V corresponding to the rotational speed N _m into an electrical signal It has become. The engine speed detector 53 is, for example, an encoder attached to the crankshaft of the engine 1 or the pump input shaft 31a, and converts the engine speed SE into an electric signal and outputs it to the controller 6. ing. The throttle opening detector 54 is, for example, a potentiometer attached to the throttle valve driving shaft or the throttle valve control actuator 1a. The throttle opening detector 54 converts the throttle opening THL into an electric signal and outputs the electric signal to the controller 6. It is supposed to. The controller 6 is constituted by an ordinary microcomputer system having, for example, a CPU, a memory, an interface and the like. In this system, as shown in FIG. 5, M as first setting means for determining a target vehicle speed V ₀ which is considered to be optimal for the accelerator operation amount ACC from the viewpoint of operability and the like.
And AP1, and the second setting means serving MAP2 is stored to determine the optimum fuel efficiency satisfying the target engine speed SE ₀ against the throttle opening THL. The first setting means MAP1 is set so that, for example, the accelerator operation amount ACC and the target vehicle speed V ₀ correspond substantially linearly. The second setting means MAP2 stores the optimal fuel consumption line in FIG. That is, if the throttle opening THL is determined by the engine characteristics, the relationship between the engine speed SE and the engine output torque TE becomes SE-.
It is determined as a curve on the TE diagram.
Only the points exist, and the points are connected over an arbitrary throttle opening THL to form an optimum fuel efficiency line. Further, the system, the actual vehicle speed V and the target vehicle speed V ₀ and the first comparison unit 61a outputs a speed deviation epsilon ₁ is compared with the actual engine speed SE and the target engine speed SE ₀ a second comparison unit 61b that outputs the engine speed deviation epsilon ₂ compares the bets are stored. Furthermore, the system, for example in FIG. 7 Te - by vehicle speed deviation epsilon ₁ and the engine rotational speed deviation epsilon ₂ based on the characteristics shown in table first for outputting a speed ratio control signal S (e) at least a second control unit 62b that outputs a throttle control signal S (THL) by the vehicle speed deviation epsilon ₁ based on the characteristics shown in table and the engine speed deviation epsilon ₂ is - a control unit 62a, for example, Te in FIG. 8 Is stored. In the above description, PI control, PD control, PID control, and the like can be arbitrarily set. The outline of the control program executed by the controller 6 together with the operation of the mechanical system will be described below with reference to FIGS. First, when the vehicle is in a steady state including a stop, the actual vehicle speed V matches the target vehicle speed V ₀ , and the vehicle speed deviation ε ₁ is zero. The actual engine speed SE matches the target engine speed SE ₀ , and the engine speed deviation ε ₂ is zero. Therefore, as shown in FIG.
The speed ratio control signal S (e) output from 2a is 0, and FIG.
As shown in (1), the throttle control signal S (THL) output from the first control means 62b is also 0, and the speed ratio e and the throttle opening THL do not change. At the time of starting, when the driver depresses the accelerator pedal 7 greatly, the accelerator operation amount ACC increases, the target vehicle speed V ₀ increases through MAP1, and the first vehicle speed V deviation ε ₁ is output. At this time, since the throttle has not been driven yet, the engine speed deviation ε ₂ is zero. As a result, as shown in FIG. 7, the speed ratio control signal S (e) outputted from the first control means 62a is small or positive, and as shown in FIG. 8, the throttle opening outputted from the first control means 62b is obtained. The control signal S (THL) becomes positive, the speed ratio e is low, and the engine speed SE is high, and changes start at the same time. Therefore, a comfortable operation can be performed without starting delay or engine stall. After sudden acceleration, the vehicle speed deviation ε ₁ is small and positive, and the engine speed deviation ε ₂
Once becomes negative, the speed ratio control signal S (e) becomes positive,
The throttle opening control signal S (THL) becomes 0 and the speed ratio e
Increases, and the throttle opening THL thereafter becomes a steady state. As a result, the engine load increases and the engine speed SE decreases. During acceleration ends, the vehicle speed deviation epsilon ₁ is Seisho, the engine speed deviation epsilon ₂ is negative small. As a result, the speed ratio control signal S (e) becomes positive and small, the throttle opening control signal S (THL) becomes 0, and the speed ratio slightly increases, so that the speed slightly increases and the engine speed SE slightly increases. Decrease. And finally, the vehicle speed difference epsilon ₁ 0, is the engine speed deviation epsilon ₂ also 0, converges to a steady state which satisfies the optimum fuel efficiency condition at the target speed. Therefore, a comfortable operation can be performed without causing overshoot. Although the description is omitted, even when the accelerator operation amount ACC is reduced, the control according to the above is performed, and the control quickly converges to a steady state that satisfies the optimum fuel consumption state at the target speed. Therefore, it is possible to improve the operability while making it compatible with running under the optimum fuel efficiency condition, and it is possible to perform all the controls including the time of starting using the same control means. The first setting means 61a, the second setting means 61b, the first control means 62a, and the second control means 62a flexibly change the characteristics according to the operating characteristics of the machine element. It is possible to improve the operability more flexibly and easily than before by changing the table settings. The present invention is, of course, not limited to the embodiment described above. For example, the accelerator opening THL is based on the vehicle speed deviation epsilon ₁ and the engine rotational speed deviation epsilon ₂ and the speed ratio e
Can be controlled functionally. As a specific example, there is a method in which the control amount is obtained using a modern control theory by modeling the entire control device. In addition, various modifications can be made without departing from the spirit of the present invention. The control device for a vehicle equipped with a fluid transmission such as a forklift according to the present invention simultaneously uses the deviation between the target speed and the actual speed and the deviation between the target engine speed and the actual engine speed. Since the speed ratio and the throttle opening are controlled, it is possible to simultaneously improve the operability and achieve traveling that meets the optimum fuel efficiency condition. In addition, the operability at the time of starting can be improved without complicating the control device. Furthermore, since the control characteristics can be flexibly changed according to the operation characteristics of the constituent mechanical elements, the operability can be further improved. As described above, there is a special effect that good operability and reliable fuel-efficient traveling can be performed without complicating the control as compared with the related art.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration explanatory view of the present invention. FIG. 2 is a conceptual diagram showing a configuration according to an embodiment of the present invention. FIG. 3 is a graph showing characteristics of the HST used in the embodiment. FIG. 4 is a diagram showing characteristics of an HST used in the embodiment.
Graph corresponding to. FIG. 5 is a block diagram showing an outline of control of the embodiment. FIG. 6 is a graph illustrating an optimal fuel consumption line stored in MAP2 in the embodiment. FIG. 7 is a table showing operation characteristics of a first control means in a table in the embodiment. FIG. 8 is a table showing operation characteristics of a second control means in a table in the embodiment. FIG. 9 is a graph showing a conventional problem. [Description of Signs] a, 1 ... engine b, 2 ... wheels c, 3 ... hydraulic transmission (HST) d ... throttle valve e ... speed ratio f, 51 ... accelerator operation amount detecting means (detector) g, 52 ... vehicle speed detecting means (detector) h, 53 ... engine speed detecting means (detector) i, 54 ... throttle opening detecting means (detector) j, MAP1 ... first setting means k, MAP2 ... second Setting means m, 61a first comparing section n, 61b second comparing section o, 4 accelerator p, 62a first controlling means q, 62b second controlling means 6 controlling means (controller) ACC ... accelerator operation amount THL ... throttle opening V ... vehicle speed V ₀ ... target vehicle speed SE ... engine speed SE ₀ ... target engine speed

Continuation of the front page (56) References JP-A-3-129160 (JP, A) JP-A-2-63933 (JP, A) JP-A-51-137225 (JP, A) JP-A-62-255657 (JP) JP-A-61-211570 (JP, A) JP-A-61-33329 (JP, A) JP-A-7-11987 (JP, A) JP-A-7-215096 (JP, A) 60-189644 (JP, A) Actual opening 55-138137 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60K 31/00 B60K 41/16 F02D 29/00 F02D 41 / 04 F16H 61/40

Claims (1)

(57) [Claim 1] A fluid type transmission interposed between an engine and wheels for continuously changing a speed ratio, and a fluid transmission which is disconnected from a throttle valve of the engine. A vehicle equipped with a hydraulic transmission, comprising: an accelerator operation amount detecting means, a vehicle speed detecting means, an engine speed detecting means, a throttle opening degree detecting means, and a target vehicle speed set by the accelerator operation amount. A first setting unit that sets a target engine speed that satisfies an optimum fuel efficiency condition by a throttle opening, and a first comparison unit that compares a real vehicle speed with a target vehicle speed and outputs a deviation. When,
A second comparing unit that compares the actual engine speed with the target engine speed and outputs a deviation; first control means that controls a speed ratio based on the two deviations; and a throttle opening based on the two deviations Control means for controlling the speed ratio and the throttle opening by simultaneously using the deviation between the target speed and the actual speed and the deviation between the target engine speed and the actual engine speed. A control device for a vehicle equipped with a hydraulic transmission, the control device comprising: