AU2019441302A1

AU2019441302A1 - Fault determination method and system for screw compressor

Info

Publication number: AU2019441302A1
Application number: AU2019441302A
Authority: AU
Inventors: Changzheng Fang; Yingying GUO; Dan Li; Jinhui Li; Shichuan XIE; Ping ZENG
Original assignee: CRRC Zhuzhou Locomotive Co Ltd
Current assignee: CRRC Zhuzhou Locomotive Co Ltd
Priority date: 2019-04-18
Filing date: 2019-10-22
Publication date: 2021-10-07
Also published as: WO2020211318A1; CN109931265A; CN109931265B; ZA202107657B

Abstract

A fault determination method and system for a screw compressor. The fault determination method comprises the following steps: step A, monitoring whether a screw compressor stops, and in cases where the screw compressor stops, proceeding to step B; and step B, after a set duration has elapsed from the time when the screw compressor stops, detecting whether a normally closed contact of a pressure switch is disconnected, and if the normally closed contact of the pressure switch is not disconnected, determining that a fault occurs in the screw compressor. In the fault determination method and system for a screw compressor, by means of existing devices, the fault state of the screw compressor can be identified in time by adding a logic determination function in a control unit according to the working principle of the screw compressor, being simple and reliable, and ensuring the running safety of an engine and a vehicle.

Description

FAULT DETERMINATION METHOD AND SYSTEM FOR SCREW COMPRESSOR

Field of the Invention The present invention particularly relates to a fault determination method and system for a screw compressor.

Background of the Invention The existing locomotive air source systemuses a screw compressor. During the control process of the screw compressor, the air pressure in the screw compressor is usually monitored by a pressure switch arranged therein. When the internal pressure exceeds a certain value, the pressure switch is disconnected, and a signal is output to prevent a locomotive from starting the screw compressor, such that the screw compressor is started with load, which damages the screw compressor. At the same time, when the internal pressure of the screw compressor is lower than the set pressure, the pressure switch outputs a signal to allow the screw compressor to start. However, in the prior art, when a broken shaft and other faults occur in the screw compressor, the screw compressor loses the ability to blow the air, but the pressure switch still outputs the signal indicating the screw compressor is available, and thus protection and prompt cannot be performed. At this time, the air source system cannot provide compressed air for a braking system, so that the effectiveness of braking forces applied by the locomotive and a vehicle cannot be guaranteed, and then the running safety of the locomotive and the vehicle is affected.

Summary of the Invention The purpose of the present invention is to provide a fault determination method and system for a screw compressor in view of the above-mentioned shortcomings of the prior art, which can identify the fault state of the screw compressor in time and ensure the running safety of a locomotive and a vehicle. In order to solve the above-mentioned technical problems, the technical solution adopted by the present invention is: A fault determination method for a screw compressor, characterized by including the following steps: step A, monitoring whether the screw compressor stops, and in case where the screw compressor stops, proceeding to step B; and step B, after a set duration has elapsed from the time when the screw compressor stops, detecting whether a normally closed contact of a pressure switch is disconnected, and if the normally closed contact of the pressure switch is not disconnected, determining that a fault occurs in the screw compressor. As a preferred manner, in step A, whether the screw compressor stops is determined by monitoring the working state of a screw compressor contactor: when the screw compressor contactor is disconnected, it is determined that the screw compressor stops; and when the screw compressor contactor is not disconnected, it is determined that the screw compressor does not stop. Further, when the screw compressor is faulty, a fault state is sent to a cab for display. As a preferred manner, the set duration does not exceed 14 seconds. Based on the same inventive concept, the present invention further provides a fault determination system for a screw compressor, characterized by including: a control unit, used for monitoring whether the screw compressor stops, and in case where the screw compressor stops, after a set duration has elapsed from the time when the screw compressor stops, detecting whether a normally closed contact of a pressure switch is disconnected, and if the normally closed contact of the pressure switch is not disconnected, determining that a fault occurs in the screw compressor. As a preferred manner, the control unit determines whether the screw compressor stops by monitoring the working state of a screw compressor contactor: when the screw compressor contactor is disconnected, determines that the screw compressor stops; and when the screw compressor contactor is not disconnected, determines that the screw compressor does not stop. Further, the system further includes a display unit arranged in a cab; the control unit is further used for sending a fault state to the display unit when the screw compressor is faulty; and the display unit is used for receiving and displaying the fault state information sent by the control unit. As a preferred manner, the set duration does not exceed 14 seconds. In the present invention, the state of the pressure switch in the screw compressor is monitored by the control unit (such as the existing locomotive control system), when the screw compressor contactor is disconnected, that is, the screw compressor stops. Since the compressed air in a compression chamber returns naturally, the air pressure in

1) the screw compressor body increases, and the pressure should exceed a set value of the rising edge of the pressure switch within a specified time, making the normally closed point of the pressure switch to be disconnected, and a signal is output to prevent the screw compressor from starting with load. If the control unit monitors that the pressure switch is not disconnected within the set duration after the screw compressor stops working, it means that there is no compressed air return, and the compression end of the screw compressor does not output the compressed air, at this time, the screw compressor has a transmission failure fault and cannot establish the pressure, at this time, it is determined that the screw compressor has a fault. The fault information can be sent to the cab for display through the control unit, so as to prompt the driver or conductor to confirm the state of the screw compressor, and find and deal with the fault in time. In the present invention, by means of existing devices (the control unit, the screw compressor contactor, the pressure switch and the cab display unit), the fault state of the screw compressor can be identified in time by adding a logic determination function in the control unit according to the working principle of the screw compressor, which is simple and reliable, and ensures the running safety of the locomotive and the vehicle.

Brief Description of the Drawings Fig. 1 is a flow chart of a fault determination method for a screw compressor in the present invention. Fig. 2 is a comparison diagram of normal and fault states of a pressure switch of the screw compressor in the present invention.

Detailed Description of Embodiments Hereinafter, the present invention will be further described in detail with reference to the drawings and specific embodiments. The flow chart of a fault determination method is shown in Fig. 1, and the comparison diagram of normal and fault states of a pressure switch is shown in Fig. 2. A fault determination method for a screw compressor in the present invention includes the following steps: step A, monitoring whether the screw compressor stops, and in case where the screw compressor stops, proceeding to step B; and step B, after a set duration has elapsed from the time when the screw compressor stops, detecting whether a normally closed contact of a pressure switch is disconnected, and if the normally closed contact of the pressure switch is not disconnected, determining that a fault occurs in the screw compressor. When the screw compressor is faulty, a fault state is sent to a cab for display. In step A, whether the screw compressor stops is determined by monitoring the working state of a screw compressor contactor: when the screw compressor contactor is disconnected, it is determined that the screw compressor stops; and when the screw compressor contactor is not disconnected, it is determined that the screw compressor does not stop. A fault determination system for a screw compressor in the present invention includes: a control unit, used for monitoring whether the screw compressor stops, and in case where the screw compressor stops, after a set duration has elapsed from the time when the screw compressor stops, detecting whether a normally closed contact of a pressure switch is disconnected, and if the normally closed contact of the pressure switch is not disconnected, determining that a fault occurs in the screw compressor. When the screw compressor is faulty, the control unit sends a fault state to a display unit. The fault determination system for the screw compressor further includes: the display unit arranged in the cab, used for receiving and displaying the fault state information sent by the control unit. The control unit determines whether the screw compressor stops by monitoring the working state of a screw compressor contactor: when the screw compressor contactor is disconnected, determines that the screw compressor stops; and when the screw compressor contactor is not disconnected, determines that the screw compressor does not stop. The set duration does not exceed 14 seconds. As shown in Fig. 1 and Fig. 2, at the moment TO, the screw compressor contactor is disconnected, its state changes from 1 to 0, and the screw compressor stops at this time. The timing starting point of the set duration is the stop moment TO of the screw compressor, the set duration is TI-TO, and the set duration does not exceed 14 seconds. For a normal screw compressor, within the set duration T-TO, because the compressed air returns,the state of the pressure switch will change from 1 to 0 if the pressure exceeds a set value of the rising edge of the pressure switch. For a faulty screw compressor, since the air cannot be compressed, there is no compressed air return, and the internal pressure of the body does not change within the

A set duration TI-TO, so the state value of the pressure switch remains at 1 from TO to T1. At this time, the control unit monitors from TO to TI that the output signal of the pressure switch does not change, and then the control unit outputs fault information to indicates that the screw compressor has a fault, so as to ensure the running safety. The embodiments of the present invention are described above with reference to the drawings, but the present invention is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments are only illustrative and not restrictive. Those of ordinary skilled in the art can still, under the enlightenment of the present invention, make many forms without departing from the spirit of the present invention and the protection scope of the claims, and all of which fall within the protection scope of the present invention.

Claims

1. A fault determination method for a screw compressor, characterized in that the fault determination method comprises the following steps:

step A, monitoring whether the screw compressor stops, and in case where the screw compressor stops, proceeding to step B; and

step B, after a set duration has elapsed from the time when the screw compressor stops, detecting whether a normally closed contact of a pressure switch is disconnected, and if the normally closed contact of the pressure switch is not disconnected, determining that a fault occurs in the screw compressor.

2. The fault determination method for the screw compressor of claim 1, wherein in step A, whether the screw compressor stops is determined by monitoring the working state of a screw compressor contactor: when the screw compressor contactor is disconnected, it is determined that the screw compressor stops; and when the screw compressor contactor is not disconnected, it is determined that the screw compressor does not stop.

3. The fault determination method for the screw compressor of claim 1, wherein in step B, when the screw compressor is faulty, a fault state is sent to a cab for display.

4. The fault determination method for the screw compressor of any of claims 1-3, wherein the set duration does not exceed 14 seconds.

5. A fault determination system for a screw compressor, characterized in that the fault determination system comprises:

a control unit, used for monitoring whether the screw compressor stops, and in case where the screw compressor stops, after a set duration has elapsed from the time when the screw compressor stops, detecting whether a normally closed contact of a pressure switch is disconnected, and if the normally closed contact of the pressure switch is not disconnected, determining that a fault occurs in the screw compressor.

6. The fault determination system for the screw compressor of claim 5, wherein the control unit determines whether the screw compressor stops by monitoring the working state of a screw compressor contactor: when the screw compressor contactor is disconnected, determines that the screw compressor stops; and when the screw compressor contactor is not disconnected, determines that the screw compressor does not stop.

7. The fault determination system for the screw compressor of claim 5, further comprising a display unit arranged in a cab;

the control unit is further used for sending a fault state to the display unit when the screw compressor is faulty; and

the display unit is used for receiving and displaying the fault state information sent by the control unit.

8. The fault determination system for the screw compressor of any of claims 5-7, wherein the set duration does not exceed 14 seconds.

1)

Fig. 1

Fig. 2