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(11) | EP 1 624 185 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Method and apparatus for determining operating parameters in hydraulic piston engines |
| (57) Apparatus for determining the operating parameters of a variable-volume hydraulic
engine comprising a plurality of propulsion members (10) oscillating about a respective
centre of oscillation (Cn) and a spherical body (6) associated with the driving shaft
(7) and movable eccentrically (E) with respect to the centre of rotation (O) of the
latter, and comprising at least two devices (50;150) each of which is respectively
arranged on an associated propulsion member (10) and is designed to detect a parameter
able to allow determination of the position of the point of eccentricity (E) of the
driving shaft (7) with respect to the centre of rotation (O) of the driving shaft
and the centres of oscillation (C1,C2) of said propulsion members (10), and a data
processing unit (1000) able to store the data detected and perform the necessary calculation.
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[0001] The present invention relates to a method and an apparatus for determining the instantaneous operating parameters of a variable-volume engine.
[0002] In the art hydraulic engines with radial pistons are known where the propulsion members consist of oscillating telescopic cylinders which bear on one side against a spherical cam of the rotating shaft and on the other side against spherical caps integral with the engine casing. Said engines may be of the fixed-volume or variable-volume type.
[0003] In variable-volume engines the spherical part of the driving shaft, in addition to rotating, may also be displaced with respect to the shaft itself, thus changing its own eccentricity and therefore the operating volume of the engine. In this way the value of the volume may be varied during operation of the engine so as to adapt it to the external load conditions, optimising the performance thereof.
[0004] For this purpose, the engine is provided with sensors which measure the speed and volume thereof, then sending the respective signals to the control circuits of the machine on which the engine is mounted.
[0005] It is also known that the speed of rotation and the angular position of the driving shaft may be detected by an incremental encoder, while the volume is detected by a sensor which measures the amplitude of the oscillation of one of the cylinders of the engine, which amplitude is proportional precisely to the swept volume of the said engine.
[0006] The volume sensor (of the induction type positioned on the engine casing on the side of one cylinder) measures essentially the maximum value of oscillation of the cylinder, thus providing a signal useful solely upon completion of each revolution of the driving shaft and resulting, therefore, in a signal and therefore data which are not continuous. These engines and the devices for detecting the position of the cylinder are for example known from EP 0,267,656 in the name of the same present Applicants.
[0007] Although fulfilling their intended function, these engines and associated devices for detecting the position of the propulsion member have certain problems essentially consisting in the fact that they require the use of two different sensors in order to measure, respectively, the speed of rotation of the shaft and the actual volume of the engine; moreover, the volume sensor has limitations in that:
- it measures only the maximum value of the oscillation of the cylinder and provides therefore only one signal per revolution instead of a continuous signal during the entire rotating movement;
- it is unable to provide any information when the engine is stopped since it is unable to measure the maximum peak value of the oscillation.
[0008] The technical problem which is posed, therefore, is that of providing an apparatus by means of which it is possible to determine the operating parameters of an engine with radial propulsion members, in particular the swept volume, the speed of rotation and the instantaneous angular position of the driving shaft.
[0009] In connection with this problem a further requirement is that this apparatus should consist of a limited number of components which can be standardized and used to obtain several measurements which may also be different from each other and which may be installed in an easy and low-cost manner also on engines of the conventional type without the need for complicated adaptation.
[0010] These technical problems are solved according to the present invention by a method for determining the instantaneous operating parameters of a variable-volume hydraulic engine according to the characteristic features of Claim 1.
[0011] The present invention relates furthermore to an apparatus for determining the instantaneous operating parameters of a variable-volume hydraulic engine according to the characteristic features of Claim 14 and to an engine equipped with said apparatus according to the characteristic features of Claim 26.
[0012] Further characteristic features will emerge from the description provided below of a non-limiting example of embodiment of the apparatus according to the invention with reference to the accompanying figures in which:
- Figure 1 shows a schematic cross-section along the plane indicated by I-I in Fig. 2 and showing an engine comprising variable-volume radial propulsion members, with a detection apparatus according to the present invention;
- Figure 2 shows a schematic cross-section along the plane indicated by II-II in Fig. 1;
- Figure 3 shows a top plan view of a propulsion member with the sensor mounted;
- Figure 4 shows a schematic cross-section along the plane indicated by IV-IV in Fig. 3;
- Figure 5 shows a schematic cross-section along the plane indicated by V-V in Fig. 3;
- Figure 5a shows a schematic diagram of the measurement performed by the sensor according to Fig. 5;
- Figure 6 shows a schematic cross-section similar to that of Fig. 5 with the driving shaft in a different angular position;
- Figure 6a shows a schematic diagram of the measurement performed by the sensor according to Fig. 6;
- Figure 7 shows a schematic cross-section similar to that of Fig. 1 of a second example of embodiment of the measuring apparatus according to the present invention;
- Figure 8 shows a partial schematic cross-section along the plane indicated by VIII-VIII in Fig. 7 of the detail of assembly of the detection sensor according to Fig. 7;
- Figure 9 shows the measurement diagram of the apparatus according to Fig. 7;
- Figure 10 shows a cross-section similar to that of Fig. 7 with the shaft rotated through a negative angle with respect to the axis of symmetry of the propulsion member;
- Figure 10a shows the measurement diagram for the engine according to Fig. 10;
- Figure 11 shows a cross-section similar to that of Fig. 7 with the shaft aligned with the axis of symmetry of the propulsion member;
- Figure 11a shows the measurement diagram for the engine according to Fig. 11;
- Figure 12 shows a cross-section similar to that of Fig. 7 with the shaft rotated through a positive angle with respect to the axis of symmetry of the propulsion member; and
- Figure 12a shows the measurement diagram for the engine according to Fig. 12.
[0013] As shown in Figs. 1 and 2, a variable-volume hydraulic engine is composed of a casing 1 housing the propulsion members 10 consisting of a cylinder 11 and a piston 12. In greater detail each of the cylinders 11 is connected to a rotating distributor 4 which is housed inside a cover 1a fixed to the casing 1, actuated by a driving shaft 4d and able to cyclically supply or discharge the cylinders 11 in synchronism with rotation of the driving shaft 7.
[0014] Inside the cylinders 11, in contact with the caps 2, the pistons 12 are telescopically movable in the radial direction and bear against the external surface of a spherical body 6 which is movable eccentrically in the radial direction with respect to the axis of the driving shaft 7 upon actuation of associated means 8, said variation in eccentricity determining also the variation in volume of the engine.
[0015] As shown, the apparatus for detecting the swept volume of the engine comprises at least one pair of sensors 50, each of which is arranged on the cap 2 of a respective propulsion member 10 with its longitudinal axis parallel and axially offset (Fig. 3) with respect to the longitudinal axis of the propulsion member 10 in the rest condition and a data processing unit 1000 for detecting and storing the signals emitted by the sensors and performing the necessary calculations, as will become clearer below.
[0016] As shown in Figs. 5 and 5a, said sensor 50 is able to measure the distance "h" of the surface of the cylinder 11 from the sensor itself.
[0017] Since the distance "s" of the axis of the sensor from the axis of the cylinder is known (Fig. 3), it is possible, by applying analytical geometrical formulae, to obtain also the position of the point of eccentricity "E" of the rotating shaft 7 and therefore the angular position of the latter, the speed of rotation thereof and the instantaneous volume of the engine.
[0018] The position of the sensor, which is axially offset with respect to the axis of symmetry of the cylinder allows, moreover, determination of the direction of rotation (clockwise/anti-clockwise) of the cylinder and therefore the driving shaft.
[0019] Figs. 7 to 12 shows a second example of embodiment by way of a variation of the apparatus for determining the instantaneous eccentricity of the spherical body 6.
[0020] In this configuration two sensors 150 are envisaged, each being arranged inside a corresponding propulsion member 10.
[0021] The sensor 150 is of the angular type and is suitable for measuring the amplitude of rotation of a pin 20 which is substantially perpendicular to the axis of symmetry of the propulsion member 10, said pin 20 being contained inside a respective seat 21 of the cap 2 of the engine with the arrangement of sealing elements 22 in between.
[0022] Said horizontal pin 20 has, connected to it, a pin 30 for supporting the cylinder 11, having a head 33 which has a spherical surface 33a resting on corresponding support elements 34 which are fixed to the casing 1a so that the head 33 itself forms a ball joint for oscillation of the propulsion member 10.
[0023] The point of intersection C1 between the axes of the transverse pin 20 and the longitudinal pin 30, respectively, therefore forms the centre of the oscillating movement of the respective propulsion member. Consequently having defined a Cartesian reference system which, for the sake of convenience, is assumed as having its origin at the centre of rotation O of the driving shaft (Fig. 9), or polar reference system, knowing nominally the position of the two centres C1,C2 of oscillation of the respective propulsion member relative to the centre O of rotation of the driving shaft and being able to obtain by means of the associated sensor 150 the respective angle α1 and α2 of the angular position of the respective cylinder C1,C2 with respect to its longitudinal axis of symmetry, it is possible to determine, by means of calculation methods which are conventional per se, the instantaneous position of the point E - corresponding to the operational eccentricity of the driving shaft /eccentric spherical body 6 assembly - with respect to the centre of rotation O of the driving shaft.
[0024] Since the position of the point E with respect to the centre of rotation O of the driving shaft is known, the operating eccentricity thereof or the instantaneous volume of the engine is therefore known.
[0025] Once the position of the point E has been determined, it is also possible to obtain the value of the angle C1-O-E or the instantaneous angular position α of the driving shaft.
[0026] In both the examples of embodiment described it is also possible to measure the value of the angle α in two successive moments of time, which also allows the instantaneous speed of rotation of the driving shaft to be easily determined.
[0027] It is therefore clear how by means of the apparatus according to the present invention it is possible to determine the operating parameters of an engine by means of the alternating measurement of the following in relation to a Cartesian/polar reference system:
- two lengths: representing respectively the distance s1,s2 of the centres of oscillation C1,C2 of two different propulsion members 10 from the point of eccentricity E defined by the intersection of the two circumferences having a centre C1,C2 and radius s1,s2, respectively;
- a length s1 and an angle α1 : representing respectively the distance of the centre of oscillation C1 of a propulsion member 10 from the point of eccentricity E and the angle between the straight line joining together the centre of oscillation C1 of the said propulsion member and the centre of rotation O of the driving shaft;
- two angles α1 and α2: representing respectively the angle between the respective straight line joining together the centre of oscillation C1,C2 of the two different propulsion members 10 and the centre of rotation O of the driving shaft,
it being then possible, by means of devices 1000 for digitally processing the signals, to perform the calculation which results in determination of the instantaneous position of the driving shaft, the instantaneous volume of the engine and if necessary the angular speed of the engine expressed in terms of modulus and direction.
[0028] The present invention relates furthermore to a method for determining the operating parameters of a variable-volume hydraulic engine which envisages the following steps:
a) locating within a Cartesian/polar reference system and with respect to the relative longitudinal axis of symmetry the known position of the respective centre of oscillation C1,C2 of at least two propulsion members 10 of the engine;
b) locating within the same reference system the centre of rotation O of the driving shaft;
c) detecting at least two parameters (s1,s2;s1,α1;α1,α2) able to allow determination of the position of the point (E) of eccentricity of the spherical body 6 of the driving shaft 7 with respect to the centre of rotation O of the said driving shaft and the two points C1,C2 of oscillation of the respective propulsion member (10);
d) processing the data relating to the position of the point E relative to the centre of rotation O in order to obtain at least one of the instantaneous operating parameters of the engine.
[0029] According to preferred embodiments of the method it is envisaged that the position of the point E of eccentricity may be determined by:
- measuring two lengths representing respectively the distance s1 and s2 of the centres of oscillation C1,C2 of two respective cylinders from the point of eccentricity E;
measuring a length s1 and an angle α1 representing respectively the distance of the centre of oscillation C1 of a cylinder from the point of eccentricity E and the angle between the straight line joining together the centre of oscillation C1 of the propulsion member and the point E of eccentricity and the straight line joining together the same centre of oscillation C1 and the centre of rotation O of the driving shaft;
- measuring two angles α1 and α2 representing respectively the angle between the straight lines joining together the centre of oscillation C1, C2 of the respective propulsion member 10 and the point E.
[0030] According to preferred embodiments the instantaneous operating parameters obtained by means of the calculation consist of: the swept volume of the engine; the direction of rotation of the driving shaft; the angular position of the driving shaft.
[0031] It is envisaged moreover that, by means of two successive measurements of the angles α1 and α2 performed at a predefined time interval it is also possible to obtain the instantaneous speed of rotation of the driving shaft by means of suitable processing of the said values of α1 and α2 within the time interval.
1. Method for determining the instantaneous operating parameters of a variable-volume
hydraulic engine, characterized in that it envisages the following steps:
a) representing within a reference system the position of the respective centre of oscillation (C1,C2) of at least two propulsion members 10 of the engine;
b) representing within the same reference system the centre of rotation (O) of the driving shaft;
c) detecting at least two parameters (s1,s2;s1,α1;α1,α2) able to allow determination of the position of the point (E) of eccentricity of the spherical body (6) of the driving shaft (7) with respect to the centre of rotation (O) of the said driving shaft and the two points (C1,C2) of oscillation of the respective propulsion member (10);
d) processing the two parameters detected in order to determine the position of the point of eccentricity (E) relative to the centre of rotation (O);
e) processing the data relating to the position of the point of eccentricity (E) in order to obtain at least one of the instantaneous operating parameters of the engine.
2. Method according to Claim 1, characterized in that said reference system is of the polar type.
3. Method according to Claim 1, characterized in that said reference system is of the Cartesian type.
4. Method according to Claim 1, characterized in that said two parameters (s1,s2) able to allow the determination of the position of the
point (E) of eccentricity are two length measurements.
5. Method according to Claim 4, characterized in that said two length parameters (s1,s2) respectively represent the distance (s1,s2) of
the centres of oscillation (C1,C2) of a respective propulsion member (10) from the
point of eccentricity (E) defined by the intersection of the two circumferences having
their centre at the respective centre of oscillation (C1,C2) and radius equal to the
said distance (s1,s2) respectively.
6. Method according to Claim 1, characterized in that said two parameters (s1,α2) able to allow determination of the position of the point
(E) of eccentricity are respectively a length and an amplitude of an angle.
7. Method according to Claim 6, characterized in that said two parameters (s1,α2) relating to the length and amplitude of an angle respectively
represent the distance (s1) of the centre of oscillation (C1) of a cylinder from the
point of eccentricity (E) and the angle (α1) between the straight line joining together
the centre of oscillation (C1) of the propulsion member and the point (E) of eccentricity
and the straight line joining together the said centre of oscillation and the centre
of rotation (O) of the driving shaft.
8. Method according to Claim 1, characterized in that said two parameters (α1,α2) able to allow determination of the position of the point
of eccentricity (E) are two angular amplitudes.
9. Method according to Claim 8, characterized in that said two angular parameters (α1,α2) respectively represent the angle between the
straight lines joining together the centre of oscillation (C1,C2) of the respective
propulsion member (10) and the point of eccentricity (E).
10. Method according to Claim 1, characterized in that said at least one instantaneous operating parameter calculated is the swept volume
of the engine.
11. Method according to Claim 1, characterized in that said at least one instantaneous operating parameter calculated is the direction of
rotation of the driving shaft.
12. Method according to Claim 1, characterized in that said at least one instantaneous operating parameter calculated is the angular position
of the driving shaft.
13. Method according to Claim 1, characterized in that it envisages further steps for detecting the angular position of the driving shaft
at two predefined moments of time so as to allow calculation of the speed of rotation
of the driving shaft.
14. Apparatus for determining the operating parameters of a variable-volume hydraulic
engine comprising a plurality of propulsion members (10) oscillating about a respective
centre of oscillation (Cn) and a spherical body (6) associated with the driving shaft
(7) and movable eccentrically (E) with respect to the centre of rotation (O) of the
latter, characterized in that it comprises at least two devices (50;150) each of which is respectively arranged
on an associated propulsion member (10) and is designed to detect a parameter able
to allow determination of the position of the point of eccentricity (E) of the driving
shaft (7) with respect to the centre of rotation (O) of the driving shaft and the
centres of oscillation (C1,C2) of said propulsion members (10), and a data processing
unit (1000) able to store the data detected and perform the necessary calculation.
15. Apparatus according to Claim 14, characterized in that said devices are proximity sensors (50) able to detect the distance (h) of the surface
of the associated propulsion member (10) from the sensor (50) itself.
16. Apparatus according to Claim 15, characterized in that said sensors (50) are arranged in position with the longitudinal axis parallel and
axially offset with respect to the longitudinal axis of the propulsion member (10).
17. Apparatus according to Claim 14, characterized in that said sensors are angular sensors (150) designed to detect the amplitude of an angle.
18. Apparatus according to Claim 17, characterized in that said angle is the angle of rotation of a pin (20) substantially perpendicular to
the axis of symmetry of the associated propulsion member (10) and constrained to a
pin (30) for supporting the said propulsion member, substantially parallel to the
said axis of symmetry of the latter.
19. Apparatus according to Claim 17, characterized in that said transverse pin (20) is contained inside a respective seat (21) of the cap (2)
of the engine with arrangement of sealing elements (22) in between.
20. Apparatus according to Claim 18, characterized in that the point of intersection (C1) between the respective axes of the transverse (20)
and the longitudinal pin (30) forms the centre (Cn) of the oscillating movement of
the respective propulsion member (10).
21. Apparatus according to Claim 14, characterized in that said detection devices are a proximity sensor (50) and an angular sensor (150).
22. Apparatus according to Claim 14, characterized in that said data processing unit (1000) is able to determine the swept volume of the engine.
23. Apparatus according to Claim 14, characterized in that said data processing unit (1000) is able determine the direction of rotation of the
driving shaft.
24. Apparatus according to Claim 14, characterized in that said data processing unit (1000) is able to determine the angular position of the
driving shaft.
25. Apparatus according to Claim 24, characterized in that said data processing unit (1000) is able to store the angular position of the driving
shaft at two predefined moments of time and subsequently calculate the speed of rotation
of the driving shaft.
26. Variable-volume hydraulic engine comprising a plurality of propulsion members (10)
oscillating about a respective centre of oscillation (Cn) and a spherical body (6)
associated with the driving shaft (7) and movable eccentrically (E) with respect to
the centre of rotation (O) of the latter, characterized in that it comprises at least two detection devices (50;150) each of which is arranged on
an associated propulsion member (10) and is designed to detect a parameter such as
to allow determination of the position of the point of eccentricity (E) of the driving
shaft (7) with respect to the centre of rotation (O) of the driving shaft and the
centres of oscillation (C1,C2) of said propulsion members (10), the motor having associated
therewith a data processing unit (1000) able to store the data detected by the devices
(50;150) and perform the necessary calculation.
27. Engine according to Claim 26, characterized in that said detection devices are proximity sensors (50) able to detect the distance (h)
of the surface of the associated propulsion member (10) from the sensor (50) itself.
28. Engine according to Claim 27, characterized in that said detection devices (50) are arranged in position with the longitudinal axis parallel
and axially offset with respect to the longitudinal axis of the propulsion member
(10).
29. Engine according to Claim 26, characterized in that said devices are angular sensors (150) able to determine the amplitude of an angle.
30. Engine according to Claim 29, characterized in that said angle is the angle of rotation of a pin (20) substantially perpendicular to
the axis of symmetry of the associated propulsion member (10) and connected to a pin
(30) for supporting the said propulsion member, substantially parallel to the said
axis of symmetry of the latter.
31. Engine according to Claim 30, characterized in that said transverse pin (20) is contained inside a respective seat (21) of the cap (2)
of the motor with the arrangement of sealing elements (22) in between.
32. Engine according to Claim 30, characterized in that the point (C1) of intersection between the respective axes of the transverse pin
(20) and the longitudinal pin (30) forms the centre (Cn) of the oscillating movement
of the respective propulsion member.
33. Engine according to Claim 26, characterized in that said detection devices are a proximity sensor (50) and an angular sensor (150).
34. Engine according to Claim 26, characterized in that said data processing unit (1000) is able to determine the swept volume of the engine.
35. Engine according to Claim 26, characterized in that said data processing unit (1000) is able to determine the direction of rotation of
the driving shaft.
36. Engine according to Claim 26, characterized in that said data processing unit (1000) is able to determine the angular position of the
driving shaft.
37. Engine according to Claim 26, characterized in that said data processing unit (1000) is able to store the angular position of the driving
shaft at two predefined moments of time and subsequently calculate the speed of rotation
of the driving shaft.