JPS645615Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a constant speed traveling device for a vehicle that allows a vehicle to travel at a constant speed at a desired set vehicle speed.

Conventionally, this type of device is known to control the throttle by driving the actuator by means of a driving means provided on an actuator connected to the throttle. A current corresponding to the difference between a voltage corresponding to the vehicle speed and a voltage corresponding to the set vehicle speed flows through the drive means to move the actuator by a predetermined amount. However, with this method, the current value flowing through the drive means is relatively large (100mA or more).
Therefore, large-capacity semiconductors and other components must be used to control the current value, resulting in a large size and the need to deal with heat generation, making it expensive and difficult to select a mounting location. There were drawbacks associated with it. In addition, the output of the F-V converter that converts vehicle speed into voltage is generally a voltage with waveforms such as triangular waves, and if these waveforms are not removed, the waveform will change when compared with the voltage corresponding to the desired set vehicle speed. The current flowing through the drive means increases or decreases depending on the height of the vehicle speed, making it impossible to accurately control the vehicle speed to the set vehicle speed. For this reason, it is inconvenient that a smoothing circuit for waveform shaping must be provided after the F-V converter to obtain a smooth DC voltage and then compare it with the voltage corresponding to the set vehicle speed.

The present invention was devised in view of the above-mentioned drawbacks of the conventional technology, and it is possible to reduce the number of parts and make it inexpensive, and to control the vehicle speed to a desired set vehicle speed with the same sensitivity in any set vehicle speed range. The purpose of the present invention is to provide a constant speed traveling device for a vehicle that can perform the following functions.

In order to achieve the above object, the constant speed traveling device for a vehicle according to the present invention has a configuration including a vehicle speed detection circuit that generates a voltage according to the vehicle speed, and a vehicle speed setting circuit that generates a DC voltage corresponding to a desired set vehicle speed. , a comparator that compares the two voltages and generates an output signal according to the value thereof, an amplifier circuit that amplifies the output of this comparator, and an actuator that is driven according to the output of this amplifier circuit and controls the throttle. A constant speed traveling device for a vehicle comprising: a speed sensor that generates a pulse responsive to vehicle speed; a waveform shaper that shapes the waveform of the pulse;
An F-V converter converts this waveform-shaped pulse into a triangular wave output voltage in which the ripple size is constant regardless of the period of the pulse that responds to vehicle speed, and the average voltage changes linearly with changes in vehicle speed. The output voltage of the triangular wave and the DC voltage generated in the vehicle speed setting circuit are compared by the comparator to generate a pulse signal at the output section of the comparator, and the pulse signal generated in the amplifier circuit is The throttle is controlled by increasing or decreasing the current flowing through the actuator by varying the ON/OFF duty ratio according to changes in vehicle speed, and regulating the amount of movement of the actuator according to this current value. There is.

The present invention will be explained below based on an embodiment shown in the drawings.

In FIG. 1, 1 is a vehicle speed detection circuit that generates a voltage according to the vehicle speed, and a speed sensor 2 that is fixed to a rotating part of the vehicle (for example, the output shaft of the engine) and generates a pulse responsive to the vehicle speed. A waveform shaper 3 shapes this pulse into a waveform. It consists of an F-V converter 4 that converts into a triangular wave output voltage that changes linearly. The waveform shaper 3 includes resistors 31, 32, 33, 34, a capacitor 35, and a transistor 36. Further, the F-V converter 4 includes capacitors 41 and 42, diodes 43 and 44, a variable resistor 45, and an operational amplifier 46. This operational amplifier 46
A triangular wave output voltage is generated at the output section.

In the illustrated embodiment, the triangular wave voltage generated in the F-V converter 4 is a sawtooth voltage.

5 is a vehicle speed setting circuit that generates a DC voltage corresponding to a desired set vehicle speed, and a resistor 5 connected in series.
1, 52, 53, 54 and a Zener diode 55 connected in parallel to these resistors 51 to 54 connected in series. The resistor 53 is a variable resistor, and the voltage generated at a dividing point A, which is appropriately divided in the variable resistor 53, is a voltage corresponding to the set vehicle speed.

6 is a comparator that compares the voltages generated in the vehicle speed detection circuit 1 and the vehicle speed setting circuit 5 and generates an output signal according to the value thereof, and the positive input terminal of the comparator 6 is connected to the It is connected to the output section of the amplifier 46, and its negative input terminal is connected to the dividing point A of the variable resistor 53.

Reference numeral 7 denotes an amplifying circuit for amplifying the output of the comparator 6, which is composed of resistors 71, 72, 73, 74 and transistors 75, 76. 8 is a resistor interposed to protect the Zener diode 55.

9 is driven according to the output of the amplifier circuit 7,
This is an actuator that controls a throttle (not shown), and in this embodiment, a servo valve 91 constitutes a part of the actuator 9, and a driving means for driving the actuator 9 is a servo valve 91, and this servo valve 91 is connected to the collector of the transistor 76. .

10 is a diode connected to the connection point between the collector of the transistor 76 and the servo valve 91.
The opening degree of the servo valve 91 changes in proportion to the value of the current flowing through the servo valve 91, and the amount of negative pressure applied to the actuator 9 can be controlled. The actuator 9 directly connected to the throttle is moved by an amount determined by this negative pressure to control the throttle.

Reference numeral 11 denotes a correction circuit that generates a voltage according to fluctuations in the power supply voltage _Vcc , and is composed of a resistor 12;
is connected in series to the resistor 54 of the vehicle speed setting circuit 5. That is, a correction circuit 11 is added to the vehicle speed setting circuit 5. Therefore, the resistance values of the resistors 51, 52, 54, 8, and 12 are respectively R ₅₁ , R ₅₂ , R ₅₄ , R ₈ , and R ₁₂ , and the overall resistance value of the variable resistor 53 is R ₅₃ , and the dividing point A If the resistance between the connection point of the variable resistor 53 and the resistor 54 is R ₅₃ ', and the Zener voltage of the Zener diode 55 is V _Z , then the voltage generated at the dividing point A of the variable resistor 53, that is, the vehicle speed setting circuit 5 The generated DC voltage V _A corresponding to the set vehicle speed is expressed by the following formula.

V _A =R ₅₃ ′+R ₅₄ /R ₅₁ +R ₅₂ +R ₅₃ +R ₅₄ ×V _Z +R ₁₂ /R ₈
+R ₁₂ × (V _cc −V _Z ) = (R ₅₃ ′ + R ₅₄ /R ₅₁ +R ₅₂ +R ₅₃ +R ₅₄ −R ₁₂ /R ₈ +R
₁₂ )×V _Z +R ₁₂ /R ₈ +R ₁₂ ×V _cc …(1) Therefore, the voltage V _A generated in the vehicle speed setting circuit 5 is:
It is a composite voltage of the constant voltage part and the part corresponding to fluctuations in the power supply voltage _Vcc .

13 is a DC power supply, 14 is a switch for power supply, and 15 is a switch for constant speed running, which is automatically returned. 16 is a transistor connected in parallel to the switch 15, and 16a is a resistor. 17 is a comparator whose negative input terminal is connected to the connection point between the resistors 51 and 52;
Connect the positive input terminal to the resistor 18 and capacitor 19
The output terminal is connected to the base of the transistor 16 via a resistor 20. The output side of the operational amplifier 46 is connected to the capacitor 19 via a resistor 21, and a diode 22 and a resistor 23 are connected in series between the resistor 18 and the capacitor 19 in parallel with the capacitor 19. A series circuit of a fuse 24, a brake switch 25 and a brake lamp 26 is connected to the power supply 13, and one end of the resistor 23 is connected to the connection point between the brake switch 25 and the brake lamp 26.

Next, the operation of this device with the above configuration will be explained.

When the power supply switch 14 is closed and the constant speed running switch 15 is turned on momentarily, the comparator 17 goes to L level and the transistor 16 turns on.
After that, even if switch 15 is opened, transistor 1
6 maintains the ON state.

Here, when the vehicle is running at a certain speed, a pulse responsive to the vehicle speed is generated in the speed sensor 2, which is shaped by the waveform shaper 3, and becomes an ON/OFF waveform at the collector of the transistor 36, as shown in FIG. The pulse waveform will be as shown. FIG. 2a shows a case where the vehicle speed is relatively high, and FIG. 2b shows a case where the vehicle speed is relatively low. When the transistor 36 is turned on,
Capacitor 42, diode 43, capacitor 4
1. Current flows through the transistor 36 and the capacitor 42 starts charging. The charge in the capacitor 42 leaks moderately through the variable resistor 45, and this leakage time is proportional to the cycle of the pulse that responds to the vehicle speed. Therefore, if the vehicle speed is high and the cycle is short, the charge in the capacitor 42 will increase; The longer the period, the less the charge on the capacitor 42 will be. The charge on the capacitor 42, that is, the output voltage V _B of the vehicle speed detection circuit 1 generated at the output of the operational amplifier 46 of the F-V converter 4
becomes a triangular wave voltage as shown by a and b in FIG. The output voltages V _B of a and b respectively correspond to the pulse waveforms of a and _b in _FIG . respectively
Assuming C ₁ and C ₂ , V _P ≈C ₁ /C ₁ +C ₂ ×V _Z , which is constant regardless of the period of the pulse that responds to the vehicle speed. Therefore, the amount of change in the average voltage in the output voltage V _B per unit vehicle speed is constant in any vehicle speed range. In other words, the average voltage of the output voltage V _B changes linearly with changes in vehicle speed, and in this embodiment, it is made to be inversely proportional to the vehicle speed.

The voltage V _B generated in the vehicle speed detection circuit 1 is
It is compared with the voltage V _A of the vehicle speed setting circuit 5 generated at point A set by the variable resistor 53 by the comparator 6,
When voltage V _B is higher than voltage V _A , that is, when the actual vehicle speed is lower than the set vehicle speed, the output of comparator 6 maintains the H level and transistors 75 and 76 are turned on continuously.
Then, the maximum current is applied to the servo valve 91 to move the actuator 9 to increase the vehicle speed and bring it closer to the set vehicle speed. When the voltage V _B is lower than the voltage V _A , that is, when the actual vehicle speed is higher than the set vehicle speed, the output of the comparator 6 becomes L level, and the transistors 75 and 76 continuously operate.
The servo valve 91 is turned OFF, and no current flows through the servo valve 91, causing the vehicle speed to drop and approach the set vehicle speed.

Also, as shown in Figure 4, when voltage V _A and voltage V _B are approximate, the ripple component of voltage V _B and voltage V _A
Among the crossing portions, the output of the comparator 6 becomes H level only in the portion where the voltage V _B is higher than the voltage V _A , resulting in a pulse signal with ON and OFF waveforms as shown in FIG. In other words, as shown by the solid line in Figure 4, the voltage
The higher V _B is, that is, the lower the vehicle speed is than the set vehicle speed, the higher the ON/OFF duty ratio of the pulse signal of the comparator 6 becomes, as shown by the solid line in FIG.
As shown by the broken line in the figure, the lower the voltage V _B is, that is, the higher the vehicle speed is than the set vehicle speed, the smaller the duty ratio becomes, as shown by the broken line in FIG. The pulse signal from the comparator 6 turns on the transistors 75 and 76.
The output voltage of the amplifier circuit 7 which is turned OFF and appears at the collector of the transistor 76 changes according to the output voltage of the comparator 6 shown by the solid line and broken line in FIG. It becomes a pulse signal.

At this time, the current flowing through the servo valve 91 is
The output voltages are as shown by solid lines and broken lines in FIG. 7, respectively, depending on the average value of the output voltage of the amplifier circuit 7.

In other words, the lower the vehicle speed is than the set vehicle speed, the more the amplifier circuit 7
As the duty ratio of ON and OFF of the pulse signal generated in The throttle opening is increased by moving the throttle by an amount determined by the amount of negative pressure, rapidly increasing the vehicle speed, and as the difference between the vehicle speed and the set vehicle speed decreases, the pulse signal of the amplifier circuit 7 is turned on and off.
Since the duty ratio of servo valve 9 becomes smaller,
1 becomes smaller, the vehicle speed is gradually increased, and the vehicle speed is controlled to the set vehicle speed.

The current flowing through the servo valve 91 is controlled by the duty control of the pulse signal generated at the output section of the comparator 6, that is, the duty control of the pulse signal generated at the output section of the amplifier circuit 7. Transistors 75 and 76 can always be used in a saturated state. Therefore, the internal power consumption of the transistors 75 and 76 is kept to a minimum, so there is almost no heat generation, and it is possible to use small and inexpensive transistors.

The triangular wave output voltage V _B generated in the F-V converter 4 has a ripple magnitude V _P that is constant regardless of the period of the pulse generated in the speed sensor 2 in response to the vehicle speed, and its average voltage is Since it changes linearly with changes in vehicle speed, the vehicle speed can be controlled to a desired set vehicle speed with the same sensitivity in any set vehicle speed range.

Now, considering the case where the power supply voltage V _cc fluctuates, since a correction circuit 11 is added to the vehicle speed setting circuit 5, the voltage V _A generated at point A is a constant voltage part as shown in equation (1) above. It becomes a composite voltage of a portion corresponding to fluctuations in the power supply voltage _Vcc . Therefore, when the power supply voltage V _cc increases, the voltage V _A increases, and as shown in FIG. 8, the voltage V _A changes from a solid line to a two-dot chain line.
Further, since the voltage V _B does not change, the ON/OFF duty ratio of the pulse signal of the comparator 6 becomes small.
However, since the output voltage of the amplifier circuit 7 varies from the solid line to the chain double-dashed line in FIG. 9, the average value of the output voltage of the amplifier circuit 7 can be kept constant by appropriately selecting the resistance value of the resistor 12 of the correction circuit 11. can do. Similarly, when the power supply voltage V _cc becomes low,
The voltage V _A becomes lower as shown by the broken line in Figure 8, and the ON/OFF duty ratio of the pulse signal of the comparator 6 increases, but the output voltage of the amplifier circuit 7 becomes as shown by the broken line in Figure 9. , the average value of the output voltage can be kept constant.

Therefore, the current flowing through the servo valve 91 is the 10th current.
From the solid line in the figure, when the power supply voltage V _cc increases, it changes as shown by the two-dot chain line, and when the power supply voltage V _cc decreases, it changes as shown in the broken line, but the average current of each remains constant, The servo valve 91 moves the actuator 9 by a predetermined amount to control the throttle, thereby controlling the vehicle speed to a desired set vehicle speed.

By closing the brake switch 25, the output of the comparator 17 becomes H level, turning off the transistor 16 and canceling constant speed running.

As described above, according to the present invention, the triangular wave output voltage generated in the F-V converter can be directly connected to the comparator without being smoothed, which eliminates the need for a smoothing circuit and reduces the number of components. It is possible to reduce the cost, and there is no need to pay attention to smoothness.

In addition, the triangular wave output voltage generated by the F-V converter has a ripple size that is constant regardless of the period of the pulse that responds to the vehicle speed, and the average voltage changes linearly with changes in vehicle speed. The vehicle speed can be controlled to a desired set vehicle speed with the same sensitivity in any set vehicle speed range.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of a constant speed traveling device for a vehicle according to the present invention, and FIGS.
FIG. 3 is a characteristic diagram of each part in the circuit shown in the figure. 1...Vehicle speed detection circuit, 2...Speed sensor,
3... Waveform shaper, 4... F-V converter, 5...
Vehicle speed setting circuit, 6...Comparator, 7...Amplification circuit,
9...actuator.

Claims (1)

[Scope of utility model registration request] A vehicle speed detection circuit that generates a voltage according to the vehicle speed, a vehicle speed setting circuit that generates a DC voltage corresponding to a desired set vehicle speed, and a comparator that compares the two voltages and generates an output signal according to the value. In the vehicle constant speed traveling system, the vehicle speed detecting circuit is configured to control the vehicle speed. a speed sensor that generates a pulse that responds to the vehicle speed, a waveform shaper that shapes the waveform of this pulse, and a waveform shaper that shapes the waveform of the pulse so that the magnitude of the ripple is constant regardless of the period of the pulse that responds to the vehicle speed and the average voltage and an F-V converter that converts the voltage into a triangular wave output voltage that varies linearly with changes in vehicle speed, and the comparator compares this triangular wave output voltage with the DC voltage generated in the vehicle speed setting circuit. By generating a pulse signal at the output section of the comparator and varying the ON/OFF duty ratio of the pulse signal generated at the amplifier circuit in accordance with changes in vehicle speed, the current flowing through the actuator is increased or decreased. A constant speed traveling device for a vehicle, characterized in that the throttle is controlled by regulating the amount of movement of the actuator according to a value.