JPH04155201A - Detecting apparatus for cylinder position - Google Patents

Abstract

PURPOSE:To detect a piston position by reading a magnetic scale on a piston rod by a sensor and inputting a digital code to a PROM to read position information. CONSTITUTION:Pressure fluid is alternately supplied to and exhausted from a head chamber 1a and a rod chamber 1b through ports 8, 9 of a cylinder 1 while a piston 5 is reciprocated. At this time a position of a rod 6 is sensed by reading a magnetic scale 10 on the rod by a sensor 11. That is, when the magnetic scale 10 is read by each reading element 11a of the sensor 11, a digital code comprising a plurality of bits different in signal sequence is outputted according to the read position and input to a PROM 22 of a control circuit 12. Position information corresponding to each digital code 16 is read by a signal read out from an oscillator 23, and a motion position of the rod 6 at this time is directly sensed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cylinder position detection device.

[Prior Art] Conventionally, as a position detection device for detecting the operating position of a piston rod in a cylinder, a Mi magnetic scale sensor attached to the piston rod is used.

There is a known device that detects the operating position by electrically measuring the displacement (for example,
- Publication No. 132203).

However, conventional position detection devices do not convert the read signal from the sensor into codes. Since the operating position is determined by performing rough arithmetic processing, there are drawbacks such as the complicated structure of the device and the difficulty of high-speed detection due to time delays caused by software intervention.

[Problem II to be Solved by the Invention] An object of the present invention is to provide a position detection device that can easily detect the position of a piston rod.

[Means for Solving the Problems] In order to solve the above problems, the position detection device of the present invention is formed by arranging magnetic parts and non-magnetic parts in a predetermined order in the axial direction on the piston rod of a cylinder. a magnetic scale; a sensor having a plurality of reading elements for reading the magnetic scale and obtaining a multi-bit digital code based on a read signal from each reading element; a sensor that determines the position of the piston rod based on the digital code from the sensor; a control circuit for detecting: the magnetic scale is formed as a non-repetitive scale with no repeatability so that the digital code at every reading position of the sensor always has a different signal arrangement; 2 corresponding to the code
It is characterized by having a PRON in which a base code or a binary IO base code is written in an address as position information, and configured to read position information corresponding to the digital code of the sensor from the PRON. .

[Operation] When each reading element of the sensor reads the magnetic scale on the piston rod, a multi-bit digital code is output from the sensor and inputted to the PRO circuit of the control circuit. The P
A binary code or a binary coded decimal code corresponding to any digital code from the sensor is written in advance as position information in the address of the ROM, and when a digital code is input from the sensor, the corresponding position information is stored. The position of the piston is directly detected from the position information read from the PROM.

Therefore, there is no need to perform complex arithmetic processing or code conversion on signals from the sensor, and the operating position in the room can be detected using only hardware.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

In FIG. 1, l indicates a cylinder, and this cylinder l
consists of a hollow cylinder body 2 whose both ends are sealed by a head cover 3 and a rod cover 4, a piston 5 slidably disposed within the cylinder body 2, and a piston rod 6 connected to the piston 5. The piston rod 6 passes through the rod cover 4 and the sensor guide 7 in a fluid-tight manner and extends to the outside. Further, 8 and 9 are boats for supplying and discharging pressure fluid.

A position detection device for detecting the operating position of the piston rod 6 is attached to the cylinder l.

This position detection device includes a magnetic scale lO attached to a piston rod 6, a sensor 11 for reading the magnetic scale attached to a rod cover 4 in a cylinder body 2 by a sensor guide 7, and a read signal from the sensor 11. and a control circuit 12 that detects the position of the piston rod 6 based on the control circuit 12, which is assembled on a substrate 13,
It is housed in a case 14 attached to the cylinder body 2.

The magnetic scale 10 has a magnetic portion le as shown in FIG.
A and the non-magnetic part 10b are arranged in a predetermined order in the axial direction of the piston rod 6, and the sensor 11 reads the magnetic part 10a and the non-magnetic part 10b of the magnetic scale lO to indicate "0". "or rl" has a plurality of reading elements 11a that output a reading signal, and the reading signal from each reading element 11a reads a plurality of bits of digital code 1.
6 (see Figure 4). The number of bits at this time is determined by the resolution of the sensor 11 and the required length for position detection, but there is an advantage that it is easier to code if a slight margin is allowed. For example, when the resolution is l■■ and the required length for position detection is l5OO*m, it is preferable to use 11 bits as shown in Figure 1.

FIG. 4 lists the digital code I6 output from the sensor 11 when the sensor 11 and the magnetic scale lO move relative to each other by one bit. here,"
0" indicates the magnetic portion lea, and "l" indicates the non-magnetic portion 10b. As can be seen from this figure, the magnetic scale lO is formed as a non-repetitive scale with no repeatability so that the digital code at every reading position of the sensor 11 always has a different signal arrangement.

In addition, the magnetic part 10a and the non-magnetic part tab in the said magnetic scale lO can also be arranged in the reverse relationship to the case of illustration.

Further, as shown in FIG. 3, the control circuit 12 includes an amplifier circuit 20 for amplifying the read signal and a comparator 21 for each reading element 11a in the sensor 11, and the compared read signal is is input to the address terminal of PROM (Programmable Read Only Memory) 22. The PROM 22 can be freely written with information, and each address can contain any digital code 1 from the sensor 11.
A binary code or a binary coded decimal code corresponding to 6 is written in advance as position information, and the corresponding position information is read from the PROM 22 in accordance with the digital code 16 output from the sensor 11. The position of 5 is directly detected. At this time, the PROM 22 is given a memory read signal from the oscillator 23 at a constant cycle, thereby enabling high-speed reading. The output from the PROM 22 can also be configured to be switchable between parallel and serial using a converter 24.

By using the PROM 22 with a large storage capacity, the remaining address terminals can be used to convert the output signal from a binary code to a binary IO base code, or to convert an output signal from a binary code to a binary IO base code.
It is possible to convert from base code to binary code.

In addition, a sensor 1 is attached to the helad cover 3 of the cylinder l.
An origin adjustment mechanism is provided for adjusting the origin position of 1 and the magnetic scale lO. This adjustment mechanism is based on the piston 5
An adjustment bolt 26 for adjusting the stroke end of the head cover 3 is fastened to the head cover 3, and a fixing nut 27 is fastened to the adjustment bolt 26.

In the cylinder l having the above configuration, the piston 5 is driven to reciprocate by alternately supplying and discharging pressure fluid to the head chamber 1a and the rod chamber 1b through the boat 8.9, and the operating position of the piston rod 6 at this time is detected by the sensor 11 reading the magnetic scale 10 on the piston rod 6. That is, when each reading element 11a of the sensor 11 reads the magnetic scale 10 on the piston lower drawer, the sensor 11 outputs a multi-bit digital code 1 whose signal arrangement differs depending on the reading position, as shown in FIG.
6 is output and input to the PROM 22 of the control circuit 12. In the PROW 22, position information corresponding to each digital code 16 is read out by a read signal from the oscillator 23, and the operating position of the piston rod 6 at that time is directly detected from this position information.

[Effects of the Invention] As described above, according to the present invention, a multi-bit digital code is output by a sensor consisting of a plurality of reading elements, and a position corresponding to the digital code is detected from among the position information written in advance in the address of the PRON. Since the operating position of the piston is detected by reading out the information, is it possible to convert the code to a negative signal from the sensor? The operating position can be directly and easily detected only by hardware without performing any complicated arithmetic processing.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing an embodiment of the present invention, Fig. 2 is a schematic configuration diagram of a position detection device, Fig. 3 is a configuration diagram of a control circuit, and Fig. 4 is a digital It is an explanatory diagram showing a code. l...Cylinder, 6...Piston rod, lO...
・Magnetic scale, loa...Magnetic part, 10b...Non-magnetic part, 11...Sensor, 11a...Reading element, 1
2...Control circuit, 16...Digital code, 22...PROM. Patent applicant NISMC Co., Ltd. Figure 1!

Claims (1)

[Claims] 1. A magnetic scale formed by arranging magnetic parts and non-magnetic parts in a predetermined order in the axial direction on the piston rod of the cylinder; and a plurality of reading elements for reading the magnetic scale; and a control circuit that detects the position of the piston rod based on the digital code from the sensor. The digital code at every reading position is formed as a non-repetitive scale so that the signal arrangement is always different; the control circuit converts the binary code or binary coded decimal code corresponding to each digital code into position information. 1. A cylinder position detection device comprising: a PROM having an address written therein; and position information corresponding to a digital code from a sensor is read from the PROM.