Hydraulic drive system

Abstract

To provide a hydraulic drive system that can prevent oversight of an abnormal operation of a hydraulic cylinder caused by a failure of a position sensor, and determine an abnormality occurring in the entire system including the hydraulic cylinder.SOLUTION: A hydraulic drive system 100 includes a hydraulic pump 120, and a hydraulic cylinder 130 that operates with hydraulic oil sent by the hydraulic pump 120. The hydraulic drive system 100 includes: a plurality of abnormality detection sensors (a speed sensor 140, a position sensor 150 and a pressure sensor 160); and an abnormality detection device 192 that monitors the plurality of abnormality detection sensors. The abnormality detection device 192 determines an abnormality of the entire system by majority when detecting an abnormality in any or two or more of the abnormality detection sensors.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hydraulic drive system including a hydraulic pump and a hydraulic cylinder that operates with hydraulic fluid delivered by the hydraulic pump. [Background technology]

[0002] Industrial equipment and vehicles are configured with hydraulic drive circuits that include hydraulic cylinders (actuators) that are driven by hydraulic pressure and hydraulic pumps that deliver hydraulic oil to the hydraulic cylinders. As an example of such a hydraulic drive circuit, Patent Document 1 discloses a hydraulic drive system that includes "a hydraulic pump that forms a closed circuit with the hydraulic actuator, a drive motor that rotationally drives the hydraulic pump in response to an input drive command, a position sensor that detects the position of a control target of the hydraulic actuator, and a control device that calculates a drive command by performing at least proportional control on a position deviation based on the input position command and the position actual result detected by the position sensor, and outputs the calculated drive command to the drive motor." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-71169 A Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, in the hydraulic drive system of Patent Document 1, the position of the controlled object of the hydraulic actuator is detected by a position sensor, and the control device performs proportional control on the standard deviation based on the position command and the position record. However, the hydraulic drive system of Patent Document 1 does not have a means for detecting a failure of the position sensor.

[0005] Therefore, if the position sensor fails, the position of the object controlled by the hydraulic actuator may not be detected accurately, or conversely, an abnormality may be detected even though the hydraulic actuator is operating normally. For this reason, there is room for further improvement in the technology of Patent Document 1.

[0006] In view of the above problems, the present invention aims to provide a hydraulic drive system that can prevent abnormal operation of a hydraulic cylinder caused by a failure of a position sensor from being overlooked and that can determine abnormalities that have occurred in the entire system including the hydraulic cylinder. [Means for solving the problem]

[0007] In order to solve the above problems, a typical configuration of a hydraulic drive system according to the present invention is a hydraulic drive system including a hydraulic pump and a hydraulic cylinder that operates with hydraulic oil delivered by the hydraulic pump, and is equipped with a plurality of abnormality detection sensors and an abnormality detection device that monitors the plurality of abnormality detection sensors, and is characterized in that when an abnormality is detected by one or more of the plurality of abnormality detection sensors, the abnormality detection device determines whether an abnormality has occurred in the entire system by majority vote.

[0008] The hydraulic drive system may include an orifice arranged on a hydraulic circuit of the hydraulic oil, the hydraulic circuit being a closed circuit, and the multiple abnormality detection sensors may include a rotation speed sensor that detects the rotation speed of the hydraulic pump, a position sensor that detects the position of the piston of the hydraulic cylinder, and a pressure sensor that detects the differential pressure before and after the orifice. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a hydraulic drive system that can prevent abnormal operation of a hydraulic cylinder caused by a failure of a position sensor from being overlooked and that can determine whether an abnormality has occurred in the entire system including the hydraulic cylinder. [Brief explanation of the drawings]

[0010] [Figure 1]1 is a diagram illustrating a hydraulic drive system according to an embodiment of the present invention. [Figure 2] FIG. 10 is a diagram illustrating an example of an abnormality determination table to which the abnormality detection device refers. DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Dimensions, materials, and other specific values ​​shown in the embodiments are merely examples for facilitating understanding of the invention and, unless otherwise specified, do not limit the present invention. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0012] Fig. 1 is a diagram illustrating a hydraulic drive system 100 of this embodiment. As shown in Fig. 1, the hydraulic drive system 100 of this embodiment is configured to include a hydraulic pump 120, a hydraulic cylinder 130, a plurality of abnormality detection sensors (described later), and a control device 190. The hydraulic pump 120, the hydraulic cylinder 130, and a plurality of abnormality detection sensors (described later) are arranged on a hydraulic circuit 110 through which hydraulic oil flows.

[0013] The hydraulic pump 120 is connected to a motor 122, and uses the motor 122 as a driving force to send hydraulic oil to the hydraulic cylinder 130. The hydraulic cylinder 130 is a so-called actuator that operates with the hydraulic oil sent out by the hydraulic pump 120. The hydraulic cylinder 130 is configured to include a cylinder 132 that forms piston chambers (a first piston chamber 136a and a second piston chamber 136b), and a piston 134 that slides within the cylinder 132.

[0014] An orifice is arranged in the hydraulic circuit 110 for hydraulic oil between the hydraulic pump 120 and the hydraulic cylinder 130. A first orifice 170a is arranged in the first circuit 112 between the hydraulic pump 120 and the first piston chamber 136a of the hydraulic cylinder 130. A second orifice 170b is arranged in the second circuit 114 between the hydraulic pump 120 and the second piston chamber 136b of the hydraulic cylinder 130. In addition, a first check valve 180a and a second check valve 180b are provided in the first circuit 112 and the second circuit 114 to bypass the respective orifices.

[0015] In this embodiment, the multiple abnormality detection sensors used are a rotation speed sensor 140, a position sensor 150, two first pressure sensors 160a, and two second pressure sensors 160b. All of these sensors are connected to a control device 190. Hereinafter, when there is no need to distinguish between the first pressure sensor 160a and the second pressure sensor 160b, they will simply be referred to as pressure sensors 160.

[0016] The rotation speed sensor 140 is connected to the hydraulic pump 120 and detects the rotation speed of the hydraulic pump 120. The position sensor 150 is connected to the hydraulic cylinder and detects the position of the piston in the cylinder 132 of the hydraulic cylinder .

[0017] The two first pressure sensors 160a are arranged before and after the first orifice 170a to detect the differential pressure across the first orifice 170a. Similarly, the two second pressure sensors 160b are arranged before and after the second orifice 170b to detect the differential pressure across the second orifice 170b.

[0018] The control device 190 controls the hydraulic drive system 100 and, as a feature of this embodiment, functions as an abnormality detection device 192 that monitors multiple abnormality detection sensors. The abnormality detection device 192 monitors the multiple abnormality detection sensors, and when an abnormality is detected by one or more of the multiple abnormality detection sensors, determines that an abnormality exists in the entire system by majority vote.

[0019] Note that predetermined threshold values ​​are set in advance for the rotation speed of the hydraulic pump 120, the position of the piston 134 in the cylinder 132, and the differential pressure between the first pressure sensor 160a and the second pressure sensor 160b. The abnormality detection device 192 detects abnormalities in the multiple abnormality detection sensors by referring to these threshold values.

[0020] Fig. 2 is a diagram illustrating an example of an abnormality determination table referred to by the abnormality detection device 192. In Fig. 2, if the position sensor 150, the rotation speed sensor 140, or the pressure sensor 160 is normal (if the values ​​are below the respective thresholds), it is indicated as OK, and if the values ​​are abnormal (if the values ​​are equal to or greater than the respective thresholds), it is indicated as NG.

[0021] 2, if the abnormality detection device 192 detects abnormalities in all of the position sensor 150, rotation speed sensor 140, and pressure sensor 160 (pattern 1), it determines that there is a malfunction somewhere in the hydraulic drive system 100 and stops operation of the entire system. "Somewhere in the hydraulic drive system 100" could be that the hydraulic cylinder 130 is malfunctioning, or that the piping of the hydraulic circuits 112 and 114 has come loose and caused a loss of hydraulic pressure, or that the hydraulic pump 120 or motor 122 has malfunctioned and stopped. In other words, it is not possible to determine the specific location of the malfunction, but in any case, it is clear that the hydraulic drive system 100 is certainly not operating.

[0022] When abnormalities are detected in two of the position sensor 150, the rotational speed sensor 140, and the pressure sensor 160 (patterns 2 to 4), that is, when the majority vote results in more abnormalities, the abnormality detection device 192 determines that the entire system is malfunctioning (not operating normally). For sensors that show normal values, the abnormality detection device 192 determines that the sensor is malfunctioning or that only the device to which the sensor is attached is operating normally.

[0023] For example, in pattern 2, the rotation speed sensor 140 of the hydraulic pump 120 indicates a normal value, but the position sensor 150 of the hydraulic cylinder 130 and the pressure sensors 160a, b of the orifices 170a, b indicate an abnormality. In this case, the abnormality detection device 192 determines that the hydraulic pump 120 is rotating normally, but that hydraulic oil is not being supplied normally due to an oil leak or the like, and as a result, the hydraulic drive system 100 is not operating normally.

[0024] Also, for example, in pattern 3, the rotation speed sensor 140 of the hydraulic pump 120 indicates that it has stopped, and the pressure sensors 160a and 160b are not detecting a differential pressure (there is no predetermined flow rate), but the position sensor 150 indicates a normal value. In this case, the abnormality detection device 192 determines that the hydraulic drive system 100 is not operating, and that the position sensor 150 is indicating a normal value due to a malfunction.

[0025] If the abnormality detection device 192 detects an abnormality in one of the position sensor, rotation speed sensor, or pressure sensor (Patterns 5 to 7), that is, if the majority vote results in fewer abnormalities, it determines that the hydraulic drive system 100 is operating normally and that the abnormality detection sensor that detected the abnormality may be at fault. In this case, the abnormality detection device 192 notifies the user of a request for inspection without stopping the hydraulic drive system 100.

[0026] For example, in pattern 5, the position sensor 150 indicates an abnormal value, but the rotation speed sensor 140 and the pressure sensor 160 indicate normal values. In this case, the abnormality detection device 192 determines that the hydraulic drive system 100 is operating normally, but that the position sensor 150 is indicating an abnormal value due to a malfunction.

[0027] As described above, according to the hydraulic drive system 100 of this embodiment, a majority vote is performed using a combination of normal / abnormal detection results from multiple anomaly detection sensors. This makes it possible to efficiently determine whether an anomaly detection sensor is malfunctioning or whether the device to which it is connected is malfunctioning. This makes it possible to prevent abnormal operation of the hydraulic cylinder from being overlooked when only the position sensor is referenced, and makes it possible to properly determine an abnormality that has occurred in the entire system including the hydraulic cylinder.

[0028] In this embodiment, a configuration using three types of anomaly detection sensors (three anomaly detection sensors) has been exemplified, but the present invention is not limited to this. The number and types of anomaly detection sensors can be changed as appropriate. However, considering the use of majority voting, it is preferable that the number of anomaly detection sensors is odd. If the number of anomaly detection sensors is even, it is preferable to preset in the anomaly detection device 192 the determination content to be made when the number of normal and abnormal results are the same.

[0029] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such examples. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations also fall within the technical scope of the present invention. [Industrial Applicability]

[0030] The present invention can be used as a hydraulic drive system including a hydraulic pump and a hydraulic cylinder that operates with hydraulic oil delivered by the hydraulic pump. [Explanation of symbols]

[0031] 100...hydraulic drive system, 110...hydraulic circuit, 112...first circuit, 114...second circuit, 120...hydraulic pump, 122...motor, 130...hydraulic cylinder, 132...cylinder, 134...piston, 136a...first piston chamber, 136b...second piston chamber, 140...rotation speed sensor, 150...position sensor, 160...pressure sensor, 160a...first pressure sensor, 160b...second pressure sensor, 170a...first orifice, 170b...second orifice, 180a...first check valve, 190...control device, 192...abnormality detection device

Claims

1. A hydraulic drive system including a hydraulic pump and a hydraulic cylinder that operates with hydraulic oil delivered by the hydraulic pump, A plurality of anomaly detection sensors; an abnormality detection device that monitors the plurality of abnormality detection sensors; Equipped with The hydraulic drive system is characterized in that, when an abnormality is detected by one or more of the plurality of abnormality detection sensors, the abnormality detection device determines that an abnormality has occurred in the entire system by majority vote.

2. the hydraulic drive system includes an orifice disposed on a hydraulic circuit of the hydraulic oil; The hydraulic circuit is a closed circuit, The plurality of abnormality detection sensors include: a rotation speed sensor for detecting the rotation speed of the hydraulic pump; a position sensor for detecting the position of the piston of the hydraulic cylinder; a pressure sensor for detecting a differential pressure across the orifice; 2. The hydraulic drive system of claim 1, including:

Images