JPH0720462B2 - Coffee mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a coffee mill having an improved configuration for controlling the operating time of a motor for driving a pulverized body.

(Prior Art) A general configuration of a conventional coffee mill is provided with a timer for setting an operating time (grinding time) of a motor for driving a crushed body, and a user appropriately uses the amount of coffee beans as a guide. It was supposed to adjust the timer.

(Problems to be Solved by the Invention) However, it is difficult for the user to match the set time of the timer with an appropriate time by using the amount of coffee beans as a guide. For this reason, the crushing time may be set too long, power may be wasted, and unpleasant noise may occur at the end of the operation due to an increase in the motor rotation speed due to a load reduction. In some cases, there was a shortage of crushing.

The present invention is intended to solve such problems,
Therefore, it is an object of the present invention to provide a coffee mill which can always make the grinding time proper and can prevent the generation of unpleasant noise, the waste of electric power, the insufficient grinding and the like.

[Structure of the Invention] (Means for Solving Problems) A coffee mill of the present invention includes a rotation detection device for detecting the rotation speed of a motor, and a rotation speed detected by the rotation detection device during a grinding operation of the coffee beans. However, after the substantially constant steady speed is reached, an operation control device for stopping the motor on condition that the steady speed is increased by a predetermined value is provided.

(Operation) During operation, until the coffee beans are sufficiently crushed, the motor rotation speed (load) becomes approximately constant, and steady rotation occurs.
After that, when the crushing is sufficient, the load is reduced and the rotation speed of the motor starts to increase. The rotation speed of the motor is detected by the rotation detection device, and the operation control device stops the motor on condition that the range of increase in the rotation speed from the steady rotation speed reaches a predetermined value.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. 1
Is a crushing case, and the crushing body 2 is disposed on the inner bottom portion thereof. 3 is a vertical axis type motor provided in the lower part of the crushing case 1, the upper end of its rotating shaft 3a is connected to the crushing body 2, and a cylindrical rotary indicator 4 is fitted to the lower end of the rotating shaft 3a. ing.
A predetermined number of vertical stripe patterns are formed on the outer peripheral surface of the rotary display 4. On the other hand, 5 is a power supply terminal, 6 is a power switch for opening and closing the energization path to the motor 3, and 7 is a rotation detecting device, which includes a light projecting section 8 for projecting light on the rotation display 4 and a rotation display. Optical sensor 9 for detecting the reflected light from the container 4
And are provided. As a result, a detection signal corresponding to the number of rotations of the motor 3 is output from the optical sensor 9 and input to the microcomputer 10, which is an operation control device. The microcomputer 10 controls the stop timing of the motor 3 by controlling the opening operation timing of the normally closed relay switch 11 provided in the energization path to the motor 3. Further, the microcomputer 10 operates the rotation detecting device 7 after a predetermined time T (time until the rotation of the motor 3 becomes substantially constant) from the start-up of the motor 3 so that the motor 10 rotates at a substantially constant rotation speed. The rotation speed of 3 is the steady rotation speed
After being stored as Rs, the difference between the rotational speed R detected thereafter and the steady rotational speed Rs, that is, the increase width of the rotation speed is calculated, and the relay switch 11 is provided on the condition that the increase width reaches a predetermined value ΔR. Is designed to be opened.

Next, the operation of the above configuration will be described. Crush case 1
Put the coffee beans inside and turn on the power switch 6,
The motor 3 is energized and activated, and the crushing body 2 is rotated to start crushing coffee beans. by this,
The rotation speed of the motor 3 suddenly rises as shown in FIG. 2, and then becomes substantially constant. After that, the load becomes substantially constant until the coffee beans are sufficiently crushed, so that the rotation speed of the motor 3 is maintained substantially constant and the rotation becomes steady. Then, when a predetermined time T elapses from the activation of the motor 3, the microcomputer 10 starts the operation of the rotation detecting device 7, and the light projecting portion 8 of the rotation detecting device 4 causes the rotation indicator 4 to move as shown by the alternate long and short dash line in FIG. The number of rotations of the motor 3 is detected by projecting the light and detecting the reflected light by the optical sensor 9. The detection signal of the rotation speed of the motor 3 is input to the microcomputer 10, and the rotation speed of the motor 3 when rotating at a substantially constant rotation speed is stored as a steady rotation speed Rs. After that, the microcomputer 10 calculates the difference between the detected rotation speed R and the steady rotation speed Rs, that is, the increase width of the rotation speed. When the increase width is less than the predetermined value ΔR, the mill operation is continued. When the crushing is sufficient, the load is reduced and the rotation speed of the motor 3 starts to increase. Immediately after that, the increase width of the rotation speed reaches the predetermined value ΔR, and under this condition, the microcomputer
An operation signal is output from 10 to the relay switch 11, and the relay switch 11 is opened. This allows the motor 3
Is cut off and the mill operation ends. It should be noted that FIG. 2 shows the relationship between the change in the rotation speed of the motor 3 and the change in the noise. As is clear from FIG. 2, as the rotation speed of the motor 3 increases at the end of the mill operation. Although there is a characteristic that the noise also rises, in the present embodiment, the noise is not increased because the motor 3 is stopped before the rotation speed greatly increases.

By the way, since the rotation speed of the motor 3 is easily affected by fluctuations in the power supply voltage and manufacturing variations among products, the rotation speed at the time of completion of pulverization varies among products even for the same product. For this reason, it is not possible to accurately determine the comminution completion time based only on the absolute value of the rotation speed.

Therefore, in the present embodiment, paying attention to the fact that the load is reduced and the rotation speed of the motor 3 starts to increase when the crushing is sufficient,
Steady rotation speed Rs of the motor 3 detected by the rotation detection device 7
Since the motor 3 is stopped by the microcomputer 10 on the condition that the range of increase in the number of revolutions reaches a predetermined value ΔR, even if there is a fluctuation in the power supply voltage or a manufacturing variation between products, the grinding is always performed. The completion time can be accurately determined, and the motor 3 can be stopped at an appropriate time. For this reason,
The coffee beans can always be crushed without excess or deficiency, the motor 3 can be reliably stopped before the unpleasant noise is generated due to the increase in the rotation speed of the motor 3, the noise can be reduced, and the power is not wasted. Moreover, since the troublesome timer operation as in the past is not necessary, the usability is improved.

In the above-described embodiment, the rotation detecting device 7 is configured to use the optical sensor 9, but the rotation detecting device 7 is not limited to this. For example, the rotation number is detected by the displacement of the pendulum caused by the rotating centrifugal force, For example, the number of rotations of the motor 3 may be detected by detecting the frequency of the rotation sound of the motor 3 with a sound wave sensor.

[Effects of the Invention] As is apparent from the above description, the present invention focuses on the fact that the rotation speed of the motor starts to increase when the crushing is sufficient,
When the coffee beans are crushed, the rotation control device stops the motor on condition that the rotation speed detected by the rotation detection device reaches a substantially constant steady rotation speed and then rises by a predetermined value from the steady rotation speed. Therefore, it is always possible to accurately judge the grinding completion time and stop the motor at an appropriate time.
It is possible to prevent generation of unpleasant noise, waste of electric power, insufficient crushing, and the like, and it is possible to eliminate the troublesome timer operation of the related art and improve the usability.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is an overall schematic configuration diagram, and FIG. 2 is a diagram showing a change characteristic of a rotation speed of a motor and a change characteristic of noise. In the drawings, 1 is a crushing case, 2 is a crushed body, 3 is a motor, 7
Is a rotation detecting device, 8 is a light projecting unit, 9 is an optical sensor, and 10 is a microcomputer (operation control device).

Claims (1)

[Claims] 1. A coffee machine housed in the grinding case is ground into a powder by rotating a grinding body arranged in the grinding case by a motor. A rotation detection device that detects the rotation speed of the motor, and during the crushing operation of the coffee beans, the rotation speed detected by the rotation detection device becomes a substantially constant steady rotation speed, and then only a predetermined value from the steady rotation speed. A coffee mill provided with an operation control device for stopping the motor on condition that the temperature rises.