Patent Application
20100287926
The invention relates to a hydraulic pump/motor provided with a rotation sensor and a fan driving device.
Conventionally, a hydraulic pump driven by an engine and a hydraulic motor driven by oil are often used in a construction machine and the like.
For example, an axial swash plate hydraulic pump/motor is provided with a rotational shaft rotatably attached in a casing, a cylinder block rotating together with the rotational shaft, a plurality of pistons fittedly inserted into a plurality of cylinder holes formed on the cylinder block so as to be able to reciprocate, a swash plate provided in the casing so as to be tilted relative to the rotational shaft for supporting tip ends of the pistons so as to be able to slidingly contact, and a valve plate slidingly contacting a rear end face of the cylinder block, and is configured to distribute oil in the cylinder holes through a port provided on the valve plate.
When using the swash plate hydraulic pump/motor as the hydraulic pump, the cylinder block is rotated by rotate-driving the rotational shaft by the engine and the like and the piston is allowed to reciprocate, thereby pressurizing the oil sucked from a low-pressure side port to the cylinder hole by the piston to discharge from a high-pressure side port.
Also, when using the swash plate hydraulic pump/motor as the hydraulic motor, the oil is supplied from the high-pressure side port to the cylinder hole and the piston is protruded from the cylinder hole to press the swash plate, thereby rotating the rotational shaft together with the cylinder block.
As such swash plate hydraulic pump/motor, the one provided with a rotation sensor for detecting a rotational speed of the cylinder block is known (refer to the Patent Document 1).
Patent Document 1: Japanese Patent Application Laid-Open No. 2002-267679
The above-described swash plate hydraulic pump changes positions of the pistons that slide in the cylinder holes arranged on the same circle by rotating the cylinder block. Also, the swash plate hydraulic motor rotates the cylinder block by change of the positions of the pistons that slide in the cylinder holes with time by supply of high-pressure oil into the cylinder holes arranged on the same circle. Therefore, in both cases of the pump and motor, the rotation of the cylinder block is whirling.
When the swash plate hydraulic pump/motor illustrated in
The invention is achieved in view of the above circumstances, and an object thereof is to provide the hydraulic pump/motor capable of detecting the rotational speed of the cylinder block with high accuracy regardless of the whirling of the cylinder block.
According to an aspect of the present invention, a hydraulic pump/motor includes: a rotational shaft rotatably attached in a casing; a cylinder block rotating together with the rotational shaft; a plurality of pistons fittedly inserted into a plurality of cylinder holes formed on the cylinder block so as to be able to reciprocate; a swash plate provided in the casing so as to be tilted relative to the rotational shaft to allow tip ends of the pistons to slide so as to be able to slidingly contact the swash plate; a valve plate that slidingly contacting a rear end face of the cylinder block, wherein the hydraulic pump/motor distributes oil into the cylinder holes through a port provided on the valve plate; a detected unit formed on an outer circumferential surface of the cylinder block; and a rotation sensor arranged in the casing in a state opposed to the detected unit for detecting the detected unit. The rotation sensor is provided on a position corresponding to a position between a deepest portion of the cylinder hole and the rear end face of the cylinder block in an axial direction of the cylinder block.
Advantageously, in the hydraulic pump/motor, the rotation sensor is arranged in a plane including a line on a sliding surface of the swash plate orthogonal to an axis of the rotational shaft and the axis.
According to another aspect of the present invention, a fan driving device includes: a hydraulic motor including a rotational shaft rotatably attached in a casing in a state in which a tip end of the rotational shaft protrudes from the casing, a cylinder block rotating together with the rotational shaft, a plurality of pistons fittedly inserted into a plurality of cylinder holes formed on the cylinder block so as to be able to reciprocate, a swash plate provided in the casing so as to be tilted relative to the rotational shaft to allow tip ends of the pistons to slide so as to be able to slidingly contact the swash plate, and a valve plate slidingly contacting a rear end face of the cylinder block, the hydraulic motor for distributing oil in the cylinder holes through a port provided on the valve plate; a bracket provided with a planar base portion having a through-hole to which the hydraulic motor is attached in a state in which a tip end of the rotational shaft is arranged on a surface side of the base portion by fittedly inserting the casing into the through-hole; and a fan attached to the tip end of the rotational shaft and is driven by the hydraulic motor. The hydraulic motor includes a plurality of detected units provided on an outer circumferential surface of the cylinder block, and a rotation sensor arranged in the casing in a state opposed to a portion between a deepest portion of the cylinder hole and the rear end face of the cylinder block in an axial direction of the cylinder block for detecting the detected units, and the fan driving device attached to the bracket in a state in which the rotation sensor is located on a rear surface side of the base portion.
Advantageously, in the fun drive device, the hydraulic motor is attached to the bracket in a state in which the rotation sensor is brought closer to a rear surface of the base portion.
Advantageously, in the fun drive device, the rotation sensor is arranged in a plane including a line on a sliding surface of the swash plate orthogonal to an axis of the rotational shaft and the axis.
The hydraulic pump/motor and the fan driving device of the invention are configured such that the detected unit is formed on the outer circumferential surface of the cylinder block and the rotation sensor for detecting the detected unit is provided on the position corresponding to the position between the deepest portion of the cylinder hole and the rear end face of the cylinder block in the axial direction of the cylinder block. Since an arranging position of the rotation sensor is on a base end side of the rotational shaft, this is less affected by the whirling of the cylinder block. Therefore, the distance between the rotation sensor and the detected unit is maintained substantially constant regardless of the whirling of the cylinder block. As a result, the detection accuracy of the rotational speed of the cylinder block may be improved as compared to the conventional one.
Further, the fan driving device of the invention is configured such that the hydraulic motor is attached to the bracket in a state in which the rotation sensor is located on a rear surface side of the bracket. As a result, it is possible to prevent dust and mud entering from outside by the rotation of the fan from attaching to the rotation sensor.
A preferred embodiment of a hydraulic pump/motor and a fan driving device of the invention is hereinafter described in detail with reference to the attached drawings. Meanwhile, in the following embodiment, an example in which the hydraulic pump/motor of the invention is applied to a swash plate hydraulic motor and the swash plate hydraulic motor is applied to the fan driving device is described.
A fan driving device 60 illustrated in
The hydraulic motor 10 converts oil supplied from a hydraulic pump 2 (refer to
The bracket 61 is a plate-like member to which the hydraulic motor 10 is attached. The bracket 61 is composed of a base portion 65 formed into an elongated flat plate shape of which dimension in a longitudinal direction is substantially the same as dimension of the radiator 80, and a side wall portion 66 formed into a flat plate shape bent from both side edges of the base portion 65 backward at a right angle. A through-hole 64 for attaching the hydraulic motor 10 is formed on a central part of the base portion 65.
As illustrated in
The fan 62 is composed of a fan boss 67 and a plurality of blades 68. Each of the blades 68 is fastened to the fan boss 67 by a bolt and the fan boss 67 is fastened to the rotational shaft 13 of the hydraulic motor 10 by a bolt 72, and when driving the hydraulic motor 10, the fan 62 rotates.
The shroud 63 is a square frame-shaped member as seen from front installed so as to enclose the fan 62 in order to improve blast performance of the fan 62, and is attached to the radiator 80 and the bracket 61 using appropriate means. A circular opening 69 is provided on a central part of the shroud 63 as illustrated in
In the fan driving device 60 having the above-described configuration, the fan 62 rotates when the hydraulic motor 10 is driven, air of which temperature is low sucked by the rotation of the fan 62 passes through the radiator 80, thereby promoting thermal exchange of the radiator 80.
Next, the hydraulic motor 10 that drives the fan 62 is described in detail with reference to
The casing 11 accommodates the rotational shaft 13, the cylinder block 14, the valve plate 16 and the swash plate 17 inside thereof and is formed into a cylindrical shape composed of a cylindrical portion 21 of which one end is opened and an end wall portion 22. Hereinafter, an end wall portion 22 side and an opening side of the casing 11 are referred to as a “tip end side” and a “rear end side”, respectively. As illustrated in
The end cover 12 is a lid body that blocks the opening on the rear end side of the casing 11. A direction switching valve 1 is incorporated in the end cover 12 to switch supply/discharge directions of oil from the hydraulic pump 2 by switching a spool la. An oil seal 23a is provided between the end wall portion 22 of the cylindrical portion 21 and the rotational shaft 13 in the casing 11. Also, an oil seal 23b is provided between the casing 11 and the end cover 12. The oil is enclosed in the casing 11 by the oil seals 23a and 23b.
The rotational shaft 13 is rotatably supported by the casing 11 and the end cover 12 through bearings 24a and 24b, respectively. Meanwhile, in a following description, a side on which the rotational shaft 13 is supported by the bearing 24a is referred to as a “base end side” of the rotational shaft and a side on which the rotational shaft 13 is supported by the bearing 24b is referred to as a “tip end side” of the rotational shaft. As illustrated in
The cylinder block 14 is coupled to the rotational shaft 13 through a spline 26 to be rotated integrally with the rotational shaft 13 in the casing 11. The cylinder block 14 is arranged such that an end face 27 on a tip end side (hereinafter, referred to as a “tip end face 27”) is opposed to the swash plate 17 and an end face 28 on a rear end side (hereinafter, referred to as a “rear end face 28”) slidingly contacts a surface of the valve plate 16, and is rotatable while contacting the valve plate 16. A plurality of cylinder holes 29 are provided on the cylinder block 14 at regular intervals in a circumferential direction around an axis of the cylinder block 14 and so as to be parallel to the rotational shaft 13, as illustrated in
The piston 15 is fittedly inserted into each cylinder hole 29 so as to be able to reciprocate. The piston 15 presses the swash plate by supply of the oil into the cylinder hole 29, thereby generating the rotational force in the cylinder block 14 by force of a rotational direction component generated when pressing the swash plate 17. As illustrated in
The valve plate 16 is formed into a circular plate shape and is fixed to the end cover 12 so as to slidingly contact the rear end face 28 of the cylinder block 14. The valve plate 16 is provided with elongated hole-shaped supply/discharge ports 31, 31 formed along the circumferential direction as illustrated in
The swash plate 17 is provided between the end wall portion 22 of the casing 11 and the cylinder block 14 and has a flat sliding surface S tilted at a predetermined angle in a plane parallel to the X-Y plane, as illustrated in
In the hydraulic motor 10 having the above-described configuration, as illustrated in
Next, the rotation sensor 50 provided in the above-described hydraulic motor 10 and a detected unit 52 detected by the rotation sensor 50 are described in detail.
As illustrated in
The rotation sensor 50 is provided with a detecting unit 51 that detects the detected unit 52 provided on an outer circumferential surface of the cylinder block 14. The detecting unit 51 is fixed to the casing 11 in a state opposed to the detected unit 52 at a regular interval. A detection result by the detecting unit 51 is transmitted to a calculating unit not illustrated. The calculating unit calculates the rotational speed of the cylinder block 14 based on the detection result by the detecting unit 51.
As the above-described rotation sensor 50, an electromagnetic pick up sensor using an MR element (magnetoresistance effect element) and a Hall element, for example, may be applied. The electromagnetic pick up rotation sensor is a general sensor having a structure obtained by winding a coil around a permanent magnet and detects change in magnetic flux between the detecting unit and the detected unit.
The detected unit 52 is a gear-shaped concavo-convex portion formed by cutting the concave portions 53 at regular intervals across the entire circumference of the outer circumferential surface of the cylinder block 14 as illustrated in
When the cylinder block 14 rotates, the concave portion 53 and a convex portion 54 of the detected unit 52 pass through the position of the rotation sensor 50, thereby periodically changing distance (magnetic field) between the detecting unit 51 and the detected unit 52. The detecting unit 51 of the rotation sensor 50 outputs alternating-current voltage generated by change in the magnetic field as a signal and transmits the signal to the calculating unit. The calculating unit shapes the alternating-current voltage into a pulse and counts a pulse number to calculate the rotational speed of the cylinder block 14 (that is to say, the rotational speed of the fan 62).
The above-described arranging position of the rotation sensor 50 is described in more detail. As illustrated in
Herein, the “rear end side of the casing” is a position opposed to a position between a deepest portion 41 of a portion in which an inner diameter of the cylinder hole 29 is a piston diameter and the rear end face 28 of the cylinder block 14 in an axial direction of the cylinder block 14. A reason to arrange the rotation sensor 50 on the rear end side of the casing 11 is as follows. The base end side and the tip end side of the rotational shaft 13 are supported by the bearings 24a and 24b, respectively. Therefore, runout of the rotational shaft 13 by whirling is the largest at a central part between the base end side and the tip end side. Therefore, when the detecting unit 51 is provided on the base end side of the rotational shaft 13 as illustrated in
Also, as described above, the hydraulic motor 10 rotates the cylinder block 14 by changing a position of the piston 15 that slides in the cylinder holes 29 arranged on the same circle with time. Therefore, the whirling of the cylinder block 14 is generated in a direction of a maximum tilt angle of the swash plate 17, that is to say, in the X-Y plane illustrated in
Herein, the “X-Z plane” is the plane including both of a line on the sliding surface S of the swash plate 17 orthogonal to an axis 13a of the rotational shaft 13 and the axis 13a. That is to say, the “line on the sliding surface S of the swash plate 17 orthogonal to the axis 13a” is the line orthogonal to a line in the direction of the maximum tilt angle of the swash plate 17. In other words, the “plane including both of the line on the sliding surface S of the swash plate 17 orthogonal to the axis 13a and the axis 13a” is the plane orthogonal to the plane including both of the line in the direction of the tilt angle on the sliding surface S of the swash plate 17 and the axis 13a (X-Y plane in
When the rotation sensor 50 is arranged in the X-Z plane orthogonal to the X-Y plane, the effect of vibration in the X-Y direction of the cylinder block 14 may be minimized. Meanwhile, the “plane including both of the line on the sliding surface of the swash plate orthogonal to the axis of the rotational shaft and the axis” includes a plane obtained by rotating the X-Z plane illustrated in
Meanwhile, when applying the variable displacement type in which the tilt angle of the swash plate 17 may be changed, the above-described X-Z plane means the plane including both of an axis of a swash plate rotating shaft for tilting the swash plate 17 (not illustrated) and the axis 13a of the rotational shaft 13.
In response to the arrangement of the detecting unit 51 of the rotation sensor 50 on the rear end side of the casing, the detected unit 52 is formed between the deepest portion 41 of the portion in which the inner diameter of the cylinder hole 29 is the piston diameter and the rear end side end face 28 of the cylinder block 14 in the axial direction of the cylinder block 14. As illustrated in
As illustrated in
Also, when the fan driving device 60 illustrated in
Meanwhile, when the fan driving device 60 is driven, dust and mud are sucked with air from outside. The dust and mud pass through the radiator 80, the fan 62 and the opening 69 of the shroud 63. However, as illustrated in
As described above, the fan driving device 60 of the embodiment has a configuration in which the detected unit 52 is provided on the outer circumferential surface of the cylinder block 14 in the hydraulic motor 10 that drives the fan 62 and the rotation sensor 50 that detects the detected unit 52 is provided on the position corresponding to the position between the deepest portion 41 of the cylinder hole 29 and the cylinder block rear end face 28 in the axial direction of the cylinder block 14. With the above-described configuration, the distance between the rotation sensor 50 and the detected unit 52 may be maintained substantially constant regardless of the whirling of the cylinder block 14. As a result, detection accuracy of the rotational speed of the cylinder block may be improved as compared to the conventional one, and it becomes possible perform the fan control with high accuracy.
Also, the fan driving device 60 of the embodiment has a configuration in which the detecting unit 51 of the rotation sensor 50 is arranged in the plane including both of the line on the swash plate 17 orthogonal to the axis 13a of the rotational shaft 13 of the hydraulic motor 10 and the axis 13a. With the above-described configuration, this is less affected by the whirling of the cylinder block 14 in the X-Y plane. As a result, the detection accuracy of the rotational speed of the cylinder block may be further improved.
Also, according to the fan driving device 60 of the embodiment, since the above-described detected unit 52 is formed to be the thick portion between the deepest portion 41 of the portion in which the inner diameter of the cylinder hole 29 is the piston diameter and the rear end side end face 28 of the cylinder block 14 in the axial direction of the cylinder block 14, the cut process may be performed easily. Also, it is possible to increase the number of the concave portions 53 to be formed regardless of the number of the cylinder holes 29, so that the detection accuracy of the rotational speed of the cylinder block 14 may be further improved.
Further, according to the fan driving device 60 of the embodiment, since it is configured such that the hydraulic motor 10 is attached to the bracket 61 in a state in which the above-described rotation sensor 50 is brought closer to the rear surface of the base portion 65, the vibration transmitted to the rotation sensor 50 when driving the hydraulic motor may be minimized, so that possibility of breakdown by the vibration of the rotation sensor may be made smaller.
In addition, according to the fan driving device 60 of the embodiment, it is configured such that the hydraulic motor 10 is attached to the bracket 61 in a state in which the above-described rotation sensor 50 is located on the rear surface side of the bracket 61, so that it is possible to prevent the dust and mud entering from the outside from attaching to the rotation sensor 50.
Meanwhile, although the case in which the hydraulic pump/motor of the invention is applied to the fan driving device is described in the above-described embodiment, the invention is not limited thereto, and may be applied to another driving device or swash plate hydraulic pump.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-016739 | Jan 2008 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2008/073287 | 12/22/2008 | WO | 00 | 7/20/2010 |
