EP2369172B1 - Fluid rotation machine with a sensor assembly - Google Patents

Description

The invention relates to a fluid rotary machine having a housing, a shaft guided out of the housing and a sensor arrangement which has a sensor which is operatively connected to the shaft and a receiver, the sensor arrangement having a receiving area in which the sensor is arranged is, and the receiving area is in fluid communication with the interior of the housing and is sealed to the outside.

Such a fluid rotation machine is out DE 195 47 537 C1 known. A pulse generator is incorporated in a rotor gear. A sensor is incorporated in a cover covering the rotor gear.

EP 0 622 547 A1 shows a speed detector for a scroll type fluid machine. Here's a pickup in a housing wall is used and interacts with the pins, which move past the speed sensor during one revolution of rotating parts.

WO 02/060734 A1 shows a unit for an electronically controlled brake system. Here a shaft is provided with an encoder that is operatively connected to the shaft. The transmitter is arranged in a receiving area which is in fluid communication with the interior of a housing and is sealed off from the outside. The sensor arrangement furthermore has a receiver which is arranged outside the housing and the receiving area.

EP 0 280 892 A2 describes a vacuum pump with a device for speed measurement. Here, a rotating element is attached to a stump of a shaft, which acts as an encoder, which is accordingly in operative connection with the shaft. A receiver is also provided. The sensor arrangement formed by the transmitter and receiver has a receiving area in which the transmitter is arranged, the receiving area being in fluid communication with the interior of the housing and being sealed off from the outside. However, the receiver is arranged within the housing and delimited by a wall in relation to the receiving area, so that it can be assumed that the receiver is arranged outside the receiving area.

Another machine is out US 6,539,710 B2 known. The first section has an externally toothed gear that interacts with an internally toothed ring. Pressure pockets are formed between the gearwheel and the toothed ring, each of which supplies pressure fluid via a rotating valve slide arrangement or with a low-pressure region get connected. The gear is connected to the shaft via a cardan shaft. The gear meshes with a crank pin, which transmits the orbiting movement of the gear wheel to a sensor shaft.

US 4,593,555 describes a hydraulic motor in which a pressure sensor is used to determine the rotational speed of the shaft.

US 6 062 123 describes an assisted steering device with a motor and a sensor that scans a position of a steering handwheel shaft. The sensor is arranged radially to the axis of the steering wheel shaft.

DE 198 24 926 C2 describes a further hydraulic steering device, in which an inner control slide is provided on its end face with a row of teeth which can be scanned by a sensor.

DE 10 2005 036 483 B4 describes a hydraulic rotary machine, the shaft of which is provided with a sensor which has a tooth structure made of teeth and grooves on its outer circumference. A transmitter is arranged in the housing and directs a light beam onto the thread structure. The light beam is reflected from the thread structure to a receiver.

In many areas of application of such machines, in particular in hydraulic rotary machines, sensors are required in order to be able to control the machine with sufficient accuracy, for example in connection with an associated diesel engine to save energy.

The sensor arrangements in the machines mentioned at the outset have proven themselves in principle. However, they often require a relatively complicated installation of the sensor. The sensor is then often in a position where it basically interferes. If the sensor is arranged in a position where it is less disturbing, there is the problem that it cannot determine the rotation of the shaft directly, but is connected to the shaft via several engagement points with play. A similar problem arises when the shaft can twist, for example at high torques within the motion train.

The invention is based on the object of advantageously arranging the sensor arrangement on the fluid rotation machine.

This object is achieved in a fluid rotary machine of the type mentioned at the outset, which has the features of claim 1.

It is advantageously used in such a configuration that the receiving area seals the inside of the machine from the outside, so that no opening is required in the sensor arrangement, through which a moving element is guided and which then has to be sealed. If you can save a seal between moving parts, this increases operational reliability. The wear remains small and the susceptibility to errors decreases. If the sensor arrangement is coupled, for example, to a hydraulic machine, then hydraulic fluid can penetrate into the receiving area and then simultaneously lubricate the contact surfaces of the transmitter with the housing or another element. This in turn means that the encoder can rotate practically freely, so that an extremely small moment is required to turn the encoder. This in turn keeps the twist of the transmission element very small when using a transmission element. A particularly simple embodiment is to arrange the receiving area within the housing. The receiving area can be designed as a receiving space.

The receiving area is preferably formed in an end cover of the fluid rotary machine. Such a structure is particularly compact. The receiving area can be designed, for example, as a bore or as an indentation in the end cover. There will be no through hole. Otherwise the tightness would no longer be guaranteed. Here too, the sensor arrangement does not require an opening through which a moving element is guided. You can make the front cover or other parts of the housing from stainless steel. A Interaction between transmitter and receiver is not disturbed if the interaction is caused by a magnetic field.

The transmitter preferably has a carrier element which cooperates with the front cover with little friction. No liquid or a fluid that has a lubricating effect is then required in the receiving area. The sensor arrangement can also be used in this way due to the low-friction interaction of the end cover and the carrier element.

The sensor arrangement has a sensor housing in which the receiving area is arranged. In this embodiment, it is the sensor housing that seals the inside of the machine from the outside. In this case too, no opening for a moving element that would have to be sealed is required in the sensor arrangement. The sensor housing can be manufactured as a separate component. On the one hand, this simplifies production. On the other hand, the sensor housing can be particularly well adapted to the needs of the sensor arrangement, in particular those of the sensor.

The encoder has a carrier element that interacts with the sensor housing with low friction. In this case, the sensor arrangement can also be used if a liquid or a fluid which penetrates into the receiving area has no lubricating effect per se, as is the case, for example, in water-hydraulic machines.

The sensor housing is preferably screwed into an end cover of the fluid rotary machine. For this purpose, the sensor housing has, for example, an external thread which is in engagement with a corresponding internal thread in the end cover. This simplifies the manufacture of the sensor housing and the assembly of the sensor arrangement on the machine. In addition, with this configuration, it is relatively simple to seal the receiving area from the outside. All you have to do is place a seal between the sensor housing and the front cover and screw the sensor housing into the front cover with sufficient force.

The receiver is preferably clipped onto the sensor housing. So you connect the receiver to the sensor housing with a detachable connection that can be established and released relatively quickly. This has the advantage that the fluid rotary machine can be provided with different types of sensor arrangements relatively easily by exchanging the receiver. Repairs are also simplified. In the case of a sensor arrangement, the receiver is usually the most error-prone part.

The transmitter preferably has a magnet. The magnet generates the magnetic field, which can also be measured on the receiver. The magnetic field only has to be a few millitesla. If the magnet itself is moved due to a movement of the encoder caused by the shaft, this causes a change in the magnetic field at the place of the recipient. It is also possible for several magnets to be arranged on the transmitter. Due to the varying magnetic field, the receiver can then draw conclusions about the movement of the encoder and thus the shaft. If the encoder has a magnet, the sensor housing should ideally be made of a material that is non-magnetic, so that the magnetic field is present undisturbed on the receiver.

The receiver preferably has a magnetoresistive or a Hall sensor element. A magnetoresistive element changes its electrical resistance when an external magnetic field is applied. This can then be read out. A Hall sensor element, when a current flows through it, provides an output voltage that is proportional to a vertical component of the magnetic field and the current. This means that even with a magnet that is not moving, a current can always be read out, in contrast to a coil magnet arrangement.

The transmitter and receiver are preferably elements of a Hall, rotation, tacho generator or optical sensor. With all these sensors, the rotating movement of the shaft, which is in operative connection with the encoder, can be detected. In the case of the Hall sensor, the transmitter has a magnet and the receiver has a Hall sensor. The tacho generator supplies a voltage proportional to the speed. In the case of the optical sensor, an LED can scan the encoder through a transparent sensor housing.

The sensor arrangement preferably has an output element for outputting a square-wave signal. However, the output element can also output an analog current signal, which varies in particular between 2 milliamperes and 20 milliamperes. Alternatively, an analog voltage signal can be output, which typically varies between 0.1 volts and 0.9 volts. However, a square wave signal has the advantage that it is less sensitive to noise. For example, a TTL signal can be selected as the square signal.

The sensor arrangement preferably has a memory in which at least two values can be stored. The storage of two values in the memory can be used in particular to determine a direction of rotation of the shaft. For example, one can first normalize two values stored at different times and then calculate a rotational speed from them, taking into account the transition from 360 ° to 0 °.

Fig. 1

einen hydraulischen Motor als Beispiel für eine Fluid-Rotationsmaschine,

Fig. 2

eine zweite Ausführungsform eines hydraulischen Motors,

Fig. 3

eine dritte Ausführungsform eines hydraulischen Motors,

Fig. 4

eine vierte Ausführungsform eines hydraulischen Motors,

Fig. 5

Darstellungen eines Ausgabesignals einer Sensoranordnung und

Fig. 6

eine schematische Darstellung der FluidRotationsmaschine mit einem Ausgabeelement und einem Speicher.

The invention is described below on the basis of preferred exemplary embodiments in conjunction with the drawing. Show here:

Fig. 1

a hydraulic motor as an example of a fluid rotation machine,

Fig. 2

a second embodiment of a hydraulic motor,

Fig. 3

a third embodiment of a hydraulic motor,

Fig. 4

a fourth embodiment of a hydraulic motor,

Fig. 5

Representations of an output signal of a sensor arrangement and

Fig. 6

is a schematic representation of the FluidRotationsmaschine with an output element and a memory.

The invention is explained below using a hydraulic motor as an example of a fluid rotation machine. However, it is not limited to hydraulic motors.

An in Fig. 1 The hydraulic motor 1 shown has a housing 2 from which a shaft 3 is led out. A mechanical power can be taken from the shaft 3.

The shaft 3 is rotatable about an axis 4. It forms the part of a movement train which, in addition to the shaft 3, has a cardan shaft 5 and an externally toothed gear 6 which is arranged in an internally toothed toothed ring 7 and forms pressure pockets with the toothed ring 7 in a manner known per se, which, depending on them Position can be supplied with hydraulic fluid under pressure or hydraulic fluid to a low pressure connection can fire. To control the fluid supply of these pressure pockets, a schematically illustrated control slide 8 is provided, which is connected to the shaft 3.

The motion train thus has a first section with the gear 6, which orbits around the axis 4. Furthermore, the movement strand in the area of the shaft 3 has a second section which rotates about the axis 4.

The housing 2 is closed on the side opposite the shaft by an end cover 9. A sensor arrangement 10 is arranged on the outside of the end cover 9. However, the sensor arrangement 10 can also be arranged at least partially in the housing 2 or in the end cover 9. With the sensor arrangement 10, the rotation of the shaft 3 should be detected as precisely as possible.

The sensor arrangement 10 can have a sensor housing 11 which surrounds a receiving region in which a transmitter 12 is arranged. The receiving area can be designed as a receiving space. The transmitter 12 has a carrier element 13, which is formed from a material that interacts with the material of the sensor housing 11 with low friction. One or more transmitter elements are arranged on the carrier element. In the present exemplary embodiment, the transmitter elements 14 are designed as magnets 29 or as permanent magnets. A receiver 15 is arranged on the outside of the sensor housing 11 and passes through the magnetic field of the transmitter elements 14 is acted upon and pass on via a line (not shown in detail) or electrical signals without lines, which contain the information about the rotational movement of the shaft 3, and a control (not shown in detail).

The end cover 9 has a through opening 16 centrally. The interior of the housing 2 communicates with the receiving area of the sensor housing 11 via the passage opening 16, so that hydraulic fluid can also penetrate from the interior of the housing 2 into the interior of the sensor housing 11. A seal 17 is arranged between the sensor housing 11 and the end cover 9, so that the hydraulic fluid cannot escape to the outside. The necessary sealing forces are ensured by a fastening arrangement with which the sensor housing 11 is fastened to the end cover 9. This fastening arrangement is symbolized here by a screw 18. In fact, multiple screws 18 will be provided.

The sensor housing 11 is formed from a material that is non-magnetic and that allows the magnetic field to pass through the transmitter elements 14, so that this magnetic field can be detected by the receiver 15.

The carrier element 13 is connected via a transmission element 19 to a second section of the movement strand which rotates about the axis 4. This is the end of the propeller shaft 5, which is in engagement with the shaft 3 via a toothing geometry 20.

The transmission element 19 is designed as a tachometer shaft, ie it is torsionally rigid. Virtually no torque is required to drive the transmitter 12, which is additionally lubricated in the receiving area or in the sensor housing 11 by the hydraulic fluid, so that the transmission element 19 is practically not subjected to torsion. The encoder 12 therefore always has exactly the same angle of rotation position as the shaft 3 with a high degree of accuracy. The deviation is at most 5 °, preferably even only at most 2 ° and in particularly preferred cases at most 1 °.

So that the transmission element 19 can be guided to the transmitter 12, the cardan shaft has a longitudinal channel 21, which also passes through the first section of the movement train. The gear 6 rotates at the same speed as the cardan shaft 5 and thus at the same speed as the transmission element 19. There is therefore no relative movement in the longitudinal channel 21 in the direction of rotation between the transmission element 19 and the cardan shaft 5. If the longitudinal channel 21 is too small Diameter in order to give the transmission element 19 the necessary free space over a full revolution, then at most there is a bending movement of the transmission element 19, which is, however, not critical.

Instead of a tachometer wave, another transmission element can be used, for example a thin metal rod or the like.

When designing after Fig. 1 Under certain circumstances, there is a deviation between the angular position of the shaft 3 and the angular position of the transmitter 12 due to play in the toothing geometry 20.

In order to eliminate this deviation, one can use a configuration as shown in Fig. 2 is shown. Here, the same elements are provided with the same reference symbols.

The transmission element 19 is longer here than in the embodiment according to Fig. 1 so it's immediate can be attached in the shaft 3. A possible game in the toothing geometry 20 then no longer plays a role.

In both cases, the transmission element 19 is connected in a rotationally fixed manner to the transmitter 12 and / or to the shaft 3, but is displaceably connected in a direction parallel to the axis 4. This can be achieved, for example, by the ends of the transmission element 19 having a polygonal cross section, for example in the form of a square. These ends of the transmission element 19 are then guided into corresponding recesses in the transmitter 12 and / or in the shaft 3, which have a corresponding polygonal cross section. The end can thus be axially displaced to a certain extent in the respective recesses, so that a change in length of the transmission element 19 can be accommodated, as can occur, for example, when the temperature changes.

Fig. 3 shows another hydraulic machine. Same elements as in the 1 and 2 are provided with the same reference numerals.

Here, too, the shaft 3 is connected to the cardan shaft 5 via a toothing geometry 20, which in turn is connected to the gear 6 via a second toothing geometry 22. A second cardan shaft 23 is provided in order to connect the gear 6 to the valve slide 8, which rotates together with the shaft 3, around the one formed between the gear 6 and the toothed ring 7 Pressure pockets to supply the hydraulic fluid in the correct position.

The transmission element 19 is connected at one end to the shaft 3 and at the other end to the encoder 12. Accordingly, the encoder 12 has the same angular position as the shaft 3 with high accuracy. Play in the toothing geometries 20, 22 has no influence here.

Fig. 3b shows a detail B from an enlarged view Fig. 3a , ie the sensor arrangement 10. Fig. 3b shows a section CC after Fig. 3c , It can be seen from this that the transmission element 19 has a square cross section at its end, which is accommodated in the carrier element 13, and the carrier element 13 has a corresponding receptacle.

The sensor housing 11 is formed, for example, from stainless steel and the carrier element 13 from a plastic, preferably PEEK (polyether ether ketone).

Instead of magnets 29 as transmitter elements 14, other transmitter elements can of course also be used.

If, for example, the sensor housing 11, the housing 2 or the end cover 9 is permeable to radiation, for example optical radiation, then the transmitter element 14 can also have an optical marking, which can be seen from the outside through the sensor housing 11, the housing 2 or the end cover 9 scanned through can be. The radiation does not necessarily have to be visible radiation. It is also possible to use radiation in the infrared or ultraviolet range. Other electromagnetic waves can also be used for signal transmission from the transmitter 12 to the outside insofar as they can penetrate the sensor housing 11, the housing 2 or the end cover 9.

The sensor housing 11 is sealed off from the end cover 9 by the seal 17. Accordingly, hydraulic fluid can penetrate inside the sensor housing 11, but not outside. The sensor housing 11 is designed such that it can absorb the pressures occurring in the interior of the housing 2. However, no seals are required in order to seal parts moving in the area of the sensor arrangement 10 against one another.

Fig. 4a shows an embodiment similar to the embodiment of FIG Fig. 3a , Identical elements are provided with the same reference symbols.

There are essentially two changes:
On the one hand, the transmission element 19 is connected to the cardan shaft 5, specifically at the end that faces away from the shaft 3. So that the transmission element 19 is arranged eccentrically in this area. However, one makes use of the knowledge that the cardan shaft 5 has the same speed as that Shaft 3 rotates and it is therefore essentially irrelevant whether the transmission element 19 is attached to a rotating and orbiting section of the propeller shaft 5 or, as in FIG Fig. 1 , on an only rotating section of the propeller shaft 5. The only requirement is that the transmission element 19 is only subjected to bending to an extent that it can withstand in operation in the long run.

A second difference relates to the sensor arrangement 10, which is shown in FIG Fig. 4b is shown enlarged.

The sensor housing 11 has an external thread 24 which is screwed into an internal thread 25 in the through opening 16 in the end cover 9. This simplifies both the manufacture of the sensor housing 11 and the assembly of the sensor housing 11. The sensor housing 11 can be designed as a turned part. The assembly is carried out simply by screwing the sensor housing 11 into the end cover 9, the screw 17 sealing the seal between the end cover 9 and the sensor housing 11.

The carrier element 13 is held in the sensor housing 11 by a snap ring 26. The transmission element 19 protrudes through the end cover 9, so that the carrier element 13 already pre-assembled in the sensor housing 11 can be placed on the transmission element 19 before the sensor housing 11 is screwed into the end cover 9.

The sensor housing 11 has a groove 27 on its outer circumference. A clip 28, only shown schematically, is clipped into the groove 27. This bracket 28 holds the receiver 15 on the end face of the sensor housing 11. The receiver 15 can be easily assembled in this way, but can also be replaced.

A magnetoresistive or a Hall sensor element 30 can be used as the receiver 15. This is particularly useful when the encoder 12 is a magnet 29. Magnetoresistive sensor elements 30 can have Wheatstone bridges that emit a signal with which the angular position of shaft 3 or that of encoder 12 that is operatively connected to shaft 3 can be measured. In particular, two output signals 31 and 32 can be a sine or a cosine, as shown in FIG Fig. 5a is shown. The angle can then be determined with the aid of these two output signals 31, 32. In Fig. 5a normalized output signals 31, 32 are shown as a function of the angle. In the case of the Hall sensor element 30, a sawtooth voltage 33 is often output. In Fig. 5b the sawtooth voltage is shown as a function of time. The angles 0 ° and 360 ° are located at the lowest voltage points. If the receiver 15 has a magnetoresistive or a Hall sensor element 30 and the transmitter 12 has a magnet 29, then the necessary elements for a Hall or rotation sensor 34 are available. Of course, other types of rotation sensors 34 are also available a Hall sensor 34 conceivable. Completely different types of sensors 34 are also conceivable. In particular, the previously mentioned optical sensor 34, in which the transmitter 12 is scanned by electromagnetic waves, represents a further possibility. In the case of a tacho generator sensor 34, a voltage proportional to the speed is supplied.

As such, the output signals 31, 32 or the sawtooth voltage 33 can be used and forwarded for further processing. However, it is advantageous if these signals are converted into a square signal 35. Such a square signal 35 represents a digital signal which can be recognized and used by a large number of consumers. Voltage losses in the connecting lines have no influence on signal quality. The slope of the edge typically varies between 5 microseconds and 50 milliseconds, and at least 90 pulses per cycle are typically used. In order to convert the sinusoidal or cosine-shaped output signals 31, 32 into the square signal 35, the output signals 31, 32 are cut into segments with a predetermined frequency, the frequency depending on the desired resolution.

Regardless of a signal type, an output element 36 ( Fig. 6 ) to spend.

In order to also obtain a direction of rotation of the shaft 3, a memory 37 as shown in FIG Fig. 6 is shown, use. The memory 37 then stores at least two values of the angular position of the shaft 3 he can use the sine or cosine output signals 31, 32 or the sawtooth voltage 33. Taking into account the transition from 360 ° to 0 °, the direction of rotation is then output in addition to the speed.

Claims (8)

1. Fluid rotary machine (1) having a housing (2), a shaft (3) which is guided out of the housing (2) and a sensor arrangement (10) having a transmitter (12), which is operatively connected to the shaft (3), and a receiver (15), wherein the sensor arrangement (10) has an accommodation area in which the transmitter (12) is arranged, and the accommodation area is fluidically connected to the interior of the housing (2) and is sealed to the outside, characterized in that the receiver (15) is arranged outside the housing (2) and the accommodation area, wherein the sensor arrangement (10) has a sensor housing (11) in which the accommodation area is arranged, and the transmitter (12) has a carrier element (13) which interacts with the sensor housing (11) with low friction.
2. Fluid rotary machine according to Claim 1, characterized in that the sensor housing (11) is screwed into an end cover (9) of the fluid rotary machine (1).
3. Fluid rotary machine according to one of Claims 1 to 2, characterized in that the receiver (15) is clipped onto the sensor housing (11).
4. Fluid rotary machine according to one of Claims 1 to 3, characterized in that the transmitter (12) has a magnet (29).
5. Fluid rotary machine according to one of Claims 1 to 4, characterized in that the receiver (15) has a magnetoresistive or Hall sensor element (30).
6. Fluid rotary machine according to one of Claims 1 to 5, characterized in that the transmitter (12) and receiver (15) are elements of a Hall, rotation, tacho generator or optical sensor (34).
7. Fluid rotary machine according to one of Claims 1 to 6, characterized in that the sensor arrangement (10) has an output element (36) for outputting a square-wave signal (35).
8. Fluid rotary machine according to one of Claims 1 to 7, characterized in that the sensor arrangement (10) has a memory (37) in which at least two values can be stored.

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