JP6117873B2 - Electric auto choke device - Google Patents

Description

  The present invention relates to an electric auto choke device in which a choke valve provided in an carburetor of an engine is operated by an electric actuator, and particularly to an apparatus capable of holding a choke valve at an intermediate position with a simple configuration.

For example, in an engine that supplies fuel by a carburetor (vaporizer), such as a general-purpose engine used for various applications such as industrial use, in order to ensure startability at cold start, the choke valve is throttled to reduce the mixture gas It is necessary to make a choking that temporarily enriches.
Such choking is performed by closing the choke valve for a predetermined time of, for example, several seconds to several tens of seconds after the engine is started, and then the choke valve is opened during normal operation.

Conventionally, in order to improve user convenience, for example, a temperature sensing device such as a bimetal or wax provided in a cylinder head or a muffler is used to detect the warm-up state of the engine and automatically open the choke valve. An auto choke device has been proposed.
In recent years, various electric auto choke devices that open and close a choke valve by an electric actuator such as a motor have been proposed.

As a prior art related to such an electric auto choke device, for example, Patent Document 1 discloses a choke when the engine is stopped in order to prevent the choke valve from being frozen and stuck in a fully closed state when the engine is stopped at an extremely low temperature. It is described that there is provided control means for controlling the actuator so that the valve is in the intermediate position and the choke valve is in the fully closed position when the cranking of the engine is stopped.
Further, in Patent Document 2, in an electric auto choke device that drives a choke valve by an electric motor via a transmission device, the lever ratio of a pair of levers constituting the transmission device changes from an intermediate opening of the choke valve to a fully open position. It is described that when the valve is closed from the fully open position, a sufficiently large torque is applied to the choke valve so that icing can be crushed even in an icing state.
Further, in Patent Document 3, in the latter half of the rotation of the choke valve from fully closed to fully open, the choke valve is rotated quickly to reduce the intake passage resistance and between the electric actuator and the choke valve. Is provided with an amplification transmission means having a cam mechanism.

JP 2012-140878 A JP 2006-057498 A JP 2003-206809 A

For example, at the time of restart after temporarily stopping the operation of the engine, or at the start-up in an environment where the temperature is relatively high, the choke valve is set at an intermediate position (so-called “open position”). There is a case where it is desired to start the engine as a state called a half choke).
When trying to perform such a half choke in an existing electric auto choke device, it was necessary to control the choke valve by detecting the opening of the choke valve with a position encoder or the like so that the choke valve is at a predetermined intermediate position. .
For this reason, the configuration and control of the apparatus are complicated, and the cost is high.
Even when such control is performed, the choke valve vibrates in the open / close direction due to the negative pressure in the intake pipe or the excitation force to the choke valve due to intake pulsation, stabilizing the choke valve opening. It is difficult to control.
In view of the above-described problems, an object of the present invention is to provide an electric auto choke device that can hold a choke valve at an intermediate position with a simple configuration.

The present invention solves the above-described problems by the following means.
The invention according to claim 1 is an electric auto choke device for driving a choke valve provided in a carburetor by an electric actuator, wherein an operating resistance of the choke valve when the choke valve is displaced from an open position to a closed position is set. An operating force increasing mechanism for locally increasing at a predetermined intermediate position and for making the operating resistance of the choke valve substantially constant when the choke valve is displaced from the closed position to the open position; A first output for stopping the operation of the actuator by driving the choke valve from the open position to the intermediate position; and an output greater than the first output and closing the choke valve from the open position. Output switching means for switching between a second output that can be driven to a position and It is an automatic choke apparatus.
According to this, when the choke valve is driven in the closing direction from the open position, if the output of the electric actuator is the first output, the choke valve stops at the intermediate position and is held in a so-called half choke state. be able to.
Further, when the output of the electric actuator is the second output, the choke valve can be driven and held to the fully closed position.
For this reason, the choke valve is appropriately held at the intermediate position in a simple configuration in which the position of the choke valve is not detected by simple control that switches the output of the electric actuator (for example, motor torque) stepwise by current value control, for example. can do.

The invention according to claim 2 is the electric auto choke device according to claim 1, further comprising a return spring for returning the choke valve to the open position when the energization of the electric actuator is stopped.
According to this, the choke valve can be reliably returned to the open position by simple control that simply stops energization of the electric actuator.

According to a third aspect of the present invention, there is provided an electric auto choke device that drives a choke valve provided in a carburetor by an electric actuator, wherein an operating resistance of the choke valve when the choke valve is displaced from a closed position to an open position is set. An operating force increasing mechanism for locally increasing at a predetermined intermediate position and for making the operating resistance of the choke valve substantially constant when the choke valve is displaced from the open position to the closed position; A first output for stopping the choke valve by driving the choke valve from the closed position to the intermediate position; and an output greater than the first output and opening the choke valve from the closed position. Output switching means for switching between a first output that can be driven to a position and It is an automatic choke apparatus.
According to this, when the choke valve is driven in the opening direction from the closed position, when the output of the electric actuator is the first output, the choke valve stops at the intermediate position and is held in a so-called half choke state. be able to.
Further, when the output of the electric actuator is the second output, the choke valve can be driven and held to the fully open position.
For this reason, the choke valve is appropriately held at the intermediate position in a simple configuration in which the position of the choke valve is not detected by simple control that switches the output of the electric actuator (for example, motor torque) stepwise by current value control, for example. can do.

The invention according to claim 4 is the electric auto choke device according to claim 3, further comprising a return spring for returning the choke valve to the closed position when energization to the electric actuator is stopped.
According to this, the choke valve can be reliably returned to the closed position by simple control that simply stops energization of the electric actuator.

According to a fifth aspect of the present invention, the choke valve is a butterfly valve that is opened and closed by rotating about a rotation axis, and the operating force increasing mechanism rotates together with the rotation axis of the choke valve, and substantially A rotation member having a guide portion formed in an arc shape concentric with the rotation shaft, and a relative displacement with respect to the guide surface portion when the rotation member rotates, and the guide portion is substantially rotated. A biasing means that presses along a radial direction of the shaft, and a diameter of the guide portion from the center of the rotating shaft is in contact with the biasing means when the choke valve is in the intermediate position. The electric auto choke device according to any one of claims 1 to 4, wherein the electric auto choke device is stepped on both sides.
According to this, the effect mentioned above can be acquired reliably with a simple configuration.

  As described above, according to the present invention, it is possible to provide an electric auto choke device that can hold a choke valve at an intermediate position with a simple configuration.

1 is an external view of a carburetor having Embodiment 1 of an electric auto choke device to which the present invention is applied. It is the figure which looked at the choke flange in the electric auto choke device of Example 1 from the direction along the rotation center axis of the choke shaft. It is a figure which shows operation | movement of the electric auto choke apparatus of Example 1. FIG. It is the figure which looked at the choke flange in Example 2 of the electric auto choke device to which the present invention is applied from the direction along the central axis of rotation of the choke shaft. It is a figure which shows operation | movement of the electric auto choke apparatus of Example 2. FIG.

  The present invention has an object to provide an electric auto choke device that can hold a choke valve in an intermediate position with a simple configuration. When the choke valve changes from a fully open position to a fully closed position or from a fully closed position to a fully open position. A mechanism for changing the operating resistance of the choke motor in a step shape at an intermediate position is provided, the magnitude of the torque of the choke motor can be switched, and the choke valve is held at the intermediate position when driven with a small torque of the choke motor. It was solved by configuring as follows.

A first embodiment of an electric auto choke device to which the present invention is applied will be described below.
The electric auto choke device according to the first embodiment is provided in a four-stroke gasoline general-purpose engine used as a driving power source for various set devices such as a generator, a construction machine, a pump, a gardening device, and a vehicle.
The electric auto choke device operates a choke valve provided in a carburetor (carburetor) that supplies an air-fuel mixture to an intake port of an engine using an electric actuator.

FIG. 1 is an external view of a carburetor having the electric auto choke device according to the first embodiment.
The carburetor 1 includes a throttle body 10, a float chamber 20, a throttle shaft 30, a choke shaft 40, a motor holding member 50, a choke flange 60, a return spring 70, a notch spring 80, a power supply means 90, and the like. .

The throttle body 10 is a main body portion of the carburetor 1 including a barrel portion that is a flow path through which combustion air (fresh air) supplied to an engine (not shown) passes.
The inlet side of the barrel portion is connected to an air cleaner (not shown).
The outlet side of the barrel part is connected to an intake port of a cylinder head (not shown).
The barrel portion has a venturi portion in which a part of the inner diameter in the flow path direction is partially reduced, and a throttle valve and a choke valve are provided on the downstream side and the upstream side of the venturi portion, respectively.
The fuel is sucked up from the float chamber 20 by the negative pressure formed in the venturi part, sprayed into the barrel, and mixed with air to form an air-fuel mixture.

The throttle valve is a butterfly valve that adjusts the output of the engine by adjusting the amount of intake air to the engine.
The throttle valve rotates about a rotation center axis disposed substantially along the vertical direction and is connected to the throttle shaft 30.

The choke valve is a butterfly valve that enriches the air-fuel mixture by reducing the amount of intake air to the venturi when the engine is cold started.
The choke valve is held in the fully open position during normal operation after warming up the engine.
In addition, the choke valve is in a fully closed position that allows only a minimum amount of air necessary for starting the engine to pass when the engine is cold started.
Further, the choke valve is set to an intermediate position (a so-called half choke state) between the fully open position and the fully closed position, for example, when restarting after temporarily stopping operation.
The intermediate position is appropriately set at an arbitrary position between the fully open position and the fully closed position in accordance with engine specifications, use conditions, and the like.

The float chamber 20 is a container-like portion in which fuel (gasoline) supplied to the venturi portion is temporarily stored, and is attached to the lower portion of the throttle body 10.
The float chamber 20 is supplied with fuel by a natural fall from a fuel tank (not shown), and the fuel liquid level inside the float chamber 20 is maintained to be substantially constant by using the float.

The throttle shaft 30 is a rotation shaft that is concentric with the rotation center axis of the throttle valve and is disposed substantially along the vertical direction, and is disposed so as to protrude upward from the throttle body 10.
A lower end portion of the throttle shaft 30 is connected to a throttle valve.
An upper end portion of the throttle shaft 30 is connected to a throttle motor 51 fixed to the motor holding member 50.
The throttle motor 51 drives the throttle valve to open and close by rotating the throttle shaft 30.

The choke shaft 40 is a rotation shaft that is concentric with the rotation center axis of the choke valve and is disposed substantially along the vertical direction, and is disposed so as to protrude upward from the throttle body 10.
The lower end portion of the choke shaft 40 is connected to the choke valve.
An upper end portion of the choke shaft 40 is connected to a choke motor 52 fixed to the motor holding member 50.
The choke motor 52 drives the choke valve from the open position side to the close position side by rotating the choke shaft 40.

The motor holding member 50 is a member provided on the upper portion of the throttle body 10 and to which the throttle motor 51 and the choke motor 52 are attached.
The throttle motor 51 and the choke motor 52 are stepping motors that drive the throttle shaft 30 and the choke shaft 40, respectively, via a reduction gear train (not shown).
The motor holding member 50 is fixed to the throttle body 10 via a bracket 53 provided so as to protrude upward from the throttle body 10.
A cover 54 that covers the throttle motor 51 and the choke motor 52 is provided on the motor holding member 50.
Further, the throttle motor 51 and the choke motor 52 operate when supplied with power from the power supply means 90. The operation of the power supply means 90 will be described in detail later.

The choke flange 60 is a member that is fixed in a state in which the choke shaft 40 projects in a flange shape from the intermediate portion between the throttle body 10 and the motor holding member 50 to the outer diameter side.
The choke flange 60 is formed in a flat plate shape along a plane orthogonal to the rotation center axis of the choke shaft 40.
The choke flange 60 functions in cooperation with the notch spring 80 as an operating force increasing mechanism according to the present invention.

FIG. 2 is a view of the choke flange 60 as viewed from the direction (upper side) along the rotation center axis of the choke shaft 40.
The choke flange 60 has an opening 61 formed in the central portion thereof, and a full open-intermediate guide portion 62, an intermediate-full close guide portion 63, a notch portion 64, a full open stopper portion 65, a full close stopper at a part of the peripheral portion. A portion 66 and the like are formed.

The opening 61 is formed at the central portion of the choke flange 60 and is a portion to which the intermediate portion of the choke shaft 40 is inserted and fixed.
In order to prevent relative rotation with respect to the choke shaft 40, the opening 61 is formed such that a part of the outer peripheral edge is straight.
The straight portion cooperates with a cut portion (not shown) formed on the outer peripheral surface of the choke shaft 40 to prevent the choke flange 60 from rotating with respect to the choke shaft 40.

The fully open-intermediate guide portion 62 is a region that contacts the notch spring 80 when the choke valve is positioned between the fully open position and the intermediate position.
The fully open-intermediate guide portion 62 is formed in an arc shape that is substantially concentric with the central axis of rotation of the choke shaft 40.

The intermediate-full closing guide portion 63 is a region that contacts the notch spring 80 when the choke valve is positioned between the intermediate position and the fully closed position.
The intermediate-fully closed guide portion 63 is formed in an arc shape that is substantially concentric with the rotation center axis of the choke shaft 40, and the radius thereof is set larger than that of the fully-open-intermediate guide portion 62.
The end on the intermediate position side (clockwise direction side in FIG. 2) of the fully open-intermediate guide part 62 is the end part on the intermediate position side (counterclockwise direction side in FIG. 2) of the intermediate-fully closed guide part 63; The notch portions 64 are arranged adjacent to each other.

The notch portion 64 is provided between the fully open-intermediate guide portion 62 and the intermediate-fully close guide portion 63, and is a portion that connects between them in a stepped manner.
The notch portion 64 is formed in a slope shape inclined with respect to the radial direction in order to absorb the difference in radius between the fully open-intermediate guide portion 62 and the intermediate-fully close guide portion 63.
The notch portion 64 cooperates with the notch spring 80 to locally increase the operating resistance of the choke valve when the choke valve is driven in the closing direction and passes through the intermediate position, and is required for the choke motor 52. It has an operating force increase function that locally increases the output torque.
This point will be described in detail later.
On the other hand, when the choke valve is driven in the opening direction, the notch spring 80 steps down the notch portion 64 and does not substantially generate an operating resistance, so that the operating force is not increased.

The fully open stopper portion 65 and the fully closed stopper portion 66 regulate the range in which the choke flange 60 can be rotated by the notch springs 80 contacting each other when the choke valve is in the fully open position or the fully closed position. .
The fully open stopper portion 65 is provided at an end portion of the fully open-intermediate guide portion 62 opposite to the notch portion 64 side, and is formed to project to the outer diameter side.
The fully closed stopper portion 66 is provided at an end of the intermediate-full closed guide portion 63 opposite to the notch portion 64 side, and is formed so as to protrude to the outer diameter side.

The return spring 70 is a biasing unit that applies a moment in the direction of opening the choke valve to the choke shaft 40.
The return spring 70 is, for example, a torsion coil spring having an intermediate portion wound substantially concentrically around the outer peripheral surface portion of the choke shaft 40.
One end of the return spring 70 is locked to the throttle body 10, and the other end is locked to the outer peripheral surface of the choke flange 60.
The return spring 70 generates a spring reaction force (restoring force) corresponding to the amount of rotation of the choke shaft 40 when the choke valve is displaced in the closing direction.
The biasing force of the return spring 70 is set to such an extent that the choke valve can be returned to the fully open position only by the biasing force of the return spring 70 when the choke motor 52 is deenergized.

The notch spring 80 is a biasing unit that presses the outer peripheral edge of the choke flange 60 toward the choke shaft 40.
As the notch spring 80, for example, a coil spring standing in a cantilever manner from the upper surface of the throttle body 10 can be used.
The notch spring 80 is fixed on the upper surface of the throttle body 10 so as to protrude upward in the vertical direction from the position offset from the outer peripheral edge of the choke flange 60 toward the choke shaft 40 when no load is applied.
In a state where the choke flange 60 is attached to the choke shaft 40, the upper end portion of the notch spring 80 is displaced with elastic deformation to the outer diameter side of the choke shaft 40 due to interference with the choke flange 60.
At this time, the notch spring 80 presses the outer peripheral edge of the choke flange 60 toward the choke shaft 40 substantially along the radial direction of the choke shaft 40 by a reaction force of elastic deformation.
During the operation of the choke valve, the outer peripheral surface portion in the vicinity of the upper end portion of the notch spring 80 slides with respect to the peripheral edge portion of the choke flange 60.

Hereinafter, the operation of the electric auto choke device according to the first embodiment will be described.
FIG. 3 is a diagram illustrating the operation of the electric auto choke device according to the first embodiment.
FIG. 3 shows the state of the choke flange 60 and the notch spring 80 as viewed from above when the choke valve is in the fully open position, the intermediate position, and the fully closed position in order from the left side.

As shown in FIG. 3, in the choke valve fully open position, the notch spring 80 is in contact with the end of the fully open-intermediate guide portion 62 on the fully open stopper portion 65 side.
At the choke valve fully closed position, the notch spring 80 is in contact with the end of the intermediate-full closed guide portion 63 on the side of the fully closed stopper portion 66.
At the choke valve intermediate position (anti-choke state), the notch spring 80 is in contact with the end portion of the fully open-intermediate guide portion 62 on the notch portion 64 side.

In the first embodiment, the power supply unit 90 can switch the output (torque) of the choke motor 52 in two steps, for example, by current control.
The power supply means 90 functions as the output switching means in the present invention.
In a state where the torque is small, the driving force by the choke motor 52 cannot overcome the operating resistance generated in the notch portion 64, and the notch spring 80 gets over (steps up) the notch portion 64 of the choke flange 60. Can not. For this reason, when the choke valve is driven in the closing direction from the fully open position, the choke valve is stopped at the intermediate position.
On the other hand, when the torque is large, the driving force by the choke motor 52 overcomes the operating resistance generated at the notch portion 64, and the notch spring 80 can reach the fully closed stopper portion 66 over the notch portion 64 of the choke flange 60. It is. For this reason, it is possible to drive the choke valve from the fully open position to the fully closed position without stopping it halfway.

When the engine is stopped, the choke valve is held in the fully open position by the urging force of the return spring 70.
The power supply means 90 detects or estimates the warm-up state at the time of engine start, and determines whether the choke valve at the time of start is in the fully closed position or the intermediate position.
When starting the choke valve in the fully closed position, the power supply means 90 supplies power so that the torque of the choke motor 52 is increased, and stops the choke valve at the intermediate position from the fully open position to the fully closed position. Drive without.
If the power supply means 90 continues energizing the choke motor 52 in this state, the choke valve is held in the fully closed position.
After the choke valve is held in the fully closed position, the engine is cranked and started by starting means such as a starter motor or a recoil starter.
The power supply means 90 estimates the warm-up state of the engine based on, for example, the engine temperature and the elapsed time after starting, and when the choking can be finished (combustion stability is ensured even after the choking is finished). In the case), the power supply to the choke motor 52 is stopped.
When the energization of the choke motor 52 is completed, the choke valve returns to the fully open position by the urging force of the return spring 70.

On the other hand, when starting the choke valve at the intermediate position, the power supply means 90 supplies power so that the torque of the choke motor 52 becomes small, and drives the choke valve from the fully open position to the intermediate position.
If the power supply means 90 continues energizing the choke motor 52 in this state, the choke valve is held at the intermediate position.
After the choke valve is held at the intermediate position, the engine is cranked and started by starting means such as a starter motor or a recoil starter.
The power supply means 90 estimates the warm-up state of the engine based on, for example, the engine temperature and the elapsed time after starting, and stops the energization of the choke motor 52 when the choking (half choke) can be finished. To do.
When the energization of the choke motor 52 is completed, the choke valve returns to the fully open position by the urging force of the return spring 70.

As described above, according to the first embodiment, the following effects can be obtained.
(1) When the torque of the choke motor 52 is reduced when the choke valve is driven in the closing direction from the fully open position, due to the operating resistance generated when the notch spring 80 reaches the notch portion 64 of the choke flange 60 The choke valve stops at an intermediate position, and a so-called half choke state can be obtained. Further, when energization to the choke motor 52 is continued in this state, it is possible to maintain the half choke state.
Further, when the torque of the choke motor 52 is increased, the choke valve can be driven without stopping halfway from the fully open position to the fully closed position.
For this reason, the choke valve is appropriately driven and held at the intermediate position in a simple configuration in which the position of the choke valve is not detected by a simple control that switches the output torque of the choke motor 52, for example, in two steps of large and small by current control. be able to.
(2) By the notch part 64 of the choke flange 60 and the notch spring 80, the actuating force (actuating resistance) at the time of passing through the intermediate position when the choke valve is closed is locally increased, so that the above-described configuration is simplified. Effects can be obtained.
(3) Since the choke valve is configured to return to the fully open position only by the urging force of the return spring 70, simple control that simply stops energization of the choke motor 52 allows the warm-up end or engine stop. The choke valve can be reliably returned to the fully open position.

Next, a second embodiment of the electric auto choke device to which the present invention is applied will be described.
Portions that are substantially the same as those of the first embodiment described above are denoted by the same reference numerals, description thereof is omitted, and differences are mainly described.
FIG. 4 is a view of the choke flange in the electric auto choke device of the second embodiment when viewed from the direction along the rotation center axis of the choke shaft (a diagram corresponding to FIG. 2 of the first embodiment).
FIG. 5 is a diagram illustrating an operation of the electric auto choke device of the second embodiment (a diagram corresponding to FIG. 3 of the first embodiment).

In the second embodiment, the return spring 70 applies a moment in the direction of closing the choke valve to the choke shaft 40, and when the choke motor 52 is not energized, the choke valve is moved to the fully closed position by the urging force of the return spring 70. Retained.
On the other hand, the choke motor 52 applies torque in the direction of opening the choke valve to the choke shaft 40 when energized.
Further, as shown in FIGS. 4 and 5, contrary to the first embodiment, the radius of the fully open-intermediate guide portion 62 of the choke flange 60 is set larger than the radius of the intermediate-fully-closed guide portion 63. Yes.
As a result, the notch portion 64 cooperates with the notch spring 80 to locally increase the operating resistance of the choke valve when the choke valve is driven in the opening direction and passes through the intermediate position. It has an operating force increase function that locally increases the required output torque.
On the other hand, when the choke valve is driven in the closing direction, the notch spring 80 steps down the notch portion 64 and does not substantially generate an operating resistance, so that the operating force is not increased.

The operation of the electric auto choke device according to the second embodiment will be described below.
FIG. 5 shows the state of the choke flange 60 and the notch spring 80 viewed from above when the choke valve is in the fully open position, the intermediate position, and the fully closed position in order from the left side.
As shown in FIG. 5, in the choke valve fully open position, the notch spring 80 is in contact with the end of the fully open-intermediate guide portion 62 on the fully open stopper portion 65 side.
At the choke valve fully closed position, the notch spring 80 is in contact with the end of the intermediate-full closed guide portion 63 on the side of the fully closed stopper portion 66.
At the choke valve intermediate position (anti-choke state), the notch spring 80 is in contact with the end of the intermediate-full-close guide part 63 on the notch part 64 side.

When the engine is stopped, the choke valve is held in the fully closed position by the urging force of the return spring 70.
The power supply means 90 detects or estimates the warm-up state at the time of engine start, and determines whether the choke valve at the time of start is in the fully closed position or the intermediate position.
When starting the choke valve in the fully closed position, the power supply means 90 does not supply power to the choke motor 52 and maintains the state where the choke valve is held in the fully closed position.
After the choke valve is held in the fully closed position, the engine is cranked and started by starting means such as a starter motor or a recoil starter.
The power supply means 90 estimates the warm-up state of the engine based on, for example, the engine temperature and the elapsed time after starting, and when the choking can be finished (combustion stability is ensured even after the choking is finished). In this case, the choke motor 52 is driven with a large torque, and the choke valve is driven to the fully open position.

On the other hand, when starting with the choke valve in the intermediate position, the power supply means 90 supplies power so that the torque of the choke motor 52 becomes small, and drives the choke valve from the fully closed position to the intermediate position.
If the power supply means 90 continues energizing the choke motor 52 in this state, the choke valve is held at the intermediate position.
After the choke valve is held at the intermediate position, the engine is cranked and started by starting means such as a starter motor or a recoil starter.
The power supply means 90 estimates the warm-up state of the engine based on, for example, the engine temperature or the elapsed time after starting, and when the choking (half choke) can be finished, the torque of the choke motor 52 is increased. To the fully open position.

After the drive of the choke valve to the fully open position is completed, the choke valve is held in the fully open position even if the torque of the choke motor 52 is reduced to a minimum torque that can overcome the urging force of the return spring 70. Is done.
Thereafter, when the energization to the choke motor 52 is stopped when the engine is stopped, the choke valve returns to the fully closed position by the urging force of the return spring 70.

According to the second embodiment described above, the following effects can be obtained.
(1) When driving the choke valve in the opening direction from the fully closed position, if the torque of the choke motor 52 is reduced, the operating resistance generated when the notch spring 80 reaches the notch portion 64 of the choke flange 60 As a result, the choke valve stops at an intermediate position, and a so-called half-choke state can be obtained. Further, when energization to the choke motor 52 is continued in this state, it is possible to maintain the half choke state.
Further, when the torque of the choke motor 52 is increased, the choke valve can be driven without stopping halfway from the fully closed position to the fully open position.
For this reason, the choke valve is appropriately driven and held at the intermediate position in a simple configuration in which the position of the choke valve is not detected by a simple control that switches the output torque of the choke motor 52, for example, in two steps of large and small by current control. be able to.
(2) By the notch part 64 of the choke flange 60 and the notch spring 80, the actuating force (actuating resistance) at the time of passing through the intermediate position when the choke valve is closed is locally increased, so that the above-described configuration is simplified. Effects can be obtained.
(3) Since the choke valve is configured to return to the fully closed position only by the urging force of the return spring 70, simple control that simply stops energization of the choke motor 52 can be performed at the end of warm-up or engine stop. Sometimes the choke valve can be reliably returned to the fully closed position. Thus, when the engine is stopped, the choke valve is returned to the fully closed position, whereby afterburning in which the unburned gas abnormally burns in the exhaust pipe such as a muffler can be suppressed.

(Modification)
The present invention is not limited to the first and second embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
(1) The shape, structure, arrangement, and the like of each component constituting the electric auto choke device are not limited to the configuration of the above-described embodiment, and can be changed as appropriate.
For example, the shape, shape, arrangement, etc. of the choke flange shape, return spring, and notch spring can be changed as appropriate.
(2) In the first embodiment, the choke valve is driven in the opening direction only by the urging force of the return spring 70 while the energization to the choke motor 52 is stopped. The output of the actuator may be used.
In the second embodiment, the choke valve is driven in the closing direction by only the urging force of the return spring 70 while the choke motor 52 is de-energized. May be used.
(3) In the first and second embodiments, the guide portions 62 and 63 of the choke flange 60 are formed on the outer peripheral edge portion and pressed toward the inner diameter side by the notch spring 80. However, the guide portion has such a configuration. For example, the guide portion formed in a groove shape or the like may be pressed toward the outer diameter side of the choke shaft. In this case, the magnitude relationship between the radius of the guide portion from the fully open position to the intermediate position and the radius of the guide portion from the intermediate position to the fully closed position may be opposite to those of the first and second embodiments.
(4) In the first and second embodiments, a stepping motor is used for the choke motor 52. However, in the present invention, since the motor itself does not need to have a positioning function, a relatively inexpensive DC motor or the like is used as the choke motor. It is also possible to use.
(5) In the first and second embodiments, the engine is a four-stroke gasoline general-purpose engine for industrial use as an example. However, the present invention is not limited to this, and other uses such as those mounted on vehicles and ships, for example. It can be applied to other engines. Further, the type of fuel is not particularly limited as long as the engine is a carburetor engine having a choke valve. The present invention can also be applied to a two-stroke engine.

1 Carburetor 10 Throttle body 20 Float chamber 30 Throttle shaft 40 Choke shaft 50 Motor holding member 51 Throttle motor 52 Choke motor 53 Bracket 54 Cover 60 Choke flange 61 Opening 62 Fully open-intermediate guide part 63 Intermediate-fully closed guide part 64 Notch part 65 Fully open stopper 66 Fully closed stopper 70 Return spring 80 Notch spring 90 Power supply means

Claims (5)

An electric auto choke device for driving a choke valve provided in a vaporizer by an electric actuator,
When the choke valve is displaced from the open position to the closed position, the operating resistance of the choke valve is locally increased at a predetermined intermediate position, and the choke valve is displaced from the closed position to the open position. An operating force increasing mechanism for making the operating resistance of the choke valve substantially constant;
A first output for stopping the choke valve by driving the choke valve from the open position to the intermediate position, and a choke valve greater than the first output from the open position. An electric auto choke device comprising: output switching means for switching between the second output that can be driven to the closed position. The electric auto choke device according to claim 1, further comprising a return spring that returns the choke valve to the open position when energization of the electric actuator is stopped. An electric auto choke device for driving a choke valve provided in a vaporizer by an electric actuator,
When the choke valve is displaced from the closed position to the open position, the operating resistance of the choke valve is locally increased at a predetermined intermediate position, and the choke valve is displaced from the open position to the closed position. An operating force increasing mechanism for making the operating resistance of the choke valve substantially constant;
A first output for stopping the choke valve by driving the choke valve from the closed position to the intermediate position, and a choke valve larger than the first output from the closed position. An electric auto choke device comprising: output switching means for switching between the first output that can be driven to the open position. The electric auto choke device according to claim 3, further comprising a return spring that returns the choke valve to the closed position when energization of the electric actuator is stopped. The choke valve is a butterfly valve that is opened and closed by rotating around a rotation axis;
The actuating force increasing mechanism rotates with the rotating shaft of the choke valve, and has a rotating member having a guide portion formed in an arc shape substantially concentric with the rotating shaft;
Urging means for relatively displacing with respect to the guide surface portion during rotation of the rotation member and pressing the guide portion substantially along the radial direction of the rotation shaft;
The diameter from the center of the rotating shaft of the guide portion is made to differ in a step shape on both sides of a region in contact with the urging means when the choke valve is in the intermediate position. The electric auto choke device according to any one of claims 1 to 4.

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