WO2006084468A1

WO2006084468A1 - Device and method for determination of parameters of a hydraulic motor

Info

Publication number: WO2006084468A1
Application number: PCT/DK2006/000074
Authority: WO
Inventors: Kim René HANSEN
Original assignee: Sauer-Danfoss Aps
Priority date: 2005-02-10
Filing date: 2006-02-09
Publication date: 2006-08-17
Also published as: DE102005005940A1; DE102005005940B4

Abstract

The invention relates to a device and a method for determination of parameters of a hydraulic motor (1), said hydraulic motor (1) having pressure chambers (5 - 11, 18) with pressures changing over time and the device comprises sensors (15, 16, 17, 25) and an analytical device (19). Hydraulic motor parameters are desired using as few sensor types as possible. The above is achieved, whereby at least three pressure sensors (15, 16, 17) are arranged in at least three different pressure chambers (5, 6, 18) of the hydraulic motor (1 ).

Description

Apparatus and method for determining parameters of a hydraulic machine

The invention relates to a device and a method for determining parameters of a hydraulic machine, wherein the hydraulic machine has time-varying pressures in pressure chambers and the device comprises sensors and an evaluation device.

Hydromachines are motors or generators that use a fluid as a hydraulic pressure medium, such as oil. There are a variety of sensors that are used in such hydraulic machines to measure actual values of the machine during operation. This makes it possible to monitor the machine and, if necessary, intervene in the control.

In US 4,679,488 a pressure sensor is described which is installed in a hydraulic motor and consists of plates stacked on top of each other, which are arranged between a rotor and an end plate of the motor. A deformation measuring plate, a channel plate and a pressure plate are stacked one above the other so that all existing pressure chambers of the hydraulic motor act on the deformation measuring plate. Through channels within the pressure plate pressure fluid from at least two pressure chambers enters the channel plate and forms there a pressure which then acts on a membrane in the Deformationsmeßplatte. From this pressure, the torque, the speed and also the rotational displacement of the hydraulic motor can be determined. To the pressure sensors other sensors, such as pressure difference sensors, speed sensors, acceleration sensors and temperature sensors are used. The large number of sensor types makes uniform handling of the sensors difficult. The different sensors have, for example, different geometric dimensions, different electrical signal outputs, a different temperature behavior and the like. For this reason, one would like to use as few different types of sensors as possible.

The invention has for its object to provide parameters to hydraulic machines available with as few different types of sensors.

This object is achieved in a hydraulic machine of the type mentioned above in that at least three pressure sensors are arranged in at least three different pressure chambers of the hydraulic machine.

With three existing pressure sensors in three different pressure chambers, it is possible to carry out two independent differential pressure measurements simultaneously. In this case, a sensor is used both as Referenzmeßstelle for the first pressure measurement and for the second pressure measurement. Thus, two differential pressure sensors are replaced by three relative pressure or absolute pressure sensors. Such measurements are useful, for example, to monitor pressure losses inside the machine. When using three pressure sensors, it is also possible to reliably determine the direction of rotation of the hydraulic machine. A direction of rotation sensor is no longer necessary for this purpose. If, for example, the three pressure sensors are arranged in a rotating hydraulic machine with at least one gear set in three different pressure chambers which expand and contract in time, then

Direction of rotation can be recognized by two sensors. It is only here necessary that the sensors deliver measured values at time intervals of half the rotation frequency of the machine. With the third pressure sensor, some redundancy can be exploited to make pressure measurements more reliable. It is envisaged that the sensors are connected to the evaluation device. This can take place via fluid lines, via a cable connection in the case of electrical or optical signals or via a radio connection in the case of line-bound signals. The connection to the evaluation device depends on which signal types the sensors supply. There may also be a mixed form of transmission of the signals from the sensors to the evaluation device. This is the case, for example, when some sensors emit electrical signals, for example temperature sensors, while other sensors, for example pressure sensors, supply hydraulic pressures via fluid connections to the evaluation device.

It is particularly preferred that at least two pressure sensors are each arranged in a pressure chamber whose volume changes over time, and at least one pressure sensor is arranged in a pressure chamber whose volume is constant over time. A pressure chamber whose volume changes over time is, for example, an expanding or contracting pressure chamber in a rotary hydraulic machine between a gear rotor and a ring gear stator. In reciprocating engines, this is the space between moving pistons and fixed boundary walls of a piston chamber. Constant volume pressure chambers are often those that are routed out to the hydraulic machine. These are, for example, connection channels. The connection channels can lead, for example, to a pump or a tank. In the first case is a pressure inlet channel and in the second case to a pressure outlet channel. There are also other connection channels in question, for example, lead to a valve or to another hydraulic machine. In such an arrangement of at least two pressure sensors -A-

in each case in a pressure chamber, which has a time-variable volume, and a pressure sensor in a pressure chamber with constant time volume, it is possible to determine the quadrant, in which the hydraulic machine is currently operated. A quadrant is characterized in that one obtains information as to whether the hydraulic machine is operated as a generator or as a motor, while at the same time the direction of rotation of the machine is detected. The direction of rotation is determined by comparing the measured values of two pressure sensors installed in each time-varying pressure chamber. If the measured value of the first pressure sensor changes in time before the measured value of the second pressure sensor, then, for example, a clockwise rotation is present as the direction of rotation. On the other hand, if the measured value of the second pressure sensor changes before the measured value of the first pressure sensor, then the hydraulic machine operates in the counterclockwise direction. To determine the quadrant then the measured value of the installed third pressure sensor in a pressure chamber is used with constant time volume. This measured value provides, for example, a high measured value or a low measured value, depending on the operating state of the pressure chamber in which the pressure sensor is installed, for example in a connection channel. From all three measured values of the first, second and third pressure sensor, the currently existing operating mode of the hydraulic machine can be determined as a quadrant. From the three pressure values of the three installed pressure sensors thus differential pressures, the speed, the direction of rotation and the quadrant can be determined. Furthermore, it is possible to determine from the parameters an accumulated damage of the cardan shaft and damage of other parts, eg the output shaft, in order to be able to obtain statements about the still expected service life. By means of re-adjustments, ie reversals of rotation, the remaining service life of the machine can be determined particularly well. It is preferred that at least one pressure sensor is arranged in at least one expanding pressure chamber at the same time and at least one pressure sensor is arranged in at least one contracting pressure chamber. In a rotary hydromachine, there is an axis that separates expanding and contracting pressure chambers. The expanding and contracting pressure chambers change in time during the rotation of a toothed ring, so that the axis also rotates. It is provided that at least one pressure sensor is arranged in one of the pressure chambers and at least one pressure sensor is arranged in one of the other pressure chambers, wherein the pressure chambers are separated from each other by the axis. The pressure sensors are arranged stationary in the pressure chambers. The measured values of the pressure sensors differ most clearly when they are recorded in pressure chambers, which are arranged offset in the circumferential direction by 180 ° from each other. This is easily possible if an even number of pressure sensors are arranged in different pressure chambers whose volume changes over time. With three pressure sensors in three different volume variable pressure chambers, the pressure sensors can be evenly distributed around the circumference, so that they are arranged at a distance of 120 °.

Preferably, at least two pressure sensors are arranged in adjacent pressure chambers at the same time. This arrangement of two adjacent pressure sensors in each one pressure chamber has particular advantages in measuring the direction of rotation of the machine. Although it can happen that the two pressure sensors measure the same pressure value for a short time. However, this does not disturb the determination of the direction of rotation.

Preferably, pressure sensors from outside the hydraulic machine from the pressure chambers can be fed. From outside supplied pressure sensors have the advantage that a disassembly of the hydraulic machine is not necessary is to install the pressure sensors inside the hydraulic machine. This is also applicable to sensors such as temperature and viscosity sensors. It is also easily possible to temporarily attach the evaluation device with the sensors for a state analysis on the hydraulic machine and then remove it again. Such diagnostic purposes extend the scope of the device according to the invention. It is also possible that a defective sensor can be replaced within a short time.

Preferably, pressure sensors from one side of the hydraulic machine from the pressure chambers can be fed. In this way, the assembly of the device according to the invention is facilitated. This can also be provided for other sensors, such as temperature sensors. Also, a connection geometry of the device according to the invention is conceivable, which has the same or similar dimensions for all hydraulic machines. The device according to the invention can then be attached, for example, as a measuring unit at the end of the hydraulic machine.

It is advantageous if pressure sensors have an external thread. With an external thread, a pressure sensor can be screwed into a designated threaded hole. If the pressure sensor in, for example, a pressure chamber is no longer needed, the threaded hole can then very easily be closed again, for example with a threaded pin. The same applies to other sensors, such as temperature sensors. If irregularities occur in the hydromachine, the corresponding sensor can be quickly and easily screwed into the prepared threaded hole. It can thus be made available a diagnostic option, without causing the hydraulic part of the hydraulic machine must be disassembled. It is preferred that electrical output signals are present at the pressure sensors. Electrical output signals can be caused by either directly on the pressure sensor, the mechanically measured hydraulic pressure is converted into an electrical signal or that the pressure sensor, a converter is connected downstream, which converts the measured hydraulic pressure into a corresponding electrical signal. The electrical output signals of the pressure sensors can then be used as measured values. It is advantageous that the electrical measured values can be further processed in a simple manner. 0

Preferably, the evaluation device has a computing unit. The recorded measured values can be further processed with a computer. For example, differential pressures can be formed in a hydraulic processing unit. With an electronic control unit, for example with a microprocessor, all conceivable arithmetic operations can be carried out. Frequent applications here are differences and multiplications.

Practically, the evaluation device has a data memory. o With a data memory, measured values can be stored continuously over time, which are then stored as a measured value table. The storage can take place continuously without interruption. Under continuous but also a series of measurements is understood that stores at certain time intervals with a time interruption a reading, z. B. once per hour 5 de. It is also conceivable then to store a measured value when the

Operating state of the machine changes, for example, when the load increases during a motor operation of the hydraulic machine or the speed changes. The measured value tables can be accessed at a later time, in order, for example, to obtain further parameters therefrom. Recorded data in a data store can also be used to analyze an error that has occurred in retrospect become. It can then be retrieved various operating conditions again. Therefore, it is also useful if the data memory also assigns a date and a time to the stored measured value. It is also possible to store calculated results from measured values in the data memory. It is also possible to store a mathematical function whose parameters are determined by the recorded measured values. Also, then, for example, the mechanical efficiency can be determined.

It is preferred that the device has a display surface. A display surface directly on or in the device according to the invention has the advantage that no further devices are needed to display or query measured values. The display surface can also be arranged directly on the evaluation device. The display surface may be formed so that the device according to the invention can be operated by touching the display surface. It is also possible to access different software menus by operating the display area, for example to start diagnostic examinations. This is easily possible with electronic displays.

The device expediently has a data interface. Data or programs can be read out via a data interface. This is necessary, for example, if there is no storage capacity available for an existing data store. Also, data or programs can be transferred from an external device to the device. Via the interface peripheral devices can be connected, such as computers, cell phones, radio receivers, printers, external hard drives or the like. In this case, the interface can work electronically via a cable or can also be designed as a radio interface. The object is achieved in a method of the type mentioned in that pressure values are measured in at least three different pressure chambers of the hydraulic machine at the same time.

From three pressure values, the speed, at least one differential pressure, the direction of rotation and the quadrant of the hydraulic machine can be determined. From this it is also possible to calculate an accumulated damage to the cardan and output shaft and gear sets of a rotary hydraulic machine. Due to the present invention, it is now easier to calculate the accumulated damage on a gear set than on the gimbal and output shafts. This is possible because the accumulated damage is defined solely by pressure and speed and not by reversing. To determine the accumulated damage, a seal of the hydraulic machine can also be used. If the pressure on the seal is known and this pressure is compared with the speed of the hydromachine, then it can also be determined where the pressure is applied to the seal. The method makes it possible to record additional parameters from the measured values, for example to deduce the service life of the hydraulic machine.

It is particularly preferred that at least two pressure values are measured in each case in a pressure chamber whose volume changes over time and at least one pressure value is measured in a pressure chamber whose volume is constant over time. In this variant, it is particularly easy to also determine the quadrant of the operated hydraulic machine. Since the volume-variable pressure chambers of a hydraulic machine are often less accessible than the pressure chambers with a constant volume, it is advantageous that at least one pressure chamber is easily accessible. Thus, for example, a pressure value is measured in at least one connecting channel. Measuring in a connection channel, that is in an inlet channel or in an outlet channel is particularly simple, since this through the connected pump or the connected tank is more easily accessible than the pressure chambers in the interior of the hydraulic machine.

It is preferred that at least one pressure value in an expanding pressure space and at least one pressure value in a contracting pressure space be measured. An expanding pressure chamber is connected, for example, to a pressure port, while a contracting pressure chamber is connected, for example, to a tank port. If a stationary pressure sensor is used to measure at an instant in an expanding pressure chamber, the measured value changes during operation of the hydraulic machine, since the expanding pressure chamber becomes a contracting pressure chamber. If one determines the pressure changes over a certain period of time, one can decide whether a pressure space is expanding or contracting. If a pressure sensor in an expanding pressure chamber and a pressure sensor are arranged simultaneously in a contracting pressure chamber, these pressure sensors deliver significantly different measured values at all times. This makes the measuring device less susceptible to interference and thus contributes to an increase in the measured value accuracy.

It is particularly preferred that measured values are recorded continuously in time. The continuous recording of measured values has the advantage that the occurrence of a fault in the interior of the hydromachine due to irregularities in the series of measurements is immediately recognized or even predictable on the basis of known comparative measured values. The continuity of the recording also has the advantage that all irregularities can be detected and analyzed.

The measured values of the sensors are preferably calculated together. The measured values of the pressure sensors can be present as hydraulic pressures or as electrical signals in order to be offset with one another become. If these pressure measurement values are to be offset against other measured values of other sensors, then it is expedient that either the calculated hydraulic pressures or directly electrical signals of the pressure sensors be present as electrical output signals. In this way, it is easily possible, for. B. to calculate measured values of temperature sensors for a temperature compensation with the other measured values. An evaluation device which operates with electrical signals can also be made very small and compact. It makes sense that measured values recorded at the same time be offset with one another in order to keep 0 measurement errors small. This is for example advantageous if one carries out a temperature compensation. It is also expedient if pressure differences are formed from pressure readings taken at the same time. From a pressure difference, for example, the direction of rotation of the hydraulic machine can be calculated. Also can be 5 determine a differential measurement of the pressure drop in the hydraulic machine. To determine the delivered torque of a hydraulic machine in engine operation, it is necessary to know a pressure difference and the speed of the engine. These measured values are obtained from the pressure measurements. Thereafter, a product of the pressure difference, the displacement and the mechanical efficiency is formed, wherein the mechanical efficiency is a function of the pressure difference and the speed.

Practically, readings are stored. Saving 5 measured values is useful when measuring values are calculated together to determine a parameter of the machine. The mechanical efficiency of the hydraulic machine as a function of pressure and speed can be determined, for example, during a development stage of the hydraulic machine with the aid of pressure, speed and torque measurements. These measured values are stored in a memory for this purpose. From the values of the pressure measurement and the speed measurement Then a stored value in the memory can be called up to determine the associated mechanical efficiency. Stored measured values or calculated parameters can also be used if the state of the hydraulic machine is to be monitored in order to derive forecasts for the future, if necessary. In the method according to the invention that means that in a data memory, the pressure difference and the speed are stored and then the corresponding mechanical efficiency is read from a stored table. Thereafter, all three factors are multiplied together. The product of this multiplication is the applied torque, which can be used for control, regulation and monitoring. The output torque can for example be displayed on a display unit or other facilities available. The knowledge of the mechanical efficiency is a prerequisite for calculating the torque or the power for any operating state of the hydraulic machine. The mechanical efficiency is calculated from the measured variables flux and pressure. If the mechanical efficiency is graphically represented, three-dimensional diagrams result, which are referred to as Q, p-shell diagrams with the parameters pressure p and flow Q. The mechanical efficiency can be obtained from an averaged Q, p shell diagram by subtracting the pressure losses that occur in the gear sets and the port channels and then subtracting the values into a n, p shell diagram with the parameters speed n and pressure p converts. The surface of the three-dimensional Q, p-shell diagram with the three axes pressure, flux and mechanical efficiency is described as a polynomial. This polynomial can then be used instead of a stored data table to determine parameters of the hydraulic machine. This improves the accuracy of the calculations. An electrical multiplication of displacement, mechanical efficiency and speed makes it possible to deduce the output power of an engine. Will then one more Multiplication over time will give you the total output power that can also be used to control, regulate and monitor.

It is preferred that readings be displayed on the device. This facilitates the monitoring of the hydraulic machine and gives an overview of a current or a past operating state of the hydraulic machine. You can also view alerts and health diagnostics that can be useful to a user in troubleshooting and maintenance.

Preferably, data is exchanged over a data interface. The data exchange via an interface makes it possible to analyze acquired measured values at a different location by reading measured values or data tables in real time or from a data memory. It is also easily possible to transmit programs or data via the data interface to the device. This can be a wired or a wireless transmission. This is expedient if the device is used for diagnostic purposes or is used in the development stage of a hydraulic machine. It is also conceivable to carry out remote queries via such a data interface without a person being directly at the machine.

The invention will be described below with reference to a preferred embodiment in conjunction with the drawings. Herein show:

Fig. 1 is a schematic representation of three sensors in three different pressure chambers of a hydraulic machine and

Fig. 2 is a schematic representation of the device according to the invention, which is mounted on a hydraulic machine. Fig. 1 shows a hydraulic machine in the embodiment of a hydraulic motor 1, for example an orbital motor OMEW type Sauer Sauer Danfoss ApS, Nordborg, Denmark, with a Zahnradstator 2 and a gear rotor 3. The gear rotor 3 performs with a propeller shaft 4 together orbital motion , so that pressure chambers 5 - 11 increase or decrease. During a rotational movement of the propeller shaft 4 and the gear rotor 3 in the direction of an arrow 12, the pressure chambers 9 - 11 enlarge and are expanding pressure chambers, while the pressure chambers 6 - 8 become smaller and thus contracting

Pressure chambers are. The gear wheel rotor 3 moves relative to pins 13 and thus forms the time-volume variable pressure chambers 5 - 11. In the pressure chambers 5 and 6 are each a first and a second pressure sensor 15, 16 are arranged. A third pressure sensor 17 is arranged in a pressure chamber 18. The pressure chamber 18 forms an outlet channel of the hydraulic motor 1. The three pressure sensors 15-17 are connected to an evaluation device 19, which together form a measuring device 20. The evaluation device 19 has a data memory, a computing unit and an interface. The stored data can be called up on a display area.

Fig. 2 shows a side view of the hydraulic motor 1 in section, wherein like components are provided with the same reference numerals. In the end region of the hydraulic motor 1 on a channel plate 21, the evaluation device 19 is mounted. The pressure sensors 15-17, not shown in FIG. 2, lead from there through bores 22-24 into the individual pressure chambers 5, 6 and 18. In the case of several gear sets, further bores may be provided which lead into pressure chambers of the other gear sets. It is not necessary that all pressure chambers of the hydraulic machine 1 are accessible to sensors. It is sufficient if at least three pressure sensors 15 -

17 in three different pressure chambers 5, 6, 18 can be attached NEN. If a temperature compensation is to be carried out, at least one temperature sensor 25 is still required. The three pressure sensors 15 - 17 are used to determine differential pressures, direction of rotation, speed, quadrant, displacement, mechanical efficiency, torque output and accumulated damage to propshaft and gear sets. With the temperature sensor 25 can be made a temperature compensation with continuously measured temperature actual values.

The evaluation device 19 in Fig. 2 is removable, so that the sensors 15 - 17, 25 can be removed, for example in the event of a sensor defect or when they are no longer needed. With removed evaluation device 19 and removed sensors 15-17, 25, the holes 22 - 24 can be closed with an adapter or a closure piece. If necessary, these holes are then easily and quickly accessible again. In the holes 22 - 24, however, there is the same pressure as in the Druckmeßräumen 5, 6, 18, so that the closure of the holes with or without the existing sensors 15 - 17, 25 must be secured against detachment. In the present hydromotor 1, therefore, there is in each case a thread in the bores 22 - 24, which corresponds with a thread on the sensors 15 - 17, 25, so that they can be screwed into the bores 22 - 24 and thus secure Have a stop during operation. The same can also be provided for closure elements of the bore, which can be screwed into the bore with a corresponding thread. In addition, seals may be provided which seal the bores 22-24 in all operating states with or without mounted sensors 15-17.

The applications of the presented device are diverse. It can both during continuous operation of the hydraulic machine 1 for monitoring, Control, regulations and diagnostics are used, as well as used for a short-term analysis, for example, after an error occurred. The measuring device 20 can also be used to evaluate a prototype of a hydraulic machine 1 for a particular application. In this case, for example, a cyclic data acquisition is performed on the prototype. The measurement data acquired by the device can then be analyzed, for example by the so-called rain-flow method standardized in ASTM Standard E1049. From this analysis it can then be concluded whether the hydromachine 1 is suitable for the tested applications. An optimization of the hydraulic machine 1 can be achieved and thus over- or undersizing of the hydraulic machine 1 can be avoided.

Claims

claims

1. A device for determining parameters of a hydraulic machine, wherein the hydraulic machine has time-varying pressures in pressure chambers and the device comprises sensors and an evaluation device, characterized in that at least three pressure sensors (15, 16, 17) in at least three different pressure chambers (5 , 6, 18) of the hydraulic machine (1) are arranged.

2. Apparatus according to claim 1, characterized in that at least two pressure sensors (15, 16) in each case a pressure chamber (5 - 11) are arranged, the volume of which changes over time, and at least one pressure sensor (17) in a pressure chamber (18) is arranged, whose volume is constant over time.

3. Apparatus according to claim 1 or 2, characterized in that at least one pressure sensor (15 - 17) in at least one NEM expanding pressure chamber (5-11) is arranged at the same time and at least one pressure sensor (15 - 17) in at least one contracting Pressure chamber (5 - 11) is arranged.

4. Device according to one of claims 1 to 3, characterized 5 records that simultaneously at least two pressure sensors (15 - 17) in mutually adjacent pressure chambers (5 - 11) are arranged.

5. Device according to one of claims 1 to 4, characterized in that pressure sensors (15 - 17) from outside the hydro- o machine (1) from the pressure chambers (5 - 11) can be fed.

6. Device according to one of claims 1 to 5, characterized in that pressure sensors (15 - 17) from one side of the hydraulic machine from the pressure chambers (5 - 11) can be fed.

7. Device according to one of claims 1 to 6, characterized in that pressure sensors (15 - 17) have an external thread.

8. Device according to one of claims 1 to 7, characterized in that electrical output signals to the pressure sensors

(15, 16, 17) are present.

9. Device according to one of claims 1 to 8, characterized in that the evaluation device (19) has a computing unit.

10. Device according to one of claims 1 to 9, characterized in that the evaluation device (19) has a data memory.

11. Device according to one of claims 1 to 10, characterized in that the device (20) has a display surface.

12. Device according to one of claims 1 to 11, characterized in that the device (20) has a data interface.

13. A method for determining parameters of a hydraulic machine by recording measured values and their evaluation, in particular using the device having the features according to one of claims 1 to 12, characterized in that Pressure values are measured in at least three different pressure chambers of the hydraulic machine at the same time.

14. The method according to claim 13, characterized in that at least two pressure values are measured in each case in a pressure chamber whose volume changes over time, and at least one pressure value is measured in a pressure chamber whose volume is constant in time.

0 15. The method according to any one of claims 13 or 14, characterized in that at least one pressure value in an expanding pressure chamber and at least one pressure value in a contracting pressure chamber is measured.

5 16. The method according to any one of claims 13 to 15, characterized in that measured values are recorded continuously in time.

17. The method according to any one of claims 13 to 16, characterized marked o records that the measured values of the sensors are offset against each other.

18. The method according to any one of claims 13 to 17, characterized in that measured values are stored. 5

19. The method according to any one of claims 13 to 18, characterized in that measured values are displayed on the device.

20. The method according to any one of claims 13 to 19, characterized marked 0 records that data is exchanged via a data interface.