JPS6249965B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive device for driving a proportional solenoid that proportionally controls the flow rate of, for example, a gas-liquid fluid.

An example of a proportional solenoid will be explained below using the structural diagram shown in FIG. 1, for example. 140,1
Reference numeral 41 denotes a housing which is fixed to each other with screws. 142a is a tubular support made of magnetic material, and is fixed to the housing 140.
Reference numeral 42b denotes a disc-shaped support made of a magnetic material, which is fixed to the housing 140, and is arc-shaped and faces each other, with the N pole on the inside and the S pole on the outside.
Two permanent magnets 143, 144 magnetized to the poles
is fixed to the housing with an adhesive.
145 is a spool that is a moving part, and housing 141
A cylindrical shaft 146 that is a fixed part fixed to
slides up and down on the outer circumference of the Spool 145
A coil 147 is wound around the coil 147. A spring 148 pushes the spool 145 downward. 1
49 is a lead wire at the beginning of winding of the coil 147, and 150 is a lead wire at the end of winding of the coil 147, both of which are connected to the drive circuit. The cylindrical shaft 146 is provided with isosceles triangular slits 146a as shown on both sides, that is, at two locations. As the spool 145 moves on the shaft 146, the opening degree of the slit 146a is changed by the spool 145, thereby controlling the amount of gas-liquid fluid flowing from the inlet pipe 152 to the outlet pipe 153. The amount of displacement, that is, the amount of movement of the spool 145 is proportional to the square root of the opening area of the slit 146a.

To explain its operation with the above configuration, if the inside of the permanent magnets 143, 144, which have arcuate cross-sections, is the north pole, and the outside of the magnets 143, 144 is the south pole, the magnetic path will start from the inside north pole of the permanent magnet 143. Shaft 1
46, the support 142b and the support 142a, and reach the outer S pole of the permanent magnet 143. Similarly, a magnetic path is formed inside the permanent magnet 144, on the shaft 146, the supports 142b and 142a, and on the outside of the permanent magnet 144. Therefore, the permanent magnet 143,1
A parallel magnetic field is applied from the inside of the shaft 146 toward the center of the shaft 146. When a current is passed through the coil 147 in this magnetic field, the coil 147
An electromagnetic force acts in the direction below the figure. Therefore, the spool 145 moves downward and stops when the force of the spring 148 is balanced. In this case, the electromagnetic force is proportional to the product of the number of turns N of the coil 147 and the current i flowing through the coil. The number of turns N is constant, and the electromagnetic force is proportional to the current flowing through the coil 147. On the other hand, the force of the spring 148 is the product of the amount of movement and the spring constant.
Therefore, the current flowing through the lead wires 149, 150 and the amount of movement are proportional to the square root of the opening area of the slit of the shaft 146, that is, the supplied current is proportional to the square root of the opening area of the slit.

However, the problem here is that friction between the spool 145 and the shaft 146 prevents smooth operation. FIG. 2 shows the characteristics of the current flowing through the coil 147 and the stroke of the spool 145. In FIG. 2, A is the characteristic when the spool 145 moves against the biasing force of the spring 148 when the current increases from low to high.
B is a characteristic when the current decreases from high to low, that is, when the spool 145 moves in the direction of the biasing force of the spring 148. As is clear from this characteristic, hysteresis occurs due to the friction. If the clearance between the spool 145 and the shaft 146 is increased in order to reduce this hysteresis, there is a major problem in that leakage of gas-liquid fluid increases and accuracy deteriorates. Therefore, in order to solve the problem, we will examine the basic cause of hysteresis caused by friction in Figure 2. Assuming that the weight of the movable part is Mg and the coefficient of friction between the shaft 146 and the spool 145 is μ, this frictional force F ₀ is μM. Therefore, hysteresis is created by the current value corresponding to F ₀ . Letting this current value be i ₀ , if the coefficient of friction between the shaft and spool is uniform, the hysteresis characteristic will be as shown in Figure 2. In Fig. 2, the drive current when increasing is
ia, and the drive current when decreasing is ib.
When controlling the spool 145 so that it is displaced from the S ₀ position to the S ₁ position, first
Current corresponding to position a ₀ ia Current from position a ₀ to a ₁
Just lowering the current to IA ₁ is not good. It is necessary to displace the spool to position S ₁ through the sequence from the a ₀ position to the b ₀ position and then to the b ₁ position. Therefore, the current value is ia ₁ −i ₀ =ib ₁ . Conversely, when moving the spool 145 from the S ₁ position to the S ₀ position, the sequence is b ₁ →a ₁ →a ₀ . As a current value
ib ₀ + i ₀ = ia ₀ .

From the above results, if the friction coefficient μ is constant, if the spool 145 continues to rise, the control current ia
If the spool often goes down, the spool can be moved accurately without hysteresis by controlling it to ia−i ₀ (i ₀ is the current corresponding to friction).

In view of the above results, it is an object of the present invention to make it possible to compensate for the hysteresis of the proportional solenoid, and in order to control the displacement amount of the proportional solenoid, the control signal corresponds to the frictional force of the sliding part of the proportional solenoid. The present invention is characterized in that it includes a hysteresis removing means that generates a signal obtained by adding or subtracting a value, and a current amplifying means that supplies a current having a value corresponding to the output signal of this means to the proportional solenoid.

Another object of the present invention is to improve the mechanical response by making the current that drives the proportional solenoid a staircase waveform that changes stepwise.

An embodiment in which the proportional solenoid drive device according to the present invention is applied to an exhaust gas purification device will be described below.

In Fig. 3, 1 is an internal combustion engine, 2 is an intake pipe,
3 is an exhaust pipe. A carburetor 4 is provided in the intake pipe 2 and is configured to supply air-fuel mixture to the engine 1. This carburetor 4 has a bench lily 6 and a throttle valve 7. Further, 5 is an air cleaner, which cleans the air taken into the engine 1.
Reference numeral 9 denotes a known air-fuel ratio detector, which is installed in the exhaust pipe 3, detects the air-fuel ratio based on the oxygen concentration in the exhaust gas, and outputs an output according to the air-fuel ratio. Further, a three-way catalyst 8 is provided downstream of the air-fuel ratio detector 9. As is well known, the three-way catalyst 8 promotes the oxidation and reduction of CO, HC, and NOx in the exhaust gas flowing into it, and purifies these harmful components. Especially when the air-fuel ratio of the engine exhaust system is around the predetermined (theoretical) air-fuel ratio (147), it purifies all CO, HC, and NOx together with high purification performance. Reference numeral 10 denotes an air pump driven by the engine 1, which serves as air supply means. Reference numeral 11 denotes a relief valve serving as a pressure regulating means, and a proportional solenoid 14 serving as a control valve for air discharged from the air pump 10.
It is provided in the middle of the supply pipe 12 leading to the inlet of the
It is for adjusting the pressure within this supply pipe line 12. One diaphragm chamber 1 of this relief valve 11
14 is connected to the conduit 12 through the conduit 13. The other diaphragm chamber 113 is connected to the pipe 17.
It is connected to a conduit 15 downstream of the proportional solenoid (air control valve) 14 through the . This relief valve 11 functions to always keep the pressure difference between the pipe line 12 and the pipe line 15 constant. The air control valve 14 has its inlet side connected to the pipe line 12 as described above, and its outlet side connected to one end of the pipe line 15, so that the spool is continuously displaced in proportion to a control signal from a control circuit 16, which will be described later. It is a proportional electromagnetic operated type that controls the amount of secondary air in proportion to this control signal. The other end of the pipe line 15 is connected to the exhaust pipe 3. The control circuit 16 determines whether the air-fuel ratio is larger or smaller than a predetermined (theoretical) air-fuel ratio at predetermined intervals based on the output signal of the air-fuel ratio detector 9, and changes the previous value to the predetermined value according to this determination signal. A control signal obtained by adding or subtracting the value is output, and the opening degree, that is, the displacement amount of the air control valve 14 is controlled by this control signal.

The detailed structure and function of the relief valve 11 will be explained. In the relief valve 11, the pressure in the pipe line 12 and the pressure in the pipe line 15 are introduced into both diaphragm chambers 114 and 113, and the pressure difference between the two pressures causes the pressure in the diaphragm 111 to
The valve body 117 and the valve seat 119 release the air in the pipe line 12 to the atmosphere by swinging the valve body 117 and the valve seat 119. In the figure, 110 is a housing, 112 is a spring,
115 is bellow frame, 116 is shaft, 12
0 is a pressure chamber open to the atmosphere. A force acts on the spring 112 to press the diaphragm 111 to the left side in the figure, that is, to close the valve body 117. Shaft 116 connects diaphragm 111 and valve body 117. Here, the first diaphragm chamber 1
13 and the second diaphragm chamber 114 have the same pressure receiving area. Let P ₂ be the absolute value of the positive pressure acting on the first diaphragm chamber 113, P ₁ be the absolute value of the positive pressure acting on the second diaphragm chamber 114, and let A be the pressure receiving area of the first and second diaphragm chambers 113, 114. Then, the force W acting in the right direction of the diaphragm 111, that is, in the direction of opening the valve body 117, becomes W=(P ₁ -P ₂ )×A. If the pressure P ₁ in the air pump side pipe line 12 increases now, the diaphragm 111 moves to the right. Therefore, the valve body 117 moves in the opening direction. Then, the opening area between the valve body 117 and the valve seat 119 increases, and the air in the pipe line 12 flows into the pressure chamber 12.
0 to the atmosphere increases, the pressure in the pipe line 12, that is, the pressure _P1 in the second diaphragm chamber 114 decreases, and the force W and the force F of the spring 112 decrease.
The pressure difference between the two pressures P ₁ and P ₂ is eventually maintained at a constant value. Even when the pressure P ₁ decreases, the pressure difference is maintained at a constant value in the same way. A detailed explanation of the proportional solenoid 14 is omitted in FIG.
If the difference between the pressure and the pressure is constant, the proportional solenoid 14
It has been confirmed experimentally that the air flow rate at the exit of the slit is approximately proportional to the square root of the opening area of the slit. Since this pressure difference is controlled to be constant by the relief valve 11 as described above, the air flow rate can be controlled in proportion to the current input to the proportional solenoid 14.

Next, the detailed configuration and functions of the control circuit 16 will be explained with reference to FIG.

In FIG. 4, an input terminal 160 is connected to the output terminal of the air-fuel ratio detector 9, and the other input terminal 161 is connected to the ground terminal of the air-fuel ratio detector 9. Note that the lead wire from the air-fuel ratio detector 9 uses a shielded wire. Input terminal 160 is connected to a non-inverting input of buffer amplifier 164 via resistor 162. A noise absorbing capacitor 163 is inserted between the non-inverting input and the ground terminal. Input terminal 161 is grounded. The buffer amplifier 164 uses an IC product number CA3130 manufactured by RCA. The inverting input terminal of the buffer amplifier 164 is connected to the output terminal. Also, the output end is comparator 1
It is connected to the non-inverting input terminal of 65. The output of the comparator 165 is the first output U/D of the control circuit 16.
It is connected to the U/D input terminal of the up-down counter 170. Variable resistor 166
A constant voltage Vc is applied to one fixed terminal of the
The other fixed terminal is grounded. 167 is an astable multivibrator, IC product number manufactured by RCA.
I am using CD4047. 4 of the terminals of the IC,
Apply constant voltage Vc to terminals 5, 6, and 14, and
By grounding terminals 8, 9, and 12, it operates as an astable multivibrator. The capacitor 168 is connected to the 3rd and 1st terminals, and the resistor 169 is connected to the 3rd and 2nd terminals.
The oscillation frequency is determined by the time constant of the resistor 169. The output of the astable multivibrator 167 is connected to one input of AND gates 175 and 176, respectively. Updown counter 17
0 uses two RCA IC product number 4029.
It is used as an up-down counter. The clock input terminal CL is connected to the output terminal of the AND gate 176, and each output terminal Q ₁ , Q ₂ , Q ₄ , Q ₅ is connected to the R-2R ladder network circuit 177 in order from the lower digit. . Each input terminal of the 5-input AND gate 171 is connected to each output terminal Q ₁ , Q ₂ , Q ₃ , Q ₄ , and Q ₅ of the up-down counter 170, respectively. Each input terminal of the 5-input OR gate 172 is connected to each output terminal Q ₁ , Q ₂ ,
They are connected to Q ₃ , Q ₄ , and Q ₅ respectively. One input terminal of the NAND gate 173 is connected to the output terminal of the comparator 165, and the other input terminal is connected to the output terminal of the AND gate 173.
It is connected to the output terminal of 1. The NAND gate 17
The output terminal of 3 is connected to the other input terminal of AND gate 175. One input terminal of the OR gate 174 is connected to the output terminal of the comparator 165, and the other input terminal is connected to the OR gate 172. The output of the OR gate 174 is connected to one terminal of an AND gate 176. The output terminal of AND gate 175 is
It is connected to the other input terminal of AND gate 176. The output of the AND gate 176 is the clock input terminal of the up-down counter 170 as described above.
It is connected to CL. R-2R Rada Network 1
The output terminal of 77 is connected to the non-inverting input terminal of buffer amplifier 178. The inverting input terminal of the buffer amplifier 178 is connected to the output terminal. The output terminal of the buffer amplifier 178 is connected to one fixed terminal of a variable resistor 179, and the variable terminal becomes the output V _Z of the control circuit 16.

To explain the operation of the control circuit 16, the resistor 1
62, capacitor 163, buffer amplifier 164
This configuration allows a relatively large current to be obtained from a high impedance input and a weak current from a low impedance. A comparator 165 connects the output voltage _VX of the buffer amplifier 164 and the variable resistor 16.
Comparing with the set voltage VR of variable terminal 6, V _X ≧
When V _R (that is, when the air-fuel ratio is smaller than the predetermined air-fuel ratio), a high-level voltage signal “1” is output, and V
When _X <V _R , a low level voltage signal "0" is output, and the output waveform is as shown in FIG. 5A. The voltage V _X has the same characteristics as the output voltage of the air-fuel ratio detector 9. The output of comparator 165 is “1”
When the value is "0", the up-down counter 170 is counting up, and when it is "0", it is counting down.
The 5-input AND gate 171 is for preventing the up-down counter 170 from overflowing, and when all the outputs of the up-down counter 170 are "1", the output of the AND gate 171 becomes "1". And when the U/D input is “1”, NAND
Since the output of the gate 173 becomes "0", the output terminal of the AND gate 175 becomes "0" and the oscillator 167
Stops the clock signal from On the other hand, 5 inputs OR
The gate 172 is provided to prevent further down-counting after all the outputs of the up-down counter 170 have become "0". When all the outputs of the up-down counter 170 become “0”, the 5-input OR gate 172
The output of is "0". Since the U/D input is "0", the output of OR gate 174 becomes "0" and the clock signal from AND gate 175 is
It is stopped at AND gate 176. In other words, U/
When the D input is 1, the up-down counter 170
When the outputs of the up-down counter 170 are all 1, and when the U/D input is 0 and the outputs of the up-down counter 170 are all 0, the clock is prohibited from being input to the clock input terminal CL. Otherwise, a clock signal is applied to the clock input. Note that the oscillator 16
The oscillation frequency of 7, that is, the frequency of the clock signal is approximately
The frequency is 100Hz, and the waveform is as shown in FIG. 5B. When the air-fuel ratio is now smaller than the predetermined air-fuel ratio and the output of the comparator 165 is "1", the up-down counter 170 is increased by one clock every one clock from the oscillator 167.
is counting up, and when the air-fuel ratio becomes larger than a predetermined air-fuel ratio and the output of the comparator 165 becomes "0", it starts counting down every clock.
Ladder network 177 is a known DA converter that converts the binary output value of up-down counter 170 into an analog voltage. buffer amplification 178
is for amplifying the output of this ladder network 177, and operates in the same way as the buffer amplifier 164, converting high input impedance to low impedance. Buffer amplifier 1 with variable resistor 179
The output voltage Vy of 78 is divided to obtain the voltage KVY. The second output of the control circuit 16 is shown in FIG.
The result is a staircase waveform as shown in .

Next, the circuit configuration of the drive circuit 17 will be explained with reference to FIG. In FIG. 6, the drive circuit 17 consists of a hysteresis removal circuit 18 and a current amplification circuit 19. The input terminal 181 of the drive circuit 17 receives the first output U/D of the control circuit 16, and the input terminal 180 receives the second output V _Z of the control circuit 16.
is input. The input 180 is connected to the operational amplifier 18 via a resistor 187 in the hysteresis removal circuit 18.
It is connected to the non-inverting input of 8. Input 181 is a control input of first analog switch 183 in hysteresis removal circuit 18 and inverter 184.
is connected to the input of A fixed voltage is applied to one fixed terminal of the variable resistor 182 from a power supply circuit (not shown).
Vc is applied, and the other fixed terminal is grounded. A variable terminal of the variable resistor 182 is connected to the input of the first analog switch 183. The first analog switch 183 is an RCA product number.
A CD4066 is used, and its output is connected to one end of a resistor 186. The output of the inverter 184 is connected to the control input of a second analog switch 185. The second analog switch 1
The input of 85 is grounded, and the output is connected to the resistor 18.
It is connected to one end of 6. The other end of the resistor 186 is connected to the inverting input of the operational amplifier 188. A resistor 189 is connected in parallel between the non-inverting input of the operational amplifier 188 and ground. resistance 1
90 is inserted between the inverting input and output of the operational amplifier 188. The output of the operational amplifier 188 becomes the output of the hysteresis removal circuit 18, and is connected to one end of a resistor 191 via the input of a current amplification circuit 19. The other end of the resistor 191 is connected to a non-inverting input of an operational amplifier 192. The output of the operational amplifier 192 is connected to the base of an NPN transistor 194. The emitter of the transistor is grounded through a resistor 195 and connected to a resistor 1.
93 to the inverting input of the operational amplifier 192. An oscillation prevention capacitor 196 is inserted between the collector and base of the transistor 194. Further, the collector of the transistor 194 is connected to one end of the coil of the proportional solenoid 14 as an output of the drive circuit 18. The other end of the coil of the proportional solenoid 14 is connected to the positive terminal of the battery via a key switch. Note that the constant voltage Vc supplied to each circuit and the power supply voltage of each operational amplifier at the ground terminal are well known and are therefore omitted.

To explain its operation with the above configuration, the second output V _Z of the control circuit 16 having the waveform shown in FIG. 5c is applied to the input terminal 180, while the input terminal
A first output U/D of the control circuit 16 having a waveform shown in FIG. 5A is applied to 81. Resistor 186 and resistor 187 have the same resistance value, and resistor 189 and resistor 190 also have the same resistance value. Resistor 186 and Resistor 1
The circuit configuration of 90 and operational amplifier 188 operates as a generally known differential amplifier circuit. Now terminal 181
When the first output U/D of the control circuit 16 input to the inverter is at a high level, that is, "1", the first analog switch 183 is turned on, and the output of the inverter 184 is at a low level, that is, "0", and the second analog switch 185 is turned off. becomes. Therefore resistance 186
Since one end of the voltage becomes O(V), the output voltage of the operational amplifier 188 becomes V _Z (v). Next, when the U/D signal is "0", the first analog switch 183
It becomes OFF and the second analog switch 185 becomes ON. Now, if the voltage at the variable terminal of the variable resistor 182 is △V (v), one end of the resistor 186 has △V
(v) is applied, so the output voltage of the operational amplifier 188 becomes [V _Z −ΔV](v). Therefore U/D
When the signal is “1”, V _Z , when the signal is “0” [V _Z −△
V] voltage as the output of the hysteresis removal circuit. Next is the current amplification circuit 19, which causes a current proportional to the voltage applied to one end of the resistor 191 to flow through the collector of the transistor 194. Since this is a generally known constant current circuit, detailed explanation will be omitted.

To explain the overall operation of the drive circuit 17, when increasing the opening area of the proportional solenoid 14,
In other words, in the case of UP, the drive current of the proportional solenoid 14 becomes a current proportional to V _Z , and when the opening area of the proportional solenoid 14 is decreased, that is, in the case of DOWN, the drive current of the proportional solenoid 14 becomes [V _Z - △V ]
The current is proportional to , as shown in FIG. 5D. In this case, the hysteresis of the proportional solenoid 14 can be almost eliminated by making the voltage ΔV correspond to the hysteresis current i ₀ explained in FIG.

In the embodiment, the case where the current flowing through the proportional solenoid 14 increases is taken as a standard, and when it decreases, io is subtracted to eliminate hysteresis, but conversely, the case where the current decreases is taken as a standard and increases. It is clear that in some cases, hysteresis can be eliminated by adding io.

As described above, the present invention includes a hysteresis removing means that generates a signal obtained by adding or subtracting a value corresponding to the frictional force of the sliding portion of the proportional solenoid to a control signal in order to control the displacement amount of the proportional solenoid;
The present invention is characterized by comprising a current amplifying means for supplying a current having a value corresponding to the output voltage of the means to the proportional solenoid, and the proportional solenoid that is generated when the drive (supply) current of the proportional solenoid is increased or decreased. This has the excellent effect of compensating for solenoid hysteresis.

Furthermore, in the present invention, the current supplied to the proportional solenoid is changed stepwise in a staircase waveform.
This has the effect of improving the responsiveness of the displacement of the sliding portion of the proportional solenoid.

[Brief explanation of the drawing]

Fig. 1 is a structural diagram of the proportional solenoid used in the present invention, Fig. 2 is a characteristic diagram of the proportional solenoid shown in Fig. 1, Fig. 3 is a configuration diagram showing an embodiment of the present invention, and Fig. 4 is a structural diagram of the proportional solenoid used in the present invention. Electrical diagram of the control circuit shown in Figure 5
This figure is an explanatory diagram of the operation of the control circuit shown in FIG. 4 and the drive circuit shown in FIG. 6, and FIG. 6 is an electric circuit diagram of the drive circuit shown in FIG. 3. 14... Proportional solenoid, 145... Spool forming a sliding part, 16... Control circuit, 18... Hysteresis removal circuit, 19... Current amplification circuit.

Claims (1)

[Scope of Claims] 1. A device for driving a proportional solenoid that is displaced in accordance with a supplied current, the proportional solenoid being biased in a predetermined direction by a spring and having a movable part that can slide relative to a fixed part. and a coil that generates a magnetomotive force that displaces the movable part in proportion to a control signal that changes to various values, and the movable part is connected to the control signal for controlling the amount of displacement of the movable part. and a hysteresis removing means for generating a signal obtained by adding or subtracting a signal value corresponding to the frictional force of the sliding part between the fixed part and the fixed part, and a current for supplying a current to the coil with a value corresponding to the output signal of this means. and an amplifying means, when the movable part is displaced against the biasing force of the spring, the current supplied to the coil is increased by an amount corresponding to the frictional force, compared to when the movable part is displaced in the direction of the biasing force of the spring. A proportional solenoid drive device characterized by increasing the size of the proportional solenoid. 2 A device that drives a proportional solenoid that is displaced in accordance with a supplied current, which has a movable part that is biased in a predetermined direction by a spring and can slide relative to a fixed part, and a movable part that can be moved to various values. and a coil that generates a magnetomotive force that displaces the movable part in proportion to a changing control signal, and calculates a control amount for controlling the amount of displacement of the movable part at every predetermined period, and uses this calculated value as the a control means that generates a corresponding step-wave control signal; and a hysteresis remover that generates a signal obtained by adding or subtracting a signal value corresponding to the frictional force of the sliding part between the movable part and the fixed part to the control signal. and current amplification means for supplying a current to the coil with a value corresponding to the output signal of the removing means, and when the movable part is displaced against the biasing force of the spring, the biasing force of the spring is increased. A proportional solenoid drive device characterized in that the current supplied to the coil is made larger by an amount corresponding to the frictional force than when the coil is displaced in the direction.