JP4120213B2 - Vehicle driving force control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a driving force control device for a vehicle equipped with a transmission having a lock-up torque converter, and more particularly to an improvement proposal for a driving force control device that achieves a target driving torque of the vehicle by engine output control. is there.
[0002]
[Prior art]
In the driving force control device that achieves the target driving torque according to the driving state of the vehicle by engine output control, the actual torque at any location in the driving system of the vehicle is detected with high accuracy and at a practically low cost. If there is a torque sensor that can be used, a configuration for feedback control of the engine output can be constructed so that the torque detected by this sensor becomes a value corresponding to the target drive torque. is there.
[0003]
However, at present, since a torque sensor that can detect torque with high accuracy and at low cost has not been put into practical use, engine output control is performed such that the target drive torque is achieved by various alternative methods. Technology has been proposed.
As one of them, the applicant of the present application previously described a speed ratio α (= Np / Ne) represented by a ratio of an output rotational speed Np to an input rotational speed (engine rotational speed) Ne of the torque converter, and an input torque (engine output). 6 is established between the torque ratio β (= Tp / Te) expressed by the ratio of the output torque Tp to the torque (Te) and the input torque capacity τ (Te / Ne ² ). Based on the fact that the operating characteristics of the torque converter can be determined in advance as the relationship between these three factors and the torque converter can be used as a kind of torque sensor, the driving force as described in Japanese Patent No. 2639143 is disclosed. A control device has been proposed.
[0004]
The driving force control apparatus described in this document is as shown in FIG. The means 51 obtains the target drive torque tTD of the vehicle from the driving state such as the accelerator pedal depression amount APO and the vehicle speed VSP, and the means 52 corresponds to the target drive torque tTd from the target drive torque tTD and the transmission gear ratio If. The obtained target torque converter output torque tTp is obtained.
[0005]
While the torque converter is in the converter state in which the lockup is released, the switch 55 is in the switching position indicated by the solid line due to the absence of the lockup signal, and determines the target engine output torque tTe as follows.
First, the means 53 uses the target torque converter output torque tTd and the target torque converter output torque tTd from the target torque converter output torque tTd and the torque converter output speed Np based on the above-mentioned operating characteristics of the torque converter (target torque converter target rotation speed (target Determine the engine speed tNe.
Next, the engine speed feedback controller 54 is used to obtain a target engine output torque tTe that makes the engine speed Ne coincide with the target engine speed tNe, and this is obtained as a target engine when the torque converter is in the converter state. The output torque tTe is output from the switch 55, and the target drive torque Ttd is achieved by controlling the output of the engine so that the target engine output torque tTe is achieved.
[0006]
[Problems to be solved by the invention]
However, as described above, the torque converter can be used as a kind of torque sensor to perform low-cost and high-accuracy driving force control when the torque converter is in a converter state in which relative rotation occurs between input and output elements. The operating characteristics of the torque converter cannot be used during the lock-up state in which the relative rotation is 0. As shown in FIG. 9, the switch 55 is set to the switching position shown by the broken line by the lock-up signal. Thus, the target torque converter output torque tTp can be used as it is as the target engine output torque tTe.
[0007]
In other words, at the time of lock-up, there is no room for the concept of the target engine speed t Ne since the calculation using the target engine speed tNe and the torque converter operating characteristics described above is impossible when obtaining the target engine output torque tTe. Since the engine speed feedback control as in the converter state cannot be adopted, the target throttle opening corresponding to the target torque converter output torque tTp (= target engine output torque tTe) is obtained and the throttle is opened. We had to rely on feed-forward control such as controlling the degree.
[0008]
For this reason, when shifting from the converter state to the lock-up state, there is a concern that the torque step is increased by switching the driving force control.
For example, as shown in FIG. 10, even if high-precision control is performed during the converter period before the instant t1, the control accuracy is lower during the lock-up period after the instant t1 than during the converter period. The steady deviation of the actual drive torque Td (actual torque converter output torque Tp) with respect to the drive torque tTd (target torque converter output torque tTp) increases, and the actual drive torque Td (actual torque converter output torque Tp) has a large step at the instant t1. There is a concern that it will have.
Since the above-described steady deviation and step are caused by control errors, the direction of the steady deviation and the direction of the step may be opposite to those in FIG. 10 and are not constant.
[0009]
In the present invention, when the torque converter is in the lock-up state, the target torque converter output torque is not used as it is as the target engine output torque as in the prior art, but the target engine output torque calculation method considering the operating characteristics of the torque converter is used. An object of the present invention is to propose a driving force control apparatus for a vehicle that can solve the problem.
Specifically, while the torque converter is in the converter state, the engine torque correction coefficient (Keng) is obtained by multiplying the torque ratio (β) of the torque converter by the target torque ratio. However, the target torque ratio here is a ratio obtained by dividing (dividing) the target engine output torque (tTe) by the target torque converter output torque (tTp). Further, the torque ratio (β) here is estimated based on the operating characteristics of the torque converter from the input / output rotational speed ratio of the torque converter. When the torque converter is in the lock-up state, the torque increasing action is not performed, so that the target engine output torque is obtained by multiplying the target torque converter output torque by the correction coefficient, thereby operating characteristics of the torque converter. The target engine output torque calculation method considering the above is realized.
[0010]
[Means for Solving the Problems]
For this purpose, the vehicle driving force control apparatus according to the present invention provides a target torque converter output torque obtained from a target driving torque of the vehicle and a shift state of the transmission while the torque converter is in the converter state. a torque converter output speed, Rutotomoni obtains a target engine rotational speed from the operating characteristics of the torque converter, the target engine output torque to match the engine speed to the target engine rotational speed, the rotational speed and the target engine rotational these engines It is obtained by feedback control based on the number, and the target engine output torque is output to the engine.
While the torque converter is in the lock-up state, the driving force control is performed as follows.
[0011]
That is, while in the converter state, the torque ratio (β) of the torque converter is obtained from the speed ratio represented by the input / output rotational speed ratio of the torque converter based on the operating characteristics, and the torque ratio is calculated as the target torque converter. The engine torque correction coefficient (Keng) is obtained by multiplying the target torque ratio represented by the ratio obtained by dividing the target engine output torque (tTe) by the output torque (tTp) ,
While the torque converter is in the lock- up state, the target torque converter output torque in the lock-up state is multiplied by the engine torque correction coefficient (Keng) obtained in the converter state immediately before the lock-up state is applied to obtain the target The engine output torque is obtained, and the engine output is controlled so that the target engine output torque is achieved.
[0014]
Note the engine torque correction coefficient as described in claim 2, it may be set individually for each operating condition.
[0015]
【The invention's effect】
According to the first aspect of the present invention, while the torque converter is in the converter state, the torque ratio of the torque converter is obtained based on the operating characteristics from the speed ratio represented by the input / output rotation speed ratio of the torque converter, The torque ratio is multiplied by a target torque ratio represented by a ratio obtained by dividing the target engine output torque by the target torque converter output torque to obtain an engine torque correction coefficient. While the torque converter is in the lock-up state, Multiply the target torque converter output torque in the lock-up state by the engine torque correction coefficient obtained in the converter state immediately before switching to the up state to obtain the target engine output torque, and output control the engine so that this target engine output torque is achieved Therefore, when calculating the target engine output torque even in the lockup state, The torque converter operating characteristics are taken into account, and the torque step when shifting from the converter state to the lock-up state that occurs when the target torque converter output torque is used as it is as the target engine output torque as before is eliminated. Can do.
[0018]
According to the invention of claim 2 , since the engine torque correction coefficient is individually set for each operating state,
Even if the control error of the engine output control system changes depending on the operating state, the engine torque correction coefficient is kept appropriate for each operating state, and the operational effect of the invention according to claim 1 is further ensured. be able to.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a power train of a vehicle provided with a driving force control device according to an embodiment of the present invention together with its control system, and the power train is composed of an engine 1 and a continuously variable transmission 2.
Although the engine 1 is an internal combustion engine, the throttle valve 3 is not mechanically connected to an accelerator pedal operated by the driver, and is separated from these to be electronically controlled by the throttle actuator 4. Eggplant.
[0020]
The throttle actuator 4 responds to a target throttle opening tTVO output by the engine controller 5 in response to a target engine output torque tTe (described later) from the driving force controller 6, thereby adjusting the opening of the throttle valve 3 to the target throttle opening. The output of the engine 1 is basically controlled to be a value corresponding to the accelerator pedal operation, but depending on how the target engine output torque tTe is given, it can also be controlled by factors other than the accelerator pedal operation And
[0021]
The continuously variable transmission 2 is a well-known V-belt type continuously variable transmission, and includes a primary pulley 8 that is drive-coupled to the output shaft of the engine 1 via a torque converter 7, a secondary pulley 9 that is aligned with the primary pulley 8, and both And a V-belt 10 spanned between pulleys.
Then, the differential gear device 12 is drivingly coupled to the secondary pulley 9 via the final drive gear set 11, and the left and right driving wheels 13L and 13R are rotationally driven by these.
[0022]
The speed change operation of the continuously variable transmission 2 is such that, among the flanges forming the V-grooves of the primary pulley 8 and the secondary pulley 9, one movable flange is brought relatively close to the other fixed flange to make the V-groove width. Narrowing the width or conversely increasing the V groove width,
The stroke positions of both movable flanges are determined by the primary pulley pressure and the secondary pulley pressure from the transmission control hydraulic circuit 14.
The torque converter 7 includes a lockup mechanism (not shown). When the lockup mechanism is fastened by the lockup pressure from the transmission control hydraulic circuit 14, the input / output elements are not connected directly from the converter state where the input / output elements are not directly connected. It shall be switched to a directly connected lockup state.
[0023]
The shift control hydraulic circuit 14 includes a step motor 15 and a lock-up solenoid 16 as shift actuators, and the transmission controller 17 drives the step motor 15 to a step position STP corresponding to the target gear ratio Ip, thereby continuously variable speed change. The gear 2 is continuously shifted so that the actual gear ratio matches the target gear ratio Ip, and the transmission controller 17 locks up the torque converter 7 by turning on the lockup solenoid 16 with the lockup signal L / U. Can be made.
[0024]
The driving force controller 6 transmits the target engine output torque tTe to the engine controller 5 and executes the driving force control aimed by the present invention.
For this reason, the driving force controller 6 receives the gear ratio Ip signal and the lockup signal L / U from the transmission controller 17, and an accelerator opening sensor 18 that detects the depression amount (also referred to as accelerator opening) APO of the accelerator pedal. The signal from
A signal from an engine speed sensor 19 for detecting the engine speed Ne from an ignition signal of the engine, etc .;
A signal from the torque converter output speed sensor 20 for detecting the torque converter output speed (primary pulley speed) Np;
A signal from a wheel speed sensor 21 that detects a vehicle speed Vw based on the number of rotations of the wheel is input.
[0025]
The driving force controller 6 obtains the target engine output torque tTe by executing the control program of FIG. 2 by a scheduled interruption every 10 msec, for example, based on the above input information, and transmits this to the engine controller 5 to transmit the present invention. The target driving force is controlled.
First, at step S1, the accelerator pedal depression amount APO is read, then at step S2, the engine speed Ne, the torque converter output speed Np, and the wheel speed Vw are read. Then, at step S3, the transmission ratio Ip and the lockup are read from the transmission controller 17. Receive signal L / U.
[0026]
In step S4, for example, the target drive torque tTd of the vehicle is determined by searching from the accelerator pedal depression amount APO and the wheel speed Vw based on the map illustrated in FIG.
In the map of the target drive torque tTd illustrated in FIG. 5, it is assumed that characteristics preferable for driving according to the driver's acceleration / deceleration will be stored in advance in the memory as map data.
In the next step S5, the target torque converter output torque (target transmission input torque) tTp is calculated by the following equation using the target drive torque tTd, the transmission ratio Ip, and the final reduction gear ratio If of the final drive gear set 11.
tTp = tTd / If / Ip (1)
[0027]
In step S6, it is checked whether or not there is a lockup signal L / U, that is, whether the torque converter 7 is in a lockup state or a converter state.
While the torque converter 7 is in the converter state, in step S7, a map showing the relationship between the target torque converter output torque tTp and the target engine speed tNe with the torque converter output speed Np as a parameter as shown in FIG. Based on the target torque converter output torque tTp and the torque converter output rotation speed Np, a target engine speed tNe for achieving the target torque converter output torque tTp is obtained.
Here, the map of FIG. 7 is obtained when two of the torque converter input torque Te, output torque Tp, input rotation speed Ne, and output rotation speed Np are determined from the torque converter operating characteristics illustrated in FIG. 6 can be calculated in advance from the torque converter operating characteristics shown in FIG.
[0028]
In step S8, a type 2 servo compensator as illustrated in FIG. 3 (a form in which the round transfer function has an integral square term) is used to match the engine speed Ne to the target engine speed t Ne (between the two). The engine speed Ne is made equal to the target engine speed t Ne by performing a feedback control calculation of the engine speed (the engine speed deviation ΔNe between the two is set to 0). ) To calculate the target engine output torque tTe.
[0029]
The reason for using the engine speed feedback control calculation method shown in FIG. 3 is as follows.
That is, in the present embodiment, the target torque converter output torque tTp is converted into the target engine speed tNe using the map of FIG. 7 obtained from the torque converter operating characteristics of FIG. If the vehicle accelerates regardless of the amount even if it changes stepwise, the target engine speed tNe changes like a ramp.
Therefore, in order to prevent the torque converter output torque from having the above-described steady deviation, it is necessary to construct an engine speed feedback control system with a “type 2 servo compensator” that does not produce a steady deviation with respect to the ramp input. This is the reason why the type 2 servo compensator shown in FIG. 3 is used.
When this servo compensator is expressed by an equation, processing is performed based on a recurrence equation derived by discretization at a sampling period of 10 msec,
△ Ne ＝ tNe−Ne
tTe = K ₁ × ΔNe + (K ₂ / S) × ΔNe + (K ₃ / S ² ) × ΔNe (2)
However, it is like the S: Laplace operator.
[0030]
In step S9, based on the torque converter operating characteristics illustrated in FIG. 6, the torque converter input / output torque Te, from the speed ratio α (= Np / Ne) represented by the ratio of the torque converter man output rotational speed Ne, Np. The torque ratio β (= Tp / Te) expressed by the ratio of Tp is searched for and obtained.
In step S10, the engine torque correction coefficient Keng is calculated by the following equation using the target torque converter output torque tTp, the target engine output torque tTe, and the torque converter input / output torque ratio β. Update the value.
Keng = (tTe / tTp) × β (3)
Here, since the torque ratio β in the above equation is (Tp / Te), the engine torque correction coefficient Keng is
Keng = (tTe / tTp) × (Tp / Te) (4)
This means a correction coefficient for canceling the torque increasing action by the torque converter.
[0031]
The above is the control when the torque converter is in the converter state, and the target engine output torque tTe (step S8) in the converter state is obtained and the engine torque correction coefficient Keng for canceling the torque increasing action by the torque converter (step S8) S10) is obtained, but when it is determined in step S6 that the torque converter is in the lockup state, in step S11, the target engine output torque tTe for achieving the target torque converter output torque tTp at the time of lockup is calculated by the following equation. calculate.
tTe = tTp × Keng (5)
The engine torque correction coefficient Keng obtained here is the engine torque correction coefficient Keng that was obtained last in step S10 and immediately before the torque converter enters the lock-up state.
[0032]
In step S12, if the torque converter is in the converter state, the target engine output torque tTe obtained in step S8 is obtained. If the torque converter is in the torque converter lockup state, the target engine output torque tTe obtained in step S11 is obtained. Transmit to the controller 5.
The engine controller 5 determines a target throttle opening tTVO that can achieve the target engine output torque tTe, and instructs the throttle actuator 4 to output the target throttle output tTVO so that the target engine output torque tTe is achieved. As a result, the target drive torque tTd is transmitted to the wheels.
[0033]
FIG. 4 is a functional block diagram of the driving force control apparatus according to the above-described embodiment. In the figure, reference numerals 51 to 55 are the same as those shown in FIG.
In the present embodiment, the target engine output torque tTe at the time of lockup is not the target torque converter output torque tTp itself as described above with reference to FIG. 9, but the torque converter input / output rotational speed ratio calculating means 56 and the engine torque correction coefficient. The learning means 57 and the engine torque correction means 58 obtain the following.
[0034]
The torque converter input / output rotational speed ratio calculating means 56 obtains a speed ratio α (= Np / Ne) represented by the ratio of the torque converter input / output rotational speeds Ne and Np, and the engine torque correction coefficient learning means 57 is shown in FIG. The torque ratio β of the torque converter obtained from the torque converter speed ratio α based on the torque converter operating characteristics illustrated in FIG. 5, the target torque converter output torque tTp from the means 52, and the target engine output from the engine speed feedback controller 54 Using the torque tTe, the engine torque correction coefficient Keng for canceling the torque increasing action of the torque converter is calculated by the above equation (3), and this is sequentially stored in the memory to update the learning value.
The engine torque correction means 58 calculates the target engine output torque tTe for achieving the target torque converter output torque tTp at the time of lockup according to the above equation (5).
[0035]
If the torque converter is in the converter state, the switching device 55 is in the switching position indicated by the solid line because there is no lockup signal L / U, and the target engine output at the time of releasing the lockup determined by the engine speed feedback controller 54. Torque tTe is output to the engine controller 5,
If the torque converter is in the lock-up state, the switching device 55 is at the switching position shown by the broken line by the lock-up signal L / U, and outputs the target engine output torque tTe obtained by the engine torque correcting means 58 to the engine controller 5. .
[0036]
According to the embodiment shown in FIGS. 1 to 7, while the torque converter 7 is in the converter state, the target torque ratio (tTe / tTp) represented by the ratio of the target engine output torque tTe to the target torque converter output torque tTp. ) And the speed ratio α (= Np / Ne) represented by the input / output rotational speed ratio of the torque converter, an engine torque correction coefficient Keng for canceling the torque increasing action is obtained,
More specifically, the target torque ratio (tTe / tTp) is multiplied by the torque ratio β of the torque converter corresponding to the speed ratio α of the torque converter obtained from the operating characteristics of the torque converter shown in FIG. Find Keng,
While the torque converter is in the lockup state, the target torque converter output torque tTd is multiplied by the engine torque correction coefficient Keng to obtain the target engine output torque tTe, and the output of the engine is controlled so that this target engine output torque is achieved. ,
Even in the lock-up state, the operational characteristics (FIG. 6) of the torque converter are taken into account when calculating the target engine output torque tTe, and the same control accuracy as in the converter state can be maintained.
[0037]
Therefore, as is apparent from FIG. 8 showing the operation waveform under the same conditions as in FIG. 10, the control accuracy does not decrease during the lock-up period after the instant t1, and the target drive torque tTd (target torque converter output) It is possible to prevent the steady deviation of the actual driving torque Td (actual torque converter output torque Tp) from increasing with respect to the torque tTp), so that the actual driving torque Td (actual torque converter output torque Tp) has a large step at the instant t1. You can eliminate the uncomfortable feeling caused by the large torque step by eliminating the concern that you have.
[0038]
Further, according to the present embodiment, when calculating the target engine output torque tTe at the time of lockup, the engine torque correction coefficient Keng immediately before the torque converter enters the lockup state is used. Even if the series changes, the engine torque correction coefficient is always kept in line with the actual situation, and the above-described operational effects can be further ensured.
[0039]
The engine torque correction coefficient Keng obtained in step S10 in FIG. 2 is a learning value for each operating state such as the engine speed Ne and the engine output torque Te, and the engine torque correcting coefficient Keng in the area corresponding to the current operating state is used. Can be studied individually.
In this case, even if the control error of the engine output control system changes depending on the operating state, the engine torque correction coefficient Keng is kept appropriate for each operating state, and the above-described effects are further ensured. Can do.
[Brief description of the drawings]
FIG. 1 is a schematic system diagram illustrating a power train of a continuously variable transmission equipped with a driving force control device according to an embodiment of the present invention, together with a control system thereof.
FIG. 2 is a flowchart showing a driving force control program through engine output control, which is executed by a driving force controller in the control system of FIG. 1;
FIG. 3 is a system diagram illustrating an engine speed feedback controller used to obtain a target engine output torque when the torque converter is in a converter state in the driving force control.
FIG. 4 is a functional block diagram of the driving force control.
FIG. 5 is a characteristic diagram of a target driving force used to obtain a target driving force in the same driving force control.
FIG. 6 is an operational characteristic diagram of the torque converter.
FIG. 7 is a characteristic diagram of a target engine speed used to determine a target engine speed for achieving a target torque converter output torque corresponding to the target driving force in the driving force control.
FIG. 8 is an operation time chart of the driving force control apparatus.
FIG. 9 is a functional block diagram showing a conventional driving force control apparatus.
FIG. 10 is an operation time chart of the driving force control apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Engine 2 Continuously variable transmission 3 Electronically controlled throttle valve 4 Throttle actuator 5 Engine controller 6 Driving force controller 7 Torque converter 8 Primary pulley 9 Secondary pulley
10 V belt
11 Final drive gear set
12 Differential gear unit
13L left drive wheel
13R Right drive wheel
14 Shift control hydraulic circuit
15 Stepping motor for shift control
16 Lock-up solenoid
17 Transmission controller
18 Accelerator position sensor
19 Engine speed sensor
20 Torque converter output speed sensor
21 Wheel speed sensor
51 Target drive torque calculation means
52 Target torque converter output torque calculation means
53 Target engine speed calculation means
54 Engine speed feedback controller
55 Target engine output torque switch
56 Torque converter input / output rotational speed ratio calculation means
57 Engine torque correction coefficient learning means
58 Engine torque correction means

Claims (2)

In achieving the target drive torque of the vehicle having a transmission that shifts the engine rotation input through the lock-up type torque converter and directs it to the wheels by the engine output control,
While the torque converter is in the unlocked converter state, the target torque converter output torque obtained from the target drive torque and the transmission state of the transmission, the torque converter output rotational speed, the operating characteristics of the torque converter, It obtains a target engine rotational speed from Rutotomoni, the target engine output torque to match the engine speed to the target engine speed, these engine speed and determined by the feedback control based on the target engine speed, this target engine output torque In a vehicle driving force control device for controlling the output of an engine to be achieved,
While the torque converter is in the converter state, a ratio obtained by dividing the torque converter output torque (Tp) by the torque converter input torque (Te) based on the operating characteristics from the speed ratio represented by the input / output rotational speed ratio of the torque converter. The torque ratio (β) of the torque converter is obtained, and the torque ratio (β) is set to a target torque ratio represented by a ratio obtained by dividing the target engine output torque (tTe) by the target torque converter output torque (tTp). Multiply to find the engine torque correction coefficient (Keng)
While the torque converter is in the lock-up state, the engine torque correction coefficient (Keng) obtained in the converter state immediately before entering the lock-up state is used as the target torque converter output torque (tTp) in the lock-up state. A vehicle driving force control device that is configured to multiply and obtain a target engine output torque (tTe) and to control the output of the engine so that the target engine output torque is achieved.   2. The driving force control apparatus for a vehicle according to claim 1, wherein the engine torque correction coefficient is individually set for each driving state.

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