JP2002310062A - Hydraulic rotating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent noise of a detection signal of a line sensor so as to improve reliability by suitably setting dimensions of a recessed part to be detected provided in a cylinder block. SOLUTION: A plurality of recessed parts 15 to be detected are provided at spaces in the circumferential direction on the outer peripheral surface 6A of the cylinder block 6. When the cylinder block 6 is rotated, the recessed part 15 to be detected is detected by an electromagnetic pickup rotation sensor 14 to output a detection signal S, and the rotational frequency of the cylinder block 6 is measured. The circumferential dimension θ1 of the recessed part 15 to be detected is made larger than the circumferential dimension θ2 of a projecting part 16 positioned between the respective recessed parts 15 to be detected. Thus, the circumferential dimension θ2 of the projecting part 16 liable to cause noise in a detection signals when it faces to the rotation sensor 14 can be made smaller so that the rotational frequency of the cylinder block 6 can be detected with high accuracy by simple structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic rotating machine suitably used as, for example, a hydraulic pump, a hydraulic motor and the like.

[0002]

2. Description of the Related Art In general, a construction machine such as a hydraulic shovel is equipped with a hydraulic rotary machine such as a hydraulic pump used as a hydraulic source of hydraulic equipment and a hydraulic motor used as a driving source for traveling or turning. These hydraulic rotary machines are constituted by, for example, swash plate type, oblique shaft type or radial piston type hydraulic rotary machines.

A hydraulic rotary machine of this type according to the related art includes a casing, a rotating shaft rotatably provided in the casing, and a plurality of cylinders provided in the casing so as to rotate integrally with the rotating shaft. And a plurality of pistons reciprocally inserted into each cylinder of the cylinder block (for example, JP-A-2000-274378).

[0004] In the prior art hydraulic rotary machine,
For example, there is a type in which a rotation sensor is provided in order to control the operating speed. In this case, the rotation sensor is disposed so as to face the outer peripheral surface of the cylinder block, and a plurality of detected concave portions are provided at regular intervals on the outer peripheral surface of the cylinder block.

[0005] When the cylinder block rotates, the gap size (magnetic field) between the sensor and the cylinder block changes periodically as each detected concave portion passes through the position of the rotation sensor. A detection signal having an AC waveform corresponding to the magnetic field change is output to an external controller or the like.

Here, a signal waveform of a detection signal by the rotation sensor will be described with reference to FIGS.

First, in FIG. 4, a plurality of cylinders 102 are bored at intervals in a circumferential direction in a cylinder block 101 driven to rotate by a rotation shaft 100, and a piston 103 can reciprocate in each cylinder 102. It is inserted in. The outer peripheral surface 1 of the cylinder block 101
01A, a plurality of detected concave portions 104 and a plurality of convex portions 105 located between the detected concave portions 104 and constituted by the original outer peripheral surface 101A of the cylinder block 101 are alternately provided. .

The detected concave portion 104 has a predetermined circumferential dimension (center angle) θ1 ′, and the convex portion 105 has a circumferential dimension θ2 ′ formed larger than the circumferential dimension θ1 ′. (Θ2 ′> θ1 ′). In this case, the circumferential dimension θ
The dimensional ratio of 1 ′ and θ2 ′ is, for example, θ1 ′: θ2 ′ = 1: 2
Set to about.

Then, as shown in FIG. 5A, when the cylinder block 101 rotates in the direction of arrow A,
When the detected concave portion 104 approaches the rotation sensor 106, for example, as shown in FIG.
The detection signal S 'output from 06 has a mountain-shaped waveform having a negative polarity. As shown in FIG. 5B, when the detected concave portion 104 is separated from the rotation sensor 106, the detection signal S ′ has a mountain-like shape having a positive polarity as shown in FIG. It becomes a waveform.

Further, as shown in FIG. 5C, when the rotation sensor 106 faces the convex portion 105 between the detected concave portions 104, the detection is performed as shown in FIG. The signal S 'slightly deviates from zero (0 V) to the positive polarity side due to the influence of residual magnetism and the like. in this case,
The ratio between the time T1 'corresponding to the detected concave portion 104 and the time T2' corresponding to the convex portion 105 in the period T0 'of the detection signal S' is determined according to the dimensional ratio of the circumferential dimensions θ1 and θ2 '. Becomes

Then, as shown in FIG. 6, the controller compares the detection signal S 'from the rotation sensor 106 with predetermined positive judgment values V1 and V2, and turns ON and OFF according to the judgment result. Pulse-shaped shaped wave signal P 'to be turned off
Is formed, the detection signal S 'is shaped into a waveform, and its frequency (the reciprocal of the period T0') is determined by the cylinder block 10.
It is determined as the number of rotations of 1.

[0012]

In the prior art described above, since the rotation sensor 106 detects the unevenness of the cylinder block 101 with high accuracy, the gap between the projection 105 of the cylinder block 101 and the rotation sensor 106 is required. Is set small.

However, when the rotation sensor 106 faces the convex portion 105, even if the cylinder block 101 slightly fluctuates due to external vibration, impact or the like,
Since a relative dimensional change between the two becomes large, a large error easily occurs in a magnetic field formed between the rotation sensor 106 and the convex portion 105.

As a result, as shown in FIG.
The noise Sn 'is likely to occur at the timing shown in FIG. Moreover, at this time, the detection signal S 'is slightly offset to the positive polarity side due to the influence of residual magnetism and the like, so that the noise Sn' is equal to the determination value V for waveform shaping.
1, may exceed V2.

For this reason, in the prior art, the waveform of the noise Sn 'is shaped into a pulse P ", so that the frequency of the shaped wave signal P' is not the frequency of the correct cycle T0 'but the frequency of the cycle T0" including an error. Therefore, it is difficult to accurately detect the rotation speed of the cylinder block 101 unless the design specification of the controller is largely changed, and there is a problem that reliability is reduced.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to suppress the occurrence of noise and the like in a detection signal with a simple structure, and to stably increase the frequency with high accuracy. An object of the present invention is to provide a hydraulic rotary machine capable of measuring and improving reliability.

[0017]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a casing, a rotating shaft rotatably provided on the casing, and a casing inside the casing so as to rotate integrally with the rotating shaft. A cylinder block having a plurality of cylinders provided in the cylinder block and extending in the axial direction while being spaced apart in the circumferential direction; a plurality of pistons reciprocally inserted into each cylinder of the cylinder block; and an outer peripheral surface of the cylinder block. And a rotation detecting means for detecting the rotation of the cylinder block.

A feature of the structure adopted by the first aspect of the present invention is that a plurality of detected concave portions detected by the rotation detecting means when the cylinder block rotates are circumferentially spaced on the outer peripheral surface of the cylinder block. The outer peripheral surface of the cylinder block is formed as a convex portion with the outer peripheral surface between each of the detected concave portions, and the circumferential dimension of each of the detected concave portions is formed larger than the circumferential dimension of the convex portion. It is in.

With this configuration, the circumferential dimension of the convex portion formed by the original outer peripheral surface of the cylinder block can be formed smaller than the concave portion to be detected.
When the cylinder block rotates, the detection signal output by the rotation detection unit is likely to generate noise if the projection and the rotation detection unit face each other. By doing so, it is possible to reduce the time for which the convex portion and the rotation detecting means face each other, and it is possible to suppress the generation of noise.

According to the second aspect of the present invention, the thickness between the detected concave portion and the inner peripheral surface of the cylinder is determined by the thickness between the outer peripheral surface of the cylinder block and the inner peripheral surface of the cylinder. It is configured to be formed in the above size.

Thus, the thickness between the concave portion to be detected and the inner peripheral surface of the cylinder is equal to the thickness between the outer peripheral surface of the cylinder block and the inner peripheral surface of the cylinder at the position of the convex portion. Therefore, even when the circumferential size of the detected concave portion is large, the strength of the entire cylinder block including the portion where the detected concave portion is formed can be ensured.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A variable displacement swash plate type hydraulic pump will be described as an example of a hydraulic rotary machine according to an embodiment of the present invention, and will be described in detail with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a variable displacement swash plate type hydraulic pump mounted on a construction machine such as a hydraulic shovel. The hydraulic pump 1 is an operation pump housed in a tank (not shown) of the construction machine. The oil is discharged to the outside as high-pressure oil.

Reference numeral 2 denotes a casing of the hydraulic pump 1. The casing 2 includes a casing body 3 formed into a bottomed tubular shape from a bottom 3A and a tubular portion 3B, and a lid covering the open end side of the tubular portion 3B. And 4.

Reference numeral 5 denotes a rotary shaft rotatably provided on the casing 2, and the rotary shaft 5 is driven to rotate by a prime mover (not shown) mounted on a construction machine.

Reference numeral 6 denotes a cylinder block provided in the casing 2. The cylinder block 6 is formed of a metal material or the like into a substantially cylindrical shape as shown in FIGS. While being splined on the side,
It rotates integrally with the rotating shaft 5. Further, the cylinder block 6 has one side end face facing a swash plate 10 described later,
The other end surface is in sliding contact with a surface of a valve plate 12 described later.

Further, on the outer peripheral surface 6A of the cylinder block 6, detection concave portions 15 and convex portions 16 to be described later are provided alternately in the circumferential direction in substantially the same manner as in the prior art. In this case, the circumferential dimension θ1 of the concave portion 15 to be detected and the circumferential dimension θ2 of the convex portion 16 are inversely related to the circumferential dimensions θ1 ′ and θ2 ′ of the prior art, as shown in Expression 1 below. When the hydraulic pump is operated, the noise of the detection signal S output from the rotation sensor 14, which will be described later, is suppressed.

Numeral 7 denotes a plurality of cylinders formed in the cylinder block 6. Each of the cylinders 7 has a substantially constant interval (center) in the circumferential direction of the cylinder block 6 around the rotation shaft 5, as shown in FIG. (Angle) α, and extends in the axial direction of the cylinder block 6. Here, the front end side of each cylinder 7 is opened at one end face of the cylinder block 6, and the base end side is formed with cylinder ports 7A, 7A,... Which communicate with supply / discharge ports 12A, 12B described later.

Numeral 8 denotes a plurality of pistons slidably inserted in the respective cylinders 7. The respective pistons 8 slide and displace (reciprocate) in the cylinders 7 as the cylinder block 6 rotates. At this time, while sucking the oil liquid from the supply / discharge passage 13A side into the cylinder 7 via the cylinder port 7A, the sucked oil liquid is discharged to the supply / discharge passage 13B side as high-pressure oil. Are mounted on the protruding ends of the pistons 8 protruding from the cylinders 7 so as to be swingable, and these shoes 9 slide on the swash plate 10 in a circular orbit. Touching.

Reference numeral 10 denotes a swash plate provided in the casing 2 located on the side of the lid 4, and the swash plate 10 can be tilted to a swash plate support member 11 on the side of the lid 4 as shown in FIG. It is supported, and its front surface is a smooth surface on which the shoe 9 slides. The shoe 9 slides on the smooth surface of the swash plate 10 in a circular orbit, and reciprocates the piston 8 along the sliding surface of the cylinder 7.

A pair of legs 10A (only one of which is shown) formed of a convex curved surface is formed on the back side of the swash plate 10, and the front side of the swash plate support member 11 corresponds to these legs 10A. A pair of concave curved portions 11A (only one is shown) are formed. The swash plate 10 is driven to tilt in the directions indicated by arrows R1 and R2 in FIG. 1 by a tilt actuator (not shown) along the concave curved portion 11A of the swash plate support member 11.

Reference numeral 12 denotes a valve plate fixedly provided on the bottom portion 3A side of the casing body 3 so as to be in sliding contact with the other end surface of the cylinder block 6. The valve plate 12 has a pair of supply and discharge portions forming an eyebrow shape. Ports 12A and 12B are formed. These supply / discharge ports 12A, 12B intermittently communicate with the respective cylinders 7 in the cylinder block 6 via the cylinder port 7A, and suck the oil liquid in the tank into the cylinder 7 from the supply / discharge passage 13A. At the same time, high pressure oil is discharged from the supply / discharge passage 13B toward an external hydraulic actuator.

Reference numerals 13A and 13B denote a pair of supply / discharge passages formed on the bottom 3A side of the casing main body 3. Of these supply / discharge passages 13A and 13B, one supply / discharge passage 13A is a low pressure side pipe (not shown). ), And the other supply / discharge passage 13B is connected to a hydraulic actuator (not shown) via a high-pressure pipe.

Reference numeral 14 denotes a rotation sensor as rotation detection means for detecting the rotation of the cylinder block 6 by using a detection concave portion 15 described later. It is fixed to the casing 2 in a state facing the outer peripheral side of the cylinder block 6 via a predetermined gap.

When the cylinder block 6 rotates, the magnetic field changes between the cylinder block 6 and the rotation sensor 14 when each detected concave portion 15 passes through the position of the rotation sensor 14. Thus, the rotation sensor 14 detects a change in the magnetic field between them, and outputs a detection signal S having an AC waveform as shown in FIG.

Reference numeral 15 denotes a plurality of detected concave portions provided on the outer peripheral surface 6A of the cylinder block 6 as detection targets by the rotation sensor 14. Each of the detected concave portions 15 has, for example, an arc-shaped cross section as shown in FIG. It is formed as a radial depression. The detected concave portion 15 has an interval θ0 substantially the same as that of the related art in the circumferential direction of the cylinder block 6.
The interval θ0 is set to a value substantially equal to the interval α between the adjacent cylinders 7 (θ0 = α).
Further, the detected concave portion 15 is formed at a substantially intermediate position between the adjacent cylinders 7, and the bottom thereof has an angle of α /
It is arranged at a position shifted in the circumferential direction by two minutes.

The detected concave portion 15 is provided with a predetermined dimension θ1 in the circumferential direction of the cylinder block 6. The circumferential dimension θ1 is set to be larger than the circumferential dimension θ2 of the convex portion 16 described later, as shown in the following equation (1).

[0038]

[Equation 1] θ1> θ2

Thus, in the cylinder block 6, since the circumferential dimension θ2 of the convex portion 16 is formed smaller than that of the prior art, the convex portion 16 and the rotation sensor 14 face each other during the rotation. The time during which noise is easily generated in the detection signal S is shortened, and the generation of noise can be suppressed.

Numeral 16 designates a plurality of convex portions formed by the original outer peripheral surface 6A of the cylinder block 6 located between the respective concave portions 15 to be detected. And has a predetermined circumferential dimension θ2.

Here, the protrusion 16 of the cylinder block 6
The thickness dimension a between the outer peripheral surface 6A and the inner peripheral surface of the cylinder 7 is set to a predetermined value based on a design standard or the like which is almost the same as that of the prior art even at the thinnest position in the radial direction. Accordingly, the cylinder block 6 has sufficient strength against the hydraulic pressure in the cylinder 7 and the like. The thickness b between the detected concave portion 15 and the inner peripheral surface of the cylinder 7 is equal to or greater than the thickness a at the position of the convex portion 16 even at the thinnest position as shown in the following equation (2). The size of the cylinder block 6 is ensured, including the portion where the detected concave portion 15 is formed.

[0042]

## EQU2 ## b ≧ a

On the other hand, reference numeral 17 denotes a controller for calculating the number of revolutions of the cylinder block 6.
When the detection signal S is input from the rotation sensor 14 shown in FIG. 5, the waveform of the detection signal S is shaped on the positive polarity side by the later-described determination values Von and Voff, and a pulse-shaped shaped wave signal P
To form Further, the controller 17 controls the shaped wave signal P
Is measured, and the measurement result is displayed on the rotation speed display 18 as the rotation speed of the cylinder block 6.

The rotation speed detecting device of the hydraulic pump 1 according to the present embodiment has the above-described configuration, and its operation will now be described.

First, when the rotary shaft 5 is driven to rotate by a prime mover such as a diesel engine, the cylinder block 6 rotates in the casing 2, and the piston 8 repeats reciprocating motion in each cylinder 7, and the suction stroke and the discharge stroke Are sequentially performed. Then, in the suction stroke, the oil liquid in the tank is sucked into the cylinder 7 from the supply / discharge passage 13A side, and in the discharge stroke, the oil liquid in the cylinder 7 is converted into high pressure oil from the supply / discharge passage 13B to the external hydraulic actuator side. To be discharged.

When the cylinder block 6 rotates, an AC waveform detection signal S shown in FIG. 3 is output from the rotation sensor 14 to the controller 17, and the detection signal S
For example, when the detected concave portion 15 approaches the rotation sensor 14, the waveform portion Sa has a negative polarity, and when the detected concave portion 15 separates from the rotation sensor 14, the waveform portion has a positive polarity waveform portion Sb.

When the rotation sensor 14 faces the convex portion 16, the detection signal S becomes a waveform portion Sc having a slightly positive polarity. Also, the time T1 corresponding to the detected concave portion 104 in the period T0 of the detection signal S and the convex portion 105
Corresponds to the time T2 corresponding to the circumferential dimension θ1, θ2.

The detection signal S is a positive judgment value Von, Voff stored in advance by the controller 17.
The waveform is shaped using (Von> Voff) to form a pulse-shaped shaped wave signal P. In this case, the shaped wave signal P is
For example, it turns on when the waveform portion Sb of the detection signal S exceeds the determination value Von, and turns off when the waveform portion Sb becomes smaller than the determination value Voff. The frequency of the shaped wave signal P (the reciprocal of the period T0) is
Is displayed on the rotation speed display 18 as the rotation speed of the cylinder block 6.

The detection signal S whose frequency is thus measured is
The projection 16 of the cylinder block 6 and the rotation sensor 14
However, in the present embodiment, the circumferential dimension θ1 of the detected concave portion 15 is changed to the circumferential dimension θ2 of the convex portion 16 as shown in the equation (1).
Since it is formed larger, the time T2 at which the convex portion 16 and the rotation sensor 14 face each other can be shortened, and the output time of the waveform portion Sc can be shortened to suppress generation of noise in the detection signal S. .

Thus, according to the present embodiment, the circumferential dimension θ1 of the detected concave portion 15 provided on the outer peripheral surface 6A of the cylinder block 6 is changed to the circumferential dimension of the convex portion 16 constituted by the original outer peripheral surface 6A. Since it is configured to be larger than θ2, the protrusion 16
Can be formed small in the circumferential direction θ2.

Thus, when the cylinder block 6 rotates, the time during which the convex portion 16 and the rotation sensor 14 face each other, that is, the time T2 of the waveform portion Sc where the noise is likely to occur in the cycle T0 of the detection signal S is shortened. As a result, it is possible to reliably suppress the occurrence of noise having a large waveform in the detection signal S as in the related art.

Therefore, the rotation sensor 14 has a simple structure.
Can output a detection signal S with high accuracy, and this detection signal S
, The shaped wave signal P can be formed stably, and its frequency can be accurately measured, so that the reliability can be improved.

The thickness b between the concave portion 15 to be detected and the inner peripheral surface of the cylinder 7 should be equal to or greater than the thickness dimension a between the convex portion 16 (outer peripheral surface 6A) and the inner peripheral surface of the cylinder 7. Therefore, even when the detected concave portion 15 is formed larger than the conventional technology, sufficient strength can be given to the peripheral wall portion of the cylinder 7 at the position of the detected concave portion 15, and the cylinder block can be provided. 6 The overall strength can be ensured.

In the embodiment, the convex portion 16 of the cylinder block 6 is also provided with a certain circumferential dimension θ2. However, the present invention is not limited to this. A configuration may be adopted in which the convex portion located therebetween is formed as a sharp corner having a circumferential dimension almost equal to zero.

Further, in the embodiment, the variable displacement type swash plate type hydraulic pump 1 has been described as an example of the hydraulic rotary machine. However, the present invention is not limited to this, and for example, the variable displacement type oblique shaft type is provided. Or a radial piston type hydraulic pump or the like, or may be applied to a fixed displacement hydraulic pump. The present invention is also applicable to a variable displacement or fixed displacement hydraulic motor.

[0056]

As described above in detail, according to the first aspect of the present invention, since the circumferential dimension of the detected concave portion of the cylinder block is formed larger than that of the convex portion, when the cylinder block rotates, The time when the convex portion and the rotation detecting means face each other, that is, the time when noise is easily generated in the detection signal output from the rotation detecting means can be shortened, and large waveform noise occurs in the detection signal as in the related art. Can be reliably suppressed. Therefore, a highly accurate detection signal can be output from the rotation detecting means with a simple structure, and the frequency of the detection signal can be accurately measured as the rotation speed of the cylinder block, and the reliability can be improved.

According to the second aspect of the present invention, the thickness between the detected concave portion and the inner peripheral surface of the cylinder is determined by the thickness between the outer peripheral surface of the cylinder block and the inner peripheral surface of the cylinder. Since it is configured to be formed in the above size, even in a state where the detected concave portion is formed larger than the conventional technology, it is possible to give sufficient strength to the peripheral wall portion of the cylinder at the position of the detected concave portion, The strength of the entire block can be ensured.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a hydraulic pump according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a cylinder block and the like as viewed from the direction of arrows II-II in FIG.

FIG. 3 is a characteristic diagram illustrating a detection signal from a rotation sensor and a shaped wave signal.

FIG. 4 is an enlarged cross-sectional view of a cylinder block used in a conventional hydraulic rotating machine as viewed from the same position as in FIG.

FIG. 5 is an explanatory diagram showing a state in which a detected concave portion passes a position of a rotation sensor when a cylinder block rotates.

FIG. 6 is a characteristic diagram showing a detection signal and a shaped wave signal by a conventional rotation sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic pump (hydraulic rotary machine) 2 Casing 5 Rotating shaft 6 Cylinder block 6A Outer peripheral surface 7 Cylinder 8 Piston 10 Swash plate 12 Valve plate 12A, 12B Supply / discharge port 13A, 13B Supply / discharge passage 14 Rotation sensor (rotation detecting means) 15 Detected concave portion 16 Convex portion 17 Controller 18 Rotation speed display

Continuing on the front page (72) Inventor Tetsuya Sakairi 650, Kandachi-cho, Tsuchiura-shi, Ibaraki Prefecture F-term in the Tsuchiura Plant of Hitachi Construction Machinery Co., Ltd. BB11 BB30 CC03 CC51

Claims (2)

[Claims] 1. A casing, a rotating shaft rotatably provided on the casing, and a plurality of circumferentially spaced axially extending shafts provided in the casing so as to rotate integrally with the rotating shaft. A cylinder block having a cylinder, a plurality of pistons reciprocally inserted into each cylinder of the cylinder block, and rotation detection arranged to face an outer peripheral surface of the cylinder block and detecting rotation of the cylinder block A plurality of detected concave portions which are detected by the rotation detecting means when the cylinder block rotates on the outer peripheral surface of the cylinder block at intervals in a circumferential direction. The outer peripheral surface of each of the detected concave portions is formed as a convex portion between the detected concave portions, and the circumferential dimension of each of the detected concave portions is the convex shape. Hydraulic rotary machine, characterized in that it has a configuration larger than the circumferential dimension of the. 2. A thickness between the detected concave portion and an inner peripheral surface of the cylinder is set to be larger than a thickness between an outer peripheral surface of the cylinder block and an inner peripheral surface of the cylinder. The hydraulic rotary machine according to claim 1, which is configured.