JP5789924B2 - Engine for portable work machine and portable work machine equipped with the same - Google Patents

Description

  The present invention relates to an engine for a portable work machine such as a chain saw or a brush cutter, and more particularly to an engine for a portable work machine having a starter and a portable work machine having the same.

  2. Description of the Related Art Conventionally, some portable engine working machines have a starter motor mounted on the engine in order to easily start the engine, as shown in Patent Document 1, for example.

JP-A-9-14112

  By the way, the above-mentioned starter motor is comprised from the cylindrical stator which covers the rotor and the rotor which wound the coil around the iron core extended in the axial direction of an output shaft. Accordingly, there is a problem that the rotor and the stator are elongated in the axial direction of the motor output shaft, the starter motor is enlarged, and a large space is required for installation.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a compact portable work machine engine and a portable work machine including the engine while suppressing an increase in the size of the starter motor.

In order to achieve the above object, an engine for a portable work machine according to a first aspect of the present invention includes:
An engine for a portable work machine that burns an air-fuel mixture in a cylinder bore by discharging a spark plug by an ignition device constituted by a magnet rotor connected to a crankshaft, an ignition coil and the magnet rotor,
Disposed in the magnet rotor to have a permanent magnet, a rotor that rotates together with the crankshaft,
A stator having a plurality of drive coils facing the permanent magnet;
Battery,
Control means for controlling energization from the battery to the drive coil and controlling energization to the spark plug based on an operation of a stop switch for turning on and off the energization to the spark plug ;
The control means includes a start mode in which the drive coil of the stator is energized to start the engine, and the stop switch is turned on to stop energization of the spark plug, and the rotor A braking mode in which a braking force is generated in the magneto rotor by increasing an electrical load with the stator, and a rotational speed of the crankshaft is decreased.
It is characterized by that .
Before SL control means by operation of the operator, may be initiated braking of the engine in the braking mode.
In the braking mode, an electrical load may be generated on the starter motor by increasing the amount of charge by the starter motor or generating heat with a resistor.

Further, in the start mode, the control means generates the braking force to the magnet rotor when the output of the rotation speed detection means for detecting the rotation speed of the engine exceeds a first predetermined value. You may control the electricity supply to.

Further, in the start mode, the control means may change the number of the coils to be energized based on the output of the rotation speed detection means for detecting the rotation speed of the engine .

Further, in the start mode, the control means may reduce the number of coils to be energized as the engine speed increases.

Further, in the start mode, the control means stops energization from the battery to the coil when the output of the rotation speed detection means for detecting the rotation speed of the engine exceeds a second predetermined value. Also good.

Further, it further comprises crank angle detection means for detecting the angle of the crankshaft,
Wherein, before performing starting of the engine, based on an output of the crank angle detecting means, so that the crankshaft front kilometers over motor driven to rotate becomes a predetermined angle, the coil from the battery You may control the electricity supply to.

Further, in the start mode, the control means is configured to cause a current generated in the coil to charge the battery when the output of the rotation speed detection means for detecting the rotation speed of the engine exceeds a third predetermined value. May be supplied to the battery.

  The battery may be detachably attached.

In the starting mode, the control unit, when the output rotational speed detecting means for detecting a rotational speed of the engine exceeds a predetermined value of the fourth, in order to reduce the rotational speed of the engine, according to the scan Tatamota An electric load may be generated in the starter motor by increasing the amount of charge or by generating heat with resistance, and a braking force may be applied to the magnet rotor to reduce the engine speed.

A portable work machine according to a second aspect of the present invention includes the engine described above.

  According to the present invention, a magnet rotor connected to a crankshaft having a plurality of permanent magnets that are annularly spaced apart in the circumferential direction, and annularly in the circumferential direction so as to face the permanent magnets in the axial direction of the crankshaft. Since a flat stator having a plurality of coils is provided, the starter motor can be reduced in size, and the engine for the portable work machine can be made compact.

The perspective view of the brush cutter carrying the engine for portable working machines which concerns on this invention. Sectional drawing of the engine mounted in the backpack type brush cutter of FIG. III-III sectional view taken on the line of FIG. IV-IV sectional view taken on the line of FIG. The control block diagram of the engine of FIG. The control flowchart before the starter motor drive of the engine of FIG. The control flowchart after the starter motor drive of the engine of FIG. (A) is a figure which shows the energization state to the coil of a stator in the time of an engine speed to 1000 rpm, (B) is a figure which shows the energization state to the coil after progress for a predetermined time from (A). (A) is a figure which shows the energization state to the coil of a stator in a certain time in an engine speed of 1000 rpm or more, (B) is a figure which shows the energization state to the coil after progress for a predetermined time from (A). The control flowchart at the time of the stop switch operation of the engine of FIG.

  Embodiments of the present invention will be described below with reference to FIGS. As shown in FIG. 1, a brush cutter 1001 equipped with a small two-cycle engine 1 (hereinafter referred to as an engine) for portable work has a rotary blade 1003 attached to the tip of an operating rod 1002, and an engine at the rear end of the operating rod 1002. 1 is attached. The output of the engine 1 is supplied to the rotary blade 1003 through a drive shaft that is inserted into the operation rod 1002. An operator attaches a handle 1007 provided on an operating rod 1002 and provided with a throttle switch 1004 for adjusting the output of the engine 1, a stop switch 1005 for stopping the engine 1, and a starter switch 1006 for driving a starter motor for starting the engine 1. The brush cutter 1001 is operated by gripping.

  As shown in FIG. 2, the engine 1 housed in the engine cover 2 includes a magnet rotor 5 fixed to one end of a crankshaft 4 rotatably supported by a crankcase 3, and a cylinder of the engine 1. A spark plug 8 connected to the ignition coil 7 of the ignition device 33, which is composed of an ignition coil 7 fixed to the block 6 and generating a high voltage by the rotation of the magnet rotor 5, is provided. A centrifugal clutch 9 is provided at the end of the crankshaft 4 on the side different from the side on which the magnet rotor 5 is attached, and the output of the engine 1 is transmitted to the drive shaft 10 via the centrifugal clutch 9 and the rotary blade 1003 ( (See FIG. 1). A piston 12 is accommodated in the cylinder bore 11 formed in the cylinder block 5 so as to be reciprocally movable. The piston 12 is connected to the crankshaft 4 via a piston pin 13, a connecting rod 14, and a crankpin 15.

  As shown in FIG. 2, a fan 16 is formed on the inner side surface (left side surface in FIG. 2) of the magneto rotor 5 facing the engine 1, and the fan 16 is driven when the engine 1 is driven to rotate the magnet rotor 5. Cooling air is sent to the engine 1. A plurality of permanent magnets 17 are embedded in the outer side surface (the right side surface in FIG. 2) facing the side away from the engine 1 of the magnet rotor 5. As shown in FIG. 3, the permanent magnets 17 are arranged on the side surfaces of the magnet rotor 5 at substantially equal intervals in the circumferential direction on a circumference centering on the rotation axis 18 (rotation axis (axis)) of the crankshaft 4. Are arranged so that the polarities appearing on the surface of the magnet rotor 5 of the adjacent permanent magnet 17 are different. FIG. 3 shows an example in which four permanent magnets 17 are arranged. For example, the number of permanent magnets 17 is increased to 6, 8, or more, and the permanent magnets 17 are arranged at substantially equal intervals in the circumferential direction. Also good. Moreover, the permanent magnet 17 may be one that is formed in an annular shape and magnetized so that different polarities appear adjacently in the circumferential direction, in addition to the configuration in which a plurality of permanent magnets 17 are arranged.

  As shown in FIG. 2, the engine cover 2 includes a flat stator 20 having a plurality of drive coils (coils) 19 so as to face the outer side surface of the magnet rotor 5 in which the permanent magnets 17 are annularly embedded. Mounted. As shown in FIG. 2 and FIG. 4, the plurality of drive coils 19 have the shaft 18 of the crankshaft 4 so that the opening of each coil ring faces the direction of the axis 18 of the crankshaft 4 and faces the permanent magnet 17. It arrange | positions at the stator 20 adjacent to the annular | circular shape in the circumferential direction on the circumference which makes a center. As shown in FIG. 2, each of the drive coils 19 is connected to a control circuit (control means) 21, and the control circuit 21 supplies power from the battery 22 to the drive coil 19 or supplies power from the drive coil 19 to the battery 22 or resistor 23. Control power supply. A stator 20 having a permanent magnet 17 on the outer side surface and a drive coil 19 so as to face the outer side surface of the magnet rotor 5 in the axial direction of the crankshaft 4 is a surface-facing direct current type. A brushless motor type starter motor 24 is configured. The battery 22 is detachably attached to the engine cover 2 that houses the engine 1.

  As shown in FIG. 5, the control circuit 21 includes a stop switch 1005, a starter switch 1006, a battery 22, a resistor 23, a current detection unit 25, and a rotation speed detection unit (rotation speed detection means) that detects the rotation speed of the engine 1. 26 is connected. The current detector 25 detects the current flowing through the drive coil 19, and the rotation speed detector 26 detects the rotation speed based on the ignition pulse transmitted from the ignition coil 7 to the spark plug 8. The outputs of the stop switch 1005, starter switch 1006, current detection unit 25, and rotation speed detection unit 26 are input to the calculation unit 27 of the control circuit 21. The calculation unit 27 outputs signals to a current control unit 28, a charge amount control unit 29, a forward / reverse switching control unit 30, and a stator pole control unit 31 of the control circuit 21, which will be described later, and the forward / reverse switching control unit 30 and the stator poles. Based on the output signal of the control unit 31, the control signal output circuit 32 of the control circuit 21 controls energization of each drive coil 19 of the stator 20. The current flowing through each drive coil 19 is controlled by the current control unit 28 and the charge amount control unit 29. When the starter switch 1006 is turned on (operation), the control circuit 21 supplies power for driving the starter motor 24 from the battery 22 to each drive coil 19 of the stator 20 to rotate the magnet rotor 5 of the starter motor 24. Then, the engine 1 is started. Further, when the starter switch 1006 is off (during non-operation), the battery 22 is charged by the current generated in the drive coil 19 of the starter motor 24 by the rotation of the magnet rotor 5.

  Before starting the engine 1 by the starter motor 24, the control circuit 21 detects the state of the starter switch 1006 in step S1, as shown in FIG. In step S2, it is determined whether or not the starter switch 1006 is operated (ON operation). If YES in the condition, the process proceeds to step S3 and the starter motor 24 is controlled by the forward / reverse switching control unit 30 of the control circuit 21. Is driven in the direction opposite to the rotation direction when the engine 1 is started (reverse driving). On the other hand, in the case of NO that does not satisfy the condition, the process returns to step S1. If the starter motor 24 is driven in reverse rotation in step S3, the current flowing through the drive coil 19 of the stator 20 of the starter motor 24 is detected by the current detector (crank angle detecting means) 25 in step S4. This detects that the piston 12 approaches the top dead center and the pressure in the cylinder bore 11 rises to increase the load on the starter motor 24 using the increase in the value of the current flowing through the drive coil 19. Thus, the current detection unit 25 detects that the piston 12 is at a predetermined position near the top dead center, that is, that the crankshaft 4 approaches a predetermined angle. Then, whether or not the current detected by the current detector 25 in step S5 is greater than or equal to a predetermined value, that is, whether or not the piston 12 is near a predetermined position near top dead center (the crankshaft 4 is near a predetermined angle). Is judged. If YES in step S5, the reverse drive of the starter motor 24 is stopped. In step S7, the starter motor 24 rotates the engine 1 in the forward direction to drive the engine 1, and the control circuit 21 starts control during forward rotation driving, which will be described later. Note that a known crank angle sensor may be provided in place of the above-described configuration in which the current detection unit 5 is used to detect the position of the piston 12 or the angle of the crankshaft 4. In this case, the angle of the crankshaft 4 is directly detected by the crank angle sensor, and based on the detected angle of the crankshaft 4, the starter motor 24 is set so that the piston 12 has a predetermined position near the top dead center, that is, a predetermined crank angle. It is good also as a structure which carries out normal rotation or reverse rotation in the direction where a rotation angle decreases.

  When the forward rotation drive is started, as shown in FIG. 7, the rotation speed detection unit 26 of the control circuit 21 detects the rotation speed of the engine 1 in step S <b> 8. In step S9, it is determined whether or not the rotational speed is lower than, for example, 1000 rpm. If YES in the condition, the process proceeds to step S10, and the stator pole control unit 31 of the control circuit 21 controls all the drive coils of the stator 20. 19 is energized to drive the magnet rotor 5, that is, the crankshaft 4, with a high torque. As shown in FIG. 8A, energization of the drive coil 19 of the stator 20 is performed so that the pole (polarity) of the adjacent drive coil 19 is reversed, and the next control timing is as shown in FIG. As shown in FIG. 8B, each pole (polarity) of the drive coil 19 is inverted from the state shown. Then, the control circuit 21 repeats energization of the drive coil 19 by alternately rotating the state of FIG. 8A and the state of FIG. 8B while alternately shortening the cycle, that is, the crankshaft. Increase the rotation of 4. If NO in step S9, the process proceeds to step S11, and it is determined whether the rotational speed is 1000 rpm or higher and is lower than 3000 rpm, which is an idling rotational speed, for example. If YES in step S 11, the process proceeds to step S 12, and the predetermined drive coil 19 of the stator 20 is energized by the stator pole control unit 31 of the control circuit 21. As shown in FIG. 9A, energization of the drive coil 19 of the stator 20 is performed so that the pole (polarity) of the adjacent drive coil 19 is reversed every other drive coil 19 only. The Then, at the next control timing, as shown in FIG. 9B from the state shown in FIG. 9A, each pole (polarity) of the energized drive coil 19 is inverted. Then, the control circuit 21 repeats energization of the drive coil 19 by repeating the state of FIG. 9A and the state of FIG. 9B while alternately shortening the cycle, that is, the rotation of the magnet rotor 5, that is, the crankshaft. Increase the rotation of 4. If NO in step S11, the process proceeds to step S13, where it is determined whether the rotational speed is 3000 rpm or higher, which is the idling rotational speed, and is lower than, for example, 10,000 rpm, which causes excessive rotation. If YES in step S13, the control circuit 21 determines that the engine 1 has started exceeding the idling speed (3000 rpm), proceeds to step S14, and the current control unit 28 of the control circuit 21. Stops supplying current from the battery 22 to the drive coil of the stator 20 of the starter motor 24. In step S 15, the control circuit 21 operates the starter motor 24 as a generator, and the current control unit 28 charges the battery 22 with the electric power generated by the drive coil 19. If NO in step S13, the process proceeds to step S16 to determine whether the rotational speed is 10,000 rpm or more. If YES in step S16, the control circuit 21 determines that the engine 1 is in an overspeed state and proceeds to step S17. In step S <b> 17, in order to reduce the rotational speed of the engine 1, the charge amount control unit 29 of the control circuit 21 increases the charge amount by the starter motor 24, or generates heat by the resistor 24 to electrically connect the starter motor 24. And a braking force is applied to the magnet rotor 5, that is, the crankshaft 4 to reduce the rotational speed of the engine 1. Note that the control circuit 21 always returns to step S8 at every predetermined period to detect the rotational speed during the control in steps S10, S12, S14, S15, and S17. Note that the rotation speeds such as 1000 rpm, 3000 rpm, and 10000 rpm described above are examples, and can be appropriately changed.

  Further, as shown in FIG. 10, the control circuit 21 detects the state of the stop switch 1005 in step S18 independently of the above-described control. In step S19, it is determined whether or not the stop switch 1005 is operated (ON operation). If YES in the condition, the process proceeds to step S20. In step S <b> 20, in order to reduce the rotational speed of the engine 1, the charge amount control unit 29 of the control circuit 21 increases the charge amount by the starter motor 24, or generates heat by the resistor 24 to electrically connect the starter motor 24. And a braking force is applied to the magnet rotor 5, that is, the crankshaft 4 to reduce the rotational speed of the engine 1. On the other hand, in the case of NO that does not satisfy the condition, the process returns to step S18.

  According to the engine 1 configured as described above, the starter motor 24 includes a magnet rotor 5 connected to the crankshaft 4 having a plurality of permanent magnets 17 that are annularly spaced apart in the circumferential direction, and the crankshaft 4 A flat stator 20 having a plurality of drive coils 19 arranged annularly in the circumferential direction so as to face the permanent magnet 17 in the direction of the axis 18 is provided. For this reason, the starter motor 24 can be made compact and the engine 1 can be made compact.

  Further, before starting the engine 1 by the starter motor 24, the starter motor 24 is driven in reverse to move the piston 12 to a position where pressure in the cylinder near the top dead center starts to be applied. For this reason, when the starter motor 24 is rotated forward to start the engine 1, the piston 12 can be prevented from exceeding the top dead center at which the pressure in the cylinder becomes maximum. It is possible to use inertial start without waste by moving a long distance in the direction in which the value decreases. Accordingly, it is possible to suppress the torque required for the starter motor 24 at the start of the engine 1 and also to reduce the required power, and it is possible to make the engine 1 compact by making the starter motor 24 and the battery 22 compact. .

  Further, when the engine 1 is started by the starter motor 24, since the drive coils 19 of all the stators 20 are energized at the start of the start, the engine 1 can be rotated with high torque. Then, by reducing the number of drive coils 19 to be energized by increasing the rotational speed, the maximum rotational speed of the starter motor 24 is increased to near the idling rotational speed, so that the engine 1 can be reliably started.

  Further, when the engine 1 is started and the rotational speed becomes a predetermined value or more, the control circuit 21 cuts off the supply of current from the battery 22 to the drive coil 19 of the stator 20. Then, the battery 22 is charged by operating the starter motor 24 as a generator. For this reason, it is possible to suppress a decrease in the battery 22 due to the operator continuing to turn on the starter switch 1006 even after the engine 1 is started, and the battery 22 is charged by driving the starter motor 24 as a generator. Therefore, the decrease of the battery 22 can be suppressed, the capacity of the battery 22 does not need to be increased, the battery 22 can be downsized, and the engine 1 can be made compact.

  Further, when the engine 1 has excessively increased in speed, such as flying, a load is applied to the starter motor 24 and braking force is applied to the magnet rotor 5 to reduce the engine 1 speed. It is possible to extend the life of the engine 1 by suppressing the excessive rotation of the engine 1. Further, the control circuit 21 can easily use the power band of the engine 1 by controlling the starter motor 24 to apply a load around the rotational speed at which the engine 1 has the maximum output. As a result, efficient work can be performed, fuel used can be reduced, work time can be shortened, and worker fatigue can be reduced.

  In addition, when the stop switch 1005 is operated, the braking force is generated in the magneto rotor 5 of the engine 1 by maximizing the electric load of the starter motor 24. Therefore, the engine 1 rotating with inertia after the stop switch 1005 is operated. Stop time can be shortened.

  Further, since the battery 22 is detachably attached to the engine 1 (on the engine cover 2 housing the engine 1), it can be easily replaced with a spare battery 22 when the battery 22 is discharged. Therefore, the starter motor 24 can be reliably used by always using the charged battery 22, and the battery 22 is removed during the operation of the engine 1, so that the brush cutter 1001 equipped with the engine 1 and the engine 1 can be removed. It can also be reduced in size and weight, and operability can be improved.

  The engine 1 for a portable work machine of the present invention is not limited to the application to the brush cutter 1001 described in the above embodiment, and various modifications and improvements can be made within the scope described in the claims. Is possible. For example, when the above-described engine 1 is applied to, for example, a chain saw, in addition to the above-described control, an electric load is generated in the starter motor 24 when the chain brake is operated as in the case of the above-described stop switch 1005 being operated. You may comprise so that the braking speed may be given to the rotor 5, ie, the crankshaft 4, and the rotation speed of the engine 1 may be reduced.

DESCRIPTION OF SYMBOLS 1 Engine 2 Engine cover 4 Crankshaft 5 Magnet rotor 7 Ignition coil 9 Centrifugal clutch 12 Piston 17 Permanent magnet 19 Drive coil 20 Stator 21 Control circuit 22 Battery 23 Resistance 24 Starter motor 25 Current detection part 26 Rotation number detection part 27 Calculation part 28 Current control unit 29 Charge amount control unit 30 Forward / reverse switching control unit 31 Stator pole control unit 32 Control signal output circuit 33 Ignition device

Claims (12)

An engine for a portable work machine that burns an air-fuel mixture in a cylinder bore by discharging a spark plug by an ignition device constituted by a magnet rotor connected to a crankshaft, an ignition coil and the magnet rotor,
Disposed in the magnet rotor to have a permanent magnet, a rotor that rotates together with the crankshaft,
A stator having a plurality of drive coils facing the permanent magnet;
Battery,
Control means for controlling energization from the battery to the drive coil and controlling energization to the spark plug based on an operation of a stop switch for turning on and off the energization to the spark plug ;
The control means includes a start mode in which the drive coil of the stator is energized to start the engine, and the stop switch is turned on to stop energization of the spark plug, and the rotor A braking mode in which a braking force is generated in the magneto rotor by increasing an electrical load with the stator, and a rotational speed of the crankshaft is decreased.
This is an engine for portable work machines. The control means can start braking of the engine in the braking mode by an operation of an operator.
The engine for a portable work machine according to claim 1 . In the braking mode, an electric load is generated on the starter motor by increasing the amount of charge by the starter motor or by generating heat with resistance.
The engine for a portable work machine according to claim 1 or 2 . In the start mode, the control means applies the braking force to the coil so as to generate a braking force on the magnet rotor when the output of the rotation speed detection means for detecting the rotation speed of the engine exceeds a first predetermined value. Control energization,
The engine for portable work machines according to any one of claims 1 to 3 . In the start mode, the control means changes the number of the coils to be energized based on the output of the rotation speed detection means for detecting the rotation speed of the engine .
The engine for a portable work machine according to any one of claims 1 to 4 , wherein the engine is used. In the start mode, the control means reduces the number of coils to be energized as the engine speed increases.
The engine for a portable work machine according to claim 5 . In the start mode, the control means stops energization from the battery to the coil when the output of the rotation speed detection means for detecting the rotation speed of the engine exceeds a second predetermined value.
The engine for a portable work machine according to any one of claims 1 to 6 . Crank angle detecting means for detecting the angle of the crankshaft;
The control means energizes the coil from the battery so as to drive the rotor to rotate at a predetermined angle based on the output of the crank angle detection means before starting the engine. To control the
The engine for a portable work machine according to any one of claims 1 to 7 , wherein the engine is a portable work machine. In the start mode, the control means supplies the current generated in the coil to charge the battery when the output of the rotation speed detection means for detecting the rotation speed of the engine exceeds a third predetermined value. Supply to the battery,
The engine for portable work machines according to any one of claims 1 to 8 , wherein the engine is used. The battery is detachably mounted;
The engine for a portable work machine according to any one of claims 1 to 9 , wherein the engine is used. In the starting mode, the control unit, when the output rotational speed detecting means for detecting a rotational speed of the engine exceeds a predetermined value of the fourth, in order to reduce the rotational speed of the engine, according to the scan Tatamota Increasing the amount of charge or generating heat with resistance to generate an electrical load on the starter motor , and applying a braking force to the magnet rotor to reduce the engine speed,
The engine for a portable work machine according to any one of claims 1 to 10 , wherein the engine is a portable work machine. The engine according to any one of claims 1 to 11 , comprising:
A portable work machine characterized by that.

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