Speed ​​detection for secondary-controlled axial piston motors

Abstract

Disclosed is an adjustable, secondary-controlled axial piston motor with a housing (1) in which an output shaft (2) is rotatably mounted with respect to an axis of rotation (3). The output shaft (2) is rotationally fixed to a cylinder drum (4) with respect to the axis of rotation (3), in which several working pistons (12) are linearly movable. According to the invention, a speed sensing device is provided for detecting the rotational speed of the output shaft (2).

Description

Technical field

[0001] The present disclosure relates to a secondary-controlled axial piston motor with adjustable displacement, which can also be called a hydrostatic motor. Secondary-controlled means consumer-controlled. Such an axial piston motor can be supplied and driven by a hydrostatic pump via a closed or open circuit, with the displacement of the axial piston motor being adjusted to control its operation. In this case, the hydrostatic pump can be unregulated.

[0002] The purpose of the present disclosure is to create an adjustable axial piston motor in which the secondary control is simplified and improved.

[0003] The problem is solved by an axial piston motor with the features of claim 1.

[0004] The claimed adjustable, secondary-controlled axial piston motor has a housing in which an output shaft is rotatably mounted with respect to an axis of rotation. The output shaft is rotationally fixed to a cylindrical drum in which several working pistons are linearly movable. According to the invention, a speed sensing device is provided for detecting the speed of the output shaft, which can also be referred to as a tachometer. This allows for improved secondary control, for example, when the axial piston motor is supplied by a pump that delivers a constant flow rate. In this case, the output speed can be set or regulated at the axial piston motor by adjusting the displacement volume and the speed is then reported back to an electronic control unit by the speed sensing device according to the invention.

[0005] In a preferred first concept, the speed detection device has a Hall sensor oriented approximately radially to the axis of rotation, and in a second concept, the speed detection device also has a Hall sensor oriented approximately axially to the axis of rotation. In both concepts, the Hall sensor is operatively connected to a structure mounted on a rotating circular cylindrical outer shell, which acts as an encoder. In both concepts, the structure has alternating raised and recessed areas.

[0006] In a first embodiment, the structure can be formed on the output shaft.

[0007] If the structure is formed at an end section or shaft journal of the output shaft, and if the first concept with the radial Hall sensor is to be used, a shaft toothing known from the prior art per se can be used, and for the axial piston motor according to the invention, for example, an output shaft can be used which can be used in another axial piston machine in an identical construction as a through-drive shaft.

[0008] The end section or shaft journal can be located inside the housing or protrude from the housing, in the latter case the structure can be formed on a rotary encoder flanged to the end section or shaft journal.

[0009] In other words, the output shaft can have an end section that also protrudes from the housing (especially from its mounting plate). This is then called a through-drive. In this case, the structure can also be formed by a rotary encoder flanged to the output shaft in the area of ​​the end section.

[0010] JP 2002-267679 A shows a sensor-like structure located approximately in the center of the outer circumference of the cylinder drum. US 8,677,884 B2 shows a sensor-like structure also located on the outer circumference of the cylinder drum, but at its distributor-side edge.

[0011] In contrast, in a second embodiment of the first concept of the invention, the structure can be formed on a circumferential circular cylindrical section of the cylinder drum, which is preferably facing away from a distributor disc. In the case of a swashplate design of the axial piston motor according to the invention, the structure is therefore adjacent to a pivoting cradle.

[0012] According to a third concept, pulsations are measured and converted into the rotational speed to be determined.

[0013] The speed detection device can thus detect a torque pulsation, which is converted into a rotational speed based on the number of working pistons (i.e., displacers). The torque pulsation can be detected, for example, using at least one strain gauge.

[0014] Alternatively, a pressure pulsation can be detected via the speed sensing device, which is (also) converted into a rotational speed via the number of working pistons (i.e., the displacers). The pressure pulsation can be detected in an additional volume located in a reversing zone, or it can be detected in a low-pressure zone.

[0015] A particularly preferred application of the axial piston motor according to the invention has a pivotable rocker arm for reversing the direction of rotation and is used in an open circuit and designed accordingly (e.g., as a traction motor, drive motor for a conveyor belt or for a rotary mechanism, or as a fan motor). The axial piston motor can preferably also be operated as a hydrostatic pump, e.g., to recover energy during braking. Therefore, the axial piston motor according to the invention can also be referred to as an axial piston machine.

[0016] In the following, two exemplary embodiments of the first concept, i.e., with the radial Hall sensor, are explained in more detail with reference to the figures. Brief description of the characters Fig. Figure 1 is a representation illustrating the two embodiments of the adjustable axial piston motor simultaneously in a perspective longitudinal section; and Fig. Figure 2 is a section of the longitudinal section of the axial piston engine. Fig. 1 for a more detailed illustration of the first embodiment. Description of the two exemplary embodiments

[0017] Fig. Figure 1 is a representation illustrating the two embodiments of the axial piston motor with adjustable displacement. It has a housing 1, which includes a housing pot 1a closed by a connecting cover 1b. An output shaft 2 is mounted in the housing pot 1a and in the connecting cover 1b, one end of which (in Fig. 1. The left outer end section has a shaft toothing for coupling a machine driven by the axial piston motor. The second (in Fig. The second end section (right) also features a splined shaft. This is also used for coupling to a machine when the identical drive shaft 2 is used in a different through-drive machine. In the axial piston motor shown here, the second end section of the output shaft 2 is housed inside the connection cover 1b and therefore does not protrude from the housing 1.

[0018] A cylindrical drum 4 is rotationally fixed to the output shaft 2 via a central shaft toothing, and is tensioned against a stationary distributor disc 8 by a spring 6. The distributor disc 8 is supported by the connection cover 1b, which contains a high-pressure channel (HD) and a low-pressure channel (ND).

[0019] The cylinder drum 4 has cylinder bores 10 evenly distributed around its circumference, each housing a working piston 12. Each working piston 12 is coupled via a piston shoe 14 to a swashplate 16 of a stationary pivoting cradle 18.

[0020] The tilting cradle 18 and thus the swashplate 16 can be adjusted in its inclination above 0 (swivelable) by means of an adjustment device not shown, in order to generate a reversal of the direction of rotation of the output shaft 2 without changing the high pressure channel HD and the low pressure channel ND.

[0021] Since the axial piston motor shown is to be supplied by a pump with a constant or unregulated flow rate, the axial piston motor is secondary-controlled or consumer-controlled. In the illustrated embodiment, this means that the inclination of the swashplate 16 is controlled in order to regulate the output speed of the output shaft 2.

[0022] To enable this control loop, the speed detection device according to the invention is provided, wherein in Fig. 1 Two different embodiments are shown simultaneously.

[0023] The first embodiment of the speed detection device according to the invention has a Hall sensor 20 which detects the change in the raised and recessed areas of a structure 22 arranged on the inner end section of the output shaft 2, which is located in the end plate 1b. This structure 22 is the shaft teeth of the inner end section of the drive shaft 2.

[0024] The second embodiment of the speed detection device according to the invention also has a Hall sensor 20, which detects the change in the elevations and depressions of a structure 122 arranged on the outer circumference of the cylinder drum 4. The structure 122 is arranged on the edge of the cylinder drum 4 that is adjacent to the swashplate 16 and thus on the opposite side from the distributor disc 8. The Hall sensor 20 is inserted in the housing 1a and extends radially to the cylinder drum 4 and thus to the drive shaft 2 and the axis of rotation 3. Due to the rotationally fixed coupling of the cylinder drum 4 to the drive shaft 2, the rotational speed of the drive shaft 2 is also detected with the second embodiment of the speed detection device according to the invention.

[0025] Fig. Figure 2 is a section of the longitudinal section of the axial piston engine. Fig.Figure 1 illustrates the first embodiment of the speed detection device according to the invention in more detail. As previously explained, the first embodiment has the Hall sensor 20, which is operatively connected to the structure 22 located on the inner end section of the output shaft 2, which is located in the end plate 1b. This structure 22 is the splined shaft of the drive shaft 2, which is used differently in the case of (identical) use in a different through-drive machine. The Hall sensor 20 is received in the end plate 1b and extends radially to the drive shaft 2 and to the axis of rotation 3.

[0026] The Hall sensor 20 is inserted into a through-hole 21 in the connection plate 1b. To seal the housing channel against the environment, a sealing ring 23 is provided between the Hall sensor 20 and the through-hole 21.

[0027] The axial piston motor according to the invention can also be used as an axial piston pump, so that the entire machine can also be referred to as an axial piston machine. In this case, the output shaft 2 acts as a drive shaft, so that the shaft can be referred to as a drive shaft.

[0028] This pump operation is particularly advantageous for enabling braking with the axial piston machine, for example when used in vehicle hydraulics. In this case, the rotational energy introduced via the drive shaft is converted into hydraulic energy. Reference symbol list 1 case 1a Housing pot 1b Connection plate 2 Drive shaft 4-cylinder drum 6 springs 8 Distributor disc 10 cylinder bore 12 working pistons 14 Piston shoe 16 Slanted disc 18 Swivel cradle 20 Hall sensor 21 Passage Exit 22; 122 Structure 23 Sealing ring HD high-pressure channel ND Low-pressure channel QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2002-267679 A

[0010] US 8,677,884 B2

[0010]

Claims

[1] Adjustable secondary-controlled axial piston motor with a housing (1) in which an output shaft (2) is rotatably mounted with respect to an axis of rotation (3), wherein the output shaft (2) is non-rotatably connected with respect to the axis of rotation (3) to a cylinder drum (4) in which several working pistons (12) are linearly movable, characterized by a speed detection device for detecting the speed of the output shaft (2). [2] Axial piston motor according to claim 1, wherein the speed detection device has a Hall sensor (20) which is aligned approximately radially to the axis of rotation (3) and which is in operative connection with a structure (22; 122) attached to a circumferential circular cylindrical outer shell which has alternating elevations and depressions. [3] Axial piston motor according to claim 1, wherein the speed detection device has a Hall sensor (20) which is aligned approximately axially to the axis of rotation (3) and which is in operative connection with a structure attached to an end face, wherein the structure has alternating elevations and depressions. [4] Axial piston motor according to claim 2 or 3, wherein the structure (22) is formed on the output shaft (2). [5] Axial piston motor according to claim 4, wherein the structure (22) is formed on an end section or shaft journal of the output shaft (2). [6] Axial piston motor according to claim 5, wherein the end section or shaft journal is arranged inside the housing (1). [7] Axial piston motor according to claim 5, wherein the end section or shaft journal protrudes from the housing (1), and wherein the structure is formed on a rotary encoder flanged to the end section or shaft journal. [8] Axial piston motor according to claim 2 or 3, wherein the structure (122) is formed on a circumferential circular cylindrical shell section of the cylinder drum (4), which is preferably facing away from a distributor disk (8). [9] Axial piston motor according to claim 1, wherein a torque pulsation can be detected via the speed detection device, which can be converted into a speed via the number of working pistons (12). [10] Axial piston motor according to claim 1, wherein a pressure pulsation can be detected via the speed detection device, which can be converted into a speed via the number of working pistons (12). [11] Axial piston motor according to claim 10, wherein the pressure pulsation is detected in an additional volume arranged in a reversing area, or wherein the pressure pulsation is detected in a low pressure area or low pressure channel (LP).

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