JPH0544465U - Clutch type electric screwdriver - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a clutch-type electric driver that is easy to use by providing a switching lever so that a detection switch can be arbitrarily turned on and off in a control circuit of the clutch-type electric driver. Therefore, the life of the control circuit is extended to obtain a control circuit for a clutch type electric driver having a long life. [Structure] The control circuit of the clutch type electric driver according to the present invention comprises a DC power supply 1, a main switch 2, and a relay switch 3.
And a series circuit of a motor 4 and a series circuit of a relay coil 6 and a thyristor 7 for operating the relay switch 3, a detection switch 8 for shutting off the output of the motor 4, a resistor R ₁ 9 and a resistor R ₂ A series circuit of 10 is connected in parallel to the relay switch 3 and the motor 4, and a switching lever 5 is provided so that the detection switch 8 can be turned on and off arbitrarily.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement of a control circuit for a clutch type electric driver.

[0002]

[Prior Art]

 FIG. 2 shows a control circuit of a clutch type electric driver according to the prior art. When performing work such as screw tightening using a clutch-type electric screwdriver according to the related art, when the main switch 2 is turned on, the motor 4 rotates. The meshing clutch 33, which is crimped and meshed by the tightening force adjusting spring 32 with adjustable pressing force, is disengaged when a load larger than the pressing force of the tightening force adjusting spring 32 acts, and at the same time the detection switch 8 operates. It operates to supply a gate current to the thyristor 7 and the thyristor 7 becomes conductive. When the thyristor becomes conductive, the relay coil 6 is excited, the contact 3a of the relay switch 3 and the movable piece 36 are inserted, the pole of the motor 4 is short-circuited, and the dynamic braking acts to complete the work.

When the main switch 2 is turned off in this state, the current supplied to the thyristor 7 is cut off, the thyristor 7 is no longer connected, and the relay coil 6 is extinguished and returns to the initial state.

As described above, the conventional clutch type electric driver has a function of reaching the preset clutch disengagement torque and stopping the rotation of the motor at the same time when the clutch operates.

[0005]

[Problems to be solved by the device]

 However, with the conventional clutch-type electric screwdriver, when you want to operate the clutch (for example, when tightening a screw on wood, the wood quality varies depending on the location, the head of the screw floats from the surface in the hard part, Even if the rusty screw is loosened, continuous hitting of the clutch is effective.) However, there is a drawback that the relay circuit operates and rotation (clutch hitting) stops. Also, when looking at the time from when the detection switch is turned on until the dynamic braking acts, the movable piece 3b causes so-called damping until the movable piece 3b of the relay switch completely contacts the contact 3a side. Since a large brake current repeatedly flows between the contact 3b and the contact 3a, the contact is easily welded and the life of the relay switch is shortened. Further, since the detection switch 4 is constantly turned on and off while the clutch 4 is being hit, there is a drawback that the life of the detection switch is short.

An object of the present invention is to make it possible to arbitrarily select the operation of a relay circuit, to obtain a clutch-type electric driver that is easy to use, and at the same time prolong the life of the control circuit.

[0007]

[Means for solving the problem]

 The above object is achieved by providing a switching lever so that the detection switch can be turned on and off arbitrarily, and by arbitrarily turning the switching lever on and off.

[0008]

[Action]

 In the control circuit configured as described above, by turning off the switching lever, the detection switch is always turned off. Therefore, the signal from the detection switch is not transmitted, the thyristor does not operate, and the relay coil does not operate. Is never excited.

[0009]

【Example】

An example of the clutch type electric driver according to the present invention is shown in FIGS. 3 and 4, and its control circuit is shown in FIG. The control circuit of the clutch type electric driver according to the present invention is a series circuit of a DC power source 1, a main switch 2, a relay switch 3 and a motor 4, and a series circuit of a relay coil 6 and a thyristor for operating the relay switch 3 is the parallel connection of relay switches 3 and the motor 4, the detection switch 8 forms a resistor R ₁ 9 and resistor R ₂ 10 and the series circuit, the gate of the thyristor 7 and the resistor R ₁ 9 and the resistor R ₂ 10 A circuit provided with a switching lever 5 so that the detection switch 8 can be turned on and off by being connected between the two. Incidentally, 34 is a leaf spring.

The operation of the clutch-type electric driver configured as described above will be described below.

First, when the main switch 2 is turned on, a current flows through the DC power supply 1, the normally closed contacts of the relay switch 3, and the motor 4. When the switching lever 5 is turned on, the detection switch 8 is turned on regardless of the switching lever 5, and when the preset torque is reached, the clutch is disengaged and the detection switch 8 is turned on to bring the detection switch 8 into conduction. When a current flows through the gate circuit and the relay coil 6 is excited and the movable piece 3b of the relay switch 3 moves from the contact 3c side to the normally open contact 3a side, a brake current flows. When the switching lever 5 is turned off, the detection switch 8 is always turned off regardless of the disengagement of the clutch, so that no current flows in the gate circuit of the thyristor and the relay coil 6 is not excited. The contacts of the relay switch 3 and the detection switch 8 are protected, and at the same time the motor 4 continues to rotate, so that the clutch is continuously hit. Here, as a method of turning off the detection switch 8, there is a method of electrically operating the switching lever 5 to cut off a signal from the detection switch 8. However, in this case, since the detection switch 8 operates in conjunction with the continuous impact of the clutch, there is a drawback that the mechanical life is shortened. The greatest feature of this embodiment is that the change lever 5 prevents the detection switch 8 from mechanically operating. As a result, even if the detection switch 8 is turned off and continuously hit, it becomes independent of the operation of the clutch, and the detection switch 8 itself mechanically secures its life.

[0012]

[Effect of the device]

 According to the present invention, the brake operation linked with the clutch can be arbitrarily selected, so that an easy-to-use clutch type electric driver can be obtained, and the number of times the detection switch is turned on and off can be minimized. Since the current flowing through the relay contact of the relay switch is minimized, the life of the control circuit can be extended.

[Brief description of drawings]

FIG. 1 is a control circuit diagram of a clutch type electric driver according to the present invention.

FIG. 2 is a control circuit diagram of a conventional clutch type electric driver.

FIG. 3 is a vertical sectional view of a clutch type electric driver.
This figure is a cross-sectional view showing a state in which the switching lever 5 is operated in the OFF direction to turn off the detection switch 8.

FIG. 4 is a cross-sectional view showing a disengaged state of the clutch in which the switching lever 5 of the embodiment shown in FIG. 3 is operated in the ON direction so that the detection switch 8 can be freely operated.

[Explanation of symbols]

 3 Relay switch 4 Motor 5 Relay selector switch 6 Relay coil 7 Thyristor

Claims (1)

[Scope of utility model registration request] 1. A detection switch for detecting the operation of a clutch, and a relay coil is excited by receiving a signal from the detection switch to operate the relay switch to cut off energization to a motor to short-circuit between poles for dynamic braking. A clutch-type electric driver having a control circuit configured to apply the clutch-type electric driver, wherein a switching lever capable of arbitrarily switching the operation of the detection switch is provided.