JPH0348046B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention operates a speed regulating element of a vehicle in response to a speed signal from a signal generating means responsive to the actual speed of the vehicle to maintain the speed at a set target speed. means for creating an adjustment signal whose value is changed with a predetermined control gain according to the difference between the actual speed of the vehicle and the target speed of the vehicle; and means for controlling a speed regulating element.

This type of vehicle speed control device is disclosed in U.S. Patent No.
It is generally known from specifications such as No. 3869019 and No. 4094378. In known devices, an error signal (adjustment signal) representing the error between the actual speed of the vehicle and a set target speed is calculated by analog electrical calculation or digital electrical calculation, and a predetermined control gain is given to this error signal. Accordingly, a correction signal having a comparison relationship with the error signal is created, and the speed governing element of the vehicle is controlled in accordance with this correction signal.

In such a device, when the vehicle load increases when the vehicle goes from a flat road to a downhill or uphill slope with a large slope, the displacement of the speed governing element becomes insufficient, and the actual speed deviates from the target speed, resulting in speed increase or I have a problem with slowing down. In order to suppress this, it may be considered to set a large proportion of the control gain or lead compensation, but in this case the governing element will be suddenly displaced in response to a slight change in the actual speed, so the speed will remain constant. Another problem arises in that the running vehicle undergoes hunting, in which the vehicle rapidly accelerates and decelerates repeatedly, resulting in poor ride comfort.

The present invention has been made to solve the above-mentioned problems.The purpose of the present invention is to prevent the actual speed from departing from the vicinity of the target speed in a transient state where the running load suddenly changes. It is an object of the present invention to provide a speed control device for a vehicle that can suppress the above-mentioned problems and does not impair ride comfort in a steady control state.

For this reason, the configuration of the present invention is such that in the vehicle speed control device having the configuration described at the beginning, the actual speed is adjusted to the target speed at least in relation to the difference between the actual speed of the vehicle and its target speed and the direction of increase or decrease of the difference. The present invention is characterized in that it includes a control means for increasing the control gain when the actual speed is away from the target speed compared to when the actual speed approaches the target speed.

The control means includes means for providing the adjustment signal with an error component depending on the difference between the actual speed and the target speed and an adjustment component for adjusting an offset, and means for applying the adjustment signal to the target speed as the actual speed increases as the vehicle load increases. and means for increasing the adjustment component of the adjustment signal when the actual speed decreases below the target speed, and decreasing the adjustment component of the adjustment signal when the actual speed increases above the target speed as the vehicle load decreases. can do.

Note that the present invention is applicable not only to a constant speed traveling device that sets the target speed of a vehicle to a constant value and maintains the actual speed at a constant value, but also to cases where the target speed is given from the outside and is changed. be.

The present invention will be described below based on embodiments shown in the accompanying drawings. In this embodiment, a microcomputer is used to realize the central control function as shown in FIG. 1, and its control program is shown in FIG.

In FIG. 1, reference numeral 10 indicates an on-vehicle DC power source (hereinafter referred to as a battery), and the battery 10 supplies power to a control circuit package 30 via an engine key switch 11 and an operation panel 20. The control circuit package 30 receives operating signals from the operating panel 20, release signals associated with several operating devices of the vehicle, and other control input signals. An actuating device 50 is connected to the output side of the control circuit package 30, and the actuating device 50 adjusts the opening degree of a throttle valve 60 of a speed-governing element of the vehicle, in this embodiment a prime mover internal combustion engine (not shown). In this way, the engine output torque is increased or decreased, and the vehicle running speed is increased or decreased.

The actuating device 50 is a reversibly rotating DC motor 51.
, an electromagnetic clutch 53 which has a biasing coil 52, is normally disconnected, and is connected when biased by the biasing coil 52;
The throttle valve 60 controls the displacement of the speed reduction mechanism 54 provided between the input plate of the clutch 53 and the DC motor 51 and the output rod 55 provided on the output plate of the clutch 53.
It has a link mechanism 56 that transmits the transmission to. Although not shown, an accelerator pedal operated by the driver is also operatively connected to the link mechanism 56.
The actuating device 50 also includes a potentiometer 57 coupled to the output plate of the clutch 53 to create a resistance value corresponding to the opening of the throttle valve 60.

The operation panel 20 has a main switch 21 inserted and connected between it and the power receiving terminal 30A of the control circuit package 30.
When the main switch 21 is closed by the driver, the circuit elements in the control circuit package 30 are enabled. Main switch 2
1 and the vehicle body ground 10A.Indicator lamp 2
2 is connected, and the lighting of this lamp 22 indicates that this device is ready for operation.

The operation panel 20 also includes a set switch 23, which has one end connected to the vehicle body ground 10A and the ground terminal 30B of the control circuit package 30, and the other end connected to a set signal input terminal 30C and a cancel signal input terminal 30D of the control circuit package 30, respectively. , a cancel switch 24.

The control circuit package 30 further has three cancel signal input terminals 30E, 30F, and 30G, and the first cancel input terminal 30E has a stop switch 12 and a stop indicator lamp 13, which are closed in conjunction with the operation of the brake pedal. The potential at the connection point of the series circuit with is applied. The second cancel input terminal 30F is given the potential of the connection point of the series circuit between the parking switch 14 and the parking indicator lamp 15, which are closed in conjunction with the operation of the parking brake, and the third cancel input terminal 30F
A clutch switch 16, which is closed in conjunction with the operation of the clutch pedal, is connected to G.

In order for the control circuit package 30 to know the actual traveling speed of the vehicle, a speed signal generator 17 generates a speed signal that responds to the actual traveling speed of the vehicle and generates a pulse train signal whose period becomes shorter as the actual speed increases. The generated pulse train signal is connected to the speed signal input terminal 17B of the control circuit package 30.
It is connected to the. The speed signal generator 17 includes a permanent magnet 17A that rotates in synchronization with a speedometer cable (not shown) provided to rotate in synchronization with the output shaft of a transmission device (not shown), and a permanent magnet 17A. It is composed of a reed switch 17B whose contacts are swung to open and close.

The control circuit package 30 has an integrated circuit chip 31 (hereinafter referred to as computer) configured as a microcomputer. A computer 31 stores control programs and control constants.
ROM, RAM for data storage, central processing unit (CPU), data lines, timing circuit, free run counter, input/output (I/O) circuit, and A
-D conversion circuit etc. are integrally constructed. Power is supplied to the power supply terminal VCC of the computer 31 by a three-terminal constant voltage circuit 32 and a smoothing capacitor 33 connected between the power receiving terminal 30A and the ground terminal 30B.
done through. The reset circuit 34 is a power receiving terminal
In response to the rise of the voltage applied to VCC, a reset signal is applied to the computer 31 to operate the computer 31 from its initial state. The control program of the computer 31 is executed based on an oscillation signal from an externally connected oscillation circuit 35.

In the control circuit package 30, a cancel signal input terminal IN is connected between the set signal input terminal 30C and the signal input terminal IN1 of the computer 31.
Buffers 38 and 39 are connected between the computer 31 and the computer 31, respectively.
tell to.

NOR gate 4 is connected to the second and third cancel signal input terminals 30F and 30G in the package 30.
0 is connected, and an OR gate 41 is connected between the output terminal of the NOR gate 40, the fourth cancel signal input terminal 30E, and the signal input terminal IN3 of the computer 34, and a cancel signal based on the operation of each operation device is connected. is transmitted to the computer 31.

A buffer 42 is connected between the speed signal input terminal 30H in the package 30 and the interrupt input terminal IRQ of the computer 31, and the interrupt program of the computer 31 is activated every time the signal level of the speed pulse train signal changes. .

Analog signal input terminal 30I of package 30
and the analog signal input terminal ANIN of the computer are directly connected, and a voltage signal from the potentiometer 57 indicating the opening degree of the throttle valve 60 is applied to an A-D conversion circuit built in the computer 31. Note that both ends of the potentiometer 57 are connected to the three-terminal constant voltage circuit 32 through terminals 30J and 30K of the package 30.

Adjustment signal output terminal 3 of control circuit package 30
A DC motor 51 of an actuating device 50 is connected between 0L and 30M, and the output terminals 30L, 30
A pair of signal output terminals of M and computer 31
A drive circuit 36 is connected between OUT1 and OUT2.

The drive circuit 36 of the DC motor 51 includes two presettable timer circuits 36A and 36B, and a first set of power transistors 44 and 45 whose conduction and cutoff are simultaneously controlled by the first front-stage transistor 43.
The main components are a second set of power transistors 47 and 48 whose conduction and cut-off are simultaneously controlled by the second pre-stage transistor 46.

Presettable timer (hereinafter referred to as timer) circuit 36
A and 36B are presettable down counters whose data is preset by the output signals from the signal output terminal group OUT1 and OUT2 of the computer 31, and immediately thereafter counts down by a constant frequency clock pulse until the data reaches "0". A high level output signal is generated until the data becomes "0".

If the first signal output terminal of the computer 31
Although predetermined data is generated from OUT1 and no data is generated from the second signal output terminal OUT2, the drive circuit 36
conducts for a time corresponding to the number of data preset in the timer 36A, simultaneously conducts the first set of power transistors 44 and 45, and directs the DC motor 51 in the direction of the arrow I (the direction in which the throttle valve 60 is opened). ).

On the other hand, the second signal output terminal group of the computer 31
When data is applied to the timer circuit 36B from OUT2, the second front-stage transistor 46 of the drive circuit 36 becomes conductive for a time corresponding to the data.
As a result, the second set of power transistors 47,
48 becomes conductive, and a current flows in the direction opposite to arrow I through the DC motor 51. In this way, the drive circuit 3
6 is a signal output terminal group OUT1 of the computer 31;
The rotation direction of the DC motor 51 can be selected according to the level of the signal generated from OUT2,
Also, the amount of rotation can be controlled.

The energizing coil 52 of the actuating device 50 is connected between the energizing signal output terminals 30N and 30O of the package 30. In the package 30, one energizing signal output terminal 30O is connected to a receiving terminal 30A, and the other terminal 30N is connected to a drive circuit 37 responsive to a signal output terminal OUT3 of the computer 31.

The drive circuit 37 is composed of a power transistor, and is connected to a signal output terminal of the computer 31.
Upon receiving a high level signal from OUT3, the energizing coil 52 is energized and the clutch 53 is connected to enable the DC motor 51 to control the opening and closing of the throttle valve 60.

2 to 6 show the establishment of a control program executed by the computer 31. FIG.

In FIG. 2, the computer 31 resets the reset circuit 3.
4 shows the flow of the main program which starts processing upon receiving a reset signal. When the computer 31 starts processing the main program, it first sets the states of internal registers, temporary memory, output terminals, etc. to preset initial states (step 101). The computer then steps 102.
At step 103, acceptance of the timer interrupt program shown in FIG. 3 is permitted, and at step 103, acceptance of the vehicle speed interrupt program shown in FIG. 4 is permitted.

The timer interrupt program will be explained with reference to FIG. The computer 31 has a built-in timer counter that generates an interrupt signal at regular intervals (for example, about 10 ms). When the computer recognizes this, it saves the register in step 201 and executes the following process. do.

The main role of the timer interrupt program is the operation panel 2.
0 and the operating states of various driving operation devices, and updating a timer counter for time measurement.

By checking the signal levels of the signal input terminals IN1, IN3, and IN2 in steps 202, 203, and 205, the set switch 2 on the operation panel 20 is activated.
3, the operation of the cancel switch 24, and the state of the cancel operation by the driving operation device are stored internally. In this case, the cancel operation is performed when the internal switch flag Fs is set to "0" in step 204, and the same flag Fs is set to "1" in step 206.
Let it represent a set operation.

The timer interrupt program also includes step 2.
At step 07, a group of timer counters (T counters) set internally for use in time measurement is incremented. At the end of these processes, the registers are restored in step 208, execution of this interrupt program is ended, and execution of the interrupted main program is resumed.

The vehicle speed interrupt program will be explained with reference to FIG. The computer 31 is activated once in one cycle of the pulse train signal based on the application of the pulse train signal from the speed signal generator 17. The role of the vehicle speed interrupt program is to internally take in sampling data for calculating the traveling speed of the vehicle.

After the computer 31 saves the register in step 301, the computer 31 reads the current data of the built-in free run counter in step 302. This read data is stored as data An.

Difference data Dv ₀ between the read data An and the previous read data An _-1 is obtained (step 303), and this is used as instantaneous vehicle speed data. Steps 304, 30
In steps 5, 306, and 307, the four instantaneous vehicle speed data Dv ₁ , Dv ₂ , Dv ₃ , and Dv ₄ used for calculation are then updated with new vehicle speed data Dv ₀ , Dv ₁ , Dv ₂ , and Dv ₃ , respectively. In this way, the latest four pieces of vehicle speed data Dv ₁ to Dv ₄ are always secured.

Next, in step 308, the read data An of this interrupt cycle is stored as the previous read data An _-1 , and in step 309, the register is restored, and the vehicle speed interrupt program is ended.

In the main program of FIG. 2, when step 104 is reached, the computer 31 checks whether there is an abnormality in the internal state. For example, the check item may be to check whether the data indicating the target speed in the temporary memory is "zero". In this case, it is impossible under normal conditions that the target speed is set immediately after the computer 31 starts, even though the set switch 23 is not operated. Therefore, step 10
4, the computer 31 determines that the target vehicle speed is "zero".
If it is recognized that this is not the case, the process proceeds to stop step 105. At stop step 105, the computer 31 stops all program processing and does not perform any operation.

If no abnormality is recognized, the computer 31 waits for a preset time in step 106. This time is set to correspond to the time during which four pieces of vehicle speed data are obtained by the vehicle speed interrupt program (FIG. 4) during a certain low speed run. Normally several hundred ms
That's fine. After this, the computer 31 performs step 1.
07 to step 112 or step 116
Or go through step 119 and go to step 10 again.
Start execution of the cycle program returning to step 7.

In step 107, the computer 31
Actual vehicle speed data (Vs) is calculated based on the total value of the vehicle speed data Dv ₁ to Dv ₄ . In this case, since the pulse train signal generated by the speed signal generator 17 is generated every time the vehicle travels a predetermined distance, the distance corresponding to the generation of the four known pulse signals is calculated using four pieces of vehicle speed data. _Dv1 ～ _Dv4
By dividing by the total value of , the actual speed Vs is obtained.

The processing of the computer 31 differs greatly depending on whether constant speed driving control is in progress or not.
Whether or not the control is in progress is determined by whether the control flag Fc is set to "1" or reset to "0" in step 108.

If it is not under control, steps 109 and subsequent steps are processed in the route indicated by symbol A. In step 109, it is determined whether the set switch 23 has been operated or not based on the switch flag Fs described above. if,
If there is no set operation, the computer repeats the process from step 107 again.

When the set switch 23 is operated and the switch flag Fs is set to "1", the computer 31 at step 110 sets the actual speed at that time.
Store Vs as the target speed Vo in the target speed area of the temporary memory. Furthermore, in step 111, a high level signal is sent from the signal output terminal OUT3 in order to connect the clutch 53 of the actuating device 50. Furthermore, in step 112, the control flag Fc is set to "1" indicating that the control is in progress, and the process returns to step 107.

Once under control, the computer 31 checks in step 113 whether or not there is a cancel operation. If there is no cancel operation, the computer performs processing along route B from step 114 onwards. In step 114, the timing of processing to be performed at preset fixed time intervals is determined from the contents of the T counter. This ensures that steps 115 and 116 are always executed at constant time intervals.

During control, the computer 31 calculates the value of the adjustment signal (adjustment amount) to be applied to the actuator 50 in order to obtain the opening degree of the throttle valve 60 necessary to maintain the actual speed at the target speed in step 115. . Step 1 based on the calculated adjustment amount
At 16, an output signal is given to the drive circuit 36 from the signal output terminal group OUT1, OUT2.

If a cancel operation is performed during control, the computer 31 follows route C and executes the processing from step 117 onwards. In step 117, data corresponding to the time required to move the DC motor 51 in the actuating device 50 to the initial position on the deceleration side is applied to the timer circuit 36B from the output terminal group OUT2.
This time is set to approximately a few seconds. Further, in step 118, the computer applies a low level signal to the signal output terminal OUT3 to disconnect the clutch 53. Furthermore, in step 119, the control flag is
Reset Fc to “0” and step 107
Return to

By executing the control program having the above-mentioned configuration by the computer, step 110 is executed after route A when the set switch 23 is operated.
Constant speed running is started under the following conditions, and during control the actuating device 50
Appropriate control signals are applied to the vehicle to maintain the actual speed of the vehicle at the target speed, and control is canceled when the cancel switch 24 or operating equipment such as a brake or a clutch is operated.

The adjustment of the throttle valve 60 in constant speed running control is determined based on the calculation in step 115, and in accordance with the spirit of the present invention, step 115
The control procedure illustrated in detail in FIG. 5 is adopted.

The adjustment amount calculation step (115) starts with calculating the error ΔV between the own speed Vs and the target speed Vo in step 401.

Based on this error vehicle speed ΔV, the target throttle valve opening degree Ao is calculated according to the next stop.

Ao= _K1・ΔV+Ai...(1) However, _K1 is a proportional constant with a negative sign, and Ai represents the basic opening.The basic opening Ai takes a preset value in the initial state at the start of control. , is an adjustment component that is adjusted based on the results learned according to the driving state during control. Further, the term K ₁ ·ΔV is an error component depending on the error between the actual speed and the target speed. Note that, if necessary, it is also possible to take into account the temporal change in the actual speed as a calculation parameter for the target throttle valve opening.

To explain the control characteristic diagram of this device shown in FIG. 7, the control based on the above equation corresponds to a locus moving on the slope of the steady control line BC shown by the broken line.

At step 403, the sign of the error vehicle speed ΔV is determined, and if the actual speed Vs is greater than the target speed Vo, the processes from step 404 onwards are executed, otherwise the processes from step 408 onwards are executed.

In step 404 and below, when the actual speed Vs is decreased to approach the target value, the high-speed side boundary line (referred to as a high-side limiter) where the error vehicle speed ΔV is set is used.
This is a measure against an increase exceeding Lh (shown in Figure 7). Here, in step 404, the high side limiter Lh is calculated using the following equation.

Lh= _K2・ΔV+ _K3 ...(2) where _K2 is a constant of proportionality with a negative sign, and _K3 is a constant of proportionality with a positive sign.

Next, in step 405, the target throttle valve opening degree Ao calculated in step 402 is set to the high side limiter.
Determine whether it exceeds Lh. When the high-side limiter Lh is not exceeded, it is considered to be in a steady region where stable control is possible (when there is little change in running load), and the target throttle valve opening degree Ao is not corrected in steps 406 and 407.

If the vehicle is traveling downhill and the running load has been significantly reduced, the throttle valve control using equation (1) will stabilize the vehicle speed at point B', but this device moves this to point B and closes the throttle valve opening to reach the target speed Vo.
It was designed to bring them closer together. That is, in step 406, the target throttle valve opening
Ao is corrected to the opening set by equation (2) on the high limiter line. In this case, the correction amount is the error vehicle speed ΔV
Therefore, an appropriate throttle valve opening degree can be obtained depending on the magnitude of the running load.

Furthermore, when the running load of the vehicle is restored from a decrease to an increase, the seventh
In order to enable control along the stability control line BC' in the figure, the offset of the basic opening Ai is corrected in step 407, and then this adjustment amount calculation step (11
When executing step 5), the value of the basic opening degree Ai in the calculation of equation (1) in step 402 is revised downward.
This modification is done by the following formula.

Ai=Lh+K ₁・ΔV...(3) On the other hand, when the actual speed Vs is smaller than the target speed Vo, in the process from step 408 onwards, the low speed boundary line (referred to as low limiter) Li
Measures will be taken to prevent the increase in energy consumption beyond (as shown in Figure 7). In this case as well, the flow of processing is the same as that from step 404 onwards.

In step 408, the low side limiter L1 is calculated using the following equation (4), and if it is determined in step 409 that the target throttle valve opening degree _A0 is smaller than this limiter L1, in step 410 the target throttle valve opening degree Ao is calculated. The limiter L1 is corrected, and in step 411, the offset of the basic opening Ai is corrected according to the following equation (5).

L1=K ₄・ΔV+K ₅ ……(4) Ai=L1−K ₁・ΔV ……(5) Note that K ₄ is a negative proportionality constant, K ₅ is a positive constant, and constant K ₄ is a constant K It may be the same as ₂ .

In steps 408 to 411, when the running load increases significantly due to uphill slopes on the lower speed side than the target speed Vo in FIG. 7, the vehicle speed is stabilized at point A' in the stability control of (1), but The throttle valve opening degree is set at point A on the limiter to bring the vehicle speed closer to the target speed Vo, and when the vehicle speed approaches the target speed due to a decrease in running load, the vehicle speed is stabilized parallel to the stability control line BC. Performs stable control along the control line BC''.

In this way, according to this device, when determining the target throttle valve opening Ai and calculating the adjustment amount for adjusting the throttle valve opening, the control gain (proportionality constant) is determined from the stable control line (Equation (1)). By correcting the target throttle valve opening Ai in line with the large high-side limiter and low-side limiter, only when the error vehicle speed changes significantly in the direction away from the target speed,
The vehicle speed can be brought closer to the target speed quickly, and stable control can be performed within the range of the set limiter.

FIG. 6 shows in detail the adjustment output step 116 for sending the calculated adjustment amount to the drive circuit 36, following the adjustment amount calculation step 115 shown in FIG.

At step 501 in FIG. 6, the computer 31 outputs data "0" from the signal output terminals OUT1 and OUT2.
is sent to timer circuits 36A and 36B. This allows these timer circuits to temporarily
Even if a high level signal is output that makes transistors 3 and 46 conductive, the output is converted to a low level and the two power transistor stages (45, 46), (47,
48) are all cut off, and the energizing current of the DC motor 51 is instantaneously reduced. This later caused one of the power transistor stages, which had been cut off, to be turned on.
This is to reliably prevent a short-circuit current from flowing across both power transistor stages when the other power transistor that has been conducting is switched to cut-off.

In step 502, the computer receives the analog signal from the potentiometer 57 that indicates the actual throttle valve opening from the analog signal input terminal ANIN, and uses the built-in A-D conversion circuit to obtain digital data As that indicates the throttle valve opening. And remember this.

In step 503, the deviation DT between the target throttle valve opening Ao and the actual opening data As is calculated. Next steps 504, 505 regarding this deviation DT
Then, it is determined whether the size is within a predetermined range. If the actual opening As is close to the target opening Ao, the deviation width ±DTw is arbitrarily determined as a dead zone.
If it is within the range, data is added (step 50).
8,509) is not performed, and the DC motor 51 is stopped in accordance with the output of step 501, so that the throttle valve opening degree is maintained.

In step 506, data S indicating the driving time to be given to the timer circuits 36A and 36B of the driving circuit 36 is calculated based on the following equation based on the magnitude of the deviation DT.

S=f(|DT|)+So...(6) According to this formula, the driving time S is proportional to the deviation DT,
It is shown to have a constant offset So.

In step 507, it is determined whether the deviation DT is a positive sign or a negative sign, and if it is a positive sign, step 508;
If it is a negative sign, the process advances to step 509.

If the deviation DT has a positive sign, step 50
8 sends the drive data S calculated by equation (6) to the timer 36A from the first signal output terminal OUT1. The power transistor 4 is activated by the operation of the timer 36A.
4 and 45 conduct, causing the DC motor 51 to rotate forward,
These increase the throttle valve opening and accelerate the vehicle. On the other hand, if the deviation DT has a negative sign,
The drive data S is sent to the timer 36B from the second signal output terminal OUT2, and the throttle valve opening degree is decreased by the reverse rotation of the DC motor 51.

In this way, the adjustment output is applied to the actuating device 50, and the DC motor 51 rotates forward or reverse at a predetermined time ratio to obtain the calculated adjustment target throttle valve opening, thereby opening the throttle valve. The degree changes along the locus shown in FIG.

Therefore, in a stable region where there are few fluctuations in the running load, this device changes the throttle valve opening relatively small in response to changes in actual speed according to the control gain determined by equation (1) above, thereby adjusting the vehicle speed. In addition, when the running load increases significantly, the target throttle valve opening is changed along a separately determined limiter line L1 or Lh, thereby substantially increasing the control gain and causing the vehicle speed to move away from the target speed. to prevent

At this time, the offset adjustment component Ai in equation (1) that determines the target throttle valve opening is also changed, so if the running load decreases, the throttle valve opening can be stabilized with the same control gain as the original control gain. By changing this, hunting is prevented and there is no significant change in ride comfort.

Although one embodiment of the present invention has been described above, the present invention is not limited to the description of this embodiment. Changes in procedures when configuring a control program, how to create data such as calculations, the format of the adjustment signal that controls the speed governing element and its application method, the selection of the actuating device, and the selection of the speed governing element to be applied, etc. This is possible within the spirit of the present invention.

As described above, according to the present invention, in relation to the difference from the actual speed of the vehicle and the direction of increase/decrease of the difference, when the actual speed departs from the target speed, compared to when the actual speed approaches the target speed. Since the control gain is increased by changing the adjustment amount of the throttle valve opening in response to the speed error in response to sudden changes in the running load, it is possible to prevent the actual speed from deviating from the target speed and to reduce the speed error. By reducing the control gain when is decreasing,
It is possible to suppress hunting and obtain a stable ride.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention, FIGS. 2 to 6 are flowcharts showing a control program for the microcomputer 31 of the device shown in FIG. 1, and FIG. 7 is a control characteristic diagram of the device. It is. 17...Speed signal generator, 20...Operation panel, 2
3...Set switch, 30...Control circuit package, 31...Microcomputer, 36...
Drive circuit, 50...actuating device, 51...DC motor, 60...throttle valve (speed regulating element).

Claims (1)

[Claims] 1. A speed control for a vehicle that operates a speed regulating element of the vehicle in response to a speed signal from a signal generating means responsive to the actual running speed of the vehicle to maintain the running speed at a set target speed. The control device includes means for creating an adjustment signal whose value is changed with a predetermined control gain according to the difference between the actual speed of the vehicle and the target speed of the vehicle, and means for controlling the speed governing element in accordance with the adjustment signal. and means for controlling, at least in relation to the difference between the actual speed of the vehicle and its target speed and the direction of increase or decrease of that difference, the actual speed approaches the target speed as the actual speed departs from the target speed. A speed control device for a vehicle, comprising a control means for increasing the control gain compared to the case where the control gain is increased. 2. The control means provides means for applying the adjustment signal with an error component depending on the difference between the actual speed and the target speed and an adjustment component for adjusting an offset; means for increasing the adjustment component of the adjustment signal when the vehicle speed decreases below the target speed, and decreasing the adjustment component of the adjustment signal when the actual speed increases above the target speed as the vehicle load decreases. A speed control device for a vehicle according to claim 1, characterized in that: