WO2002027290A2

WO2002027290A2 - Non-contact type rotary positioning sensor

Info

Publication number: WO2002027290A2
Application number: PCT/KR2000/001083
Authority: WO
Inventors: Hyomoon Lee
Original assignee: Control & Measurement Systems Co., Ltd.
Priority date: 2000-09-29
Filing date: 2000-09-29
Publication date: 2002-04-04
Also published as: AU2000276891A8; AU2000276891A1; WO2002027290A3

Abstract

The present invention relates to a non-contact type rotary positioning sensor which can accurately measure the magnitude of the magnetism caused by the rotation of a rotating body by eliminating the imbalance of the magnetism that can be generated due to the eccentricity of the rotating body, by sensing with one hall element the magnitude of magnetism detected by two sensing bars located in different places. The non-contact type rotary positioning sensor (1) consists of a housing (30) with a receipt seat (32) formed on the bottom, a cover (20) with sensor mounting holes (22) and through hole (24) for covering the housing (30), a rotating body (40) whose one end seats on the receipt seat (32) of the housing (30) and whose flange (44) in the middle is joined to the circumference of the through hole (24) of the cover (20) to be supported in a rotatable manner within the housing (30) and whose top end is formed with a coupling slot (42a), a rotary shaft (10) whose one end is coupled with the rotating body (40) by a coupling protuberance (12) inserted into the coupling slot (42a) and whose other end is coupled with the rotary object to be measured, a permanent magnet (50) inserted into the base of the rotating body (40), sensing bars (60) and (62) placed in parallel around the base of the rotating body (40) to detect the location of the permanent magnet (50), and a PCB (70) placed in the housing (30) so as to join with the sensing bars (60) and (62) by interposing a hall element (72).

Description

NON-CONTACT TYPE ROTARY POSITIONING SENSOR

Field of the Invention

The present invention relates to a non-contact type rotary positioning sensor, and more specifically to a non-contact type rotary positioning sensor which can accurately measure the magnitude of the magnetism caused by the rotation of a rotating body by eliminating the imbalance of the magnetism that can be generated due to the eccentricity of the rotating body, by sensing with one hall element the magnitude of magnetism detected by two sensing bars located in different places.

Background of the Invention

Conventionally, a rotary positioning sensor is used to apply continuously changing physical changes of a rotating body to electric circuits, and rotary positioning sensors equipped with electric signal output facility are utilized in various ways in many industries. For example, they are used for opening degrees control of the engine throttle valve for a transport vehicle, rotation angle control of a steering shaft, treading control of an electromagnetic accelerator pedal, positioning control of heavy equipment or farm machines, or on-off measurement of a fluid feed valve.

The methods of measuring rotary positioning include potent iometric sensing, coded disk shaft encoder sensing, hall elements sensing, magneto-resistive sensing, and inductive sensing types. And in actual use, it should be possible to operate at temperatures of -40C to +70C required by extreme operating conditions of commercial vehicle or heavy equipment and maintain a minimum endurance period of about 5 million times with 2% required by environmental conditions of dust and vibration.

However, the potent iometric rotary positioning sensor, which is made of a printed circuit board(hereinafter to be referred to as PCB) or a ceramic board processed with resistance tracks, has drawbacks such as change of electric characteristics due to temperatures and limits to the endurance period and measuring extent due to brush ware.

For example, firstly, because of a wide-range change in resistance characteristic value according to temperature change, which is a general characteristic of electric resistance, the initial value adjusted at factory according to the characteristics of each engine exceeds the limit value in many cases of actual use.

Secondly, because of the rolling wear contact structure between electric resistance track and brush, there is a change in durability reliability and a lack of accuracy due to the electrical noise caused by the peripheral electric devices and extreme operating conditions (dust, moisture, vibration, temperature).

Thirdly, because of the mechanical structure due to rolling contact between electric resistance track and brush, extra mold should be made and mechanical performance testing should be done in order to change the electrical characteristics, which entails more time and cost. Examples include the limit to rated capacity (0.5 watt rated for commercial vehicle, 1.5 watts for heavy equipment) and change in resistance value (2.5 k, 5 k, single track, double track).

Summary of the Invention It is an object of this invention to provide a non-contact type rotary positioning sensor that can accurately measure the magnitude of magnetism caused by rotation by eliminating the imbalance of magnetism that can occur due to the eccentricity of the rotating body, by having one hall element sense the magnitude of magnetism detected by two sensing bars located in different positions.

It is another object of this invention to provide a non-contact type rotary positioning sensor that can quantitatively detect each position of the rotating body, by adopting the method of digital detecting the present location by converting the detected signals into high-resolution digital signals using analog-to-digital converter, as well as utilizing as output signals of the sensor by measuring by means of change in voltage the changes of current detected by the hall element according to the magnitude of magnetism.

It is yet another object of this invention to provide a non-contact type rotary positioning sensor that can eliminate limited life and electric sparks that can occur due to mechanical ware, reduce the number and size of parts, and save the manufacturing cost, by substituting a non-contact type photocoupler for a contact type switch of mechanical structure such as limit switch.

It is still yet another object of this invention to provide a non-contact type rotary positioning sensor that enables to obtain accurate output values that have high linear degrees and low hysteresis in output signals, by stabilizing unstable amplitude or seismic level caused by extreme operating conditions such as temperature change, power source noise, noise due to amplification, electric motor, compressor, dust, moisture, and vibration.

It is further another object of this invention to provide a non-contact type rotary positioning sensor that can output analog and digital signals with the same product and operate two or more signal switches in various rotary positions, by modifying microprocessor algorithm without changing the external appearance of the sensor.

In accordance with this present invention, a non-contact type rotary positioning sensor consists of a housing with a receipt seat formed on the bottom, a cover with sensor mounting holes and through hole for covering the housing, a rotating body whose one end seats on the receipt seat of the housing and whose flange in the middle is joined to the circumference of the through hole of the cover to be supported in a rotatable manner within the housing and whose top end is formed with a coupling slot, a rotary shaft whose one end is coupled with the rotating body by a coupling protuberance inserted into the coupling slot and whose other end is coupled with the rotary object to be measured, a permanent magnet inserted into the base of the rotating body, sensing bars placed in parallel around the base of the rotating body to detect the location of the permanent magnet, and a PCB placed in the housing so as to join with the sensing bars by interposing a hall element.

Brief Description of the Drawings

Other objects and aspects of the present invention will become apparent from the following description of embodiments with reference to the accompanying drawing in which:

FIG. 1 is a perspective view of a non-contact type rotary positioning sensor of the present invention.

FIG. 2 is an exploded view of a rotating body illustrated in FIG. 1.

FIG. 3 is an exploded view of the non-contact type rotary positioning sensor illustrated in FIG. 1.

FIG. 4 is a schematic plane view of a permanent magnetic and sensing bars in accordance with the present invention.

FIG. 5 is a graph showing the relation between voltage and angle of rotation at the rotary positioning sensor of the present invention

FIG. 6 is a flowchart showing the processing at programmable signal processor .

FIG. 7 is a block diagram in accordance with the present invention.

Detailed Description of the Embodiments First, as shown in FIG. 1, non-contact type rotary positioning sensor 1 according to the present invention is equipped with a rotary shaft 10 with spline formed for joining with the object to be measured such as engine, motor frame or pedal, and a rotary shaft 10 is mounted on a housing 30 in a rotatable manner. The top of the housing 30 is covered with a cover 20, and the rear of housing 30 has a number of wires protruded. At the ends of these wires 74, terminals of various forms not shown are inserted to be connected with connectors or wire harnesses not shown. In the cover 20 are formed sensor mounting holes 22, which penetrate the housing 30 to couple the rotary positioning sensor 1 of the present invention with the object to be measured. At one end are formed adhesives injecting holes 26 for injecting adhesives such as silicone to prevent float of wires 74. Next, as shown in FIGs. 2 and 3, the rotary shaft 10 is joined to the rotating body 40 through a coupling protuberance 12 which is formed at bottom thereof, and around the rotating body 40 are placed two sensing bars 60 and 62. In bottom end base 46 of the rotating body 40 is inserted a permanent magnet 50, and the sensing bars 60 and 62 sense the positioning of the permanent magnet 50 transmitted through the rotary shaft 10 and transmit it to a PCB 70. The permanent magnet 50 is inserted in advance during insertion of plastic injecting molding of the rotating body 40, fixed securely to the rotating body 40, and reciprocates and rotates at an angle of about 90 in a reciprocal direction by the actions of the rotating body 40 and a return spring 82.

Here, at the top end head 42 of the rotating body 40 is formed coupling slot 42a for inserting the coupling protuberance 12 of the rotary shaft 10, so by inserting the coupling protuberance 12 into the coupling slot 42a and fixing it, the rotary force of the rotary shaft 10 is exactly transmitted to the rotating body 40. Also, in the middle of the rotating body 40 is formed a joining flange 44. Therefore, at the same time when the top end head 42 of the rotating body 40 is inserted into the through hole 24 of the cover 20 during assembly, it is possible to support the rotating body 40 within the housing 30 in a rotatable manner, as the joining flange 44 is joined at a suitable interval between the bottom end circumference of the through hole 24 and sensor mounting holes 22. Around the top of through hole 24 are formed teeth 24a. In the bottom base 46 of the rotating body 40 is inserted the permanent magnet 50, and between this base 46 and the joining flange 44 is wound the return spring 82 for returning to the original position the rotating body 40 rotated by the rotary shaft 10.

Sensing bars 60 and 62 placed opposite each other at a given interval at both ends of the permanent magnet 50 are placed parallel in a manner of embracing the base 46 of the rotating body 40. Also, at the ends of sensing bars 60 and 62 are formed the vertically extending extensions 60a and 62a respectively, and in the gap between extensions 60a and 62a is placed a hall element 72. This hall element 72 is joined to PCB 70, acting the role of transmitting the displacements of permanent magnet 50 sensed through sensing bars 60 and 62.

In the housing 30 forming the external appearance of rotary positioning sensor 1 are formed lengthwise two long slots 34 where the sensing bars 60 and 62 are inserted, and between these long slots 34 is formed receipt seat 32 where receipt protuberance 48 formed on the base 46 of the rotating body 40 is received in a rotatable manner. Also, on the bottom of the housing 30 are formed fixing holes 36 for fixing the PCB 70, and at the rear end is formed bottom crimp terminal 38 for preventing float by crimping wires 74 together with top crimp terminal 28 formed at the bottom end of the cover 20.

To assemble, first place two sensing bars 60 and 62 in long lost 34 of the housing 30, and place the PCB 70 on the bottom of the housing 30 while placing the hall element 72 between extensions 60a and 62a of sensing bars 60 and 62. At this time, fix the hall element 72 on the bottom of the housing 30 by welding, for example. Next, place on the receipt seat 32 of the housing 30 the base 46 of rotating body 40 that has permanent magnet 50 inserted. At this time, between the joining flange 44 of the rotating body 40 and the base 46 is the return spring 82 wound in advance, and one end of the return spring 82 is fixed on the joining flange 44 and the other end is supported by the inner wall of the housing 30.

Next, put and join the cover 20 on the top of the housing 30, while inserting a rubber 0-ring 80 in the top end head 42 of the rotating body 40 to prevent inflow of water or foreign matter from outside. In this process, insert wires 74 connected to the rear end of the PCB 70 between the top crimp terminal 28 of the cover 20 and the bottom crimp terminal 28 of the housing 30 to crimp them, and then inject adhesives such as silicone through adhesives injecting holes 26 for assembly.

In such a state of assembly, join the coupling protuberance 12 of the rotary shaft 10 to the coupling slot 42a formed on the top end head 42 of the rotating body 40 to complete assembly, and mount the rotary positioning sensor of the present invention on the object to be measured through sensor mounting holes 22. At this time, the rotary shaft 10 is assembled in such a manner that it can rotate as a single body together with the rotating part of the object to be measured.

Next, FIG. 4 is a sketch showing layout of the sensing bars and permanent magnet of the present invention. As shown here, we can see that the pair of sensing bars 60 and 62 is placed opposite each other across a given interval (air gap) between both ends when each of the pair is positioned on a straight line with both ends of the permanent magnet 50. Also, since the hall element 72 is placed between the upper and lower extensions 60a and 62a formed opposite each other on both ends of sensing bars 60 and 62, the magnetic field strength according to variation of the distance between both ends of the permanent magnet 50, which is transmitted through the rotary shaft 10 and the rotating body 40, can be transmitted to the hall element 72.

Since both ends of sensing bars 60 and 62 that are embracing the permanent magnet 50 are placed in such a manner that one magnetic field strength of the same permanent magnet 50 is transmitted to one hall element 72 of the same point, the imbalance of magnetic force line caused by the inconsistency of air gap between the rotating body 40 and sensing bars 60 and 62 can be compensated. The electric signal detected at the hall element 72 is converted into digital signal by the PCB 70 before it is outputted as output signal and switch signal.

Next, FIG. 5 is a graph showing the relation between voltage and angle of rotation at the rotary positioning sensor of the present invention. In this graph, the abscissa represents angle of rotation (θ )of the permanent magnet 50 and the ordinate represents output voltage (Vref). Signals outputted from sensor 1 are shown by a graph between angle of rotation (θ ) and output voltage (Vref).

As illustrated here, we can see output voltage (Vref) is obtained in proportion to angle of rotation (θ ) in the rotary positioning sensor 1 of the present invention. Also, it is designed to obtain at least two short-circuit signals at two or more given voltage potentials of output signal. At this time, it is possible to change appropriately as necessary the on-off state of short-circuit signal. (Namely, it is also possible to maintain connection or insulation by keeping it on or off.)

FIG. 6 is a flowchart showing the processing at a programmable signal processor 94 that sends out 1/0 port output signals by comparing and computing the signal converted into digital signal at analog-to-digital converter 98 and the switch value (W) set up in the program.

As shown in the flowchart, watchdog timer 102 and microprocessor operate one after another at step S10 and step S12, and when digi tali zed signal is inputted (step S14) from analog-to-digital converter 98, it, first of all, decides whether the third switch value (SW3) is less than digital signal value (W) . If the third switch value (SW3) is less than digital signal value (W) (yes at step S15), the second switch (SW2) and the third switch (SW3) are turned on and the first switch (SW1) is turned off (step S16). On the other hand, if the third switch (SW3) value is greater than digital signal value (W) (no at step S15) , the second switch (SW2) value and digital signal value (W) are compared for judgment (step S18).

Namely, if the second switch (SW2) value is less than digital signal value (W) (yes at step S18), the second switch (SW2) is turned on and the first switch (SW1) and the third switch (SW3) are turned off (step S20). If the second switch (SW2) value is greater than digital signal value (W) (no at step S18) , the first switch (SW1) value and digital signal value (W) are compared for judgment (step S22).

If the first switch (SW1) value is greater than digital signal value (W) (no at step S22), the first switch (SW1) is turned on and the second switch (SW2) and the third switch (SW3) are turned off (step 24). If the first switch (SW1) value is less than digital switch value (W) (yes at step S22), all switches (SW1-SW3) are turned off (step S26).

FIG. 7 is a block diagram according to the present invention. As mentioned above, a pair of sensing bars 60 and 62 detects the change of magnetic field generated from the permanent magnet 50 that is rotating together with the rotating body 40 by means of the rotary shaft 10. And the composite magnetic field intensity detected at sensing bars 60 and 62 are transmitted to the PCB 70 by the hall element 72 placed between extensions 60a and 62a of sensing bars 60 and 62 that are assembled in protrusion by a given length in one direction from one side of the PCB70, so that the imbalance of magnetic field generated due to the eccentricity of the rotating body 40 is compensated. At this time, the instantaneous intensity of magnetic field detected in proportion to each angle of rotation of the permanent magnet 50 is amplified to high-level voltage through amplifier (AMP) 90, before it is given as output signal of rotary positioning sensor 1 through wires 74 via compensating circuit 91.

Filter 92 located at the front end of input voltage (Vref) is composed of RC circuit, and it stabilizes within 0.1% the voltage supplied from the electromagnetic controller of the object to be measured such as engine or electric motor for stable supply to the integrated circuit of the hall element 72 and the programmable signal processor 94, so stable output signal can be guaranteed even during unstable power supply.

The signals amplified to high-level voltage are converted to digital signals at analog-to-digital converter (ADC) 98 of the programmable signal processor with built-in nonvolatile memory (EEP ROM), before they are selectively processed so that they can be operated within the range of voltage inputted in advance in the processor 94.

On the other hand, signals are given in standard time unit to oscillator (OSC) 96 mounted on the PCB 70 separately and independently so that the programmable signal processor 94 can operate in time sequence. The watchdog time (WDT) 102 mounted on the PCB 70 separately and independently is installed to prevent malfunction of the programmable signal processor 94, and after the programmable signal processor 94 activates a given loop it is automatically activated by the signal of the watchdog timer 102 to initialize the program.

The programmable signal processor 94 generates signals when it passes a given voltage level that has two or more inputted output signals set up and an activates photocoupler 104 as non-contact type relay switch located in the high-voltage area of 10 Vdc or more. The photocoupler 104 has switches 1 to 3 (SW1, SW2, SW3) built in.

The PCB 70 is equipped with independent current circuit so that the photocoupler 104 can operate as short-circuit switch of high-voltage power source separately from the hall element 72.

According to the present invention, it is possible to provide a semi-permanent sensor, that can operate smoothly even under extreme operating conditions of vehicle or farm machine while maintaining an exact measurement error range of 1%, and that can maintain an endurance period of more than 1,000 times, because it is possible to add a non-contact rotary positioning measurement method that senses the magnetic field strength according to the movement of the rotating body that has permanent magnet built in, and a switch function that can change the position of switch without mechanical change by converting the obtained magnetic field strength into electric and digital signals using current circuit that has a programmable signal processor built in.

Claims

What is claimed is:

1. A non-contact type rotary positioning sensor comprising: a housing with a receipt seat formed on the bottom, a cover with sensor mounting holes and through hole for covering the housing, a rotating body whose one end seats on the receipt seat of the housing and whose flange in the middle is joined to the circumference of the through hole of the cover to be supported in a rotatable manner within the housing and whose top end is formed with a coupling slot, a rotary shaft whose one end is coupled with the rotating body by a coupling protuberance inserted into the coupling slot and whose other end is coupled with the rotary object to be measured, a permanent magnet inserted into the base of the rotating body, sensing bars placed in parallel around the base of the rotating body to detect the location of the permanent magnet, and a PCB placed in the housing so as to join with the sensing bars by interposing a hall element.

2. A non-contact type rotary positioning sensor according to claim 1 wherein the imbalance of magnetic force line caused by the inconsistency of air gap between the rotating body and sensing bars is compensated due to both ends of sensing bars that are embracing the permanent magnet are placed in such a manner that one magnetic field strength of the same permanent magnet is transmitted to one hall element of the same point .

3. A non-contact type rotary positioning sensor according to claim 1 further including a programmable signal processor to change the operating position of switch without external shape and internal hardware change by converting the obtained magnetic field strength into electric and digital signals using current circuit that has a built in.

4. A non-contact type rotary positioning sensor according to claim 1 further including a filter on the PCB to stabilizes within 0.1% the voltage supplied from the electromagnetic controller of the object to be measured such as engine or electric motor for stable supply to the integrated circuit of the hall element 72 and the programmable signal processor 94, so stable the hysteresis of sensing output signal during unstable power supply.

5. A non-contact type rotary positioning sensor according to claim 1 wherein the PCB is provided with at least of one photocoupler switching device.