JPH0739331Y2 - Rotational position detector for compressor electric motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a compressor in which an induction motor and a compression element that is rotationally driven by a rotor of the induction motor are housed in the same case, and particularly, The present invention relates to mounting of a detection device that detects the rotational position of the induction motor.

(B) Prior Art Generally, as a rotational position detecting device for an electric motor for a compressor, there is a device described in JP-A-63-23585. In the one disclosed in this publication, a gear or an encoder is directly connected to the rotary shaft of an electric motor, and a sensor for detecting a pulse train during rotation by the gear is provided to detect the rotational position of the rotor.

(C) Problems to be solved by the device In the rotational position detecting device for an electric motor configured as described above, the sensor must be provided directly inside the compressor. Therefore, the sensor has anti-Freon resistance, temperature resistance, and pressure resistance. There was a problem with sex. Further, it is necessary to use a permanent magnet in the rotating part, and as a method of attaching the permanent magnet to the rotating part, an adhesive was generally used, but when an adhesive is used, the adhesive is stored, compounded, However, there are problems such as management of adhesion treatment, reliability for high-speed rotation, resistance to freon in the compressor, resistance to temperature, resistance to pressure, etc., and sufficient long-term reliability cannot be ensured.

In order to solve such a problem, the present invention provides a rotational position detecting device that does not cause a problem such as anti-Freon property even if a general-purpose type sensor or a permanent magnet is used.

(D) Means for Solving the Problems The present invention is a compressor in which an electric motor and a compression element which is connected to the electric motor via a rotary shaft and is driven by the electric motor are housed in a single hermetic container. A bottomed cylinder inserted from the outside of the hermetically sealed container toward the permanent magnet rotating with the rotary shaft while keeping the hermetically sealed container airtight, a magnetic detector provided at the bottom of the cylinder, and the rotary shaft. It is equipped with a disc that rotates together with the rotation axis and the center of rotation coincides with the disc, and a non-magnetic member that covers the magnetic detector and fixes it on the disc so that the rotation of the rotor changes the output of the magnetic detector. It was made in.

Further, the member is provided with a through-hole for looking through the permanent magnet.

(E) Action The rotational position detection device configured as described above can prevent freon resistance of the magnetic detector, deterioration of performance due to entry of dust, water, etc., and separation of permanent magnets due to centrifugal force. is there.

(F) Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of the compressor. In this figure, reference numeral 1 is a closed container in which a compression element 4 and a three-phase induction motor 3 are housed. The three-phase induction motor 3 includes a stator 5 around which a three-phase winding is wound, and a rotor 6 which is rotated by a magnetic field generated by the stator 5.
And consists of. Shaft 13 of this rotor (axis of rotation)
A compression element 4 is connected to the. The compression element 4 includes a crank portion 14 that rotates about a shaft 13 as a crankshaft 2, a roller 8 that rotates in the cylinder 7 by the crank portion 14, an upper bearing portion 10 and a lower bearing portion 11 that seal the opening of the cylinder 7. It is composed of a cup muffler 12 attached to the upper bearing portion. A vane 9 is in contact with the roller 8 and divides the inside of the cylinder 7 into a high pressure chamber and a low pressure chamber. 1
The balancers 6 and 17 are provided so as to dynamically or statically balance with the crank portion 14 of the crankshaft 2. A discharge pipe 18 is attached to the upper wall of the closed container 1.

FIG. 2 is a II-II sectional view of the compressor shown in FIG.
In this figure, 19 is a discharge port, 20 is a suction port, and the spaces 21 and 22 in the cylinder 7 are divided into a high pressure chamber and a low pressure chamber, respectively. Further, the roller 8 rotates in the direction of the solid arrow in FIG. 2, and the contact position where the roller 8 contacts the cylinder 7 is displayed in 360 degrees as the rotational position. In the state shown in FIG. 2, the rotational position of the roller 8, that is, the crankshaft 2 (shaft 13) is 18
It is at 0 degrees.

3 and 4 are a cross-sectional view and a top view of a main part showing a state in which a position detector for detecting the rotational position of the compression element 4 is attached to an actual compressor. In this figure, since the compression element 4 rotates simultaneously with the rotor 6 via the crankshaft 2 (the shaft 13 of the rotor 6), if the rotation angle of the rotor 6 is detected, the rotation angle of the compression element 4 will actually be detected. Can be detected. The position detector comprises a magnet 23 adhered to a disk 22 and a magnetic detector (Hall element) 24. The disk 22 is attached to the shaft 13 by bolts 25 so that the center of rotation is aligned. The positional relationship between the magnet 23 and the Hall element 24 is such that the Hall element 24 detects magnetism and changes the output when the rotation angle shown in FIG. 2 is "0" degree. Therefore, the output of the compression element 4 (rotor) changes at every rotation angle of "0" degrees. The hall element 24 is provided at the back of the pipe 27 by inserting a bottomed pipe 27 from the side surface side of the hermetic container 1 of the compressor. The pipe 27 is welded to the closed container 1 so that the high pressure gas inside the compressor does not leak.

The pipe 27 is made of copper, for example, into which the hall element 24 is inserted, and a cap is welded to one end to form a bottom. The Hall element 24 is mounted on a substrate having a size that fits in the pipe 27 and then inserted into the pipe 27 together with this substrate.

FIG. 5 is a top view of the disk 22, and FIG. 6 is a sectional view taken along line VI-VI of the disk 22 shown in FIG. In these drawings, 50 is a hole through which the bolt 25 passes, and the stepped portion of the bolt 25 holds this hole to fix the disk 22. (Also,
Concavities and convexities may be provided in the holes so that the bolt and the disk do not run idle) so that the disk 22 rotates with the rotor. 51 and 52 are openings, and the compressed refrigerant is used for the disk 22.
Makes it easier to pass through. Reference numeral 53 denotes a fixing member (magnet fixing holder) for the permanent magnet 23, which is made of a non-magnetic material. 54,5
Reference numeral 5 denotes a caulking portion, which is used for fixing the holder 53 to the disc 22 by inserting the burring of the holder 53 into the hole of the disc 22 for caulking. 56 is a through-hole, holder 53
Is provided so that a part of the permanent magnet 23 can be seen when the permanent magnet 23 is fixed. By removing the permanent magnet 23 from the through hole 56, a mark such as a polarity display displayed on the magnet can be confirmed, and a difference in polarity of the permanent magnet 23 can be prevented.

Incidentally, FIG. 7 is a sectional view showing a state before the holder 53 is caulked to the disk 22. Further, FIG. 8 is a development view of the holder 53 obtained by punching or bending a sheet metal.

FIG. 9 is a sectional view of a disk to which a holder 60 is attached showing another embodiment. The difference from the holder 56 shown in FIG.
The point is that the holder 60 is attached to the disc with rivets 57 and 58. Incidentally, 59 is a through-hole for looking through the permanent magnet.

FIG. 10 is a control circuit diagram for controlling the operation of the compressor shown in FIGS. In this figure, 27 to 29 are stator windings of the induction motor 5, which are star-connected. When the three-phase alternating current is applied to the stator windings 27 to 29, the rotor 5 rotates and the magnet 23 attached to the disk 22 rotates. Therefore, every time the rotor 5 (compression element) makes one revolution, the output of the Hall element 24 changes, and the position detection circuit 30 converts this change into a signal and outputs it to the control unit 31. 32
〜37 is a switching element that performs ON / 0FF operation, and is connected in a three-phase bridge shape, and the DC power supplied from the DC power supply 39 to the three-phase stator windings 27-29 is converted into the three-phase AC power. And output. These switching elements (semiconductor switching elements such as transistor elements, FET elements, and GTO elements) 32-37 are provided with diodes that form a discharge circuit for the accumulated charge and a circulation circuit for circulating current generated in the stator windings 27-29, respectively. It is connected. The DC power supply 39 may be either AC power rectified and smoothed or DC power from a battery. Further, the switching elements 32 to 37 are turned on / off by the control unit 31 via the base drive circuit 38.
It is controlled by a signal from. This controller is mainly
Comprised of CPU, RAM, I / O interface, etc., calculates the frequency based on the speed signal from the speed command circuit 40,
The ON / OFF operation of the switching elements 32 to 37 is controlled so that the AC power of this frequency is supplied to the stator windings 27 to 29.

Hereinafter, ON / OFF control of the switching elements 32 to 37 for obtaining the AC power of the calculated frequency will be described.

FIG. 11 is an explanatory diagram showing a process of making ON / OFF signals to be supplied to the switching elements 32 to 37 based on PWM logic. An ON / OFF signal of the switching elements 32 to 37 is obtained by modulating a sin waveform having a frequency equal to a desired frequency (three waveforms in FIG. 11 because there are three phases) and a triangular wave. At this time, the frequency of the triangular wave determines the resolution of the AC waveform output from the bridge circuit. That is, the higher the frequency of the triangular wave, the better the resolution.However, if the switching speed of the switching element is exceeded, the switching element will not operate.Therefore, the frequency of the triangular wave should be an appropriate frequency in consideration of the switching element used. To set. As can be seen from this figure, when the amplitude of the triangular wave and the amplitude of the sin wave are set appropriately, the ON / OFF time of each switching element changes.
That is, the voltage amplitude of the AC power output from the bridge circuit changes. At this time, the frequency of the triangular wave may be changed with respect to the frequency of the sin wave. The generation of the switching signal is not limited to the above-described method, and any method can be used as long as it can output AC power of a desired frequency and can arbitrarily change the output voltage of this AC power during one cycle of AC.

Therefore, when such a waveform generation method is used, the AC power is f
(Output frequency), V (= output voltage), Ph (= output phase)
It is obtained based on the setting conditions of. That is, the ON / OFF signals of the switching elements 32-37 are calculated based on such conditions. Note that f is equal to the frequency signal given from the speed command circuit, and the basic value of V is determined based on the value of f such that V / f = constant value. The operating efficiency of the machine is set to be good at each frequency. Ph value is 0 to 36
By changing to 0 °, one cycle of AC power is output. If the advance amount ΔPh of Ph is increased, the resolution in one cycle becomes worse, and if this value is made smaller, the resolution becomes better, but due to the relationship between the switching time that the switching element can respond and the processing capacity of the control unit 31, the The optimum value of ΔPh is set in advance.

FIG. 12 is a flowchart showing a basic operation (operation of the control unit 31) when outputting AC power of frequency f. In this flowchart, at step S1, the frequency f
Judge whether or not there was a change. That is, it is determined whether the speed signal from the speed command circuit 40 has changed. When the frequency f is changed, the process proceeds to step S2 to calculate V (basic value of output voltage) and ΔPh (phase advance amount).
Then, it proceeds to step S3. In this step, it is determined whether or not there is a signal from the position detection circuit. That is, it is determined whether or not the compression element of the compressor (rotor of the induction motor) has reached a rotation angle of "0". When this signal is received,
Go to step S4. In this step, the phase Ph is set to "0" and the rotation angle of the rotor is aligned. At the same time, the rotation speed N of the rotor, that is, the speed of the rotor is calculated from the signal input last time and the signal input this time. Also step
When there is no signal in S3, the process proceeds to step S5. In this step, the value of the phase Ph is advanced by ΔPh. Then step S6
At, it is determined whether the phase Ph is between the phases Phh and Ph1. When the phase Ph satisfies the condition of step S6, the process proceeds to step S7, and the value of V is + VU (20% of the value of V
The value of f is + fU (5 to 7% of the value of f)
The value of Ph is increased by the value of PhU (10 degree). If the condition of step S6 is not satisfied, step
Proceeding to S8, the value of V is decreased by -VD (about 10% with respect to the value of V) and the value of f is decreased by -fD (about 5-7% with respect to the value of f). By performing steps S6 to S8 as described above, when the rotor is between Ph1 and Phh, the frequency and voltage of the AC power supplied to the stator winding, that is, the electric motor of the compressor are increased, and The drive torque of the electric motor is increased. At other times, the drive torque is reduced. Therefore, when the compression element is in the compression process and the electric motor requires a large torque, the torque can be increased. The values of Ph1 and Phh will be described later. Next, in step S9, it is determined whether or not the rotation speed N of the rotor calculated in step S4 is a value (ROLL) smaller than the value given by the speed command circuit by a predetermined value. The ratio of the ROLL value to N may be different for each frequency, or may be a constant ratio. When the rotation speed N is low, the process proceeds to step S10.
In this step, the values of V, f, and Ph are respectively corrected to the + side. Next, in step S11, it is determined whether or not the rotation speed N of the rotor calculated in step S4 is a value (ROLH) larger than the value given by the speed command circuit by a predetermined value. The ratio of the value of ROLH to N may be different for each frequency, or may be a constant ratio or a constant value. When the rotation speed N is high, the process proceeds to step S12. In this step, the values of V, f, and Ph are corrected to the negative side. The correction widths in steps S10 and S12 are voltage and comma number of volts, and frequency and comma number Hz.
It is a degree. Step S13 is a step of outputting the switching signal. In this step, the ON / OFF states of the staging elements 32 to 37 are set to one cycle time / 360 / Ph based on the values of f, V, and Ph obtained in the above steps.
It is something that is maintained for a time. (When the minimum unit of Ph is 1 degree) For example, the switching signal for one cycle based on this flowchart is as shown in FIG.

FIG. 13 is a voltage waveform diagram of AC power obtained when the flowchart shown in FIG. 12 is executed. This voltage V27, V2
8, V29 are voltages applied to the stator windings 27 to 29 of the induction motor, and as an example, the case where the voltage waveform is in the phase state shown in FIG. 13 will be described. "0" degree in the figure is when a signal is output from the position detection circuit. That is, when the position of the magnet provided on the rotor and the position of the Hall element match. V = V + V when the phase angle becomes Ph1 in this one cycle (the position of this phase angle Phh is calculated from the time of one cycle obtained from the rotation speed of the rotor and the time corresponding to the phase angle).
Since U, f = f + fU, and Ph = Ph + PhU, the voltage waveform is raised like the dotted line. This dotted voltage waveform has a larger output voltage than the basic voltage waveform (solid line voltage waveform),
The frequency is higher than the basic frequency and the phase is advanced. That is, the phase angle Ph1 of the voltage waveform shown by the dotted line leads the phase angle Phh of the voltage waveform shown by the solid line by about 10 degrees. The phase angle between Ph1 and Phh corresponds to the compression process of the compression element and requires a large torque.

FIG. 14 is a vibration characteristic diagram showing a vibration state of the compressor when driving the compressor. This vibration is obtained from the output of the acceleration sensor mounted on the compressor.
The operating conditions at this time are those when the frequency of the AC power supplied to the stator winding is 30 Hz. In this figure OF
The F side (left side of the dotted line) is when the control method according to the present invention is not used, and the ON side (right side of the dotted line) is when the control method of the present invention is used. It can be seen that the vibration amplitude is reduced from LOFF to LON (reduced to about 1/3) by using the control method of the present invention. That is, the vibration is small.

Figure 15 shows the phase angles Ph1 and Phh when the compressor is driven at 30 Hz.
It is a characteristic view which shows the relationship between a vibration waveform. In this figure, the waveform of i is a vibration waveform when the control method of the present invention is not used. There are peaks of the vibration amplitude at the phase angle of 130 degrees and at the phase angle of 270 degrees. The waveform in ii is a vibration waveform when Ph1 = 100 degrees and Phh = 250 degrees using the control method of the present invention. Similarly, iii is a vibration waveform when Ph1 = 130 degrees and Phh = 270 degrees, and iv also has Ph1 = 150 degrees and Ph
This is the vibration waveform when h = 300 degrees. From these results, Ph1 is at 130th position, Phh is at 270th position, and Ph1 and Phh values are near the phase angle where the vibration amplitude peaks when the control method according to the present invention is not used (the compression element of the compressor is Is an appropriate value, and the vibration of the compressor can be reduced. Therefore, noise can be reduced at the same time as the vibration is reduced.

Although the torque of the induction motor is increased by one step between the rotational positions Ph1 and Phh in the above-described embodiment, the torque may be increased in two steps in this section, or the sections before and after this section may be increased. The torque may be increased step by step including. Further, the torque may be continuously increased.

FIG. 16 and FIG. 17 are a sectional view and a top view of a main part showing another embodiment of the rotational position detecting device. The difference from the cross-sectional view shown in FIG. 3 is that the bottomed pipe 42 is inserted along the shaft 13 of the rotor 6 from the upper side of the closed container 1 and the discharge pipe 18 side. 42 is a Hall element, 43 is a closed terminal of the compressor, 44
Is a mounting bolt, and a resin cover is attached so as to cover the sealed terminal and the opening of the pipe 41.
By covering the pipe 42 with a cover, it is possible to prevent dust and rainwater from entering the pipe 41.

(G) Effect of the Invention The present invention relates to a compressor in which an electric motor and a compression element which is connected to the electric motor through a rotary shaft and which is driven by the electric motor are housed in a single hermetically sealed container. A bottomed tube inserted while maintaining the airtightness of the closed container from the outside of the closed container toward a permanent magnet that rotates with the magnet, a magnetic detector provided on the bottom of the cylinder, and the rotary shaft rotating together with It is equipped with a disk whose center of rotation coincides with this axis of rotation and a non-magnetic member that covers the magnetic detector and fixes it on the disk, so that the rotation of the rotor changes the output of the magnetic detector. The permanent magnet can be easily attached to the disc, and at the same time, it can be easily attached to the correct position.

Further, by providing the member with a through-hole for looking through the permanent magnet, it is possible to easily confirm the mark such as the polarity discrimination of the permanent magnet and prevent the permanent magnet from being attached incorrectly.

[Brief description of drawings]

FIG. 1 is a sectional view of a compressor using the control system of the present invention, FIG. 2 is a sectional view of the compressor shown in FIG. 1 taken along line II-II, and FIG. 3 is an actual compressor equipped with a position detector. 4 is a top view of the compressor shown in FIG. 3, FIG. 5 is a top view of the disk shown in FIG. 3, and FIG. 6 is a view shown in FIG. VI-VI sectional view of the disk, FIG. 7 is an assembled view of the disk shown in FIG. 6, FIG. 8 is a developed view of the holder shown in FIG. 7, and FIG. 9 is a holder according to another embodiment. FIG. 10 is a cross-sectional view of the disk, FIG. 10 is a control circuit diagram used in the compressor shown in FIGS. 1 to 3, and FIG. 11 is an explanatory view showing ON / OFF change of the switching element shown in FIG. FIG. 12 is a flow chart showing the operation of the control unit shown in FIG. 10, FIG. 13 is a voltage waveform diagram of AC power obtained when the flow chart shown in FIG. 12 is executed, and FIG. Vibration characteristic diagram showing the vibration state of the compressor when it is driven, Fig. 15 is a vibration waveform diagram when the compressor is driven at 30 Hz, and Fig. 16 shows the mounting state of the Hall element, etc. FIG. 17 is a cross-sectional view of the essential parts of the compressor of the embodiment, and FIG. 17 is a top view of the compressor shown in FIG. 1 ... Compressor, 4 ... Compression element, 5 ... Induction motor, 6 ... Rotor, 22 ... Disk, 23 ... Magnet, 24 ... Hall element,
27 to 29 ... Stator winding, 30 ... Position detection circuit, 31 ... Control unit,
32 to 37 ... Switching element, 40 ... Speed command circuit, 53 ... Holder, 59 ... Transparent port.

Claims (2)

[Scope of utility model registration request] 1. A compressor comprising an electric motor and a compression element, which is connected to the electric motor via a rotary shaft and is driven by the electric motor, in a single hermetically sealed container, the permanent shaft rotating together with the rotary shaft. A bottomed cylinder inserted into the magnet from the outside of the airtight container while keeping the airtightness of the airtight container, a magnetic detector provided at the bottom of the cylinder, and a rotary shaft that rotates together with the rotary shaft. It is characterized by comprising a disk whose centers of rotation coincide with each other, and a non-magnetic member which covers the permanent magnet and is fixed on the disk, so that the output of the magnetic detector is changed by the rotation of the rotor. Rotating position detection device for compressor electric motor. 2. A utility model registration claim characterized in that the member is provided with a through-hole for looking through the permanent magnet.
A rotational position detecting device for a compressor electric motor according to the above item.