JPH0464598B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electric indicator used for a vehicle speedometer, engine revolution meter, etc. The present invention relates to an ultrasonic motor-driven indicating instrument that uses an ultrasonic motor as a pointer drive source that provides instructions by comparing the positions of an index and a rotating pointer.

[Conventional technology]

Traditionally, it has been used as an electric indicator for use in vehicle speedometers, engine tachometers, etc.
Various voltmeters and ammeters are used as pointer drive sources, and in particular, moving coil type meters and crossed coil type movable magnet type meters allow you to select the indicated torque according to the installation environment and freely control the rotation speed. Since the moving angle can be selected, it is used in many indicating instruments.

In addition, indicating instruments using stepping motors are also easy to control when the input signal is a pulse signal, such as Utility Model Application No. 52-142886,
It is known from publications such as No. 54867, and various configurations have been proposed.

In contrast to eddy current instruments that use transmission cables, which are conventionally known for vehicle speedometers and engine tachometers, these electrical indicating instruments do not cause faulty indications or abnormal transmission noise due to irregular rotation of the cable. It is used in many vehicles as an indicator.

[Problem that the invention seeks to solve]

However, when a moving coil type meter or a crossed coil type movable magnet type meter is used as an electric indicating meter, especially when used under conditions of severe vibration such as in a vehicle, the vibration tends to cause the pointer to oscillate. Countermeasures such as installing damper oil on the pointer shaft or magnet case, or applying a large drive current to increase torque are taken to alleviate this problem. Since it is a control device, it has the problem of poor responsiveness to changes in the input signal, and even if the drive current is increased, needle runout occurs in response to input signals with a large period in the low speed range. Couldn't solve the problem.

In addition, in the case of an indicating instrument that uses a stepping motor as its driving source, its rotational torque itself is not very large, so when used under conditions of severe vibration, smooth stepping drive cannot be obtained and large torque is required. In order to achieve this, a fairly large motor must be used, which is an obstacle to making the device smaller and thinner.

Furthermore, since all of the above-mentioned electric indicating instruments always include a magnetic element called electric-magnetic coupling, there is considerable influence of external magnetic fields or conversely the influence of the magnetism of the instrument itself on external electromagnetic devices, and The problem was that the instruments had to be housed inside to prevent magnetic interference inside and outside.

[Means to solve the problem]

The present invention employs an ultrasonic motor, which has been attracting attention recently, as the drive source of an indicating instrument, thereby making the instrument smaller and thinner, enabling stable indications even under conditions of severe vibration, and further improving external The aim is to provide an indicating instrument that is completely free from magnetic interference even in environments with large magnetic fields.The stator part of an ultrasonic motor is fixed to the housing, and the pointer is fixed to the rotor output shaft of the rotor part. The instrument body is composed of a readable index plate arranged and fixed, and receives an electric signal according to the amount of change in the measurement event, outputs a control signal to drive the stator part, and controls the rotation of the rotor part. a positioning control means for controlling the signal supply to the piezoelectric vibrator of the stator portion in response to a rotational position signal from the position detection means based on the stator; and a positioning control means for applying a drive signal to the piezoelectric vibrator based on the control signal from the control means. and a driving means.

[Effect]

The positioning command means receives an electric signal according to the amount of change in a determination event such as the running speed of a vehicle, and a rotation from a position detection means that detects the rotational position of the rotor part of the ultrasonic motor or a pointer linked thereto. Based on the position signal, the designated position of the rotor portion, that is, the pointer, is determined, and based on this, the pointer instructs the index plate to rotate to the corresponding position. Due to its large rotational torque and static torque, the ultrasonic motor provides stable instructions without causing needle runout even under severe external vibration conditions, and also provides accurate instructions without external magnetic interference.

〔Example〕

It is also known that an ultrasonic motor can obtain a large rotational torque due to its structural characteristics, and also has a large static torque when not in operation due to its frictional engagement.

Ultrasonic motors are broadly divided into traveling wave type ultrasonic motors and torsion coupler type ultrasonic motors depending on their mechanical characteristics.
JP-A-59-122387, JP-A-61
It is known as -52167 etc.

A typical structure of the traveling wave ultrasonic motor is the disk type shown in FIG. This is done by applying alternating current voltages with a 90 degree phase difference to two pieces of piezoelectric ceramics 1 with a phase difference of 90 degrees to each other, a traveling wave is generated, and an elastic material such as stainless steel 2
Vibration with an elliptical locus in the opposite direction occurs, and by pressing the rotating body 3 against this vibration with an appropriate pressure via the lining material 4, the rotating body 3 moves and rotates in a direction opposite to the direction of the traveling wave. Reference numeral 5 designates a fixing base, and a nut 6 connects a stator portion 7 made of a piezoelectric ceramic 1 and an elastic body 2 to a rotor portion 8 made of a rotating body 3 and a lining material 4 under appropriate pressure.

In addition, as shown in Fig. 2, the torsion coupler type ultrasonic motor has a plurality of piezoelectric vibrators 9 that vibrate in the thickness direction by an electric signal applied in the thickness direction, and the polarization directions are adjacent and antiparallel. A stator portion 13 is constructed by connecting vertical vibrators 10 stacked so that The torsion connector 11 is fixed to the torsion connector 11 by a bolt 15 and a spring 16 pressed by the bolt 15.
It is formed by properly pressing against the upper surface of the. In this type, by applying an electric signal to the piezoelectric vibrator 9, stretching vibration is generated in the piezoelectric vibrator 9, which is resonantly amplified by the vertical vibrator 10, and causes a strong torsional vibration in the torsional coupler 11. As a result, elliptical vibration, which is a combination of torsional vibration and longitudinal vibration, is generated on the upper surface of the protrusion of the torsion coupler 11, and the vertical vibration gives buoyancy to the rotor 14, which is pressed against this surface, and the rotational force is applied to the torsional vibration. 14 rotations.

In principle, the above two types are representative, but it is unnecessary to go into detail here as it can be designed in various shapes based on the same operating principle using ultrasonic vibration.

As described above, various types of ultrasonic motors can be used depending on the conditions of use, and speed control and position control can be applied depending on the content of the measurement event. In particular, in the traveling wave type ultrasonic motor mentioned above, each
Two piezoelectric ceramics 1 with a phase shift of 90°
The direction of the traveling wave can be changed by switching and applying alternating current voltages with phase shifts between positive and negative phases, and the direction of rotation of the rotor portion 8 can also be controlled freely, allowing position control. suitable for

The present invention focuses on the fact that the powerful rotational torque and static torque of the ultrasonic motor can withstand severe external vibration due to its operating principle, and takes advantage of the characteristics of small size and thinness without magnetic interference, for example. The present invention aims to provide an indicating instrument that can be used as a drive source for an indicating instrument such as a speedometer of a vehicle and provides accurate instructions through its position control function, and will be described in detail below.

FIG. 3 shows an embodiment applied to a vehicle speedometer, showing a specific configuration of an indicating instrument body incorporating an ultrasonic motor.

In the figure, a stator portion 19 of an ultrasonic motor 18 is fixed in a housing 17 by a fixing base 20 with bolts 21, and a pointer 24 is fixed to the tip of a rotor output shaft 23 of a rotor portion 22. Guidelines 2
An index plate 26 having a scale 25 as an index indicating the running speed of the vehicle is fixed to the stepped portion of the housing 17 below 4, and a see-through plate 27 is also fixed to the stepped portion of the housing 17 above. There is. The base of a pointer 24 is fixed to the tip of the rotor output shaft 23 by press-fitting or the like through a hole provided in an index plate 26. It can also be fixed to 23.

The structure of the main body of the indicator using the ultrasonic motor 18 as a driving source can be configured extremely simply as described above.The circuit section 28 inputs a signal corresponding to the traveling speed from the input terminal, and the pointer 24 is controlled by position control based on the input terminal.
Rotation instruction control can be performed.

As shown in FIG. 3A, the rotating portion of the ultrasonic motor 18 is surrounded by a housing 17, which provides a sufficiently stable directed drive, but it also tends to come into contact with the periphery of the rotor portion 22. When the parts are arranged, the rotor part 22 is housed together with the stator part 19 in a case-like fixing base 20 as shown in FIG. 4, and only the rotor output shaft 23 is guided out. There is no need to worry about contact with other parts. Furthermore, the bearing 29 allows the rotor output shaft 23 to rotate smoothly, and its sealing effect prevents iron powder from adhering to the rotor portion 22 and the stator portion 19 and causing problems in rotation.

In order to indicate the running speed of the vehicle using the indicator, the position of the rotor portion 22 is controlled and the pointer 24 is
The rotation of the rotor must be stopped at the scale 25 position of the index plate 26 corresponding to the running speed, and such position control requires a position detection means that detects the rotational position of the rotor portion 22 and provides feedback. is not particularly shown in the structure of the indicating instrument because it can be easily constructed using a generally well-known rotary encoder or the like.

The circuit configuration for making the indicator shown in Figure 3 or Figure 4 function as a travel speedometer is as follows:
The basic configuration will be explained with reference to FIG.

An electric signal corresponding to the running speed of the vehicle can be obtained by a pulse generator 30 provided in the gearbox of the automobile or the wheel portion of the two-wheeled motor vehicle, which is constructed of, for example, an electromagnetic pickup or a photo sensor. A pulse signal with a frequency proportional to the traveling speed generated from the pulse generator 30 is input to the positioning control circuit 31,
1, the running speed is sequentially detected based on the period or frequency of the pulse signal, and a control signal based on the magnitude of the measured value is supplied to the drive circuit 32. Based on the control signal, the drive circuit 32 drives the piezoelectric ceramics 33 and 34, which are laminated with a phase shift of 90 degrees, in the stator portion 19 of the ultrasonic motor 18.
An alternating current signal with a phase shift of 90 degrees is applied to generate a traveling wave in the stator portion 19 together with the elastic body, thereby causing the rotor portion 22 to rotate in the opposite direction to the traveling wave.

The rotation of the rotor portion 22 is transmitted to, for example, a rotary encoder 35 as a rotation position detection means, and the rotation state (rotation position) of the rotor portion 22 is detected by the rotary encoder 35.
A rotation position signal corresponding to the rotation position is fed back to the positioning control circuit 31.

The positioning control circuit 31 receives the rotational position signal from the rotary encoder 35 and the pulse generator 30.
A control signal is supplied to control the rotation of the pointer 24 fixed to the rotor portion 22 at a corresponding speed position on the scale 25 based on a detection signal corresponding to the traveling speed determined based on the signal from the rotor portion 22. The drive circuit 32 controls the phase switching of the AC signal to the piezoelectric ceramics 33 and 34 and the rotation speed.

Regarding the responsiveness to changes in running speed in the positioning control circuit 31, speed detection by measuring the period of a pulse signal is good, but it is also possible to put it into practical use by a frequency measurement method, and the smoothness of the instructions will not differ greatly. . Positioning control determines whether the change is in an increasing direction or a decreasing direction based on the previous detected speed and the latest detected speed, and also based on the rotational position signal from the rotary encoder 35, and then the obtained direction is determined. The rotation direction of the rotor portion 22 is controlled in accordance with the speed change by determining the rotation direction and controlling the phase of the AC signal to the piezoelectric ceramics 33 and 34 in the drive circuit 32 by switching. Furthermore, the drive signal output from the drive circuit 32 that was controlling the rotation in the increasing or decreasing direction is stopped based on the rotation position signal from the rotary encoder 35 corresponding to the latest detected speed, and the rotor portion 22 is moved to that position. By stopping the pointer 24 fixed to the rotor output shaft 23, the pointer 24 is kept stopped on the corresponding scale 25 on the index plate 26. Stopping the drive signal stops the vibration of the stator section 19, and the rotor section 22, due to its strong static torque due to friction with the stator section 19, provides stable commands that are completely unaffected by external vibrations.

As described above, using the ultrasonic motor 15 as the driving source, the vehicle's running speed can be determined by comparing the pointer 24 and the indicator plate 26 in the same way as with conventional indicating instruments, and the external appearance of the indicator is as shown in Fig. 3B. Although there is no change as shown in FIG. 1, the thickness of the meter is determined only by the ultrasonic motor 18, indicator plate 26, and pointer 24, and is extremely thin compared to conventional moving coil type meters. In addition, in conventional instruments with pointer shafts, in order to obtain smooth indications, it was necessary to make improvements to the bearings, etc., but there is no concern about securing the driving torque for these stable indications, and the accompanying There is no need to add peripheral members.

Furthermore, due to the driving principle of the ultrasonic motor 18, magnetic interference with the outside may occur, leading to indication errors.
In addition, since there are no elements that cause magnetic interference to external electromagnetic devices, there is no need for protective measures such as shielding cases, and the structure can be extremely compact.

Moreover, the rotation of the rotor portion 22 is extremely smooth and has excellent responsiveness, so it can easily follow changes in measurement events, and in combination with its strong rotational torque, provides extremely stable measurement instructions. becomes possible.

Additionally, irregular and minute fluctuations in measurement events can be easily dealt with by providing a circuit-wise insensitivity width within the positioning control circuit 31, which has conventionally been buffered with damper oil, for example.

Note that the embodiment described above uses a single housing 17.
Although the configuration is shown in which the speedometer is a single unit with the ultrasonic motor 18 housed inside, the assembly structure is not limited to this and various modifications are possible. For example, when installed in parallel with other instrument bodies in one housing, as shown in Fig. 6,
The ultrasonic motor 18 is temporarily fixed to a dedicated fixed housing 36 (U-shaped frame), and the index plate 26 is mounted on this housing 36 to form the instrument body. It can also be housed and fixed within the housing 17. Also,
The index plate 26 is not limited to a separate type dedicated to a single instrument;
It is also possible to form a single plate integrated with the index plate 38 of another adjacent meter 37, and to provide a scale serving as an index on the corresponding surface.

In particular, as a vehicle indicating instrument, in addition to the travel speed meter, an engine tachometer, fuel level gauge, coolant temperature gauge, etc. are arranged side by side as a single instrument, or are housed in one housing. However, if an ultrasonic motor is used as a drive source for each of these various indicating instruments, the entire instrument device can be made smaller and thinner, and stable indications from each instrument can be obtained. In this case as well, it is possible to use a common indicator plate for each instrument and install and fix the ultrasonic motors below it, or alternatively, each instrument has an independent indicator plate and the inside is covered with a facing plate. You can also use it as Also, instead of using the rod-shaped pointer shown in each of the above embodiments as a pointer, a rotating disk may be fixed to the rotor output shaft, and a linear pointer or color-coded partitions may be applied on this disk. It is also possible to form a scale on a transparent plate disposed above the pointer instead of below the pointer and see through it.

In any case, by using an ultrasonic motor as the pointer drive source of the indicating instrument and fixing the pointer directly to the rotor output shaft or through an enlarging mechanism using gears, it is possible to obtain This results in an extremely high-performance indicating instrument.

〔Effect of the invention〕

As described above, the present invention uses an ultrasonic motor as a pointer driving source of an indicating instrument, fixes the stator part to the housing side, fixes the pointer to the rotor output shaft of the rotor part, and compares it with the indicator on the indicator plate. By adopting a configuration that controls positioning to achieve reading,
In particular, when used under severe vibration conditions such as in vehicles, it is possible to provide stable instructions without needle deflection due to the effects of vibration, and it is also possible to obtain accurate instructions without external magnetic interference. Since there is no need to add any additional elements, the instrument structure becomes extremely compact, and when combined with the compact and thin performance of the ultrasonic motor, the entire instrument device can be made smaller and thinner.

In addition, the low-speed drive stability of the ultrasonic motor makes it possible to reliably control the rotational position of the instrument pointer.
Following changes in measurement events becomes a natural movement,
Its indicating performance can also be superior to that found in conventional electric indicating instruments, and a particularly significant effect can be expected when applied to vehicle indicating instruments used under severe vibration conditions.

[Brief explanation of the drawing]

1 and 2 are representative structural diagrams of an ultrasonic motor applied to the indicating instrument of the present invention, and FIG. 3A is a sectional view showing one embodiment of the ultrasonic motor-driven indicating instrument according to the present invention. , Fig. 3B is a front view of the same indicator, Fig. 4 is a cross-sectional view of main parts showing another configuration of the ultrasonic motor in the indicator shown in Fig. 3, and Fig. 5 is a front view of the same indicator as shown in Fig. 3. FIG. 6 is a cross-sectional view showing another embodiment of the ultrasonic motor-driven indicator structure according to the present invention. 17, 36...Housing, 18...Ultrasonic motor, 19...Stator part, 20...Fixing base,
22... Rotor portion, 23... Rotor output shaft, 2
4...Guide, 25...Scale as an indicator, 26...
... Index plate, 30 ... Pulse generator, 31 ... Positioning control circuit, 32 ... Drive circuit, 33, 34 ...
...Piezoelectric ceramic, 35...Rotary encoder as position detection means.

Claims (1)

[Claims] 1. The stator part of the ultrasonic motor is fixed to the housing, and a pointer is fixed to the rotor output shaft of the rotor part, which rotates due to the vibration of the stator part, and is almost perpendicular to the rotor output shaft, so that the pointer can be read in comparison with this pointer. The instrument body is constructed by arranging and fixing an index plate with an index representing the amount of change in the measurement event, and receives an electric signal corresponding to the amount of change in the measurement event, and the stator part of the ultrasonic motor is connected to the electric signal. Positioning control that outputs a control signal for driving according to the signal, and controls the signal supply to the piezoelectric vibrator in response to a rotational position signal from a position detection means based on rotation of the rotor due to vibration of the stator. and a drive means for applying a drive signal to a piezoelectric vibrator of a stator portion based on a control signal from the control means.