JP2000205141A - Method and device for diagnosing failure of pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a pump failure related to a hydraulic circuit by determining the actual fluid flow carried in a cylinder, determining an expected fluid flow, and judging the pump state according to the flows. SOLUTION: In a first control block 302, at least one cylinder is commanded to move by an electronic control module. In a second control block 304, the actual hydraulic fluid is judged, and the fluid flow rate to the cylinder is determined. The fluid flow rate to the cylinder can be determined according to the actuating time of the cylinder and the distance covered during the actuation of the cylinder. In a third control block 306, an expected fluid flow rate is determined. In a fourth control block, the pump state is determined. The pump state of failure or actuation can be determined by mutually comparing the expected and actual pump flow rates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates generally to hydraulic control circuits. More particularly, the present invention relates to an apparatus and method for detecting a pump failure associated with a hydraulic circuit.

[0002]

BACKGROUND OF THE INVENTION The catastrophic failure of hydraulic pumps is often due to metal debris being scattered throughout the hydraulic system, making repairs expensive and time consuming.

[0003]

If a pump failure is detected before a tragic failure, repairs will be completed before external damage occurs, reducing the cost of repairs. The present invention addresses one or more of the above problems.

[0004]

SUMMARY OF THE INVENTION In one aspect of the present invention, a method for detecting a pump failure is disclosed. The method includes determining an actual fluid flow through the cylinder, determining an expected fluid flow, and determining a pump condition in response to the actual and expected fluid flows. In yet another aspect of the present invention, a method for determining a pump failure is disclosed. The method includes determining an actual efficiency of the pump, comparing the actual efficiency of the pump with expected efficiency, and determining a pump condition in response to the comparison.

In another aspect of the present invention, a method for determining a pump failure is disclosed. The method includes moving at least one cylinder to an extension, determining a working fluid pressure, and determining a pump condition in response to comparing actual fluid pressure to expected fluid pressure.
In another aspect of the present invention, an apparatus for detecting a failure of a pump connected to a hydraulic circuit having a pump engine and at least one cylinder is disclosed. The equipment is
A cylinder position detecting device which detects a cylinder position and transmits a cylinder position signal in response thereto, and detects an engine speed and transmits an engine speed signal in response thereto. An engine speed detection device. The apparatus also includes a controller adapted to receive the cylinder position signal and the engine speed signal and to determine pump status in response thereto.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an apparatus and method for detecting the failure of a pump located in a hydraulic circuit. FIG. 1 illustrates one embodiment of a hydraulic circuit 102.
Hydraulic circuit 102 includes a pump engine 104 that drives a pump 106. In a preferred embodiment, the pump 10
Reference numeral 6 denotes a constant displacement pump. Pump 106 sends working fluid to circuit 102. Specifically, pump 106 sends fluid to fluid actuator 110 via control valve 108. In the preferred embodiment, the actuator 110
Is a cylinder. Although one fluid actuator 110 and valve 108 are shown in FIG. 1, multiple cylinders and valves may be connected to pump 106. Valve 108 controls fluid flow to cylinder 110.
Fluid flows through valve 108 to head end 118 of cylinder 110 and to rod end 13 of cylinder 110.
Exit 2 returns to fluid sump 112, the tank. Tank 112 is also attached to pump 106. Circuit 1
02 includes a relief valve 114 connected between the pump 106 and the tank 112.

The circuit 102 includes an electronic control module (EC
M) 116. The ECM 116 is electrically connected to the valve 108. The ECM 116 receives input from the sensors and controls the position of the cylinder 110 in response by controlling, in part, the position of the valve 108.
ECM 116 sends a command signal to valve 108 to control the position of valve 108 and will control the amount of fluid flowing to cylinder 110. Thus, the position of the cylinder 110 may be controlled by the ECM 116. Sensor inputs received by ECM 116 include engine speed signals, cylinder position signals, fluid temperature signals, and fluid pressure signals. Software executing on the ECM 116 may determine the state of the pump 106 in response to sensor input.

[0008] The circuit 102 includes an engine speed sensor 124 for detecting the speed of the pump engine 104. Engine speed sensor 124 sends the detected speed signal to ECM 116. In one embodiment, speed sensor 124 is a device that responds to the passage of a gear tooth by a magnetic pickup mounted on engine 104, as is known in the art. Cylinder position sensor 126 is included to determine the position of cylinder 110. In one embodiment, sensor 126 is a displacement detection rod attached to cylinder 110 to detect cylinder displacement. The displacement rod detects the cylinder displacement and generates a cylinder displacement signal in response. In one embodiment, a fluid temperature sensor 120 is included in circuit 102. The fluid temperature sensor 1120
The temperature of the working fluid is detected, and a temperature signal is generated in response thereto.

In a preferred embodiment, the hydraulic circuit 102
Is located on a soil moving machine 202 such as the tracked tractor illustrated in FIG. Soil moving machine 20
2 is at least one lift cylinder 110A, 110B
And a work implement 208 controllably attached to at least one angle cylinder 110C.

FIG. 3 illustrates a flow chart of one embodiment of the method of the present invention. The method detects pump failure by detecting a decrease in fluid flow to the cylinder. In a first control block 302, at least one cylinder 110 is commanded to move by ECM 116. In a preferred embodiment, the pump flow is determined during the uplift correction of work implement 208. That is, pump flow is determined while lifting through the lift cylinders 110A and 110B, as opposed to when the tool 208 is lowering, to minimize the effects of load overrun. Load overrun is a condition in which an external load pulls the cylinder with enough force to move the piston. Thus, the lift cylinders 110A, 110B are commanded to move. Furthermore, the pump flow rate is 3
It is preferable to be obtained when the value is not more than the upper limit such as 500 Psi. The upper limit is determined by the characteristics of the relief valve 114, and the upper limit does not exceed the relief set value. The relief set value is the relief valve 1
Reference numeral 14 denotes the pressure at the time of opening. Further, for ascending precision, the pump flow rate is preferably determined when the control valve 108 is commanded to fully open to eliminate variability in valve position.

[0011] The viscosity of the working fluid can affect the decisions made in the present invention. Thus, in a preferred embodiment, the working fluid is at an operating temperature, for example, 180 to 22
Up to 0 degrees Fahrenheit, reducing the possibility of fluid viscosity changing due to variable temperature.

In a second control block 304, the actual working fluid is determined. In the preferred embodiment, fluid flow to cylinder 110 is determined. The fluid flow to the cylinder depends on the length of time the cylinder 110 is moving,
It may be determined in response to the distance covered during the operation of the cylinder 110. The initial position of the cylinder 110 and the start time at which the cylinder 110 is moving
Detected in response to 0 being commanded to move.
The time at which the cylinder stops moving and the stop position of the cylinder 110 are detected. In a preferred embodiment, the difference between the start and stop times must exceed a predetermined minimum length of time to ensure accurate measurements. If the time difference does not exceed the minimum length of time, for example 3 seconds, the flow rate is not determined and the method is started again.

Next, the actual flow rate is determined by the following equation. Cylinder flow rate = (stop position-start position) * cylinder piston area / (stop time-start time) If one or more cylinders are moved at the same time, the same calculation is required every time each cylinder is moved. The sum of the flows in the cylinder is added to determine the total fluid flow.

Alternatively, a flow sensor (not shown) may be used to determine the fluid flow entering head end 118 of cylinder 110 and exiting rod end 132 of cylinder 110. Although a flow sensor may be used in the present invention, determining flow in the manner described above provides a more reliable and less expensive approach to determining flow.

In a third block 306, an expected fluid flow is determined. In a preferred embodiment, the expected fluid flow is determined in response to the following relationship: Expected fluid flow rate =
∫ (Rated pump efficiency * (Pump area * Pump speed) dt where Pump speed is measured (eg, by an engine speed sensor. Rated pump efficiency is the rated efficiency,
Pump area is predetermined based on cylinder size

The rated pump efficiency used in the above relationship is a rated efficiency that represents the initial efficiency of the pump before it is used. Ideally, the rated pump efficiency is 100%, ie, when it is manufactured, the pump is 100% efficient. However, new pumps are usually only 95-98% efficient. The pump manufacturer or user may obtain the rated efficiency by creating the pump efficiency map 402 as shown in FIG. Pump efficiency map 402
Represents pump efficiency as a function of flow rate and pump engine speed. Pump efficiency map 402 may be determined empirically as a function of flow rate and pump speed.
The pump speed may be determined by detecting the pump engine speed and multiplying the engine speed by a constant drive ratio. Thus, once the pump flow is determined, the pump speed is detected and the efficiency map 402 may be used to determine the rated pump efficiency. Pump efficiency decreases over the life of the pump. Thus, indicating a pump failure,
The actual flow rate and the expected flow rate may be compared to determine when the pump efficiency drops below an acceptable level. Another expression of the above relationship that describes the expected flow is: expected flow = rated efficiency * pump displacement * engine speed.

In a fourth control block 308, the pump status is determined. In the first embodiment, the pump state may be either a failure or an operation. The pump state may be determined in response to comparing the expected and actual pump flow rates. In the first embodiment, the actual flow rate is divided by the expected flow rate to determine the degradation factor. When the degradation coefficient drops below the operating threshold, it is determined that the pump condition is failing or has failed. For example, the activation threshold may be 90%. That is, if the actual flow rate is less than 90% of the expected flow rate, the pump is failing. If the actual flow is greater than or equal to 90% of the expected flow, the pump state is determined to be operational. Thus, the pump state may be determined based on a comparison between the expected flow rate and the actual flow rate. In another embodiment, the state may include a numerical value corresponding to the pump deterioration coefficient. That is, the actual flow rate is 91% of the expected flow rate
If, the state indicates that the pump is running at 91% of the expected flow rate. Thus, the operator will be informed that the pump can operate, but will need to be repaired in the near future.

In a preferred embodiment, the hydraulic pressure of pump 106 may be incorporated into a determination related to pump status.
In one embodiment, the pump efficiency map 402 is developed based on working fluid pressure. That is, for a given fluid pressure, the flow rate changes and the measured engine speed also changes. Then, all three parameters, pressure, flow rate, and speed, create a pump efficiency map for a particular pressure or pressure range. For example, the performance map may indicate that the rated efficiency is 98% at 3500 Psi with respect to the measured speed and flow rate. In one embodiment, the multiple efficiency map need only be developed in relation to multiple fluid pressures. Once the pump condition is checked, the appropriate rated pump efficiency may be used for the detected fluid pressure.

Therefore, the pressure sensor 128
It just needs to be incorporated in Pressure sensor 128 detects the working fluid pressure and responds to the pressure signal with ECM 116.
Send to The expected pump flow is then calculated by the following equation: Expected pump flow = ∫ (pump area * pump speed) * (rated efficiency)) dt Therefore, in one embodiment, the pressure of the pump determines whether the pressure is within a limited limit with respect to the rated pump efficiency map. To be detected. If multiple maps are used for different pressures, the appropriate map is selected and the corresponding rated pump efficiency is selected for use in the above equation.

In another embodiment, multiple performance maps may be used for different fluid viscosities. Viscosity is obtained by the temperature of the working fluid. Thus, if the operating temperature of the fluid fluctuates, an appropriate map may be used to determine the condition of the pump in view of fluid viscosity, pressure, flow and engine speed.

FIG. 5 is a flowchart of another method of the present invention. The method causes the pump 106 to pump fluid at a high pressure to determine whether the pump has reached that pressure. The method detects pump failure by detecting a decrease in fluid pressure from pump 106. In a first control block 502, the cylinder 110 is moved to an extended position. In a preferred embodiment, the cylinder 11
A 0 is commanded to move beyond one of the maximum extension positions, or end points, or the maximum extension. As mentioned above, in the preferred embodiment, the lift cylinder is commanded to move during the lifting operation.

Next, in a second control block 504, the pump pressure is measured. Pump pressure is at a maximum as cylinder 110 is commanded to move past the end point. This is because the pump attempts to provide fluid flow to the inoperable cylinder 110.

In a third block 506, the pump pressure is compared to the expected pump pressure. The expected pump pressure may be determined by using a pressure look-up table as a function of pump engine speed. The look-up table may be developed empirically. Fourth control block 508
In, the pump state is determined according to a comparison between the actual pump pressure and the expected pump pressure. If the actual pump pressure is not within a specific range of the expected pump pressure, for example, 10%, the pump is determined to be faulty.

The present invention provides a method for detecting a failure of a pump, wherein the pump is connected to a hydraulic circuit having a plurality of cylinders. The method includes commanding to move at least one cylinder, determining an actual flow rate through the commanded cylinder, determining an expected flow rate, and determining a pump condition according to the actual and expected flow rates. And In another embodiment, the actual and expected efficiencies are compared to determine a pump condition. In yet another embodiment, one of the cylinders is commanded to move to a limit position. The fluid pressure may be detected and compared to the expected fluid pressure. The pump state may be determined according to the comparison.

If it is determined that the pump has failed, a controller, such as an electronic control module (ECM), notifies the operator with a built-in or external pump failure indication, such as a warning light. It should just be like. Further, the fault may be categorized for the operator based on the severity of the fault. The operator may be instructed whether to schedule or stop the maintenance of the machine according to the severity of the failure.

The pump failure test of the present invention is either performed automatically when appropriate operating conditions such as temperature, pressure, or the operator initiates the test during a rise correction. It is good if it is. In the automatic mode, the system constantly monitors the operator's blade lift control, lift cylinder position, and, in the preferred embodiment, the hydraulic pump. Once the automatic mode determines the required demand conditions, the necessary data is recorded and analyzed to determine the status of the pump. The operator starts the test by inputting a command sequence using, for example, an alphabet keyboard. The ECM receives the command and starts the test. Alternatively, a button or another commonly used actuation method may be used. Other aspects, objects, and advantages of the present invention are illustrated in the drawings,
It can be obtained from the disclosure and the claims.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of a hydraulic circuit.

FIG. 2 is a view showing a track type tractor.

FIG. 3 is a flowchart illustrating one method of operation of the present invention.

FIG. 4 is a diagram showing a performance curve of a pump.

FIG. 5 is a flowchart illustrating another method of the present invention.

[Sign]

 102 hydraulic circuit 104 pump engine 106 pump 110 cylinder 116 electronic control module 124 engine speed sensor 126 cylinder position sensor

Continued on the front page (72) Inventor Kennis El Stratton Illinois, United States 61525-8453 Dunlap North Hickory Grove Court 616 (72) Inventor Joseph F. Duffy Illinois 61548-9306 Metamora Rural Route 3 Box 22 E

Claims (12)

[Claims] 1. A method for detecting a failure of a pump connected to a hydraulic circuit having at least one cylinder, the method comprising: commanding at least one of the cylinders to move; Determining an actual flow rate flowing through the at least one commanded cylinder; determining an expected flow rate flowing through the at least one commanded cylinder; comparing the actual flow rate with the expected flow rate; and determining a pump state according to the comparison. Judgment is a method consisting of steps. 2. The step of determining an actual pump flow rate comprises: determining a start time of the command; determining a first position of the cylinder at the start time; determining an end time of the command; Determining the second position of the cylinder; determining the actual flow rate in response to the start time, the end time, the first position, and the second position; and determining the pump state. The method of claim 1, wherein the step comprises determining a pump failure in response to the actual flow rate being less than the operating threshold of the expected flow rate. Determining the expected flow rate; determining a pump speed; determining a pump pressure; determining a temperature of the fluid; determining a viscosity of the fluid in response to the temperature; The method of claim 1, comprising determining the expected flow rate in response to pressure and the viscosity. 4. The step of determining the expected flow rate includes determining a pressure of the working fluid, comparing the pressure with a desired rated pressure, and responsive to the pressure being within the rated pressure range. 4. The method according to claim 3, wherein the expected fluid flow rate is determined. 5. The step of determining an expected flow rate comprising: determining that a rise correction is commanded; and in response to the rise correction and the pump pressure being within the pressure range, the fluid flow rate being determined. 5. The method according to claim 4, comprising the step of: 6. The step of determining the flow rate of fluid flowing through the cylinder includes determining that the hydraulic valve is fully open, and determining the fluid flow rate in response to the hydraulic valve being fully open. 6. The method according to claim 5, comprising the steps of: 7. The method of claim 1, wherein commanding at least one cylinder comprises commanding the at least one cylinder with means for performing a lift correction.
The method described in. 8. A method for detecting a failure of a pump connected to a hydraulic circuit having a plurality of cylinders, the method comprising: commanding one of the cylinders to move; determining an actual efficiency of the pump; Determining the expected efficiency of the pump, comparing the actual and desired efficiencies, and determining the pump condition in response to the comparison. 9. A method for detecting a failure of a pump connected to a hydraulic circuit having at least one cylinder, the method comprising: commanding at least one of the cylinders to move; Commanding the fluid to be pumped up by pressure, determining the pump engine speed, determining the pump flow rate, detecting the actual maximum pump pressure, comparing the actual pump pressure with the expected maximum pump pressure, Determining the pump failure in response to the flow rate and the comparison. 10. The step of determining a pump failure includes: determining a maximum cylinder end position; and determining the pump speed and the pump flow rate in response to the cylinder being located at the maximum position. 10. The method of claim 9, wherein the method comprises: 11. A device for detecting a failure of a pump connected to a pump engine and a hydraulic circuit having at least one cylinder, the device detecting a position of the cylinder, and in response thereto, a cylinder position signal. A cylinder position detecting device that transmits the engine speed, an engine speed detecting device that detects the speed of the engine and emits an engine speed signal in response thereto, the cylinder position signal and the engine Receiving a speed signal and determining an actual fluid flow rate in response to the cylinder position signal; determining an expected fluid flow rate in response to the engine speed signal and rated pump efficiency and pump area; A controller adapted to determine a pump condition in response to the flow rate. 12. A pressure sensor adapted to detect an actual fluid pressure and generate a pressure signal in response thereto, and detect a temperature of the actual fluid and emit a temperature signal in response thereto. A temperature sensor adapted to receive the pressure signal and the temperature signal, the cylinder position signal and the engine speed signal, and in response to the actual and expected flow rates. 12. The apparatus according to claim 11, wherein the apparatus is adapted to determine.