JPS6214818Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is arranged in the middle of the air supply pipe of a driving device for a dental handpiece that supplies compressed air from a compressed air source to the handpiece through the air supply pipe. The present invention relates to a drive speed control valve that adjusts the amount of compressed air supplied to the drive speed control valve.

Conventionally, methods for controlling the speed of a dental air turbine include mechanically varying the opening and closing of a valve manually or by stepping on a foot, and a motor-driven method in which a needle is rotated by a motor to control the flow rate. In the case of the former manual operation, due to valve operation,
There were problems in that the treatment had to be temporarily interrupted, and in the case of foot operation, air piping was required to reach the foot pedal. The latter was developed in view of the problems of the former and is widely used, but because it uses a motor to rotate a needle to control the flow rate, the response speed is slow and the motor cannot be rotated in the normal direction. There were drawbacks such as a complicated control circuit due to the reverse rotation, and improvements were still desired.

The present invention was developed in view of the above, and converts changes in electrical signals into electromagnetic force through current and coils, and uses changes in this electromagnetic force to vertically displace a plunger, which is a valve body, to supply air to the handpiece. The present invention provides a driving speed control valve for an air turbine that controls the amount of air turbine.

The present invention will be described in detail below with reference to the attached drawings showing preferred embodiments of the invention. Fig. 1 is a vertical sectional view showing the speed control valve of the invention in a fully closed state, and Fig. 2 shows the same in a half-open state. The vertical sectional view, FIG. 3, is an embodiment of an electric circuit used to drive the control valve of the present invention.
That is, the present invention is a drive speed control valve that is incorporated in a driving device for a dental air turbine that supplies compressed air from a compressed air source to a handpiece through an air supply pipe, and that is provided in the middle of the air supply pipe. An air flow path 11, a vertically slidable plunger 12 capable of varying the effective cross-sectional area of the air flow path 11, a spring 13 that presses the plunger 12 downward, and a spring 13 that allows the plunger 12 to slide up and down. The valve body 1 includes a coil 14 that generates a magnetic field to stop the valve at an appropriate position, and a drive circuit 2 connected to the coil 14.
4 is varied by the drive circuit 2, and the magnetic field generated thereby and the spring 13
The vertical position of the plunger 12 can be changed appropriately by counteracting the elasticity of the air flow path 11, and as a result, the effective cross-sectional area of the flow path 11 is changed, thereby increasing the amount of driving air supplied to the handpiece. This is a driving speed control valve for a dental air turbine, characterized in that it controls the speed of a dental air turbine. 1st
The structure of the control valve shown in FIGS. 1 and 2 is no different from the structure of a normal solenoid valve, but when the plunger 12 is fully open, the upper end surface of the control valve is the cylinder part of the frame 15 into which the plunger 12 is loosely fitted. 15
It is important that it does not come into contact with the inner upper surface of 1. In the control mechanism of the control valve of the present invention, which will be described later, when moving downward from the fully open state in the closing direction, the coil 14 is energized due to the magnetic hysteresis effect between the upper end surface of the plunger 12 and the inner upper surface of the cylinder portion 151. This is because there is a risk that the current flowing and the lowered position of the plunger 12 will not be proportional to each other. In order to prevent the upper end surface of the plunger 12 from coming into contact with the inner upper surface of the cylinder section, an upper limit of the current value applied to the coil 14 may be set, or a non-magnetic material may be attached to the upper end surface of the plunger 12 or the inner upper surface of the cylinder section 151. There are methods such as attaching an appropriate spacer to the body, but in this figure, a spacer 152 is attached to the inner upper surface of the cylinder portion 151. The lower end of the plunger 12 is a known needle type valve body, and a seal 12 is provided on the contact surface with the valve seat 111 of the flow passage 11.
1 is attached, which not only provides airtightness but also serves as the spacer described above. In FIG. 3, the drive circuit 2 includes a current control transistor 21 that controls the current flowing through the coil 14, an operational amplifier 22, and a feedback resistor 23, and V _IN is a control signal (voltage) and the resistance value of the feedback resistor 23. When V is R, the current flowing through the coil 14 is determined by V _IN /R.

In the above configuration, FIG. 1 shows a state in which the coil 14 is completely closed only by the spring force of the spring 13 with no current flowing through the coil 14. Next, when a current flows through the coil 14, the plunger 12 is moved by an electromagnetic force. , and begins to open the air flow passage. At this time, the plunger 12 stops at a position where the spring 13 and the electromagnetic force are balanced (FIG. 2). When the current increases further and reaches the maximum value within the setting range,
The plunger 12 is located at the highest position and the flow path 11
is fully opened (not shown). On the other hand, this transition from fully open to closed is performed by the opposite effect to that described above, and in the end, the desired opening degree of the flow path 11 is determined by the balance between the electromagnetic force caused by the current flowing through the coil 14 and the spring force of the spring 13. It will be decided. coil 1
The current applied to 4 is converted into electromagnetic force here,
It serves as the power source for the vertical movement of the plunger 12,
Since the plunger 12 is loosely fitted into the cylinder portion 151 so as to be vertically slidable, the plunger 12 retains a state in which it can quickly respond to minute changes in the electromagnetic force. Further, the current flowing through the coil 14 is determined and controlled by the transistor 21 based on the signal V _IN and the resistor R as described above, but the signal V _IN is inputted by the operator's foot switch or the like. It is also possible to incorporate a sensor signal from a handpiece feedback circuit (for example, a sensor that reads and provides feedback if there is a discrepancy between the desired air turbine speed and the actual speed). In this way, the control valve of the present invention allows a minute electric signal generated by the sensor of the handpiece to be immediately transmitted to the plunger 12 according to the operator's intention.
It is possible to move the air turbine, control the amount of compressed air sent to the air turbine, and control its driving speed with good responsiveness.

Although the control valve of the present invention is used to control the driving speed of the air turbine, it can be used only for opening and closing like a normal electromagnetic valve. As for the general usage of this control valve, it is preferable to arrange the above-mentioned normal solenoid valve in front of the control valve on the air supply pipe and use these together.

As mentioned above, the control valve of the present invention controls the amount of air for driving the air turbine by changing the control signal, so it is extremely easy to operate compared to the conventional method of mechanically opening and closing the valve. The operator's fatigue is minimized, the response to control signals is good, and the structure and drive circuit are simple, so it has many advantages over conventional motor-driven systems.In addition, it is inexpensive and robust. . ...The effects of this invention are extremely large.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view showing the speed control valve of the present invention in a fully closed state, Fig. 2 is a longitudinal cross-sectional view showing the speed control valve in a half-open state, and Fig. 3 shows the electric circuit used to drive the speed control valve of the present invention. It is an example figure. Explanation of symbols, 1...Valve body, 11...Flow path,
12...Plunger, 13...Spring, 1
4... Coil, 2... Drive circuit, 21... Current control transistor, 22... Operational amplifier, 23...
...Return resistance.

Claims (1)

[Scope of utility model registration request] This is a drive speed control valve that is incorporated in a driving device for a dental air turbine that supplies compressed air from a compressed air source to a handpiece through an air supply pipe, and is provided in the middle of the air supply pipe, and includes an air flow passage 11.
, a vertically slidable plunger 12 that can vary the effective cross-sectional area of the flow path 11, a spring 13 that presses the plunger 12 downward, and a spring 13 that slides the plunger 12 up and down and stops it at an appropriate position. It consists of a valve body 1 including a coil 14 that generates a magnetic field, and a drive circuit 2 connected to the coil 14, and the drive circuit 2 varies the current flowing through the coil 14 and generates it. By counteracting the magnetic field and the elasticity of the spring 13, the vertical position of the plunger 12 can be changed as appropriate, and as a result, the effective cross-sectional area of the flow path 11 is changed, thereby allowing the fluid to be supplied to the handpiece. A driving speed control valve for a dental air turbine, characterized in that the driving speed control valve controls the amount of driving air.