JPH03181664A - Speed control device of mechanical type continuously variable transmission - Google Patents

Abstract

PURPOSE:To avoid repeating operation of unexpected speed increase or speed decrease and also to improve the responsiveness of speed control by drive-controlling a transmission means responding to the output of comparison between the deflection voltage and the correcting standard voltage, and the polarity of the deflection voltage. CONSTITUTION:An AC component included in a deflection voltage between a speed setting voltage c and a speed detection voltage b is picked up by an AC component picking up means 9, and the resultant AC component voltage h is added to a standard voltage e1 for normal rotational direction or a standard voltage e2 for the reverse rotational direction through an adding means 10. The resultant corrected standard voltage g1 or g2 is compared with the deflection voltage d in a comparison means 7, and a transmission means 1 is driven in response to the comparison output f and the polarity of the deflection voltage. In this case, even though the rotation of the mechanical type continuously variable transmission 2 is at a low speed, the deflection voltage d is always within the insensible band owing to the corrected voltage g1 or g2, as far as the corrected standard voltage g1 or g2 is converted followingly, and the rotation speed is within the insensible range. As a result, the repeating operation of unexpected speed increase or speed decrease can be avoided even though a detecting means 3 in which the pulse number of one rotation is small is used.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a speed control device for a mechanical continuously variable transmission, and in particular to a speed control device that uses a magnetic sensor or the like as a speed detection means with a small number of pulses per rotation. It relates to things that use things.

<Prior Art> FIG. 7 is a block diagram of a conventional speed control device for a mechanical continuously variable transmission.

The speed change means 1 mechanically changes the speed of the mechanical continuously variable transmission 2. A reversible motor (forward/reverse motor) is used as the speed change means l, and when it stops, the rotational speed of the mechanical continuously variable transmission 802 is fixed at a certain speed, and when it rotates in the forward direction, the speed change member is moved in the forward direction, thereby changing the speed of the machine. The rotational speed of the mechanical continuously variable transmission 192 is increased, and the speed change member is moved in the negative direction by reversing the rotational speed, thereby decelerating the rotational speed of the mechanical continuously variable transmission 2.

The speed detection means 3 outputs a frequency signal a proportional to the rotation speed of the mechanical continuously variable transmission 2. As the speed detecting means 3, a magnetic sensor is used which is provided opposite to a gear attached to the output shaft 4 of the mechanical continuously variable transmission@2. The magnetic sensor detects the passage of gear teeth one by one as the output shaft 4 rotates, and the faster the rotation speed, the higher the frequency of the frequency signal a. This frequency signal a becomes a sine wave.

The frequency-voltage conversion means 5 converts the frequency signal a into a speed detection voltage, and the frequency signal a is at the "H" level during the positive half-wave period and at the 'L' level during the negative half-wave period. A waveform shaping circuit that outputs a rectangular wave, a monostable multivibrator that generates a rectangular wave with a constant pulse width based on the rising and falling timing of the output waveform of this waveform shaping circuit, and a monostable multivibrator that smooths the output waveform of the monostable multivibrator. The higher the frequency of the frequency signal a, which is a sine wave, the higher the level of the speed detection voltage becomes.
And the AC bones become smaller.

The deviation amplification means 6 generates a speed setting voltage C proportional to the set speed for the mechanical continuously variable transmission 82 and a frequency voltage conversion means 5.
Amplify the difference between the manually generated speed detection voltage d and the deviation voltage d
This is what is output as. The deviation voltage d can be expressed as d=cb if the amplification factor is omitted.

The comparison means 7 has a reference voltage eI for forward rotation which is a positive voltage and a reference voltage e for reverse rotation which is a negative voltage. It compares the reference voltage e2 for reversal and outputs a comparison output f. The above reference voltage e1 for forward rotation ultimately becomes a reference for speed increase for the mechanical continuously variable transmission 1)2, and the reference voltage e2 for reverse rotation ultimately serves as a reference for deceleration for the mechanical continuously variable transmission 2. becomes. The comparison output f is e
, ≦d≦e1, the output is zero, when d>el, the output is positive, and when d<ez, the output is negative. The range of e, ld≦e1 becomes a dead zone.

The driving means 8 manually receives the comparison output f from the comparison means 7,
When the output is zero, the transmission means 1 is stopped, when the output is positive, the transmission means 1 is driven to rotate in the forward direction, and when the output is negative, the transmission means 1 is driven in the reverse direction.

■ When the rotational speed of the mechanical continuously variable transmission 20 is at the set speed or sufficiently close to it, the deviation voltage d between the speed detection voltage and the speed set voltage C is small, and e2≦d.
When ≦e (in the dead zone), the comparison output f becomes zero output, so the drive means 8 stops the transmission means 1, and the transmission member in the transmission means 1 also stops. Therefore, no speed change control is performed on the mechanical continuously variable transmission fi2, and the rotational speed of the mechanical continuously variable transmission [2 remains unchanged.

■ When the rotational speed of the mechanical continuously variable transmission 2 becomes considerably slower than the set speed, the speed detection voltage also decreases accordingly, and the deviation voltage d between the speed detection voltage and the speed setting voltage C (= c-b) increases to the positive side and exceeds the reference voltage e1 for forward rotation, which is the upper limit of the dead zone, resulting in die.As a result, the comparison output f becomes a positive output, and the drive means 8 drives the transmission means 1 for forward rotation. Then, the speed change member is moved in the forward direction to increase the rotational speed of the mechanical continuously variable transmission 2. This speed increase control is performed until the deviation voltage d returns to the dead zone (e, ≦d≦6+), and when the deviation voltage d returns to the dead zone, the same state as (■) occurs and the speed increase control stops.

■ When the rotational speed of the mechanical continuously variable transmission 2 becomes much faster than the set speed, the speed detection voltage also increases accordingly, and the deviation voltage d between the speed detection voltage and the speed setting voltage C (= c-b) increases to the negative side and becomes lower than the reference voltage eg for reversal which is the lower limit of the dead zone, and d<e
As a result, the comparison output f becomes a negative output, and the driving means 8
drives the speed change means l in the reverse direction to move the speed change member in the negative direction to reduce the rotational speed of the mechanical continuously variable transmission 2. This deceleration control is performed until the deviation voltage d returns to the dead zone (ex≦d≦e+), and when the deviation voltage d returns to the dead zone, the same state as (2) occurs and the deceleration control stops.

<Problems to be Solved by the Invention> In order to improve the responsiveness of the speed control of the mechanical continuously variable transmission 2, it is desirable to make the time constant of the frequency-voltage conversion means 5 as small as possible. As will be explained, when a magnetic sensor is used as the speed detection means 3, the time constant of the frequency-voltage conversion means 5 cannot be made very small.

When the speed setting voltage C is set high and the rotational speed of the mechanical continuously variable transmission 2 is high, the frequency signal a from the speed detection means 3 has a high frequency. In this case, when the rotational speed of the mechanical continuously variable transmission 1) 2 is at or near the set speed, the high-frequency frequency signal a is transmitted to the frequency-voltage conversion means 5, as shown in FIG. 8(a). Since the frequency signal a is high in frequency, the speed detection voltage S converted by is contains an alternating current component with a small amplitude, but as is clear from the above explanation, it has a dead zone (et ≦d≦e+>
It's in. Therefore, the mechanical continuously variable transmission 2 maintains a high-speed rotational state at a stable rotational speed at or near the set speed.

However, when the speed setting voltage C is set low and the rotational speed of the mechanical continuously variable transmission 1) 2 is slow, the frequency signal a from the speed detection means 3 has a low frequency.

In this case, when the rotational speed of the mechanical continuously variable transmission 2 is at or near the set speed, the frequency signal a of a low frequency is transmitted to the frequency-voltage conversion means 5 as shown in FIG. 8(b). The converted speed detection voltage is the frequency signal a
Since the frequency is low, it includes an alternating current component with a large amplitude.

In this case, even though the rotational speed of the mechanical continuously variable transmission 20 is at or near the set speed, the deviation voltage d is out of the dead zone (e!≦d≦e).

That is, when the deviation voltage d exceeds the normal rotation reference voltage e, which is the upper limit of the dead band, and d>e, the comparison output f becomes a positive output, and the mechanical continuously variable transmission 2 On the contrary, when the deviation voltage d is lower than the reference voltage e8 for reversal which is the lower limit of the dead zone and d<eg, the comparison output f becomes a negative output, and the mechanical idler Gear shift I! 2 is decelerated, and such speed increase and deceleration are repeated, resulting in a very unstable rotational speed.

However, since the rotational speed of the mechanical continuously variable transmission 2 was originally at or near the set speed, the speed increase or deceleration described above should not occur.

In order to avoid such inconvenience, the speed detection means 3
The frequency of the frequency signal a is increased by increasing the number of teeth of the gear attached to the output shaft 4 of the mechanical continuously variable transmission 2, facing the magnetic sensor that constitutes the magnetic sensor. It is considered that the amplitude of the alternating current component included in the above should be reduced.

However, since magnetic sensors convert changes in magnetic flux into voltage when the teeth of a gear pass one by one, each tooth must be made a certain size large. There is a limit on the number of teeth, and it is not possible to increase the number of teeth beyond the - window.

Therefore, as another measure to avoid the above-mentioned inconvenience, it is conceivable to set the time constant of the frequency-voltage conversion means 5 to a large value. In this way, when the rotational speed of the mechanical continuously variable transmission 2 is at or near the set speed, and when the set speed is set high, the deviation voltage d will be reduced by the AC component as shown in FIG. 9(a). In addition, even when the set speed is set low, the deviation voltage d has a small amplitude AC component as shown in Figure 9(b), resulting in a dead zone (6g≦d5e+). It will fit inside.

For the above reasons, in the conventional speed control device for a mechanical continuously variable transmission, the time constant of the frequency-voltage conversion means 5 is set to be large.

However, if the time constant of the frequency-voltage conversion means 5 is set large, the responsiveness of the speed control of the mechanical continuously variable transmission 812 will be sacrificed. In the past, this was considered unavoidable, but poor responsiveness means that it takes a long time to control the speed change, which is not at all desirable.

The present invention was devised in view of the above circumstances, and is a method of frequency-voltage conversion in order to improve the responsiveness of speed control of a mechanical continuously variable transmission and shorten the time required for speed change control. Assuming that the time constant of the means is set small,
However, even if a large alternating current component occurs in the deviation voltage from the frequency-voltage conversion means when the rotational speed of the mechanical continuously variable transmission is low and at or near the set speed, the reference voltage for forward rotation and the reference voltage for reverse rotation It is an object of the present invention to prevent a reference voltage from being exceeded and to prevent unexpected repeated speed increases and decelerations in a rotational state at or near a set speed.

<Means for Solving the Problems> In order to achieve the above object, the present invention has the following configuration.

That is, the speed control device for a mechanical continuously variable transmission of the present invention includes a speed change means for changing the speed of the mechanical continuously variable transmission, and a speed control device provided in the output system of the mechanical continuously variable transmission. speed detection means for outputting a frequency signal proportional to the rotational speed of the mechanical continuously variable transmission; a frequency-voltage conversion means having a small time constant for converting the frequency of the frequency signal into a speed detection voltage; deviation amplification means for amplifying the difference between the proportional speed setting voltage and the speed detection voltage and outputting it as a deviation voltage; an addition means for adding the AC voltage from the dispensing means and a reference voltage and outputting the result as a corrected reference voltage; a comparison means for comparing the deviation voltage and the correction reference voltage; and a comparison output of the comparison means; and drive means for driving and controlling the speed change means according to the comparison output of the comparison means and the polarity of the deviation voltage.

<Effect> The effects of the above configuration of the present invention are as follows.

The AC dispensing means extracts the AC component included in the deviation voltage or the speed detection voltage and supplies it to the addition means as an AC voltage, and the addition means adds the base*ii pressure and the AC voltage to determine the correction standard. A mechanical continuously variable transmission Even if the rotational speed is low and at or near the set speed within the dead zone, and the amplitude of the AC component included in the deviation voltage or speed detection voltage increases, the correction reference voltage will change accordingly, and the rotational speed will change. As long as is within the dead zone, the deviation voltage will always fall within the dead zone due to the corrected reference voltage.

Therefore, even if a speed detection means such as a magnetic sensor with a small number of pulses per rotation is used, the time constant of the frequency-voltage conversion means may be set small so that the deviation voltage will contain an alternating current of large amplitude in a low speed rotation state. Despite this, unexpected repeated operations of acceleration and deceleration can be avoided.

<Example> Hereinafter, an example of the present invention will be described in detail based on the drawings.

Village 1 large cliff group 1)! I is a block diagram of a speed control device for a mechanical continuously variable transmission according to a first embodiment of the present invention.

In FIG. 1, 1 is a speed change means for mechanically changing the speed of the mechanical continuously variable transmission 2, and 3 is a speed detection device that outputs a frequency signal a (sine wave) proportional to the rotational speed of the mechanical continuously variable transmission 2. Means 5 is a frequency-voltage conversion means for converting the frequency signal a into a speed detection voltage S; 6 is amplification of the difference between the speed setting voltage C proportional to the set speed for the mechanical continuously variable transmission 2 and the speed detection voltage S; 8 is a drive means for controlling the speed change means 1 based on the comparison output r from the comparison means 7.

The frequency-voltage conversion means 5 is a waveform shaping circuit that outputs a rectangular wave of "H" level during the positive half-wave period of the frequency signal a and "L" level during the negative half-wave period, as in the conventional example. , consists of a monostable multivibrator that generates a rectangular wave with a constant pulse width from the rising and falling timing of the output waveform of this waveform shaping circuit, and a smoothing circuit that smoothes the output waveform of the monostable multivibrator. There is.

Transmission means 1 for mechanically shifting the mechanical continuously variable transmission 41) 2
is composed of a reversible motor (forward/reverse motor), and when the reversible motor stops, the rotational speed of the mechanical continuously variable transmission 2 is fixed at a certain speed, and when the reversible motor rotates forward, the transmission member is moved in the forward direction. The rotational speed of the mechanical continuously variable transmission 2 is increased, and the speed change member is moved in the negative direction by reverse rotation of the reversible motor to reduce the rotational speed of the mechanical continuously variable transmission 2.

The speed detection means 3 includes a magnetic sensor (not shown) provided opposite to a gear (not shown) attached to the output shaft 4 of the mechanical continuously variable transmission 2. This magnetic sensor converts the change in magnetic flux when the teeth of a gear pass one by one into voltage, but the number of teeth on the gear is small, about 60, and despite this, it is difficult to convert frequency to voltage. The time constant of the means 5 is set to be small.

In addition to the above-mentioned means, there is also an AC dispensing means 9 which is composed of a bypass filter that allows only the AC component of a certain frequency or higher to pass from the deviation voltage d, and an AC component voltage from the AC dispensing means 9. By adding the positive reference voltage e for forward rotation, the corrected reference voltage g+ (-el
+h), and an addition means lO which adds a negative reference voltage e2 for reversal to the AC component voltage and outputs a corrected reference voltage gt (at +h) for reversal for the transmission means l.

The comparison means 7 receives the deviation voltage d input from the deviation amplification means 6.
The normal rotation correction reference voltage g1 and the reverse rotation correction reference voltage gt from the adding means 10 are compared. The comparison output f from the comparison means 7 is g! When ≦d≦g, the output is zero, when dig, the output is positive, and when d<gz, the output is negative.0gt≦d≦g1
The range becomes a dead zone. The drive means 8 inputs the comparison output f from the comparison means 7, sets the transmission means 1 to a stopped state when it is a zero output, drives the transmission means 1 in forward rotation when it is a positive output, and drives the transmission means 1 in forward rotation when it is a negative output. The transmission means 1 is driven in the reverse direction.

Next, the operation of this first embodiment will be explained.

[1] Speed increase control When the rotational speed of the mechanical continuously variable transmission 2 becomes considerably slower than the set speed, the speed detection voltage decreases accordingly, and the speed detection voltage becomes the speed setting voltage C. deviation voltage d
(= c - b) increases to the positive side and is the upper limit of the dead zone, which is the reference voltage e for forward rotation.

exceeds.

Therefore, the corrected reference voltage g for normal rotation from the addition means 10, which is the sum of the AC component voltage from the AC dispensing means 9 and the reference voltage e1 for normal rotation, is g,<d, and the comparison output by the comparison means 7 f becomes a positive output, and the driving means 8 drives the transmission means 1 to rotate in the normal direction, moving the transmission member in the forward direction, and increasing the rotational speed of the mechanical continuously variable transmission 2. This speed increase control is performed until the deviation voltage d returns to the dead zone (ex=gz≦d≦g+=8+), and when it returns to the dead zone, the speed increase control is stopped.

Since the time constant of the frequency-voltage conversion means 5 is made small, the mechanical continuously variable speed I! 2, and the time required to stabilize the rotational speed of the mechanical continuously variable transmission 2 to or near the set speed is sufficiently short.

[2] Deceleration Control Mechanical Continuously Variable Transmission 1) When the rotational speed of 2 becomes considerably faster than the set speed, the speed detection voltage also increases accordingly, and the speed detection voltage and the speed setting voltage C increase. The deviation voltage d (=c-b) increases to the negative side and becomes lower than the reversal reference voltage et, which is the lower limit of the dead zone.

Therefore, the corrected reference voltage gt for reversal from the addition means 10, which is the sum of the AC component voltage from the AC dispensing means 9 and the reference voltage for reversal e, is g,<d, and the comparison output by the comparison means 7 f becomes a negative output, and the driving means 8 drives the transmission means 1 in the reverse direction to move the transmission member in the negative direction, thereby decelerating the rotational speed of the mechanical continuously variable transmission 812. This deceleration control is performed until the deviation voltage d returns to the dead zone, and when it returns to the dead zone, the deceleration control is stopped.

In this case as well, since the time constant of the frequency-voltage conversion means 5 is small, the responsiveness of deceleration control for the mechanical continuously variable transmission 2 is good, and the rotation speed of the mechanical continuously variable transmission 1) 2 is set at or below the set speed. The time required to stabilize up to the vicinity is sufficiently short.

[3] Mechanical continuously variable transmission 1 as described in [1] and [2] above for stability control.
) 2 will settle at or near the set speed. In other words, the speed detection voltage C and the speed setting voltage C
The deviation voltage d is small and falls into the dead zone (ex≦d≦et). However, even if it is in the dead zone, the frequency-voltage conversion means 5 smooths the output waveform of the monostable mano-5 vibrator in which a rectangular wave with a constant pulse width is intermittent, so the speed detection signal is Contains minutes.

The higher the rotational speed of the mechanical continuously variable transmission 2, the smaller the alternating current, and the lower the rotational speed of the mechanical continuously variable transmission 2, the larger the alternating current.

Hereinafter, the operation of the stability control will be explained separately for the case where the mechanical continuously variable transmission 2 is in a high speed rotation state and the case where it is in a low speed rotation state.

ia+ High-speed rotation state Suppose that the speed setting voltage C is set high and the mechanical continuously variable transmission 2 is in a high-speed rotation state, and the rotation speed is at or near the set speed (dead zone). 3, the frequency of the frequency signal a (sine wave) is high,
The amplitude of the alternating current component included in the speed detection signal converted into voltage by the frequency-voltage conversion means 5 is small.Since the speed setting voltage C set high in the deviation amplification means 6 is constant, this and the speed detection voltage The alternating current component of the deviation voltage d resulting from amplifying the difference between the current and the current has a small amplitude as shown in FIG. 2(a).

The alternating current component of this deviation voltage d is extracted by the alternating current dispensing means 9 to become an alternating current component voltage, which is input to the adding means lO. The adding means 10 adds the alternating current voltage to the normal rotation reference voltage e and outputs a normal rotation correction base, and also adds the reverse rotation reference voltage and the reverse rotation correction reference voltage to output the reverse rotation correction reference voltage. The corrected reference voltage g+ for forward rotation and the corrected reference voltage g for reverse rotation have an alternating current component with the same amplitude as the alternating current component voltage. However, since the amplitude of the alternating current component included in the speed detection signal is small, the alternating current component included in the deviation voltage d is also small, and similarly, the alternating current component included in the forward rotation correction reference voltage g+++reverse rotation correction reference voltage g is also small. small.

As is clear from FIG. 2(a), the mechanical continuously variable transmission 41
) 2 is in a high-speed rotation state and the rotation speed is at or near the set speed, the deviation voltage d is the normal rotation correction reference voltage g
1 and the correction reference voltage g2 for reverse rotation <e* +
h=gt≦d≦g+=eI+h).

Therefore, the mechanical continuously variable transmission 2 maintains a high-speed rotational state at a stable rotational speed at or near the set speed.

(bl Low speed rotation state Suppose that the speed setting voltage C is set low and the mechanical continuously variable transmission 2 is in a low speed rotation state, and the rotation speed is at or near the set speed (dead zone). In this case, The frequency of the frequency signal a from the speed detection means 3 is low, and the amplitude of the alternating current component included in the speed detection signal obtained by converting the frequency signal a into a voltage by the frequency-voltage conversion means 5 is large, and the speed is set low in the deviation amplification means 6. Since the voltage C is constant, the AC component of the deviation voltage d resulting from amplifying the difference between this voltage and the speed detection voltage S also has a large amplitude as shown in FIG. 2(b).

However, the alternating current component of this deviation voltage d is extracted by the alternating current dispensing means 9 and becomes an alternating current voltage, which is included in the corrected reference voltage gI for forward rotation and the corrected reference voltage g for reverse rotation created by the adding means 10. The amplitude of the alternating current component also increases in accordance with the deviation voltage d.

Therefore, as shown in FIG. 2(b), even when the mechanical continuously variable transmission 2 is in a low-speed rotation state and the rotational speed is at or near the set speed (dead zone), the deviation voltage d containing a large AC component is , it falls within the dead zone (ga≦d≦g+) between the corrected reference voltage for normal rotation g+ and the corrected reference voltage for reverse rotation g2, which has an alternating current component of the same magnitude as the alternating current component of the deviation voltage d.

That is, since the deviation voltage d does not deviate from the dead zone, the mechanical continuously variable transmission 2 maintains a low-speed rotational state at a stable rotational speed at or near the set speed.

As described above, a magnetic sensor with a small number of pulses per rotation is used as the speed detection means 3, and the time constant of the frequency-voltage conversion means 5 is set small, so that the deviation voltage d is large when the rotation speed is low. Even though this occurs, it is possible to prevent unexpected repeated speed increases and decelerations as in the case of high speed rotation. Since the time constant of the frequency-voltage conversion means 5 is set small, the speed control of the mechanical continuously variable transmission 2 has good responsiveness, and the time required for speed change control can be shortened. Incidentally, it has been confirmed that the time can be reduced to about 1/3 compared to the conventional example.

In the second embodiment of the 1-star implementation team, illustration is omitted, but as is clear from the explanation of the first embodiment, the waveform of the speed detection voltage from the frequency-voltage conversion means 5 and the waveform of the speed detection voltage from the deviation amplification means 6 are Considering that the waveform of the deviation voltage d is similar to that of the speed detection voltage d, instead of passing the deviation voltage d through the AC dispensing means 9 to create the AC component voltage in the first embodiment, the speed detection voltage is amplified with the same amplification factor as the deviation amplification means 6, and then passed through the AC dispensing means 9 without passing through the deviation amplification means 6 to create an AC component voltage. In this case as well, effects completely equivalent to those of the first embodiment can be obtained.

In place of the alternating current dispensing means 9 using a bypass filter in the first embodiment, an averaging circuit 1 for averaging the deviation voltage d from the deviation amplifying means 6 is used, as shown in FIG. and,
A subtraction circuit 12 that subtracts the deviation voltage d from the averaged voltage i output from the averaging circuit 1), and a polarity inversion circuit 1 that inverts the polarity of the subtraction voltage j output from the subtraction circuit 12.
3, and is configured so that the polarity inversion voltage k is input to the addition means lO instead of the alternating current voltage component 1 in the first embodiment.

Deviation voltage d and average voltage i in low speed rotation state.

The waveforms of the subtraction voltage j and the polarity reversal voltage are shown in (a) in Figure 4.
) to (d).

In this case as well, effects similar to those of the first embodiment can be obtained.

Fudedo emergency team A fourth embodiment will be explained based on FIG. 5.

Deviation amplification means 6 and AC dispensing means 9 in the first embodiment
An absolute value converting means 14 is inserted between the deviation amplifying means 6 and the driving means 8, and a polarity determining means 15 is inserted between the deviation amplifying means 6 and the driving means 8. The output of the absolute value converting means 14 is the AC dispensing means 9
and comparison means 7.

There is one reference voltage e in the adding means lO,
Correction base 1 from addition means 10 to comparison means 7! 1 for voltage
It is one. Instead, a polarity determining means 15 is provided to determine the polarity of the deviation voltage d, and the comparison output f1 from the comparing means 7 and the determination output r! from the polarity determining means 15! The driving means 8 is configured to be driven by the following.

The polarity determining means 15 is irrelevant when the rotational speed is at or near the set speed. It functions to return to the dead zone when it is out of the dead zone.

That is, when the rotational speed of the mechanical continuously variable transmission 2 moves out of the dead zone and shifts to the low speed side, the deviation voltage d (= c - b
) becomes positive, and the polarity determining means 15 supplies this positive voltage to the driving means 8 as the determination output r2 (at this time, the comparison output f
, is a positive output>, the driving means 8 drives the transmission means 1 in normal rotation to increase the rotational speed of the mechanical continuously variable transmission 2 and return it to the dead zone.

Conversely, when the rotational speed moves out of the dead zone and shifts to the high speed side, the deviation voltage d (=c-b) becomes negative, but the polarity determining means 15 outputs this negative voltage as the determined output r2 to the driving means 8.
(also at this time, the comparison output f.

(positive output), the drive means 8 drives the transmission means 1 in reverse to reduce the rotational speed of the mechanical continuously variable transmission 2 and return it to the dead zone. When returning to the dead zone, the comparison output f1 becomes a zero output.

FIG. 6 shows the waveforms of the main parts when the rotational speed is at or near the set speed.

The absolute value signal l and the corrected reference voltage g to be compared in the comparison means 7 are the absolute The value signal l never exceeds the corrected reference voltage g, thus preventing an unexpected speed increase, tiIi, speed repetition.

Therefore, this embodiment also provides the same effects as the first embodiment.

<Effect of the invention> According to the present invention, the following effects are achieved.

That is, extract the AC component included in the deviation voltage or speed detection voltage, add this AC voltage to the reference voltage to create a corrected reference voltage, and compare or compare the corrected reference voltage with the deviation voltage. Since the speed change means is drive-controlled in accordance with the difference voltage polarity and the deviation voltage polarity, when the rotational speed of the mechanical continuously variable transmission is in a low speed state and is at or near the set speed within the dead zone, the deviation voltage or the speed Even if the amplitude of the alternating current component included in the detection voltage increases, the correction reference voltage changes accordingly, and as long as the rotation speed is within the dead band, the deviation voltage will always be within the dead band of the correction reference voltage. Therefore, even if a magnetic sensor with a small number of pulses per revolution is used as the speed detection means, or even if the time constant of the frequency-voltage conversion means is set small, unexpected speed increases may occur. , it is possible to avoid repeated deceleration operations.

Since the time constant of the frequency-voltage conversion means is set small, the responsiveness of speed control of the mechanical continuously variable transmission can be improved and the time required for speed change control can be shortened.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a speed control device for a mechanical continuously variable transmission according to a first embodiment of the present invention, and Fig. 2 shows deviation voltages in a high speed rotation state and a low speed rotation state in the case of the first embodiment. A waveform diagram showing the relationship with the corrected reference voltage, FIG. 3 is a block circuit diagram of the AC dispensing means according to the third embodiment, FIG. 4 is an operation waveform diagram thereof, and FIG. 5 is according to the fourth embodiment. A block diagram of the speed control device of a mechanical continuously variable transmission, FIG. 6 is its operation waveform diagram, FIG. 7 is a block diagram of the speed control device of a conventional mechanical continuously variable transmission, and FIG. 8 is its operation. FIG. 9 is an operational waveform diagram when the time constant of the frequency-voltage conversion means is increased in the conventional example. l...Transmission means, 2...Mechanical continuously variable transmission, 3...
- Speed detection means, 5... Frequency-voltage conversion means, 6.
... Deviation amplifying means, 7... Comparison means, 8... Driving means, 9... AC dispensing means, lO... Adding means, 1
5...Polarity determination means, a...Frequency signal, b...
Speed detection voltage, C... Speed setting voltage, d... Deviation voltage, e,... Reference voltage for forward rotation, e,... Reference voltage for reverse rotation, f... Comparison output, g+... Correction reference voltage for forward rotation, g o... Correction reference voltage for reverse rotation, h... AC component voltage.

Claims (1)

[Claims] (1) A speed change means for changing the speed of the mechanical continuously variable transmission, and a speed detection means provided in the output system of the mechanical continuously variable transmission and outputting a frequency signal proportional to the rotational speed of the mechanical continuously variable transmission. and a frequency-voltage conversion means with a small time constant for converting the frequency of the frequency signal into a speed detection voltage, and a difference between a speed setting voltage proportional to a set speed for the mechanical continuously variable transmission and the speed detection voltage. deviation amplification means for amplifying and outputting the amplified deviation voltage; AC dispensing means for extracting an alternating current component included in the deviation voltage or speed detection voltage; an adding means for adding and outputting the result as a corrected reference voltage; a comparing means for comparing the deviation voltage and the corrected reference voltage; A speed control device for a mechanical continuously variable transmission, comprising a drive means for controlling the speed change means accordingly.