EP2369173A2 - Fluid rotation machine with a sensor assembly - Google Patents

Abstract

The machine i.e. hydraulic motor (1), has a housing (2), and a shaft (3) guided in the housing and rotatable around an axis. The shaft forms a part of a movement section, and a sensor arrangement (10) has a transducer (12) and a receiver (15). A channel (21) is provided in the movement section, and the transducer is connected with a torque transmission element (19) i.e. speedometer shaft, that is guided to a section of the movement section through the channel, where the section of the movement section is removed far away from the transducer than a transducer-sided end of the movement section.

Description

The invention relates to a fluid rotary machine having a housing, a guided out of the housing shaft which is rotatable about an axis and forms part of a moving train, and a sensor arrangement comprising a transmitter and a receiver.

Such a machine is off US Pat. No. 6,539,710 B2 known. The first section has an externally toothed gear which cooperates with an internally toothed ring gear. Between the gear and the ring gear pressure pockets are formed, which are supplied via a rotating valve spool assembly each with pressurized fluid or connected to a low pressure region. The gear is connected via a cardan shaft with the shaft. The gear is engaged with a crankpin, which transmits the orbiting motion of the gear to a sensor shaft.

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

US Pat. No. 6,062,123 describes a power-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 spool is provided on its front side with a row of teeth that can be scanned by a sensor.

DE 10 2005 036 483 B4 describes a hydraulic rotary machine whose shaft is provided with a donor having on its outer periphery a tooth structure of teeth and grooves. In the housing, a transmitter is arranged, which directs a light beam to the threaded structure. From the thread structure of the light beam is reflected to a receiver.

In many applications of such machines, especially in hydraulic rotary machines, one needs sensors to control the machine with sufficient accuracy can, for example in conjunction with an associated diesel engine to save energy.

The sensor arrangements in the machines mentioned in the introduction have proven themselves in principle. But they often require a relatively complicated installation of the sensor. The sensor is then often in a position where it basically bothers. If the sensor is placed in a position where it interferes less, there is the problem that it can not directly detect the rotation of the shaft, but is in communication with the shaft through a plurality of play-engaged engagement points. A similar problem arises when the shaft can twist, for example, at large-βen torques within the movement train.

The invention has for its object to provide a simple way to determine the rotation of the shaft with relatively high accuracy.

This object is achieved in a fluid rotary machine of the type mentioned above in that a channel is provided in the motion strand and the encoder is connected to a torque transmitting transmission element, which is guided through the channel to a portion of the moving beach, the farther from the dealer is removed as a geberseitiges end of the movement strand.

In this embodiment, one can arrange the sensor at a position where it practically does not bother, namely on one end of the machine. The rotation of the shaft is then transmitted by means of the transmission element to the encoder. The rotation of the shaft can then be detected on a section of the moving train, ie transmitted to the transmission element, which is arranged closer to the section of the shaft protruding from the housing. This has reduced the size of the segment of motion that can give rise to errors.

Preferably, the moving train has at least a first portion and a second portion, wherein the first portion and the second portion are engaged with each other via an engagement point and the torque transmission element bridges the engagement point. In many cases, it is necessary to assemble the motion train from two or more sections and to connect the sections with each other via an engagement point, which may also be referred to as a coupling or connection. Such a site of intervention can be designed with reasonable effort practically not play. This is especially true when this engagement point is formed by a tooth geometry. If the transmission element bridges such a point of engagement, one can eliminate the error that can be caused by the game here.

In a preferred embodiment, the first section orbits around the axis. The orbiting motion of the first section of the motive string and the resulting Connected play in the motive strand no longer plays a role, because the transmission element is guided through the channel to the second section. The transmission element can be guided into the second section. In some cases, however, it is also sufficient to connect the transmission element with a part of the moving train, which rotates synchronously with the second section. Thus, one can avoid at least one inaccuracy resulting from an implementation of the orbiting into a rotating motion and the associated play. Rather, the rotational movement is transmitted directly to the encoder of the sensor arrangement.

Preferably, the first section rotates at the same speed as the second section. The first section not only orbits so, but it also rotates. Since it rotates at the same speed as the second section, there is no relative rotation between the transmission element and the inner wall of the channel in the first section. Thus, if the clear cross section of the channel is not large enough in any case, the transmission element is subjected to only one bending. Otherwise there are no further loads on the transmission element.

Preferably, the transmission element is designed as a tachometer shaft. A tachometer shaft transmits a rotational movement even if it is bent. A tachometer shaft has a high torsional rigidity, so that the transmission of the movement of a End can be made to the other end of the transmission element with high accuracy.

Preferably, the transmission element with the second portion and / or the encoder rotatably, but longitudinally displaceably connected. It is therefore possible that the transmission element expands or contracts, which can be done for example under the influence of temperature inside the machine. Such a connection can be realized for example by the fact that the transmission element has a polygonal cross-section at one end, which is inserted into a corresponding polygonal-shaped opening in the second section and / or in the encoder.

Preferably, the transmission element has a maximum twist, which is smaller than the sum of the games in all engagement points of the movement strand, which are bridged by the transmission element. It is of particular advantage here that the encoder in the sensor arrangement requires almost no moment to be rotated. Thus, there is only a very small difference in the torques at both ends of the transmission element. The risk that results in a rotation of the second portion, an angular deviation between the two ends of the transmission element is thus very low. In contrast, results in a connection between sections of the moving train, which is formed for example by the engagement of two gears, practical always a deviation, because such an intervention can not be designed practically free of play.

Preferably, the transmission element is connected to the shaft. In this case, the rotational movement of the shaft is transmitted directly to the sensor of the sensor arrangement, so that the rotational movement of the shaft can be detected with high accuracy.

Preferably, the sensor assembly comprises a sensor housing with a receiving space for the encoder, wherein the receiving space is in fluid communication with the interior of the housing and is sealed to the outside and the receiver is arranged outside of the sensor housing. Such a design of the sensor arrangement can also be used in other fluid machines that are not provided with a transmission element described above. Such a sensor arrangement is also not limited to machines in which a part of the movement section orbits. Advantageously, use is here made of the fact that the sensor housing seals the interior of the machine to 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 the reliability. The wear remains small and the susceptibility to errors decreases. For example, if the sensor assembly is coupled to a hydraulic machine, then hydraulic fluid may enter the receiving space and then lubricate the same Contact surfaces between sensor housing and encoder. This in turn means that the encoder in the sensor housing can rotate virtually freely, so that an exceptionally small moment is required to turn the encoder. This, in turn, keeps the distortion of the transmission element very small when using a transmission element.

Preferably, the encoder has a carrier element which cooperates with low friction with the sensor housing. In this case, one can use the sensor arrangement even if the liquid or the fluid which penetrates into the receiving space does not have a lubricating effect per se, as is the case, for example, with water-hydraulic machines.

Preferably, the sensor housing is screwed into a front cover of the machine. The sensor housing has for this purpose, for example, an external thread, which is in engagement with a corresponding internal thread in the end cap. This simplifies the manufacture of the sensor housing and the mounting of the sensor arrangement on the machine. Moreover, in this embodiment, it is relatively easy to seal the receiving space to the outside. You just have to arrange a seal between the sensor housing and the front cover and screw the sensor housing with sufficient force in the front cover.

Preferably, the receiver is clipped onto the sensor housing. So you connect the receiver with the Sensor housing with a detachable connection that can be made and released relatively quickly. This has the advantage that the machine can be relatively easily provided with different types of sensor arrangements by replacing the receiver. Also, a repair is simplified. In a sensor arrangement, the receiver is usually the most error-prone part.

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 und

Fig. 4

eine vierte Ausführungsform eines hydraulischen Motors.

The invention will be described below with reference to preferred embodiments in conjunction with the drawing. Herein show:

Fig. 1

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

Fig. 2

a second embodiment of a hydraulic motor,

Fig. 3

a third embodiment of a hydraulic motor and

Fig. 4

a fourth embodiment of a hydraulic motor.

The invention will be explained below with reference to a hydraulic motor as an example of a fluid rotary machine. However, it is not limited to hydraulic motors.

An in Fig. 1 illustrated hydraulic motor 1 has a housing 2, from which a shaft 3 is led out. On the shaft 3, a mechanical power can be removed.

The shaft 3 is rotatable about an axis 4. It forms the part of a movement train, which in addition to the shaft 3 a propeller shaft 5 and an externally toothed gear 6, which is arranged in an internally toothed toothed ring 7 and forms with the toothed ring 7 in a conventional manner pressure pockets which, depending on their Position can be supplied with hydraulic fluid under pressure or discharge hydraulic fluid to a low pressure port. To control the liquid supply of these pressure pockets, a schematically illustrated spool 8 is provided, which is connected to the shaft 3.

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

The housing 2 is closed on the opposite side of the shaft by a front cover 9. Outside on the front cover 9, a sensor arrangement 10 is arranged. With the sensor assembly 10, the rotation of the shaft 3 should be detected as accurately as possible.

The sensor arrangement 10 has a sensor housing 11 which surrounds a receiving space in which an encoder 12 is arranged. The encoder 12 has a support member 13 which is formed of a material which cooperates with low friction with the material of the sensor housing 11. On the carrier element one or more donor elements are arranged. In the present embodiment, the encoder elements 14 are formed as permanent magnets. On the outside of the sensor housing 11, a receiver 15 is arranged, which is acted upon by the magnetic field of the encoder elements 14 and via a line not shown or wireless electrical signals that contain the information about the rotational movement of the shaft 3, and a controller, not shown pass on.

The front cover 9 has centrally a through opening 16. Via the passage opening 16, the interior of the housing 2 is in communication with the receiving space of the sensor housing 11, so that hydraulic fluid from the interior of the housing 2 can also penetrate into the interior of the sensor housing 11. Between the sensor housing 11 and the end cover 9, a seal 17 is arranged so that the hydraulic fluid can not escape to the outside. The necessary sealing forces are ensured by a mounting arrangement with which the sensor housing 11 is attached to the front cover 9. This fastening arrangement is symbolized here by a screw 18. In fact, a plurality of screws 18 will be provided.

The sensor housing 11 is formed of a material which is non-magnetic and which allows the magnetic field from the transducer elements 14 to pass, 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 engaged with the shaft 3 via a Verzahnungsgeomtrie 20.

The transmission element 19 is designed as a tachometer shaft, i. it is torsionally stiff. To drive the encoder 12, which is additionally lubricated in the sensor housing 11 by the hydraulic fluid, virtually no torque is required, so that the transmission element 19 is practically not claimed to torsion. The encoder 12 thus always has exactly the same angular position as the shaft 3 with a high degree of accuracy. The deviation amounts to a maximum of 5 °, preferably even to a maximum of 2 ° and in particularly preferred cases to a maximum of 1 °.

So that the transmission element 19 can be guided to the encoder 12, the propeller shaft has a channel 21, which also passes through the first portion of the moving train. This channel 21 may also be referred to here as a "longitudinal channel", because it passes through at least a portion of the movement strand lengthwise. The gear 6 rotates at the same speed as the cardan shaft 5 and thus at the same speed Thus, there is no relative movement between the transmission element 19 and the cardan shaft 5 in the channel 21 in the direction of rotation. If the channel 21 has too small a diameter to allow the transmission element 19 the necessary clearance over a full revolution, then takes place possibly a bending movement of the transmission element 19, which is not critical.

Instead of a tachometer shaft, one can also use another transmission element, for example a thin metal rod or the like.

In the embodiment according to Fig. 1 Under certain circumstances, a deviation between the angular position of the shaft 3 and the angular position of the encoder 12 due to a game in the tooth geometry 20 results.

In order to eliminate this deviation, one can use an embodiment as shown in FIG Fig. 2 is shown. Here, the same elements are provided with the same reference numerals.

The transmission element 19 is formed here longer than in the embodiment according to Fig. 1 so that it can be fixed directly in the shaft 3. A possible play in the gearing geometry 20 then no longer plays a role.

In both cases, the transmission element 19 is rotatably connected to the encoder 12 and / or with the shaft 3, but slidably connected in a direction parallel to the axis 4. This can for example be achieved in that the ends of the transmission element 19 have 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. This allows the end to be displaced axially to a certain extent in the respective recesses, so that a change in length of the transmission element 19 can be accommodated, as may arise, for example, in the event of a temperature change.

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

Again, the shaft 3 is connected via a tooth geometry 20 with the propeller shaft 5, which in turn is connected via a second tooth geometry 22 with the gear 6. A second propeller shaft 23 is provided to connect the gear 6 with the valve spool 8 which rotates together with the shaft 3 to supply the hydraulic fluid in the correct position to the pressure pockets formed between the gear 6 and the toothed ring 7.

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 high accuracy the same angular position as the shaft 3. Game in the toothing geometries 20, 22 is here without influence.

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

The sensor housing 11 is formed, for example, of stainless steel and the support member 13 made of a plastic, preferably PEEK (polyetheretherketones).

Instead of magnets as donor elements 14, of course, other donor elements can be used.

If, for example, the sensor housing 11 is permeable to radiation, for example optical radiation, then the transmitter element 14 can also have an optical marking which can be scanned from outside through the sensor housing 11. 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, if they can penetrate the sensor housing 11, are used for the signal transmission from the transmitter 12 to the outside.

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

Fig. 4a shows an embodiment similar to the embodiment according to Fig. 3a , The same elements are provided with the same reference numerals.

• Zum einen ist das Übertragungselement 19 mit der Kardanwelle 5 verbunden und zwar an dem Ende, das von der Welle 3 abgewandt ist. Damit ist das Übertragungselement 19 zwar in diesem Bereich exzentrisch angeordnet. Man macht sich aber die Erkenntnis zunutze, dass die Kardanwelle 5 mit der gleichen Geschwindigkeit wie die Welle 3 rotiert und es somit im Grunde unerheblich ist, ob man das Übertragungselement 19 an einem rotierenden und orbitierenden Abschnitt der Kardanwelle 5 befestigt oder, wie in Fig.' 1, an einem nur rotierenden Abschnitt der Kardanwelle 5. Die einzige Voraussetzung ist, dass das Übertragungselement 19 nur in einem Umfang auf Biegung beansprucht wird, den es im Betrieb auf Dauer auch aushalten kann.

In essence, there are two changes:

• On the one hand, the transmission element 19 is connected to the propeller shaft 5 and indeed at the end which faces away from the shaft 3. Thus, the transmission element 19 is indeed arranged eccentrically in this area. However, one makes use of the knowledge that the cardan shaft 5 rotates at the same speed as the shaft 3 and thus it is basically irrelevant whether the transmission element 19 is attached to a rotating and orbiting portion of the cardan shaft 5 or, as shown in FIG. ' 1, on a merely rotating portion of the propeller shaft 5. The only requirement is that the transmission element 19 is subjected to bending only to an extent that it can withstand during operation in the long run.

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

The sensor housing 11 has an external thread 24 which is screwed into an internal thread 25 in the passage opening 16 in the front cover 9. As a result, both the production of the sensor housing 11 and the assembly of the sensor housing 11 is simplified. The sensor housing 11 may be formed as a rotating part. The assembly takes place simply in that the sensor housing 11 is screwed into the front cover 9, wherein by sealing the seal 17 seals between the end cover 9 and the sensor housing 11.

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

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

Claims (12)

Fluid rotary machine comprising a housing, a guided out of the housing shaft which is rotatable about an axis and forms part of a moving train, and a sensor arrangement comprising a transmitter and a receiver, characterized in that provided in the motion strand, a channel (21) is and the encoder (12) is connected to a torque transmitting transmission element (19), which is guided through the channel (21) to a portion of the moving train, which is further away from the encoder (12) as a geberseitiges end of the moving train. Rotary machine according to claim 1, characterized in that the movement strand at least a first portion (4) and a second portion has, the first portion (4) and the second portion via an engagement point engage with each other and the torque transmitting element bridges the engagement point. Rotary machine according to claim 2, characterized in that the first section (4) orbits around the axis (3). Rotary machine according to claim 3, characterized in that the first section rotates at the same speed as the second section. Rotary machine according to one of claims 1 to 4, characterized in that the transmission element (19) is designed as a tachometer shaft. Rotary machine according to one of claims 1 to 5, characterized in that the transmission element (19) with the movement strand and / or the encoder (12) rotatably, but is longitudinally displaceably connected. Rotary machine according to one of claims 1 to 6, characterized in that the transmission element (19) has a maximum twist, which is smaller than the sum of the games in all engagement points (20, 22) of the movement strand, which are bridged by the transmission element (19) , Rotary machine according to one of claims 1 to 7, characterized in that the transmission element (19) is connected to the shaft (3). Rotary machine according to one of claims 1 to 8, characterized in that the sensor arrangement (10) has a housing (11) with a receiving space for the encoder (12), wherein the receiving space with the interior of the housing (2) is in fluid communication and is sealed to the outside and the receiver (15) outside the sensor housing (11) is arranged. Rotary machine according to claim 9, characterized in that the encoder (12) has a carrier element (13) which interacts with the sensor housing (11) in a low-friction manner. Rotary machine according to claim 9 or 10, characterized in that the sensor housing (11) in an end cover (9) of the machine (1) is screwed. Rotary machine according to one of claims 9 to 11, characterized in that the receiver (15) is clipped onto the sensor housing (11).

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