JPH094478A - Revolution control device for prime mover - Google Patents

Abstract

PURPOSE: To hold a rotating position of an electric motor with a worm gear when the stepping-out phenomenon is generated in the electric motor, and to change the holding position at need. CONSTITUTION: A reduction gear 22 formed of a worm gear 25 is provided between a governor lever 3 of a governor 2 and an output shaft 21A of a stepping motor, and the tip of a turning lever 27 to be integrally turned with a worm wheel 24 is connected to the governor lever 3 through a link 7. A hexagonal hole is formed in the stepping motor at the output shaft 21A side so as to be positioned at the inner peripheral side of a worm 23, and a hexagonal part 29A or 29B of a hexagonal wrench 29 is connected (fitted) to (in) this hexagonal hole freely to be disconnected. The worm gear 25 is subsidiarily rotated with the output shaft 21A of the stepping motor by the hexagonal wrench 29, and the worm wheel 24 is rotated in the arrow D direction so as to manually turn the turning lever 27 and the governor lever 3 in the speed reduction L direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation speed control device for a prime mover which is provided in a construction machine such as a hydraulic excavator and is suitable for controlling the rotation speed of the prime mover.

[0002]

2. Description of the Related Art Generally, a construction machine is equipped with a diesel engine as a prime mover, and a hydraulic pump or the like is driven by the diesel engine.

Therefore, the conventional construction machine is provided with a control lever such as a throttle lever in a driver's cab, and when a driver or the like tilts the control lever, the operation force at this time is transmitted through a control cable, a link rod or the like. The engine speed is controlled through the governor of the engine. However, in the case of mechanically connecting the control lever and the governor of the engine with a control cable, a link rod, or the like, there is a disadvantage that a large operating force is required due to a large mechanical resistance.

In order to improve such drawbacks and to remotely control the governor of the engine electrically, an electric motor for driving the governor lever of the governor is provided near the engine, and a fuel lever or an up / down switch is provided in the operator's cab. And a controller such as a microcomputer. The controller outputs a drive signal to the electric motor based on the command signal from the rotation speed command means, and the governor lever of the governor is electrically driven by open loop control. It is known to rotate by a motor.

Therefore, a case where a conventional engine speed control device of this type is used in a construction machine will be described with reference to FIGS. 4 and 5. FIG.

In the figure, 1 is a diesel engine (hereinafter referred to as "engine") as a prime mover mounted on a construction machine.
2) indicates a governor provided in the engine 1, the governor 2 includes a governor lever 3, and the governor lever 3 is rotated in an acceleration H direction or a deceleration L direction to change the rotational speed of the engine 1. It increases or decreases.

Further, the governor 2 is provided with stoppers 4A, 4B for restricting the turning range of the governor lever 3, and the governor lever 3 is constantly urged toward the stopper 4A by a spring 5 as an urging means. Then, when the governor lever 3 contacts the stopper 4A, the governor 2
Sets the rotation speed of the engine 1 to the minimum rotation speed (idle rotation speed or zero), and sets the rotation speed of the engine 1 to the maximum rotation speed (full rotation speed) when the governor lever 3 contacts the stopper 4B.

Reference numeral 6 denotes a stepping motor as an electric motor for rotating the governor lever 3 of the governor 2. A rotating lever 6A is attached to the output shaft of the stepping motor 6, and the rotating lever 6A is connected via a link 7. And is connected to the governor lever 3. Then, the stepping motor 6 is rotated forward or backward by the output of a drive pulse signal from the controller 9 described later, and the governor lever 3 is rotated via the link 7 in the speed-up H and speed-down L directions.

Reference numeral 8 denotes a command device provided in the operator's cab of the construction machine as a rotation speed command means for commanding the rotation speed of the engine 1. The command device 8 is constituted by a fuel lever or an up / down switch, and operates. A person or the like manually outputs a command signal corresponding to the operation amount to the controller 9.

Reference numeral 9 denotes a controller which is provided in a driver's cab or the like, and which is constituted by a microcomputer or the like. The controller 9 inputs to the input unit 10 an input signal to which a command signal from the command device 8 is input. The target rotation speed of the engine 1 is calculated based on the command signal thus generated, and the drive pulse signal output from the output unit 11 and the operation unit 12 that causes the output unit 11 to output the drive pulse signal to the stepping motor 6 The counter 13 as a monitor means for counting the number of pulses and outputting the counted value to the arithmetic unit 12.

Here, the arithmetic unit 12 of the controller 9
Causes the output unit 11 to output a drive pulse signal until the count value of the counter 13 reaches a value corresponding to the target rotation speed. Then, the arithmetic unit 12 of the controller 9 outputs the output unit 1
1 constitutes drive signal output means, and the stepping motor 6 is rotated by the drive pulse signal, so that the rotation speed of the engine 1 is controlled to the target rotation speed.

The rotation speed control device for the engine 1 according to the prior art has the above-mentioned configuration. For example, when a driver or the like outputs a desired rotation speed command from the command device 8 to the controller 9, the calculation of the controller 9 is performed. The unit 12 calculates the target rotation speed of the engine 1 based on the command signal from the command device 8, and outputs the drive pulse signal from the output unit 11 until the count value of the counter 13 reaches a value corresponding to the target rotation speed.

The stepping motor 6 is normally and reversely rotated by the drive pulse signal at this time, so that the rotating lever 6A and the governor lever 3 are rotated in the speed increasing H and decelerating L directions to rotate the engine 1. The open loop control is performed so that the number becomes the target rotation speed corresponding to the command signal.

Here, the stepping motor 6 rotates according to the number of pulses of the drive pulse signal by external power supply, and has a torque characteristic as shown in FIG.

That is, the stepping motor 6 is rotated by a driving pulse signal from the controller 9 with a rotational force (driving torque τ 2) larger than the urging force of the spring 5 (urging torque τ 1). Further, even when the output of the drive pulse signal is stopped, the stepping motor 6 stops the governor lever 3 at an arbitrary rotational position with a constant holding force (stop torque τ3) while the voltage is applied (power is supplied). , Its rotational position is maintained.

The stepping motor 6 has a characteristic that the holding force (stop torque τa) at the time of stop becomes a torque larger than the drive torque τ2 at the time of rotation. When the voltage application (power supply) is cut off when the engine 1 is stopped, the stepping motor 6 loses its holding force completely, and the governor lever 3 is moved by the spring 5 to the position of the stopper 4A at the minimum rotation speed side. To allow it to be turned into.

[0017]

In the prior art described above, when a driver or the like outputs a desired rotation speed command from the command device 8 to the controller 9, a drive pulse is output from the output unit 11 of the controller 9 to the stepping motor 6. When the signal is output, the stepping motor 6 directly rotates the governor lever 3 of the governor 2 via the link 7 or the like.
Even when the stepping motor 6 rotates in the direction and comes into contact with the stopper 4B, the stepping motor 6 continues to rotate in the speed increasing direction H as long as the rotation speed command is output from the command device 8.

Therefore, in the prior art, when the governor lever 3 comes into contact with the stopper 4B, the stepping motor 6 is accelerated by the link 7 and the rotating lever 6A.
An overload acts in the direction opposite to the direction, and due to the overload at this time, the stepping motor 6 causes a step-out phenomenon as shown by a characteristic line 14 shown by a dotted line in FIG. There is a problem that the torque drops sharply.

Also, when the voltage level supplied from the outside decreases during the rotation of the stepping motor 6,
Stepping motor 6 due to the drop in voltage level
The driving torque as a rotational force sharply decreases, and the stepping motor 6 is in a so-called step-out state.

When the stepping motor 6 is in a so-called step-out state at a time To, for example, as indicated by a dotted line 14 in FIG. 5 during the rotation of the stepping motor 6, the driving torque (stepping torque) of the stepping motor 6 ( (Rotational force) rapidly decreases, so the rotational force at this time is the spring 5
Becomes smaller than the urging force (urging torque τ1) of the stepping motor 6, the stepping motor 6 is forcibly rotated by the external force (spring 5) regardless of the drive pulse signal.

As a result, when the stepping motor 6 goes out of step, the governor lever 3 causes the spring 5 to move due to a sudden decrease in the driving torque of the stepping motor 6.
The urging force (biasing torque τ 1) of the stepping motor 6 may forcefully rotate in the deceleration L direction. In this case, it becomes difficult to control the rotation speed thereafter. Therefore, the rotation lever 6A and the governor lever 3 on the stepping motor 6 side are difficult. There is a problem in that an additional labor-intensive work such as once removing the link 7 from between and to manually rotating the governor lever 3 is required.

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention is forcibly rotated in the direction opposite to the original rotation direction when an electric motor such as a stepping motor causes a step-out phenomenon. Control, the rotation position of the electric motor can be held by the worm gear, and the holding position can be changed as needed, so that the rotation speed of the prime mover can be easily changed. The purpose is to provide a device.

[0023]

In order to solve the above-mentioned problems, the present invention provides a prime mover, a governor attached to the prime mover, for increasing or decreasing the number of revolutions of the prime mover according to a turning angle of a governor lever, An electric motor for rotating a governor lever of a governor, a rotation speed command means for commanding a rotation speed of the prime mover, and a drive signal output means for outputting a drive signal to the electric motor based on a command signal from the rotation speed command means. It is applied to the rotation speed control device of the prime mover.

The feature of the configuration adopted by the invention of claim 1 is that between the governor lever of the governor and the electric motor, a worm gear type that decelerates the rotation of the electric motor and transmits it to the governor lever of the governor. The speed reducer is provided, and the output shaft side of the electric motor is provided with a connecting portion to which an external drive means for rotating the output shaft is detachably connected.

Further, in the invention according to claim 2, the electric motor is constituted by a stepping motor, the reduction gear is connected to an output shaft of the stepping motor, and is rotated by the stepping motor, and the worm. A worm wheel that meshes with the worm wheel to decelerate the rotation of the worm, and a rotating lever having a base end side connected to a rotation shaft of the worm wheel and a tip end side connected to a governor lever of the governor via a link.

[0026]

With the above construction, according to the invention of claim 1, since the worm gear type speed reducer is provided between the governor lever of the governor and the electric motor, the reverse rotation stop (self-lock) action of the worm gear is achieved. A large holding force can be generated, and even if the electric motor goes out of step, the reverse rotation stop (self-lock) action of the worm gear can be used to eliminate the situation where the governor lever is forcibly rotated. it can.

If the rotation speed of the electric motor is too high while the rotational position of the electric motor is held by the reverse rotation stop (self-locking) action of the worm gear, it is provided on the output shaft side of the electric motor. By connecting the external drive means to the connecting portion, the worm gear can be complementarily rotationally driven together with the output shaft of the electric motor by the external drive means, and by appropriately rotating the governor lever by this, the rotational speed of the prime mover can be set to a desired value. It can be lowered (lowered) to the number of rotations.

Further, according to the invention of claim 2,
When the worm is rotated by the stepping motor, this rotation is transmitted to the rotating shaft of the worm wheel while being decelerated by the worm wheel meshing with the worm, and further transmitted to the governor lever of the governor via the rotating lever and the link. Then, by rotating the worm with the stepping motor, the governor lever of the governor can be rotated with a large driving torque via the worm wheel, the rotating lever and the link.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In the embodiment, the same components as those in the conventional technique shown in FIG. 4 described above are denoted by the same reference numerals, and description thereof will be omitted.

1 and 2 show the first embodiment of the present invention.

In the figure, reference numeral 21 denotes a stepping motor as an electric motor for rotating the governor lever 3. The stepping motor 21 has the same structure as the stepping motor 6 described in the prior art, and a drive pulse output from the controller 9. The signal is normally or reversely rotated by the signal.
The stepping motor 21 has an output shaft 21A, and a worm 23 described later is fixedly provided on the output shaft 21A.

A speed reducer 22 transmits the rotation of the stepping motor 21 to the governor lever 3. The speed reducer 22 includes a worm gear 25 including a cylindrical worm 23 and an hourglass-shaped worm wheel 24, and a central axis of the worm wheel 24. The rotary shaft 26 is composed of a rotary shaft 26 and a base end side thereof is connected (fixed) to the rotary shaft 26, and a distal end side thereof is connected to the governor lever 3 via the link 7.

Here, the worm 23 is connected to the output shaft 21A of the stepping motor 21 so as to rotate integrally therewith, and is meshed with the worm wheel 24 at a lead angle γ, whereby the worm wheel 24 is moved in the directions C and D as shown by arrows. Rotate to. The worm wheel 24 decelerates the rotation of the worm 23 based on the gear ratio of the worm gear 25 and rotates in the directions C and D as indicated by the arrows, so that the rotating lever 27 increases the speed H, It is adapted to rotate in the deceleration L direction.

The worm gear 25 has a relatively large reverse rotation stop (self-lock) by reducing the lead angle γ of the worm 23 (for example, an angle of 10 to 15 degrees or less).
Even if the driving torque of the stepping motor 21 suddenly decreases, for example, when the stepping motor 21 goes out of step, the worm 23 is forcibly driven by the driving torque from the worm wheel 24 side. The rotation (reverse rotation) is restricted, and the worm 23 (stepping motor 2
It exerts a self-locking function to hold the output shaft 21A) of No. 1 in a stopped state.

28 is the output shaft 2 of the stepping motor 21.
1A shows a hexagonal hole serving as a connecting portion, and the hexagonal hole 28 opens on the end face of the worm 23 as shown in FIG. 2 to form a regular hexagonal bottomed hole on the inner peripheral side of the worm 23. Is formed in. A hexagon wrench 29 described later is detachably connected to the hexagon hole 28, and the worm 23 and the output shaft 21A of the stepping motor 21 are forcibly rotated by the hexagon wrench 29 as needed. .

Further, 29 denotes a hexagonal wrench which serves as an external driving means for rotating the output shaft 21A of the stepping motor 21, and the hexagonal wrench 29 is formed by bending a rod body made of a high strength metal material into a crank shape. And hexagonal portions 29A and 29B that are detachably fitted into the hexagonal holes 28 of the worm 23. In the hexagon wrench 29, one hexagonal portion 29A is fitted in the hexagonal hole 28 of the worm 23 in the direction of arrow A in FIG. 1, and the other hexagonal portion 29B is rotated by a manual operation or the like (hexagonal portion 2).
By rotating it around 9A), the worm 2
3 (the output shaft 21A of the stepping motor 21) is rotated in the forward and reverse directions, and the worm wheel 24 and the like are indicated by arrows C and D.
Rotate in the direction.

The hexagonal wrench 29 is pulled out from the hexagonal hole 28 when the stepping motor 21 normally rotates, and stored in an arbitrary storage place such as a tool box attached to the construction machine. You should take it out.

The engine speed control device for the engine 1 according to the present embodiment has the above-mentioned construction, and its basic operation is not significantly different from that of the prior art.

However, according to this embodiment, the governor lever 3 of the governor 2 and the output shaft 21A of the stepping motor 21 are used.
A reduction gear 22 composed of a worm gear 25 is provided between the rotation lever 2 and the worm wheel 24 to rotate integrally therewith.
The tip end side of 7 is connected to the governor lever 3 via the link 7, and a hexagonal hole 28 is formed on the output shaft 21A side of the stepping motor 21 on the inner peripheral side of the worm 23, and the hexagonal hole 28 is formed in the hexagonal hole 28. Since the hexagonal portion 29A or 29B of the hexagonal wrench 29 is detachably connected (fitted), the following operational effects can be obtained.

That is, when electric power is supplied from the controller 9 to the stepping motor 21 to drive the engine 1, the stepping motor 21 rotates according to the number of pulses of the drive pulse signal. Worm wheel 2 through worm 23
4 can be rotated in the directions of arrows C and D, and the rotation lever 2
The governor lever 3 of the governor 2 can be rotated in the speed-up H and speed-down L directions via the link 7 and the link 7.

When the stepping motor 21 turns the governor lever 3 to an arbitrary turning position to stop the drive pulse signal output from the controller 9 to the stepping motor 21, a voltage is applied (power supply).
As long as the stepping motor 21 has a constant holding force (stop torque τ3 shown in FIG. 5), the governor lever 3 is stopped at an arbitrary rotation position in cooperation with the reverse rotation stop (self-lock) action of the worm gear 25. Thus, the rotational position can be maintained and the rotational speed of the engine 1 can be maintained at an arbitrary rotational speed.

When the engine 1 is stopped, the stepping motor 21 turns the turning lever 27 in the deceleration L direction through the worm gear 25, and the governor lever 3 contacts the stopper 4A. 21
Power is cut off (stopped). When the power supply is stopped, the holding force of the stepping motor 21 is completely lost. Therefore, the governor lever 3 is held in contact with the stopper 4A by the spring 5, and the governor lever 3 is stopped by the external vibration (impact) or the like. The governor lever 3 can be rotated in the speed-increasing H direction from the position where it is in contact with the stopper 4A when the engine 1 is driven next time.

On the other hand, the stepping motor 21 is temporarily out of step due to an impact or a decrease in voltage level when the governor lever 3 collides with the stopper 4B during the operation of the engine 1 (at the time of high load and high rotation). When the driving torque by the stepping motor 21 suddenly decreases, the worm 2 is stopped by the reverse rotation stop (self-locking) action acting between the worm 23 and the worm wheel 24.
Worm gear 2 consisting of 3 and worm wheel 24
5 rotation (reverse rotation) can be automatically controlled, and the governor lever 3
Can be reliably prevented from being forcedly rotated in the deceleration L direction by the urging force of the spring 5.

When the engine speed of the engine 1 is too high when the reverse rotation is stopped by the worm gear 25 and a large noise or vibration is generated in the surroundings, the output shaft 21A side (worm 23) of the stepping motor 21 is connected. By connecting a hexagonal wrench 29 serving as an external drive means to the hexagonal hole 28 provided, the worm gear 25 can be complementarily driven to rotate together with the output shaft 21A of the stepping motor 21 by the hexagonal wrench 29, and the worm wheel 24 is indicated by an arrow D. By rotating the rotary lever 27 and the governor lever 3 in the direction, the rotary lever 27 and the governor lever 3 can be manually rotated in the deceleration L direction, and the rotational speed of the engine 1 can be reduced (lowered) to a desired rotational speed.

Even when the engine speed of the engine 1 is too low when the reverse rotation is stopped by the worm gear 25, the output shaft 21A (worm 23) of the stepping motor 21 is additionally driven to rotate by the hexagon wrench 29. , While rotating the worm wheel 24 in the direction of the arrow C, the rotation lever 27 and the governor lever 3 are accelerated H
The rotation speed of the engine 1 can be increased to a desired rotation speed by rotating the engine 1 in the direction by manual operation.

Therefore, according to the present embodiment, even when the stepping motor 21 is out of step, the output shaft 21A of the stepping motor 21 is forcibly rotated in the direction opposite to the original rotation direction. 25, the output shaft 21A of the stepping motor 21 is kept in a stopped state until it can be reliably prevented and the external impact (overload) or the drop in the voltage level that caused the out-of-step is eliminated. You can

When it is desired to change or finely adjust the rotation speed of the engine 1 in this state, a hexagon wrench 29 is connected to the output shaft 21A side (worm 23) of the stepping motor 21 via a hexagon hole 28. The hex wrench 29 can be used to supplementarily rotate the worm gear 25 together with the output shaft 21A of the stepping motor 21, and the rotational speed of the engine 1 can be easily changed (fine adjustment) without removing the link 7 or the like as in the prior art. can do.

When the stepping motor 21 is pulled out of the step-out state and is returned to the normal operation (rotation) mode, the governor lever 3 of the governor 2 is moved to the stepping motor 2.
The rotation speed of the engine 1 can be accurately controlled based on the drive pulse signal from the controller 9.

Further, the output of the drive pulse signal output from the controller 9 to the stepping motor 21 is stopped,
When the governor lever 3 is held at an arbitrary rotational position, the worm gear 25 including the worm 23 and the worm wheel 24 has a reverse rotation stop (self-locking) action, so that the governor lever 3 is stopped at the arbitrary rotational position. In such a case, the current value (voltage level) to be supplied to the stepping motor 21 can be surely lowered.

As a result, the overall power consumption can be reduced, the energy efficiency can be improved, and the durability and life of the stepping motor 21 can be surely extended. Then, the heat generation and the like of the controller 9 can be surely reduced, and the reliability and durability of the rotation speed control device can be greatly improved, and various effects can be obtained.

Next, FIG. 3 shows a second embodiment of the present invention. In this embodiment, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. To do
The feature of this embodiment is that the output shaft 2 of the stepping motor 21 is
The external drive means for rotating 1A is constituted by the electric tool 31.

Here, a hexagonal wrench rod 32 is attached to the rotating portion 31A of the electric power tool 31, and the wrench rod 32 is rotationally driven in the forward and reverse directions by energization from a power source 33. The tip end side of the wrench rod 32 is connected to the output shaft 21A side (worm 23) of the stepping motor 21 via the hexagonal hole 28 illustrated in FIG. The worm gear 25 is additionally driven to rotate together with the output shaft 21A.

Thus, in this embodiment having the above-described structure, it is possible to obtain substantially the same effects as the first embodiment. However, particularly in this embodiment, the external drive means is used as the electric tool 31 (wrench). By including the rod 32), a large driving force can be generated, and the rotation speed can be adjusted (changed) in a short time.

In each of the above embodiments, the hexagonal hole 28 is formed on the inner peripheral side of the worm 23 as the connecting portion provided on the output shaft 21A side of the stepping motor 21, but the present invention is not limited to this. However, for example, a quadrangular or D-shaped hole (recess) is formed as a connecting portion on the inner peripheral side of the worm 23, and external driving means (for example, the tip side of the wrench rod 32) can be connected to the connecting portion. It may have a shape. In this case, the connecting portion such as the hexagonal hole 28 does not necessarily have to be formed in the worm 23. For example, when the output shaft 21A of the stepping motor 21 extends to the tip end side end surface of the worm 23, the tip end side of the output shaft 21A. A hexagonal hole 28 is formed on the inner peripheral side of the output shaft 21A so as to open at the end face.
It suffices to form a connecting portion such as.

In each of the above embodiments, the governor lever 3
Although the spring 5 has been described as urging the spring 5 in the direction of deceleration L as the urging means, the present invention is not limited to this. For example, when the spring 5 or the like as the urging means is omitted, the engine 1 is stopped. Stepping motor 21
The governor lever 3 may be rotated in the deceleration L direction via the speed reducer 22 and returned to the position where the governor lever 3 contacts the stopper 4A in preparation for the next drive of the engine 1.

In particular, by reducing the lead angle γ of the worm 23 (32, 42) to, for example, an angle of 10 degrees or less, the reverse rotation stopping (self-locking) action of the worm gear 25 (34, 44) can be further increased. For example, even if the driving torque of the stepping motor 21 suddenly decreases when the stepping motor 21 is out of step, the worm 23 is driven by the driving torque from the worm wheel 24 side.
Can be reliably regulated from being forcibly rotated (reverse rotation), and the worm 23 (the output shaft 21A of the stepping motor 21) can be held in a stopped state.

Further, in each of the above-mentioned embodiments, the rotation speed of the engine 1 is controlled by the open loop control by rotating the stepping motor 21 forward and backward by the drive pulse signal from the controller 9. The present invention is not limited to this. For example, a rotation angle detecting means such as a potentiometer for detecting the rotation angle of the rotation lever 27 is provided, and the rotation of the engine 1 is based on the detection signal from the rotation angle detector. The number may be feedback-controlled.

[0058]

As described in detail above, according to the invention of claim 1, a worm gear type speed reducer is provided between the governor lever of the governor and the electric motor, and the output shaft side of the electric motor is provided. Since the external drive means is provided with the connecting portion that is detachably connected, it is possible to prevent the electric motor from being forcibly rotated in the direction opposite to the original rotation direction when the electric motor causes a step-out phenomenon. The rotation position of the electric motor can be held by the reverse rotation stop (self-lock) action of the worm gear. If the rotation speed of the motor is too high while the rotation position of the electric motor is held by the reverse rotation stop (self-locking) action of the worm gear, the connection part provided on the output shaft side of the electric motor should be connected. By connecting the external drive means, it is possible to supplementarily rotate the worm gear together with the output shaft of the electric motor by the external drive means,
Thereby, the governor lever can be appropriately rotated to easily change (adjust) the rotation speed of the prime mover to a desired rotation speed. In addition, when the electric motor eliminates the step-out condition and returns to the normal operation (rotation) mode, the electric motor can accurately control the rotational speed of the prime mover again, and the reliability and safety of the rotational speed control device of the prime mover can be improved. It is possible to significantly improve the sex.

Further, according to the invention of claim 2,
Since the worm is rotated by the stepping motor, this rotation is reduced by the worm wheel meshed with the worm, transmitted to the rotation shaft of the worm wheel, and further transmitted to the governor lever of the governor via the rotation lever and the link. By rotating the worm with a stepping motor, the governor lever of the governor can be rotated with a large driving torque through the worm wheel, the rotating lever and the link, and the rotating position of the governor lever can be controlled with high accuracy by the stepping motor. The reliability of the engine speed control device can be further improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an engine speed control device according to a first embodiment of the present invention.

FIG. 2 is a left side view showing the reduction gear in FIG. 1 in an enlarged manner.

FIG. 3 is an overall configuration diagram showing an engine speed control device according to a second embodiment of the present invention.

FIG. 4 is an overall configuration diagram showing a conventional engine speed control device.

FIG. 5 is a characteristic diagram showing torque characteristics of a stepping motor.

[Explanation of reference numerals] 1 engine (motor) 2 governor 3 governor lever 4A, 4B stopper 7 link 8 command device (rotation speed command means) 9 controller (drive signal output means) 21 stepping motor (electric motor) 21A output shaft 22 reducer 23 Worm 24 Worm Wheel 25 Worm Gear 26 Rotating Shaft 27 Rotating Lever 28 Hexagonal Hole (Connecting Part) 29 Hexagonal Wrench (External Driving Means) 31 Electric Tool (External Driving Means) 32 Wrench Rod

Claims (2)

[Claims] 1. A prime mover, a governor attached to the prime mover, for increasing or decreasing the number of revolutions of the prime mover according to a rotation angle of the governor lever, an electric motor for rotating the governor lever of the governor, and a number of revolutions of the prime mover. In the rotational speed control device for the prime mover, the governor lever of the governor and the rotational speed commanding means for instructing the above are provided, and drive signal output means for outputting a drive signal to the electric motor based on a command signal from the rotational speed commanding means. A worm gear type speed reducer, which reduces the rotation of the electric motor and transmits it to the governor lever of the governor, is provided between the electric motor and the output shaft side of the electric motor for rotating the output shaft. A rotation speed control device for a prime mover, comprising a connecting portion to which an external drive means is detachably connected. 2. The electric motor is constituted by a stepping motor, and the speed reducer is connected to an output shaft of the stepping motor and is rotated by the stepping motor, and the worm meshes with the worm to decelerate rotation of the worm. 2. The rotational speed of the prime mover according to claim 1, wherein the worm wheel comprises a worm wheel and a rotating lever whose base end side is connected to a rotary shaft of the worm wheel and whose front end side is connected to a governor lever of the governor via a link. Control device.