Today we introduce a national invention patent for the invention - flow control valve and slide valve position detection device for flow control valve. The patent was filed by Amitek Co., Ltd. and was issued an authorization announcement on November 2, 2016.
Description
The present invention relates to a spool type flow control valve used as a fluid flow control valve, and to a spool position detecting device for a flow control valve.
Background of the invention
In the field of, for example, a construction machine/vehicle or other machine/vehicle, a fluid pressure device such as a fluid pressure cylinder is used as a drive actuator of a work device. When the fluid pressure device is driven, the pressure fluid that controls the direction and flow rate is supplied to the desired fluid pressure port via the flow control valve. As the flow control valve, various pilot valves are used. The flow control valve is configured as a servo valve, and the position detector detects the position of the spool of the flow control valve, and feeds back the spool position detection data to the actuator that drives the spool.
Among the position detectors, various types of position detectors such as resistive, electromagnetic or optical are known. A resistive position detector using a potentiometer has difficulty in durability due to the presence of a mechanical contact type contact. On the other hand, the optical sensor can be detected in a non-contact manner, but in the case where the surrounding environment is likely to be dirty, there is a difficulty in maintenance. An electromagnetic sensor using an AC-excited coil has an advantage that it can be detected in a non-contact manner and has durability even in an environment where the surrounding environment is easily dirty. However, there is a problem in how to compensate for variations in coil impedance caused by temperature characteristics, thereby enabling highly accurate position detection. In addition, regardless of the type of sensor, it is desirable to provide a position detector that is simple in construction and inexpensive to manufacture.
Further, in the flow rate control valve, there are various sizes corresponding to the purpose of use. In the conventional spool position detecting device, if the maximum displacement amount of the spool as the detection target is different, it is necessary to use a position sensor having a detectable range corresponding thereto. Therefore, at present, different position detecting devices must be prepared for various types of flow control valves of various sizes.
Summary of the invention
The present invention has been made in view of the above problems, and provides a flow control valve having an electromagnetic position detector which is simple in structure, excellent in durability, can be adapted to a harsh use environment, and has superior temperature characteristic compensation. Performance, and manufacturing costs are cheap. Further, a spool position detecting device for a flow control valve having the same advantages is provided. At the same time, a spool position detecting device that can be shared even for flow control valves of different sizes is provided.
In the flow control valve according to the present invention, a spool having a plurality of valve bodies is slidably accommodated in a sleeve having a plurality of ports, and the spool is linearly moved by an actuator to perform flow rate control. The utility model is characterized in that it has a substantially linear target probe which is installed at one end of the spool valve and is made of a magnetically responsive material, and an opening which is disposed at one end of the sleeve to allow the target probe. Passing through; a sensor housing mounted at the one end of the sleeve for detecting a linear position of the target probe.
FIG. 1 is a view showing an example of a system for driving control of a fluid pressure cylinder using a spool type flow control valve according to an embodiment of the present invention.
Wherein the sensor housing has a tubular portion formed with an internal space allowing the entry of the target probe, the internal space being coupled to the opening of the one end of the sleeve, the tubular portion The first coil and the second coil are disposed around the tubular portion in the sensor housing at a predetermined interval in the axial direction, and the first coil is disposed in the same manner as the first coil. The target probe is inductive, and the target probe has a tapered front end portion with a gradually decreasing volume, so that the magnetic responsiveness with respect to the first coil changes gradually in one direction corresponding to the linear position of the target probe. And the second coil is configured to induce the linear displacement of the target probe at least within a predetermined linear displacement range of the target probe, and to perform the difference between the outputs of the first and second coils. Synthesizing to detect the linear position of the target probe, that is, the position of the spool.
Further, the first coil is located on the proximal side with respect to the target probe, the second coil is located on the distal end side, and a magnetic responsive shielding member is annularly provided inside the second coil, the target The probe is configured to have a length of a sensing region of the second coil having its distal end entering the distal end side, and the magnetic responsive shielding member is used when the distal end thereof enters the sensing region of the second coil on the distal end side The second coil is not induced by the target probe.
According to one embodiment, the present invention further provides a circuit for rectifying an AC detection signal obtained by differentially combining the outputs of the first and second coils to generate a DC detection voltage signal, and a gain setting circuit. The DC detection voltage signal is amplified, and in the gain setting circuit, the resistance element having the predetermined temperature characteristic is used as the resistance element for gain setting, and the specification of the resistance element for setting the gain is set. Temperature characteristics to counteract impedance changes caused by eddy current losses and temperature characteristics of elements within the circuit. Thereby, the eddy current loss and the temperature characteristics of the elements in the circuit can be compensated.
According to a preferred embodiment, the plurality of flow control valves differing in the maximum displacement amount of the spool valve by the size of the opening provided at one end of the sleeve, and relative to the sleeve The mounting structure of the sensor housing at one end is generalized, and the length of the internal space formed by the cylindrical portion in the sensor housing becomes the longest of the plurality of flow control valves The size corresponding to the maximum displacement amount of the spool valve is such that the target probes of different sizes are used for the plurality of flow rate control valves, but the same ones including the first coil and the second coil are included. The sensor housing can be commonly applied to the plurality of flow control valves. Therefore, since the same sensor housing including the first coil and the second coil can be commonly applied to a plurality of flow rate control valves, it is possible to prepare different positions for each type of flow control valves of various sizes. The detection device reduces manufacturing costs by generalization.
Description
The present invention relates to a spool type flow control valve used as a fluid flow control valve, and to a spool position detecting device for a flow control valve.
Background of the invention
In the field of, for example, a construction machine/vehicle or other machine/vehicle, a fluid pressure device such as a fluid pressure cylinder is used as a drive actuator of a work device. When the fluid pressure device is driven, the pressure fluid that controls the direction and flow rate is supplied to the desired fluid pressure port via the flow control valve. As the flow control valve, various pilot valves are used. The flow control valve is configured as a servo valve, and the position detector detects the position of the spool of the flow control valve, and feeds back the spool position detection data to the actuator that drives the spool.
Among the position detectors, various types of position detectors such as resistive, electromagnetic or optical are known. A resistive position detector using a potentiometer has difficulty in durability due to the presence of a mechanical contact type contact. On the other hand, the optical sensor can be detected in a non-contact manner, but in the case where the surrounding environment is likely to be dirty, there is a difficulty in maintenance. An electromagnetic sensor using an AC-excited coil has an advantage that it can be detected in a non-contact manner and has durability even in an environment where the surrounding environment is easily dirty. However, there is a problem in how to compensate for variations in coil impedance caused by temperature characteristics, thereby enabling highly accurate position detection. In addition, regardless of the type of sensor, it is desirable to provide a position detector that is simple in construction and inexpensive to manufacture.
Further, in the flow rate control valve, there are various sizes corresponding to the purpose of use. In the conventional spool position detecting device, if the maximum displacement amount of the spool as the detection target is different, it is necessary to use a position sensor having a detectable range corresponding thereto. Therefore, at present, different position detecting devices must be prepared for various types of flow control valves of various sizes.
Summary of the invention
The present invention has been made in view of the above problems, and provides a flow control valve having an electromagnetic position detector which is simple in structure, excellent in durability, can be adapted to a harsh use environment, and has superior temperature characteristic compensation. Performance, and manufacturing costs are cheap. Further, a spool position detecting device for a flow control valve having the same advantages is provided. At the same time, a spool position detecting device that can be shared even for flow control valves of different sizes is provided.
In the flow control valve according to the present invention, a spool having a plurality of valve bodies is slidably accommodated in a sleeve having a plurality of ports, and the spool is linearly moved by an actuator to perform flow rate control. The utility model is characterized in that it has a substantially linear target probe which is installed at one end of the spool valve and is made of a magnetically responsive material, and an opening which is disposed at one end of the sleeve to allow the target probe. Passing through; a sensor housing mounted at the one end of the sleeve for detecting a linear position of the target probe.
FIG. 1 is a view showing an example of a system for driving control of a fluid pressure cylinder using a spool type flow control valve according to an embodiment of the present invention.
Wherein the sensor housing has a tubular portion formed with an internal space allowing the entry of the target probe, the internal space being coupled to the opening of the one end of the sleeve, the tubular portion The first coil and the second coil are disposed around the tubular portion in the sensor housing at a predetermined interval in the axial direction, and the first coil is disposed in the same manner as the first coil. The target probe is inductive, and the target probe has a tapered front end portion with a gradually decreasing volume, so that the magnetic responsiveness with respect to the first coil changes gradually in one direction corresponding to the linear position of the target probe. And the second coil is configured to induce the linear displacement of the target probe at least within a predetermined linear displacement range of the target probe, and to perform the difference between the outputs of the first and second coils. Synthesizing to detect the linear position of the target probe, that is, the position of the spool.
Further, the first coil is located on the proximal side with respect to the target probe, the second coil is located on the distal end side, and a magnetic responsive shielding member is annularly provided inside the second coil, the target The probe is configured to have a length of a sensing region of the second coil having its distal end entering the distal end side, and the magnetic responsive shielding member is used when the distal end thereof enters the sensing region of the second coil on the distal end side The second coil is not induced by the target probe.
According to one embodiment, the present invention further provides a circuit for rectifying an AC detection signal obtained by differentially combining the outputs of the first and second coils to generate a DC detection voltage signal, and a gain setting circuit. The DC detection voltage signal is amplified, and in the gain setting circuit, the resistance element having the predetermined temperature characteristic is used as the resistance element for gain setting, and the specification of the resistance element for setting the gain is set. Temperature characteristics to counteract impedance changes caused by eddy current losses and temperature characteristics of elements within the circuit. Thereby, the eddy current loss and the temperature characteristics of the elements in the circuit can be compensated.
According to a preferred embodiment, the plurality of flow control valves differing in the maximum displacement amount of the spool valve by the size of the opening provided at one end of the sleeve, and relative to the sleeve The mounting structure of the sensor housing at one end is generalized, and the length of the internal space formed by the cylindrical portion in the sensor housing becomes the longest of the plurality of flow control valves The size corresponding to the maximum displacement amount of the spool valve is such that the target probes of different sizes are used for the plurality of flow rate control valves, but the same ones including the first coil and the second coil are included. The sensor housing can be commonly applied to the plurality of flow control valves. Therefore, since the same sensor housing including the first coil and the second coil can be commonly applied to a plurality of flow rate control valves, it is possible to prepare different positions for each type of flow control valves of various sizes. The detection device reduces manufacturing costs by generalization.
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