WO2018221107A1

WO2018221107A1 - Impact work machine

Info

Publication number: WO2018221107A1
Application number: PCT/JP2018/017229
Authority: WO
Inventors: 英貴山田
Original assignee: 工機ホールディングス株式会社
Priority date: 2017-05-31
Filing date: 2018-04-27
Publication date: 2018-12-06
Also published as: JPWO2018221107A1; JP6927296B2

Abstract

Provided is an impact work machine capable of suitably controlling a drilling speed. An impact work machine (1) comprises: a motor (3) for varying the pressure in a pressure chamber (7); an impact element (8) and an intermediate element (9) that impact a tip tool (10) due to the varied pressure in the pressure chamber (7); a distance sensor (20) for detecting the speed of drilling in a material to be cut; and a control unit capable of controlling the rotation speed of the motor (3) on the basis of the detection results from the distance sensor (20). The control unit can execute control of the rotation speed of the motor (3) based on the detection results from the distance sensor (20) in a rotation impact mode where the tip tool (10) is impacted while being rotated.

Description

Hammering machine

The present invention relates to a hammering machine such as a hammer drill having a configuration in which a tip tool is hit using a change in pressure in a pressure chamber.

In a hammering machine such as a hammer drill, a hammer is reciprocated by a motor to expand / compress the air in the cylinder and move the hammer in the cylinder back and forth. Strikes and drives the tip tool via the mesonator (striking operation), and transmits the rotational force of the motor to the tip tool to rotate and drive the tip tool itself (rotation operation). In a hammer drill, a drilling operation on a work material is made possible by a rotary hammering operation that combines this hammering motion and a rotational motion.

JP 2017-13173 A

There is a desire to maximize the drilling speed during work. Here, in the rotation operation, the drilling speed is also maximized by maximizing the rotation speed of the motor. However, in the case of the striking operation and the rotational striking operation for striking the tip tool due to fluctuations in pressure in the pressure chamber, the operation of the striking mechanism for striking the tip tool will not catch up with the motor speed if the motor speed is too high. In addition, the striking force becomes insufficient, and the perforation speed decreases. Since the rotation speed of the motor at which the drilling speed is maximized varies depending on the mass of a member (for example, striking element or meson) constituting the striking mechanism, the hardness of the work material, etc., it is difficult to set in advance.

The present invention has been made in view of such a situation, and an object thereof is to provide a striking work machine capable of appropriately controlling the drilling speed.

One embodiment of the present invention is a striking work machine. This striking machine
A motor that varies the pressure in the pressure chamber;
A striking mechanism for striking a tip tool using fluctuations in pressure in the pressure chamber;
Drilling speed detecting means for detecting the speed of drilling the work material;
A control unit capable of controlling the number of rotations of the motor based on a detection result by the punching speed detection means.

The drilling speed detection means may include a distance sensor that detects a distance between the facing work material and itself.

The motor may be a brushless motor.

The control unit is capable of executing a rotation impact mode in which the impact tool is struck while rotating the tip tool and an impact mode in which the impact tool is struck without rotating the tip tool, and is based on a detection result by the drilling speed detection means. Whether to execute the rotation speed control of the motor may be switchable depending on the mode.

The control unit can execute rotation speed control of the motor based on a detection result by the punching speed detection means in the rotation hitting mode, and does not have to execute the rotation speed control in the hitting mode. .

The control unit may be capable of switching whether or not to execute the rotational speed control of the motor based on a detection result by the punching speed detection means in the rotary impact mode.

The rotational speed control of the motor based on the detection result by the punching speed detection means is
As a result of increasing the rotation speed of the motor from the current rotation speed, the rotation speed of the motor is further increased when the drilling speed is increased, and the rotation speed of the motor is decreased when the drilling speed is decreased. And
As a result of lowering the rotation speed of the motor from the current rotation speed, when the drilling speed is increased, the rotation speed of the motor is further decreased, and when the drilling speed is decreased, the rotation speed of the motor is increased. Control may be performed.

The controller may not make the rotation speed of the motor higher than a predetermined rotation speed regardless of the drilling speed.

Pressure detecting means for detecting the pressure in the pressure chamber;
The controller may be capable of controlling the number of rotations of the motor based on a detection result by the pressure detection unit.

The rotational speed control of the motor based on the detection result by the pressure detection means is within a range where the drilling speed satisfies a predetermined condition.
As a result of increasing the rotational speed of the motor from the current rotational speed, when the pressure in the pressure chamber decreases, the rotational speed of the motor is further increased, and when the pressure in the pressure chamber increases, the motor Reduce the rotation speed,
As a result of lowering the rotational speed of the motor from the current rotational speed, when the pressure in the pressure chamber becomes lower, the rotational speed of the motor is further reduced, and when the pressure in the pressure chamber becomes higher, Control to increase the number of revolutions may be used.

It should be noted that any combination of the above-described constituent elements, and those obtained by converting the expression of the present invention between methods and systems are also effective as aspects of the present invention.

According to the present invention, it is possible to provide an impact working machine capable of appropriately controlling the drilling speed.

1 is a side sectional view of an impact work machine 1 according to an embodiment of the present invention. FIG. 3 is a circuit diagram of the impact work machine 1. The time chart which shows an example of the time change of the rotation speed of the motor 3 in a drilling speed priority mode, and a drilling speed. 4 is a control flowchart of the impact work machine 1 in the drilling speed priority mode. The time chart which shows an example of the time change of the rotation speed of the motor 3, the drilling speed, and the pressure in the pressure chamber (air chamber) 7 in a feeling priority mode. The control flowchart of the hit working machine 1 in the feeling priority mode.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or equivalent component, member, process, etc. which are shown by each drawing, and the overlapping description is abbreviate | omitted suitably. In addition, the embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

FIG. 1 is a side sectional view of an impact work machine 1 according to an embodiment of the present invention. With reference to FIG. 1, the front-rear and vertical directions are defined. The striking work machine 1 is a hammer drill, and can apply a turning work, a drilling work, and a crushing work to a work material such as concrete or stone by applying a rotational force and a striking force to the tip tool 10. . Since the configuration from the rotation of the motor 3 to the rotation and impact of the tip tool 10 in the impact work machine 1 is well known, only a brief description will be given below.

The striking work machine 1 is AC-driven here, and a power cord 15 for connecting to an external AC power source extends from the lower rear end of the housing 2 (lower end of the handle portion 2a). The rear portion of the housing 2 is a handle portion 2a, and a trigger switch 16 is provided on the handle portion 2a for the user to switch between driving and stopping of the motor 3. A motor 3, a motion conversion mechanism 4, a rotation transmission mechanism 5, a cylinder 11, and a retainer sleeve (tool holding part) 12 are held in the housing 2. The cylinder 11 and the retainer sleeve 12 are rotatable with respect to the housing 2 about the front-rear direction. In the cylinder 11 and the retainer sleeve 12, a piston 6, a striker 8, and an intermediate 9 are provided so as to be capable of reciprocating in the front-rear direction. A pressure chamber (air chamber) 7 is provided between the piston 6 and the striker 8. The front end tool 10 is detachably held at the front end portion of the retainer sleeve 12.

Here, the motor 3 is an inner rotor type brushless motor, and is provided in a lower portion of the housing 2. A control board 40 for controlling the driving of the motor 3 is provided behind the motor 3 in the housing 2. The rotation of the motor 3 about the vertical direction is converted into a reciprocating motion in the front-rear direction of the piston 6 by a motion conversion mechanism 4 such as a crank mechanism. By the reciprocating motion of the piston 6, the pressure (air pressure) of the pressure chamber 7 fluctuates (expands / compresses), and the striker 8 is driven back and forth back and forth. The striker 8 strikes the intermediate piece 9, and the intermediate piece 9 strikes the tip tool 10. On the other hand, the rotation of the motor 3 about the vertical direction is converted into the rotation of the cylinder 11 and the retainer sleeve 12 about the front-rear direction by the rotation transmission mechanism 5 including a pair of bevel gears. The tip tool 10 is rotationally driven together with the retainer sleeve 12. The user can change the operation mode of the impact work machine 1 with a mode setting dial 13 provided at the upper part of the housing 2, a hammer mode (impact mode) in which impact force is applied to the tip tool 10 without applying rotational force, It is possible to switch between a hammer drill mode (rotary impact mode) in which both the rotational force and the impact force are applied to the tool 10. A shaft (depth gauge) 17 extending in the front-rear direction above the housing 2 is a member for determining the drilling depth by contacting the work piece with the front end, and is at a predetermined position in the front-rear direction with respect to the housing 2. Attached.

The striking work machine 1 according to the present embodiment includes a distance sensor 20 and a pressure sensor 30. In the hammer drill mode, pressure is controlled under the conditions of control for maximizing the drilling speed (drilling speed priority mode) and a drilling speed of a certain level or more. The control (feeling priority mode) for minimizing the pressure in the chamber 7 can be executed. The user can select which control is to be performed by the control switching button 14. The distance sensor 20 is provided in the housing 2 at a position below the pressure chamber 7 and faces the front outside the housing 2. The distance sensor 20 detects the distance between the work material facing itself. The pressure sensor 30 is provided in the piston 6, faces the pressure chamber 7, and detects the pressure in the pressure chamber 7.

FIG. 2 is a circuit diagram of the impact work machine 1. In FIG. 2, the distance sensor 20 and the pressure sensor 30 are shown together in one block. A diode bridge 103 as a rectifier circuit is connected to the AC power supply 50 via a noise countermeasure circuit 51. An inverter circuit 102 is connected to the output side of the diode bridge 103 via a power factor correction circuit 104. The noise countermeasure circuit 51 has a role of preventing noise generated in the inverter circuit 102 from being transmitted to the AC power supply 50 side. The diode bridge 103 converts the alternating current of the alternating current power supply 50 into a direct current and supplies it to the inverter circuit 102. The inverter circuit 102 has switching elements Tr1 to Tr6 such as FETs and IGBTs connected in a three-phase bridge, and supplies a drive current to the stator coils U1, V1, and W1 of the motor 3.

The motor control unit 105 that controls the inverter circuit 102 includes a controller 106. A control signal (for example, a PWM signal) is sent from the controller 106 to each switching element of the inverter circuit 102 via the control signal output circuit 107. Detection signals from the hall elements S1 to S3 are sent to the rotor position detection circuit 101. The signal output from the rotor position detection circuit 101 is sent to the controller 106 and the motor rotation number detection circuit 108. The motor rotation speed detection circuit 108 calculates the actual rotation speed of the motor 3. The signal output from the motor rotation speed detection circuit 108 is sent to the controller 106. The controller 106 includes a microprocessor that calculates a control signal to be output to the control signal output circuit 107, a memory that stores a program, an arithmetic expression, and data used to control the rotation speed of the motor 3, a timer that measures time, Have The controller 106 performs control in an operation mode (hammer mode or hammer drill mode) corresponding to the rotational position of the mode setting dial 13. Further, in the hammer drill mode, the controller 106 executes control in the drilling speed priority mode or the feeling priority mode according to the operation of the control switching button 14. The controller 106 detects the current flowing through the motor 3 based on the voltage across the resistor Rs provided in the current path of the motor 3.

FIG. 3 is a time chart showing an example of temporal changes in the rotation speed of the motor 3 and the drilling speed in the drilling speed priority mode. The drilling speed is calculated from the time change of the output signal of the distance sensor 20 in the controller 106. First, the controller 106 drives the motor 3 to rotate at the initial rotational speed. Thereafter, the controller 106 increases the rotational speed of the motor 3 at time t1. As a result of increasing the rotation speed of the motor 3 at time t1, the drilling speed has increased, so the controller 106 further increases the rotation speed of the motor 3 at time t2. As a result of increasing the rotational speed of the motor 3 at time t2, the drilling speed has further increased, so the controller 106 further increases the rotational speed of the motor 3 at time t3. The increments of the rotation speed of the motor 3 at the times t1, t2, and t3 are equal.

As a result of increasing the rotation speed of the motor 3 at time t3, the drilling speed has decreased, so the controller 106 decreases the rotation speed of the motor 3 at time t4. The decrease range of the rotation speed of the motor 3 at time t4 is smaller than the increase width of the rotation speed of the motor 3 at time t3, and is halved in the illustrated example. As a result of the decrease in the rotation speed of the motor 3 at time t4, the drilling speed has increased. Therefore, the controller 106 further decreases the rotation speed of the motor 3 at time t5. A decrease width of the rotation speed of the motor 3 at time t5 is equal to a decrease width of the rotation speed of the motor 3 at time t4. As a result of reducing the rotation speed of the motor 3 at time t5, the drilling speed has decreased, so the controller 106 increases the rotation speed of the motor 3 at time t6. The increase width of the rotation speed of the motor 3 at time t6 is smaller than the decrease width of the rotation speed of the motor 3 at time t5, and is halved in the illustrated example. As a result of increasing the rotation speed of the motor 3 at time t6, the drilling speed has increased, so the controller 106 further increases the rotation speed of the motor 3 at time t7. The increase width of the rotation speed of the motor 3 at time t7 is equal to the increase width of the rotation speed of the motor 3 at time t6. The controller 106 continues the control to calculate the drilling speed and change the rotation speed of the motor 3 after time t7.

FIG. 4 is a control flowchart of the impact work machine 1 in the drilling speed priority mode. When the controller 106 detects that the trigger switch 16 is turned on (YES in S1), it starts the motor 3 (S2), and controls the rotational speed of the motor 3 to a predetermined rotational speed N1 (initial value of the variable N1) (S3). . The controller 106 determines whether or not the hammer drill mode is selected based on the rotational position of the mode setting dial 13 (S4). If the mode is not the hammer drill mode (NO in S4), the controller 106 drives the motor 3 as long as the trigger switch 16 is on. If the trigger switch 16 is turned off (NO in S5), the motor 3 is stopped (S6).

In the hammer drill mode (YES in S4), the controller 106 detects the current flowing through the motor 3 based on the voltage across the resistor Rs when the trigger switch 16 is on (YES in S7) (S8). The controller 106 detects the distance to the work material from the output signal of the distance sensor 20 and substitutes it into the variable L0 if the actual load state, that is, the current flowing through the motor 3 is equal to or greater than a predetermined value (YES in S9) ( Similarly, after t seconds, the distance to the work material is detected and substituted into the variable L1 (S11), and the difference between the variable L0 and the variable L1 (L0−L1) is substituted into the variable ΔL1 (S12). If the variable ΔL does not contain a value (NO in S13), the controller 106 substitutes the current rotational speed N1 of the motor 3 for the variable N, and substitutes the value of the variable ΔL1 for the variable ΔL (S19). The controller 106 substitutes N + ΔN1 for the variable N1, controls the rotational speed of the motor 3 to N1 (S21), and returns to step S7.

If the variable ΔL has a value in step S13 (YES in S13), the controller 106 determines whether or not the rotational speed of the motor 3 has been decreased immediately before (S14). When the rotation speed of the motor 3 is increased immediately before (NO in S14), the controller 106 changes the drilling speed (YES in S15) and increases the drilling speed (YES in S17). Is substituted for the variable N, and the value of the variable ΔL1 is substituted for the variable ΔL (S19). The controller 106 substitutes N + ΔN1 for the variable N1, controls the rotational speed of the motor 3 to N1 (S21), and returns to step S7. When the drilling speed decreases in step S17 (NO in S17), the controller 106 substitutes the value of the variable ΔN1 for the variable ΔN (S17a), and substitutes a value that is ½ times ΔN for the variable ΔN1 (S17b). . The controller 106 substitutes the current rotational speed N1 of the motor 3 for the variable N, and substitutes the value of the variable ΔL1 for the variable ΔL (S20). The controller 106 substitutes N−ΔN1 for the variable N1, controls the rotation speed of the motor 3 to N1 (S22), and returns to step S7.

When the rotational speed of the motor 3 is decreased immediately before (YES in S14), the controller 106 changes the drilling speed (YES in S16) and increases the drilling speed (YES in S18). Is substituted for the variable N, and the value of the variable ΔL1 is substituted for the variable ΔL (S20). The controller 106 substitutes N−ΔN1 for the variable N1, controls the rotation speed of the motor 3 to N1 (S22), and returns to step S7. When the drilling speed is reduced in step S18 (NO in S18), the controller 106 substitutes the value of the variable ΔN1 for the variable ΔN (S18a), and substitutes a value that is ½ times ΔN for the variable ΔN1 (S18b). . The controller 106 substitutes the current rotational speed N1 of the motor 3 for the variable N, and substitutes the value of the variable ΔL1 for the variable ΔL (S19). The controller 106 substitutes N + ΔN1 for the variable N1, controls the rotational speed of the motor 3 to N1 (S21), and returns to step S7.

If the drilling speed has not changed in each of steps S15 and S16 (NO in S15 or NO in S16), controller 106 returns to step S7. It should be noted that the presence / absence of a change in drilling speed in steps S15 and S16 has a predetermined width, and if the change is less than the predetermined width, it is determined that there is no change, and if the change is greater than or equal to the predetermined width, it is determined that there is a change. If the trigger switch 16 is OFF in step S7 (NO in S7), the controller 106 stops the motor 3 (S6). The controller 106 does not make the rotation speed of the motor 3 higher than a predetermined rotation speed (allowable maximum rotation speed) regardless of the drilling speed. This is to protect the striking mechanism.

FIG. 5 is a time chart showing an example of temporal changes in the rotation speed of the motor 3, the drilling speed, and the pressure in the pressure chamber (air chamber) 7 in the feeling priority mode. The pressure in the pressure chamber 7 is detected by the pressure sensor 30 and fed back to the controller 106. First, the controller 106 drives the motor 3 to rotate at the initial rotational speed. Thereafter, the controller 106 reduces the rotational speed of the motor 3 at time t1. As a result of reducing the rotational speed of the motor 3 at time t1, the drilling speed is equal to or higher than a predetermined value, and the pressure in the pressure chamber 7 is reduced. Therefore, the controller 106 further reduces the rotational speed of the motor 3 at time t2. As a result of reducing the rotational speed of the motor 3 at time t2, the drilling speed is equal to or higher than a predetermined value, and the pressure in the pressure chamber 7 further decreases. Therefore, the controller 106 further reduces the rotational speed of the motor 3 at time t3. . The amount of decrease in the rotation speed of the motor 3 at the times t1, t2, and t3 is equal.

As a result of reducing the rotational speed of the motor 3 at time t3, the pressure in the pressure chamber 7 is reduced, but the drilling speed falls below a predetermined value. Therefore, the controller 106 increases the rotational speed of the motor 3 at time t4. The increase range of the rotation speed of the motor 3 at time t4 is smaller than the decrease width of the rotation speed of the motor 3 at time t3, and is halved in the illustrated example. As a result of increasing the rotation speed of the motor 3 at time t4, the pressure in the pressure chamber 7 increased, but the drilling speed returned to a predetermined value or more. Therefore, the controller 106 decreases the rotation speed of the motor 3 at time t5. . The decrease width of the motor 3 at time t5 is smaller than the increase speed of the motor 3 at time t4, and is halved in the illustrated example. As a result of reducing the rotational speed of the motor 3 at time t5, the pressure in the pressure chamber 7 is reduced, but the drilling speed falls below a predetermined value. Therefore, the controller 106 increases the rotational speed of the motor 3 at time t6. The increase width of the rotation speed of the motor 3 at time t6 is smaller than the decrease width of the rotation speed of the motor 3 at time t5, and is halved in the illustrated example. As a result of increasing the rotational speed of the motor 3 at time t6, the pressure in the pressure chamber 7 has increased, but the drilling speed has become equal to a predetermined value, so the controller 106 maintains the rotational speed of the motor 3.

FIG. 6 is a control flowchart of the impact work machine 1 in the feeling priority mode. In this figure, steps up to step S12 are the same as those in FIG. 4, and illustrations prior to step S9 are omitted. After substituting the difference between the variable L0 and the variable L1 (L0-L1) for the variable ΔL1 in step S12, the controller 106 checks whether the drilling speed is too slow (is not lower than a predetermined value) (S30). If the drilling speed is not too slow (YES in S30), the controller 106 detects the pressure in the pressure chamber 7 based on the signal from the pressure sensor 30, and substitutes it in the variable P1 (S31). When the variable P does not contain a value (NO in S32), the current rotational speed N1 of the motor 3 is assigned to the variable N, and the value of the variable P1 is assigned to the variable P (S39). The controller 106 substitutes N−ΔN1 for the variable N1, controls the rotational speed of the motor 3 to N1 (S41), and returns to step S7.

If the variable P has a value in step S32 (YES in S32), the controller 106 determines whether or not the number of revolutions of the motor 3 has been increased immediately before (S33). When the controller 106 increases the rotational speed of the motor 3 immediately before (YES in S33), the pressure in the pressure chamber 7 changes (YES in S34), and the pressure in the pressure chamber 7 decreases (S36). YES), the current rotational speed N1 of the motor 3 is substituted into the variable N, and the value of the variable P1 is substituted into the variable P (S38). The controller 106 substitutes N + ΔN1 for the variable N1, controls the rotational speed of the motor 3 to N1 (S40), and returns to step S7. When the pressure in the pressure chamber 7 increases in step S36 (NO in S36), the controller 106 substitutes the value of the variable ΔN1 for the variable ΔN (S36a), and substitutes a value that is ½ times ΔN for the variable ΔN1. (S36b). The controller 106 substitutes the current rotational speed N1 of the motor 3 for the variable N, and substitutes the value of the variable P1 for the variable P (S39). The controller 106 substitutes N−ΔN1 for the variable N1, controls the rotational speed of the motor 3 to N1 (S41), and returns to step S7.

When the number of revolutions of the motor 3 is decreased immediately before (NO in S33), the controller 106 changes the pressure in the pressure chamber 7 (YES in S35), and the pressure in the pressure chamber 7 decreases (S37). YES), the current rotational speed N1 of the motor 3 is substituted into the variable N, and the value of the variable P1 is substituted into the variable P (S39). The controller 106 substitutes N−ΔN1 for the variable N1, controls the rotational speed of the motor 3 to N1 (S41), and returns to step S7. If the pressure in the pressure chamber 7 has increased in step S37 (NO in S37), the controller 106 substitutes the value of the variable ΔN1 for the variable ΔN (S37a), and substitutes a value that is ½ times ΔN for the variable ΔN1. (S37b). The controller 106 substitutes the current rotational speed N1 of the motor 3 for the variable N, and substitutes the value of the variable P1 for the variable P (S38). The controller 106 substitutes N + ΔN1 for the variable N1, controls the rotational speed of the motor 3 to N1 (S40), and returns to step S7.

If the pressure in the pressure chamber 7 does not change in each of steps S34 and S35 (NO in S34 or NO in S35), the controller 106 returns to step S7. The determination of whether or not there is a change in the pressure in the pressure chamber 7 in steps S34 and S35 has a predetermined width. If the change is less than the predetermined width, it is determined that there is no change. Is determined. If the drilling speed is too slow in step S30 (NO in S30), the controller 106 proceeds to step S41 if the number of rotations of the motor 3 is increased immediately before (YES in S42). If the rotation speed of the motor 3 is decreased immediately before (lowering), the process proceeds to step S40 (the rotation speed of the next motor 3 is increased).

According to the present embodiment, the following effects can be achieved.

(1) In the punching speed priority mode, the striking mechanism is controlled in order to detect the change in the drilling speed when the rotation speed of the motor 3 is changed by the output signal of the distance sensor 20 and to control the drilling speed to the maximum. The optimum rotation speed of the motor 3 (the rotation speed of the motor 3 at which the drilling speed is maximized), which varies depending on the mass of the constituent members (for example, the striker 8 and the intermediate element 9) and the hardness of the work material, is appropriately derived to perform drilling. You can maximize speed.

(2) In the feeling priority mode, the pressure change in the pressure chamber 7 when the number of revolutions of the motor 3 is changed is detected by the output signal of the pressure sensor 30, and the pressure is adjusted under the condition that the drilling speed is a predetermined value or more. Since the control is performed so that the pressure in the chamber 7 becomes the lowest, the reaction force can be reduced while maintaining a perforation speed of a certain level or more, and the work feeling can be improved.

(3) Since the user can switch between the punching speed priority mode and the feeling priority mode, the user himself can select and change the ability of the hitting work machine 1 according to the user's preference and the situation of the work site. And convenient.

The present invention has been described above by taking the embodiment as an example. However, it is understood by those skilled in the art that various modifications can be made to each component and each processing process of the embodiment within the scope of the claims. By the way. Hereinafter, modifications will be described.

In addition to the drilling speed priority mode and the feeling priority mode described in the embodiment, the controller 106 can execute a rotation speed fixing mode that fixes the rotation speed of the motor 3 regardless of the drilling speed and the pressure in the pressure chamber 7. It may be. In this case, the rotation speed fixing mode may be selected with the mode setting dial 13. The number of rotations of the motor 3 in the rotation number fixing mode may be selectable from a plurality of stages.

The punching speed detecting means may be an acceleration sensor instead of the distance sensor 20. Since the integration of the acceleration becomes the speed, the drilling speed can be detected also by a signal from the acceleration sensor. If the shaft 17 as a depth gauge is slidable back and forth with respect to the housing 2 and the shaft 17 is retracted by the work material as the drilling progresses, the drilling speed can be detected from the retracted amount of the shaft 17. it can. The retraction amount of the shaft 17 can be detected by, for example, providing a magnet at a predetermined interval on the shaft 17 and providing a magnetic sensor on the support portion of the shaft 17 on the housing 2 side.

DESCRIPTION OF SYMBOLS 1 ... Blow working machine (hammer drill), 2 ... Housing, 3 ... Motor (brushless motor), 4 ... Motion conversion mechanism, 5 ... Rotation transmission mechanism, 6 ... Piston, 7 ... Pressure chamber (air chamber), 8 ... Batter , 9 ... Meson, 10 ... Tip tool, 11 ... Cylinder, 12 ... Retainer sleeve (tool holder), 13 ... Mode setting dial, 14 ... Speed setting button, 15 ... Power cord, 16 ... Trigger switch, 17 ... Shaft ( Depth gauge), 20 ... distance sensor, 30 ... pressure sensor

Claims

A motor that varies the pressure in the pressure chamber;
A striking mechanism for striking a tip tool using fluctuations in pressure in the pressure chamber;
Drilling speed detecting means for detecting the speed of drilling the work material;
A striking work machine comprising: a control unit capable of controlling the number of rotations of the motor based on a detection result by the punching speed detection means.
The striking work machine according to claim 1, wherein the drilling speed detection means includes a distance sensor that detects a distance between the facing work material and itself.
The striking work machine according to claim 1 or 2, wherein the motor is a brushless motor.
The control unit is capable of executing a rotation impact mode in which the impact tool is struck while rotating the tip tool and an impact mode in which the impact tool is struck without rotating the tip tool, and is based on a detection result by the drilling speed detection means. The striking work machine according to any one of claims 1 to 3, wherein whether or not to execute rotation speed control of the motor can be switched according to a mode.
The said control part can perform rotation speed control of the said motor based on the detection result by the said punching speed detection means in the said rotation impact mode, and does not perform the said rotation speed control in the said impact mode. The blow work machine described in 1.
6. The striking work according to claim 4 or 5, wherein the control unit can switch whether or not to execute the rotational speed control of the motor based on a detection result by the punching speed detecting means in the rotational striking mode. Machine.
The rotational speed control of the motor based on the detection result by the punching speed detection means is
As a result of increasing the rotation speed of the motor from the current rotation speed, the rotation speed of the motor is further increased when the drilling speed is increased, and the rotation speed of the motor is decreased when the drilling speed is decreased. And
As a result of lowering the rotation speed of the motor from the current rotation speed, when the drilling speed is increased, the rotation speed of the motor is further decreased, and when the drilling speed is decreased, the rotation speed of the motor is increased. The hitting work machine according to any one of claims 1 to 6, wherein the hitting work machine is a control to perform.
The striking work machine according to any one of claims 1 to 7, wherein the control unit does not make the rotation speed of the motor higher than a predetermined rotation speed regardless of the drilling speed.
Pressure detecting means for detecting the pressure in the pressure chamber;
The striking work machine according to any one of claims 1 to 8, wherein the control unit is capable of controlling a rotation speed of the motor based on a detection result by the pressure detection unit.
The rotational speed control of the motor based on the detection result by the pressure detection means is within a range where the drilling speed satisfies a predetermined condition.
As a result of increasing the rotational speed of the motor from the current rotational speed, when the pressure in the pressure chamber decreases, the rotational speed of the motor is further increased, and when the pressure in the pressure chamber increases, the motor Reduce the rotation speed,
As a result of lowering the rotational speed of the motor from the current rotational speed, when the pressure in the pressure chamber becomes lower, the rotational speed of the motor is further reduced, and when the pressure in the pressure chamber becomes higher, The striking work machine according to claim 9, which is a control for increasing the number of rotations.