JPS5837708A - Position controller - Google Patents

Abstract

PURPOSE:To keep the accuracy of position control for a long time stably, by performing the position control of a body to be controlled taking an output of a position detector as a reference value, when a relative needle position has consecutive zero state for a prescribed time or longer. CONSTITUTION:A power supply detection circuit 303 provides an output for a prescribed time after the application of power supply. A switching circuit 301 transmits an initial value R0 to a latch circuit 302 during this output and gives an output of an A/D converter 31 to the latch circuit 302 during the stop of the output. The initial value R0 is equal to a value A/D-converting an output value of a variable resistor 2 at the time when a needle 11 is fully closed. The latch circuit 302 receives an output of the detection circuit 303, stores the output value of the swithing circuit 301 just before, i.e. the R0 and takes the value as a reference value at the time when the needle 11 is fully closed. An operation circuit 32 operates a relative needle position and applies the result to the addition circuit 33. The addition circuit 33 outputs the sum of the output values of the circuits 32 and 302 to a comparison circuit 34 as an objective needle position.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a position control device suitable for controlling the needle position of a variable orifice that controls the amount of exhaust gas recirculation in an internal combustion engine.The position control device can be applied in various fields. It is a common control device, and there are various types.

FIG. 1 is a configuration diagram showing a gGR amount control device in which a conventional position control device is applied to needle position control of a variable orifice that controls the amount of exhaust gas recirculation (hereinafter abbreviated as EGTL) in an internal combustion engine. In this figure, reference numeral 1 includes a needle 11 as a position controlled body, a diaphragm chamber 12, a control negative pressure input part 13, an inlet 14 for introducing exhaust gas, and an output port connected to an intake manifold. This is a variable orifice that controls the amount of EGR. 2 is a position detector that converts and detects the position (mechanical position) of the needle 11 into an electrical signal; here, it is a variable resistor whose movable terminal is provided to interlock with the needle 11;

3 is a position control device, which includes the variable resistor 2 and the A/D converter 3.
1. Arithmetic circuit 32 for computing the target position, addition circuit 33,
It includes a comparison circuit 34 and a drive circuit 35. 4 is a reference power line, 51 and 52 are electromagnetic valves, and 6 is a negative pressure source.

That is, in the above device, the variable orifice 1 moves the needle 11 in proportion to the magnitude of the negative pressure in the diaphragm chamber 12.
Since the position of the needle 11 and the amount of EGR are in a proportional relationship, the magnitude of the negative pressure in the diaphragm chamber 12 is controlled to control the position of the needle 11.
The position of the needle 11 is variable, with one end to which the KA/DA/D converter voltage is applied via the reference power supply I14, and the other end grounded. It is converted into a voltage signal by resistor 2, and A/
In this case, the relationship between the position of the needle 11 and the output voltage of the variable resistor 21 is a linear equation as shown in Figure @2, and when the position of the needle 11 is zero, that is, fully closed. At this time, the output voltage of the variable resistor 2 is V in FIG.

5, the relationship between the position of the needle 11 and the position of the movable terminal of the variable resistor 2 is adjusted in advance.

The A/D converter 31 converts the output voltage of the variable resistor 2 into a digital value and outputs the digital value to the comparison circuit 34.

On the other hand, the calculation circuit 32 calculates the position of the needle 11 such that the optimum EGR amount for each operating condition can be obtained from the engine rotation speed, cooling water temperature, etc. Result (relative needle target position when the position of the needle 11 when the needle 11 is fully closed is set to zero)
In this case, when the input parameters POs Pl and PR-Pa are analog voltages, A/D conversion is performed and the result b is input to the arithmetic circuit 32 .

Further, this arithmetic circuit 32 is composed of, for example, a microcomputer.

The adder circuit 33 corresponds to the output voltage V''OKOK of the variable resistor 2 when the needle 11 is fully closed as shown in FIG.

is the reference value (needle 11 reference position) and the arithmetic circuit 32
In addition to the output value of , that value is outputted to the comparator circuit 34 as the absolute target needle position (hereinafter referred to as target needle position) of the needle 11. This comparison circuit 34 is an addition circuit 33
The output value of the A/D converter 31 is compared with the output value of the A/D converter 31, and control signals for the solenoid valves 51 and 520 are generated according to the difference between these two input signal values.

FIG. 3 is a diagram for explaining the operation of such a comparison circuit 34, and the horizontal axis represents the output value of the addition circuit 33 and the A/D converter 3.
In other words, it shows the difference between the target needle position and the actual needle position.

Further, the large shaded area indicates a range where the position of the needle 11 has not reached the target needle position, and in this area A, the comparison circuit 34 sends an output signal to the drive circuit 35 to operate the solenoid valve 52. Therefore, the solenoid valve 52
is driven. At this time, the solenoid valve 51 is not driven, and as a result, the negative pressure of the negative pressure source 6 is guided to the diaphragm chamber 12, and the needle 11 is controlled to be raised toward the target needle position. The areas shown by +D and -D are dead zones, and are areas where it is determined that the position of the needle 11 matches the target needle position, and the solenoid valves 51 and 52 are not driven in this area. Region B indicates the range in which the position of the needle 11 exceeds the target needle position. In this region B, the comparator circuit 34 sends an output signal to the drive circuit 35 to operate the solenoid valve 51, Therefore, the solenoid valve 51 is driven. At this time, the solenoid valve 52 is not driven, and one side of the solenoid valve 51 is open to the atmosphere, so the atmosphere is introduced into the diaphragm chamber 12, and the needle 11 is controlled to be lowered toward the target needle position. be done.

After the above 5K, A/D converter 31 and adder circuit 3
The position is controlled so that the difference between the two input signal values of No. 3 falls within the dead zone (10D, -D), and the optimum EGR amount can be obtained.

However, in the conventional device 3 described above, the value BLo corresponding to the output voltage Vo of the variable resistor 2 when the needle 11 is fully closed is set as a reference value (needle 11 reference position) and added to the output value of the arithmetic circuit 32 in the adder circuit 33. However, since the output voltage To has been adjusted in advance, it contains an adjustment error, and this adjustment error appears as a control error. Furthermore, the reference position that has been adjusted in advance also fluctuates due to aging, and the output voltage Vo may change, making it extremely difficult to maintain the initial accuracy for a long period of time.

This invention solves the above problem by storing the output signal of the position detector when the relative needle target position remains zero for a predetermined period of time or more, and controlling the position of the position controlled object using this value as a reference value. The purpose of the present invention is to provide a position control device that eliminates the problem.

The present invention will be described in detail below with reference to FIG. Fourth
The figure shows that the position control device according to the present invention is used in an internal combustion engine.
FIG. 4 is a configuration diagram showing an example of an EGR amount control device applied to needle position control of a variable orimeter that controls the GR amount; in FIG. 4, the same reference numerals as in FIG. 1 indicate the same or corresponding parts.

In the figure, 301 is a switching circuit, 3o2 is a two-way circuit, and 3o2 is a two-way circuit.
03 is a power-on detection circuit, 304 is an OR circuit, 305 is a time circuit, and 306 is a zero detection circuit.

That is, the power-on detection circuit 303 generates the output signal for a predetermined period of time, for example, one second or less, from the time when the power is turned on to the position control device 3. The switching circuit 301 selects the initial value Ro and sends it to the latch circuit 302 while the power-on detection circuit 303 is generating an output signal, and
While the output signal is stopped, the output signal of the A/D converter 31 is selected and sent to the latch circuit 302. Here, the initial value Ro is equal to the value obtained by A/D converting the output value of the variable resistor 2 when the needle 11 is fully closed.

However, when the needle 11 is in the fully closed position, the A/D conversion result of the output value of the variable resistor 2 may be different from the initial value Ro, but even in this case, the value is close to the initial value Ro. , Also, as described later, immediately after starting the control,
Since the output value of the A/D converter 31 when the needle 11 is fully closed is stored in the latch circuit 302, its influence can be ignored.

The latch circuit 302 receives the output signal of the power-on detection circuit 303 via the OR circuit 304, stores the output value of the switching circuit 301 immediately before the output of the signal stops, that is, Ro, and stores that value when the needle 11 This is the reference value when fully closed. Further, the calculation circuit 32 calculates the above-mentioned relative needle position and applies it to the addition circuit 33. The adder circuit 33 outputs the sum of the output values of the arithmetic circuit 32 and the latch circuit 302 to the comparator circuit 34 as a target needle position. Hereinafter, the point that the position of the needle 11 is controlled to be the target needle position is the same as in the case of FIG. 1.

On the other hand, the zero detection circuit 306 generates an output signal when the output value of the arithmetic circuit 32 is zero, and sends the signal to the time circuit 305. The time circuit 305 applies an output signal to the latch circuit 302 via the OR circuit 304 only when the zero detection circuit 306 continues to generate the output signal for a continuous predetermined period of time. Further, the switching circuit 301 is connected to the power-on detection circuit 30.
After 3 stops the output signal, the output signal of the A/D converter 31 is selected and applied to the latch circuit SO2, so the latch circuit 302 selects the output signal of the A/D converter 31 and applies it to the latch circuit SO2. The output value of the converter 31, that is, the output value of the human/D converter 31 when the needle is fully closed is stored. below,
The target needle position is calculated using the stored value of the latch circuit 302 as the value when the needle 11 is fully closed, and the position of the needle 11 is controlled to become the target needle position in the same manner as the conventional device shown in FIG.

Here, the set time of the time circuit 305 is set to be longer than the time required for the needle 11 to reach the fully closed position from the fully open position. Immediately after the power of the position control device 3 is turned on, the initial value RO is used as a reference value until the output value of the arithmetic circuit 32 becomes zero, but generally the opportunity to reduce the EGR amount to zero is when the EGR control is started. After that, it can occur within a short time, so the period of using the initial value Ro is extremely short and does not pose a problem.

In the above-mentioned embodiment, a case has been described in which the present invention device is applied to the needle position control of a variable orifice that controls the amount of EGR in an internal combustion engine, but the invention is not limited to this, and the present invention is not limited to this. It goes without saying that the device of the present invention can be applied to any position control system equipped with a position detector that converts into electrical signals.

Further, in the above embodiment, the reference position of the needle 11 is set to the fully closed position of the needle 11, but the present invention is not limited to this. Furthermore, the latch circuit 302
can be either volatile or non-volatile; however, in the case of non-volatile, the power-on detection circuit 30
3 and the switching circuit 301 are unnecessary. Furthermore, the same effect can be obtained by comparing the value obtained by subtracting the contents of the latch circuit 302 from the output signal of the A/D converter 31 with the output value of the arithmetic circuit 32 using the comparator circuit 34.

As described above, according to the present invention, the output signal of the position detector when the relative needle position remains zero for a predetermined period of time or more is stored, and this value is used as the reference value. This eliminates the need to adjust the positional relationship between the controlled object and the position detector, and furthermore, since the positional relationship is not affected by changes over time, position control accuracy can be maintained stably for a long period of time. The effect is that it can be done.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the structure of an example of an EGR amount control device for an internal combustion engine to which a conventional device is applied; Fig. 2 is a graph showing the relationship between the position of the needle and the output voltage of the variable resistor in Fig. 1; 3 is a diagram for explaining the operation of the comparison circuit in FIG. 1, and FIG. 4 is an EGR amount control in which the position control device according to the present invention is applied to needle position control of a variable orifice that controls the BGR amount of an internal combustion engine. FIG. 1 is a configuration diagram showing an example of a device. DESCRIPTION OF SYMBOLS 1... Variable oriice, 11-Needle (position controlled object), 2... Variable resistor (position detector), 3--Position control device, 31-A/D converter, 32--Arithmetic circuit, 33
- addition circuit, 34 - comparison circuit, 35 - drive circuit, 301
--Switching circuit, 302--Latch circuit, 303--
Power-on detection circuit, 304-OR circuit, 30 B-...
Time circuit, 306--Zero detection circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Makoto Kuzuno - Figure 1 Figure 4

Claims (1)

[Claims] a position detector that converts and detects the horizontal position of the positionally controlled body into an electrical signal; a calculation means that calculates the amount of displacement of the positionally controlled body from the reference position; A reference value detection means detects that the value is the reference value corresponding to the reference position and outputs a signal, and the reference value detection means outputs a signal indicating that the calculation result is the reference value for a continuous predetermined period of time. and a reference position storage means for storing the output value of the position detector at the time detected by the time measurement means, and the memory value of the storage means is A position control device that controls the position of the position-controlled body using a reference value.