JP3128082B2 - Work machine of construction machine provided with rotation position detection device and composite rotation position sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation position detecting device for detecting a rotation angle of a rotating portion of a construction machine, a robot, or the like. In particular, a failure of the rotation position detecting device can be reliably achieved by combining two sensors. The present invention relates to a rotation position detection device capable of determining an absolute rotation position having high precision and high resolution and a work machine of a construction machine provided with a rotation position sensor.

[0002]

2. Description of the Related Art Rotary position sensors include an analog type and a digital type, and a rotary potentiometer is a typical analog type, and an optical type is a digital type. Or there is a magnetic rotary encoder. Rotary potentiometers generally have lower detection accuracy than rotary encoders due to linearity, temperature characteristics, and the like, and are used independently according to the purpose of use. That is,
The rotary potentiometer is used when less precision is required, and the rotary encoder is used when higher precision is required.

[0003] Since the rotary potentiometer takes out a change in the resistance value as an electric signal, the rotation angle (rotation amount) from a predetermined reference position can be maintained even when the detection target (control target) is stopped. This is required, so-called absolute detection is possible. On the other hand, a rotary encoder forms a scale with a large number of irregularities and slits in the circumferential direction of a disk or the like, and detects the irregularities and slits to detect a rotation angle, and can determine only a relative rotation amount. There are an incremental type and an absolute type that requires the absolute rotation amount.

Therefore, in order to increase the detection accuracy of the rotary encoder, it is necessary to increase the minimum detectable angle (resolution), and to obtain high resolution, the pitch and width of the scale must be reduced.

[0005]

However, in the case of the absolute type rotary encoder, 00...
It is necessary to number 0, 00 ... 01, ...,
Increasing the resolution not only makes it difficult to arrange elements for reading numbers, but also makes it difficult to withstand harsh environments such as construction machinery with a lot of vibration and dust. Peripheral equipment becomes complicated, and the equipment becomes expensive. For this reason, the rotary encoder
When high resolution is required or when used for construction machines, the incremental type is used.

However, as described above, the incremental type rotary encoder can determine only the amount of rotation, and cannot determine the absolute rotation position (absolute rotation angle). Then, when trying to obtain the absolute rotational position using an incremental type rotary encoder, it is necessary to move a boom or the like of a construction machine to be detected once to a reference position, which is extremely troublesome for a large construction machine or device. It takes time to reset.

Therefore, if a rotary potentiometer is used to determine the absolute rotational position, the desired detection accuracy cannot be obtained, and the control accuracy is reduced. That is, as shown in FIG. 4, the rotary potentiometer has a theoretical rotary angle range of −60 ° to + 60 ° during which the output voltage changes from 0V to 5V. The output voltage of the potentiometer changes linearly with respect to the detected rotation angle, as indicated by the dashed line. However, the output voltage of the rotary potentiometer fluctuates due to manufacturing accuracy, for example, as shown by a solid line,
In addition, a so-called temperature drift or the like occurs, and high detection accuracy cannot be obtained.

On the other hand, when a conventional rotational position sensor is used in a construction machine or the like, the rotational position sensor is placed in an airtight container, and a screw-type connector or a ground seal type connector is used at a lead wire outlet. It prevents dust and moisture from entering the inside of the sealed container. However, the screw-in type connector is expensive and increases the cost of the detection device. In addition, the ground seal type connector deteriorates in waterproofness when it is repeatedly attached and detached, and water enters into the sealed container to cause a malfunction, thereby lowering the reliability of the rotational position detecting device.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the prior art. By combining two sensors, it is possible to reliably determine the failure of the rotational position detecting device and to provide an absolute and high resolution having high accuracy and high resolution. It is an object of the present invention to provide a working machine of a construction machine provided with a rotation position detection device for which a rotation position is required, and to provide a composite rotation position sensor capable of preventing intrusion of moisture into a closed container at low cost. It aims to provide a working machine for construction machinery.

[0010]

Means for Solving the Problems To achieve the above object,
Claims relating to a composite rotational position sensor according to the present invention
Reference numeral 1 denotes a double-axis rotary potentiometer, a rotary encoder in which an input shaft is connected to a rotary shaft on one side of the rotary potentiometer, a base supporting the rotary encoder and the rotary potentiometer, and a base fixed to the base. And a cap covering the rotary encoder, and a sealing filler filled in the cap.

According to a second aspect of the present invention, a potentiometer supporting portion for supporting a rotary potentiometer and an encoder supporting portion for supporting a rotary encoder are formed on a base with a predetermined gap therebetween. A connecting portion of the encoder with the input shaft is disposed in a gap between the two supporting portions, and a window for connecting both shafts is formed in a base on a side of the connecting portion disposed in the gap. .

[0012]

In the composite rotational position sensor according to the present invention having the above-described structure, the cap covering the rotary encoder is filled with a sealing filler such as a resin to prevent moisture or dust from entering the cap. Can be prevented. Moreover, expensive components such as a screw-in type connector are not required, and the cost can be reduced.

A gap is provided in the base for arranging a connecting portion between the rotary shaft of the rotary potentiometer and the input shaft of the rotary encoder, and a window for connecting both shafts is provided on a side of the connecting portion arranged in the gap. Due to the formation, the two shafts can be easily connected, and the sensor can be quickly assembled.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a construction machine working machine provided with a rotational position detecting device and a composite rotational position sensor according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram of a rotation position detecting device according to an embodiment of the present invention.

In FIG. 1, the rotational position detecting device comprises a composite rotational position sensor 10 and an absolute rotational position calculator 100 which receives an output signal of the composite rotational position sensor 10 and outputs an absolute rotational position. Composite rotation position sensor 1
0 is an incremental type rotary encoder 12 and a rotary potentiometer 14 as described in detail later.
The output signal of the rotary encoder 12 is input to the counter 106 of the absolute rotation position calculator 100 and the reference point detection circuit 104.

As shown in FIG. 3, the rotary encoder 12 has a gear 70 rotatably provided.
When the gear 70 rotates, the detection unit 72 detects the teeth 74 of the gear 70 passing ahead and outputs a detection signal. ing. The gear 70 is provided with a reference point called a Z-phase 76 at a portion that most frequently passes in front of the detection unit 72.

The absolute rotation position calculator 100 includes a counter 106 for counting the output signal of the rotary encoder 12, a rotation position calculation circuit 110 connected to the output side of the counter 106, and a failure determination circuit 112. When the key switch of the engine is turned on, a count value corresponding to the absolute rotation angle detected by the rotary potentiometer 14 is preset as an initial value of the counter 106 as described later, and the initial value is input to the counter 106. The output signals of the rotary encoder 12 are added and counted.

Further, the absolute rotational position calculator 100 includes an analog / digital converter (A / D converter) 114 to which an output signal of the rotary potentiometer 14 is input. Potential detection angle calculation circuit 1 for receiving output signal
16 are provided. This potentiometer detection angle calculation circuit 1
Reference numeral 16 is connected to a counter 106, and A /
The count value of the counter 106 corresponding to the rotation angle detected by the rotary potentiometer 14 is obtained based on the output signal of the rotary potentiometer 14 received via the D converter 114, and the counter 10 is used as an initial value.
6 is output. Further, a potentiometer detection angle calculation circuit 11
6 is input to the failure determination circuit 112.

Note that the reference point detection circuit 104
When the Z phase 76 of the gear 70 is detected based on the signal output from the counter 2, a reset signal for resetting the count value so far is output to the counter 106.
Starts a coefficient based on the Z phase 76.

As shown in FIG. 2, the composite rotary position sensor 10 has an incremental rotary encoder 12 and a dual-axis rotary potentiometer 14 arranged coaxially. Then, the input shaft 1 of the rotary encoder 12
6 and rotary shaft 18 on one side of rotary potentiometer 14
Is inserted into the coupling 20, fixed to the coupling 20 by a plurality of screws 22, and connected via the coupling 20.

The fixed base 24 supporting the rotary encoder 12 and the rotary potentiometer 14 has a hat-like appearance, and has a concave portion 26 formed at the center on the side of the flange portion 25. Is a potentiometer supporting portion 28 provided with a mounting hole. In addition, the fixed base 24 includes an encoder support 3 on which the top of the cap facing the potentiometer support 28 fixes the rotary encoder 12.
0, a gap 3 for disposing the coupling 20 between the potentiometer support 28 and the encoder support 30.
2 are provided.

In the rotary potentiometer 14, the rotating shaft 18 is inserted into the gap 32 from a mounting hole formed in the potentiometer support 28, the mounting flange 34 is brought into close contact with the potentiometer support 28, and a plurality of rotary potentiometers are provided along the circumferential direction. It is fixed to the potentiometer support 28 by a mounting plate 36 screwed to the support 28.
In addition, the rotary encoder 12 includes a mounting plate 40 in which the input shaft 16 is inserted into the gap 32 from a mounting hole formed in the encoder support portion 30 and a plurality of mounting flanges 38 are screwed to the encoder support portion 30 along the circumferential direction. Is fixed to the encoder support 30. The fixed base 24 has a window 42 on the side of the coupling 20 arranged in the gap 32 for connecting the rotary shaft 18 and the input shaft 16 by tightening the screw 22. A flow path 46 for injecting a filler 44 such as resin is formed on the opposite side of the flow path. In addition,
The window 42 is closed by a lid 48 after connecting the shaft.

The rotary encoder 12 fixed to the fixed base 24 is covered by a cap 50. The cap 50 has a fixing flange 52, and the fixing flange 52 is fixed to the flange 25 of the fixing base 24 by a screw 54. The cap 50 has a lead wire 56 of the rotary potentiometer 14 and the rotary encoder 1.
An outlet 60 for leading the second lead wire 58 to the outside is formed to protrude. And the outlet 60
Has a grommet 62 through which the lead wires 56 and 58 pass.
Is arranged. The grommet 62 is fixed by a pressing plate 64 fixed to the end of the take-out opening by a screw, and prevents the filler 44 filled in the cap 50 from leaking.

The reference numeral 66 shown in FIG.
8 is an input shaft integrally formed with the input shaft 8 and connected to a detection target (not shown). Reference numeral 68 denotes a lead wire 5
6 and 58 show the connectors to which they are connected. The leads 56 and 58 of the rotary potentiometer 14 and the rotary encoder 12 are connected to the absolute rotational position calculator 100 shown in FIG.

The operation of the embodiment constructed as described above is as follows. When the detection target is still stopped after the key switch of the engine (not shown) is turned on, the rotation position detection device does not output the signal because the rotary encoder 12 is of the incremental type.

On the other hand, the A / D of the absolute rotational position calculator 100
The converter 114 converts an analog signal, which is output from the rotary potentiometer 14 and indicates the absolute rotational position of the detection target, into a digital signal, and converts the analog signal into a digital signal.
Send to 6. The potentiometer detection angle calculation circuit 116
A / D converter 114 every predetermined time, for example, every 0.1 ms
The detection signal of the rotary potentiometer 14 is fetched through the converter, converted into a count value of the counter 106 representing the absolute rotation angle, preset as an initial value in the counter 106 first, and constantly output to the failure determination circuit 112.
Then, the rotation position calculation circuit 110 calculates the absolute rotation position based on the count value of the counter 106 and outputs the calculated absolute rotation position to a control device or a display device (not shown).

When the object to be detected is rotated, the rotary encoder 12 rotates the gear 70, and the teeth 74 formed on the gear 70 are rotated.
Sequentially pass in front of the detection unit 72. Then, the detecting section 72 outputs a detection signal to the counter 106 and the reference point detection circuit 104 every time the tooth 74 passes forward. Therefore, the counter 106 operates the potentiometer detection angle calculation circuit 11.
6 is used as an initial value with the absolute rotation angle signal of the rotary potentiometer 14 output by
10 and output from the rotation position calculation circuit 110 as an absolute rotation angle. However, in this case, since the absolute rotation angle signal of the rotary potentiometer 14 is used as a reference, the absolute rotation angle of the rotary encoder 12, which has a high resolution characteristic but includes a reference point error, is measured.

When the gear 70 rotates, the Z-phase
Passes through the front of the detection unit 72, the detection unit 72 outputs a signal indicating that the Z phase 76 has passed to the absolute rotation position calculator 1
Output to 00. The reference point detection circuit 104 includes a detection unit 72
When it is detected that the Z-phase 76 has passed in front of the detection unit 72 based on the output signal of the detection unit 72, a signal for clearing the count value so far is output from the reference point detection circuit 104 to the counter 106 to the counter 106. .

For this reason, the counter 106 is cleared to zero when the Z phase 76 of the rotary encoder 12 is detected. Thereafter, the output signal from the reference point of the rotary encoder 12 is counted, and the counted value is used as the rotational position calculating circuit 110. And the failure determination circuit 112. On the other hand, since the output signal of the potentiometer detection angle calculation circuit 116 is subsequently input to the failure determination circuit 112, the output signal of the potentiometer detection angle calculation circuit 116, which should be equal except for the error, and the count value of the counter 106 Can detect a failure of the composite rotational position sensor 10. If the output signal of the potentiometer angle calculation circuit 116 is 0, it is possible to detect disconnection, and if the output signal is maximum, it is possible to detect short-circuit. On the other hand, since the rotation position calculation circuit 110 calculates and outputs the absolute rotation angle starting from the Z phase 76 from the count value of the counter 106 based on the output signal of the rotary encoder 12, the rotation position calculation circuit 110 has the high resolution characteristics of the rotary encoder 12 together with the high resolution characteristics. Also, the absolute rotation angle can be measured with high accuracy of the reference point.

As described above, in the rotational position detecting device of the embodiment, the rotary encoder 1
2 is provided with a failure determination circuit 112 which receives an output signal of the counter 106 for counting the output signal of the counter 2 and an output signal of the rotary potentiometer 14 and detects a failure, so that the failure determination circuit 112 includes the rotary encoder 12 and the rotary potentiometer. By monitoring the output of the rotary potentiometer 14 or the rotary encoder 12 when the difference between the two outputs exceeds a predetermined value, or when the output of the rotary potentiometer 14 becomes 0 or the maximum value, Can be detected, and an erroneous rotation position signal is input to the control device, thereby preventing runaway of a controlled machine such as a construction machine.

Further, the rotary encoder 12 immediately after the start is started.
Until the Z-phase 76 is detected, a high-resolution absolute rotation angle based on the output signal of the rotary potentiometer 14 including an error at the reference point is output. After the Z-phase 76 is detected, a highly accurate An absolute rotation angle based on the output signal of the incremental rotary encoder 12 can be output.

In the above embodiment, the magnetic rotary encoder 12 has been described. However, an optical rotary encoder may be used. The rotary potentiometer may be a single-rotation type or a multi-rotation type.

The composite rotational position sensor 10 is assembled as follows. First, the reference point of the coupling 20 is fixed to the input shaft 16 of the rotary encoder 12 so as to be fixed, and the rotary potentiometer 14 and the rotary encoder 12 are fixed to the support portions 28 and 30 of the fixed base 24. Thereafter, the reference points of the input shaft 16 and the rotating shaft 18 are aligned, and the screw 22 is tightened from the window 42 of the fixed base 24 to connect the input shaft 16 and the rotating shaft 18.

After connecting the shafts, the window 42 is covered with a lid 48, and the cap 50 is put on the rotary encoder 12 while the lead wires 56 and 58 are pulled out from the outlet 60.
It is fixed to the fixing base 24 by screws 54. Next, the lead wires 56 and 58 are passed through the grommet 62, and the grommet 62 is fixed to the outlet 60 by the holding plate 64. After that, the filling material 44 is filled into the cap 50 through the flow channel 46, and the leads 68 and 58 are completed by attaching the connector 68 thereto.

As described above, in the composite rotational position sensor 10 according to the embodiment, since the filling material 44 is filled in the cap 50 and hermetically sealed, it is not necessary to use an expensive screw-in type connector. And moisture cap 5
0 can be completely prevented, and an inexpensive rotational position sensor with few failures can be obtained. In addition, since the window 42 for connecting the input shaft 16 and the rotary shaft 18 is formed in the fixed base 24, the two shafts can be easily connected, and the sensor can be assembled quickly.

[0036]

As described above, according to the composite rotational position sensor of the present invention, the cap is filled with the filler and sealed, so that it is not necessary to use an expensive screw-in type connector. It is possible to completely prevent dust and moisture from entering the inside of the cap, and it is possible to obtain an inexpensive rotational position sensor with few failures. Further, the formation of the window for connecting the input shaft of the rotary encoder and the rotary shaft to the rotary potentiometer on the base facilitates assembly of the sensor.

[Brief description of the drawings]

FIG. 1 is a block diagram of a rotation position detection device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a composite rotational position sensor according to an embodiment of the present invention.

FIG. 3 is a schematic explanatory diagram of a rotary encoder.

FIG. 4 is an explanatory diagram of output characteristics of a rotary potentiometer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Composite rotation position sensor 12 Rotary encoder 14 Rotary potentiometer 16 Input shaft 18 Rotation shaft 20 Coupling 24 Fixed base 28 Potentiometer support part 30 Encoder support part 42 Window 44 Filler 50 Cap 70 Gear 72 Magnetic sensor 76 Reference point (Z phase) REFERENCE SIGNS LIST 100 absolute rotation position calculator 104 reference point detection circuit 106 counter 110 rotation position calculation circuit 112 failure determination circuit 116 potentio detection angle calculation circuit

Claims (2)

(57) [Claims] 1. A double-axis rotary potentiometer, a rotary encoder having an input shaft connected to a rotary shaft on one side of the rotary potentiometer, a base supporting the rotary encoder and the rotary potentiometer, and A working machine of a construction machine provided with a composite rotation position sensor, comprising: a cap fixed to the rotary encoder and covering the rotary encoder; and a sealing filler filled in the cap. 2. The base, wherein a potentiometer supporting portion for supporting the rotary potentiometer and an encoder supporting portion for supporting the rotary encoder are formed with a predetermined gap therebetween, and a rotation shaft of the rotary potentiometer and a rotary shaft of the rotary encoder are formed. A connection portion with the input shaft is disposed in the gap between the two support portions, and a window for connecting the two shafts is formed in the base beside the connection portion disposed in the gap. A construction machine working machine provided with the composite rotational position sensor according to claim 1 .