JP3461622B2 - Electromagnetic impact device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic hitting device used for rock drills, breakers and the like. 2. Description of the Related Art Conventionally, a hitting device used for a rock drill, a breaker or the like reciprocates a piston in a cylinder by hydraulic pressure or pneumatic pressure to hit a tool such as a rod or a chisel. The pneumatic impact device has a simple mechanism and is inexpensive, but generates a large amount of noise due to exhaust, and has an energy utilization efficiency of 15 to 15%.
It is extremely low at 20%. [0003] The hydraulic hitting device has an energy utilization efficiency of about 50 to 60%, and the energy utilization efficiency required for operation of the hydraulic hitting device, including an engine, a motor such as an electric motor, and a hydraulic pump, is low. , Lower. Also,
As a pressure source for the working fluid, a compressor is used in the case of pneumatic pressure, and a motor and a hydraulic pump are provided in the case of hydraulic pressure. Therefore, a striking device having a reciprocating striking mechanism in which a cylinder is provided with a stator of a linear motor and a piston is a movable element of the linear motor has been proposed. [0005] However, it is difficult to obtain the propulsive force of the piston required by a rock drill, a hydraulic breaker, and the like with a conventional electromagnetic striking device using a linear motor. There is a problem that the hitting power when hitting is insufficient. SUMMARY OF THE INVENTION The present invention solves such a problem in a striking device, and has a simple mechanism, requires a small number of equipments, has a high energy utilization efficiency, and can obtain a sufficient thrust of a piston. It is intended to provide a device. According to the present invention, there is provided a striking apparatus having a reciprocating striking mechanism in which a linear motor stator is provided in a cylinder and a piston is a movable element of the linear motor. The above problem is solved by providing a ferromagnetic partition member for partitioning the coil. When the electromagnetic striking device is driven, a current is supplied to the coil of the stator, and a magnetic field is generated in the energized coil to reciprocate the piston. Magnetic lines of force are characterized in that they easily pass through a portion having a large relative magnetic permeability, and at this time, the magnetic lines of force flow intensively in the partition member. Accordingly, the lines of magnetic force concentrate in the gap between the rear end of the piston and the partition member, and the magnetic flux density is higher than that without the partition member. [0008] Magnetic energy is stored in places where the magnetic permeability is low and the magnetic flux density is high. Since the magnetic permeability of the ferromagnetic piston and the partition member is very large compared to the magnetic permeability in air, most of the magnetic energy is stored in the gap between the piston and the coil. Therefore, the magnetic energy in the gap between the piston and the partition member is
When the magnetic energy is much larger than that without the partition member, the propulsive force of the piston becomes larger. As described above, the provision of the ferromagnetic partition member increases the propulsive force of the piston in this electromagnetic striking device, and the large striking force required by striking devices such as rock drills and breakers. Is obtained. FIG. 1 is an explanatory view of a configuration of a breaker provided with an electromagnetic hitting device according to an embodiment of the present invention, and FIG. 2 is an explanatory view of an analysis result of a magnetic line of force in a lower half portion of a piston and a coil. It is.
In this breaker 1, a cylinder 2 is provided with a cylindrical coil 5 constituting a stator of a linear motor, and a piston 3 which is a movable element of the linear motor is provided inside the cylinder. The coil 5 is divided into five sections by a ferromagnetic partition member 6 at equal intervals in the front-rear direction (left and right in the figure).
As the partition member 6, a laminated plate made of a ferromagnetic material is used. This coil 5 is connected to a power supply 12 via a switch 13 which is opened and closed by a control signal from a control device 11. The piston 3 has a large-diameter portion 3F whose front portion is made of a ferromagnetic material, and a small-diameter portion 3R whose rear portion is made of a nonmagnetic metal. There is a gap G between the large-diameter portion 3F and the coil 5, the small-diameter portion 3R is supported by a bearing 8 provided behind the coil 5, and the piston 3
It can reciprocate back and forth inside. A chisel 4 is inserted in front of the cylinder 2 so as to be slidable back and forth by a predetermined distance. A spring 7 for urging the piston 3 forward is mounted on the rear end of the piston 3. At the rear of the cylinder 2, two position detectors 9 and 10 are provided at a predetermined distance in front and rear to detect the position when the piston 3 reciprocates back and forth. The detectors 9 and 10 are each connected to the control device 11. When the switch 13 is opened and no current is supplied to the coil 5, the piston 3
At a position where it moves forward and abuts the rear end face of the chisel 4. The front position detector 9 detects the rear end position of the piston 3 in this state and sends a signal to the control device 11. The control device 11 which has received the signal from the position detector 9
Sends a signal to the switch 13 to close the switch 13 and current is supplied to the coil 5. Energized coil 5
A magnetic field is generated therein, and the large-diameter portion 3F of the piston 3 made of a ferromagnetic material is magnetized. At this time, as shown in FIG.
On the lower side of the piston 3, the direction of the current flowing through the coil 5 is from the back side of the drawing to the front side. Has become. Here, since a forward force acts on the coil 5 in accordance with Fleming's left-hand rule, a backward force acts on the piston 3 as its reaction force. The piston 3 to which the rearward force has acted has a spring 7
Retract and accelerate while compressing. When the piston 3 continues to retreat and the rear end of the piston 3 reaches the position of the rear position detector 10, the position detector 10 detects the rear end position of the piston 3 and sends a signal to the control device 11. The control device 11 having received the signal from the position detector 10
To the switch 13 to open the switch,
The supply of the current to the coil 5 is stopped. When the supply of current to the coil 5 is stopped, the magnetic field disappears, so that the backward thrust acting on the piston 3 is lost, and the piston 3
The reversing speed is reduced by the reaction force of the spring 7, and then stops. Thereafter, the piston 3 is advanced / accelerated by the force of the compressed spring 7, and the advanced piston 3 hits the rear end face of the chisel 4. Front position detector 9
Detects the rear end position of the piston 3 in this state and sends a signal to the control device 11. The control device 11 that has received the signal from the position detector 9 closes the switch 13 again,
Since current is supplied to the coil 5, the piston 3 starts retreating again, and the same cycle is repeated thereafter. In this cycle, after the control device 11 receives a signal from the rear position detector 10, the switch 1
If the time until the signal for interrupting the current is sent to the piston 3 is changed, the stroke of the piston 3 changes and the energy stored in the spring 7 changes, so that the speed of the piston 3 at the time of impact can be controlled. . In this embodiment, the spring 7 is mounted on the rear end of the piston 3. However, a pressure chamber is provided behind the piston 3, gas is sealed in the pressure chamber, and the gas is pressurized when the piston 3 retreats. The piston 3 may be configured to be advanced by the reaction force of the gas. In the operation of the above-mentioned electromagnetic striking device, the magnetic force lines 14 are characterized by being easy to pass through a portion having a large relative magnetic permeability, so that the rear end portion of the large diameter portion 3F of the piston 3 as shown in FIG. Is near the ferromagnetic partition member 6,
The lines of magnetic force 14 flow in the partition member 6 in a concentrated manner. Therefore,
The lines of magnetic force 14 are concentrated in the gap G between the rear end of the large-diameter portion 3F of the piston 3 and the partition member 6, and the magnetic flux density is higher than that without the partition member 6. The magnetic energy is represented by the following equation, and is stored at a place where the magnetic permeability is low and the magnetic flux density is high. W = B ² / (2μ) W: magnetic energy B: magnetic flux density μ: magnetic permeability The magnetic permeability of the large-diameter portion 3F of the piston 3 made of a ferromagnetic material and the partition member 6 is much higher than the magnetic permeability in air. , Most of the magnetic energy is stored in the gap G between the rear end of the large diameter portion 3F of the piston 3 and the coil 5. Therefore, the magnetic energy in the gap G between the rear end of the large diameter portion 3F of the piston 3 and the partition member 6 is much larger than that without the partition member 6. The propulsive force of the piston 3 is expressed by the following equation. As the magnetic energy increases, the propulsive force of the piston 3 also increases. F = ∂W / ∂X F: Propulsion force of the piston W: Magnetic energy X: Displacement of the piston in the front-rear direction As described above, by providing the ferromagnetic partition member 6, this electromagnetic striking device In this case, the propulsive force of the piston is increased, and a large impact force required by an impact device such as a rock drill or a breaker is obtained. In this embodiment, the coil 5 is divided into five sections at equal intervals in the front-rear direction by the ferromagnetic partition member 6, but if it is desired to improve the acceleration at the time of starting the piston 3, The space between the partition members 6 of the coil 5 is made dense, and the space between the partition members 6 behind the coil 5 is sparsely arranged. When it is desired to suppress the fluctuation of the propulsive force of the piston 3, the number of sections of the coil 5 by the section members 6 may be increased. As described above, the electromagnetic striking device of the present invention has a simple mechanism, requires less equipment, and can provide a large piston propulsion force. In a hitting device such as a tool or a breaker, a required large hitting force can be applied to a tool. Also, since the electromagnetic force is used as the driving force, the efficiency of energy utilization is higher than that of pneumatic or hydraulic hitting devices, the energy saving effect is large, and the stroke and speed of the piston can be electrically controlled. Operation becomes easy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of a configuration of a breaker provided with an electromagnetic hitting device according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of an analysis result of magnetic lines of force in a lower half part of a piston and a coil. [Description of Signs] 1 Breaker 2 Cylinder 3 Piston 4 Chisel 5 Coil 6 Partition member 7 Spring 8 Bearing 9 Position detector 10 Position detector 11 Controller 12 Power supply 13 Switch G Gap

Claims (1)

(1) A striking device provided with a reciprocating striking mechanism in which a cylinder is provided with a stator of a linear motor and a piston is a movable element of the linear motor. An electromagnetic striking device, comprising a ferromagnetic partition member for partitioning the magnet.