JPH03194179A - Piston/cylinder clearance evaluating device for oil-hydraulic operating device - Google Patents

Abstract

PURPOSE:To enhance the reliance upon evaluating the clearance between a piston and a cylinder by measuring the time required for the piston to be intruded for a certain distance into the cylinder filled with a working oil, and thus performing the evaluation of the clearance. CONSTITUTION:To evaluate the clearance between a piston (b) and cylinder (a) of a swash plate type piston pump, first the cylinder (a) is fixed to a holding jig 9, and a cylinder hole (e) is filled with working oil (f). In this condition the bottom of the piston (b) is inserted in the cylinder hole (e), and a drive motor 19 is operated to rotate the cylinder (a) along with the holding jig 9 and rotary shaft 8. This is followed by releasing the hole of an elevating/sinking plate 24, etc., made by an elevating/sinking cylinder 27, and a push rod 26 is sunk by the own weight of a weight 25 toward the piston (b) together with this elevating/sinking plate 24. At this time, a measuring means 4 measures the time required for the piston (b) to be intruded a certain distance into the cylinder hole (e), and the clearance is evaluated from this intruding time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for evaluating the clearance between a piston and a cylinder of a hydraulic actuating device such as a swash plate type piston pump or a swash plate type piston motor.

(Prior Art) Hydraulic actuating devices such as swash plate type piston pumps and swash plate type piston motors are used in so-called H3 for agricultural machinery such as lawn mowers.
It has been conventionally used in hydraulic transmission devices such as T (hydrostatic transmission).

As is well known, this type of hydraulic actuation device includes a cylinder that is rotatably provided around a rotary wheel, and a plurality of cylinder holes that are bored in the cylinder approximately parallel to the rotary wheel. For example, in a swash plate type piston pump, each piston is sequentially reciprocated along the swash plate while rotating around a rotation axis together with the cylinder. By doing so, the hydraulic oil is pushed out from the suction side to the discharge side.

On the other hand, in the HST and the like, this type of hydraulic actuating device operates at high pressure and high speed, so a proper clearance is required between each piston and cylinder inserted into each cylinder hole. If the clearance is smaller than necessary, the sliding resistance of the piston increases and the operability of the hydraulic actuator decreases. For this reason, in the manufacturing process of such a hydraulic actuating device, the clearance is usually measured, and it is evaluated whether the clearance is within an appropriate range.

Conventionally, such an evaluation method involves holding the cylinder fixed, filling each cylinder hole with hydraulic oil, and pushing each piston into the cylinder hole with a constant load. There is a known method of measuring the pushing speed of the piston, which has a certain correlation, and evaluating the clearance from the pushing speed. In this evaluation method, each piston is simply pushed into the cylinder hole of a fixedly held cylinder, so the clearance can be evaluated relatively easily. If different, the average clearance between each piston and cylinder is evaluated.

However, in the hydraulic actuating device, since the cylinder rotates around the rotation axis when the hydraulic actuating device is operated, each piston reciprocates while rotating with respect to the cylinder. The effective resistance at any given time may differ from the average resistance described above. For example, if the cylinder hole has a high roundness and each piston has an elliptical cross-section and a low roundness, the effective clearance of each piston during operation of the hydraulic actuator will be approximately It is given by the difference between the maximum radius and the radius of the cylinder hole, and is different from the above average clearance.

Therefore, even if the clearance between the cylinder and each piston is evaluated to be within the appropriate range using the evaluation method described in Section 2, the effective clearance during operation of the hydraulic actuator may not be within the appropriate range. However, there was a risk that the operability of the hydraulic actuator would deteriorate.

(Problems to be Solved) The present invention eliminates such inconveniences and makes it possible to easily evaluate the clearance between the cylinder and the piston in a hydraulic actuating device in accordance with the actual operating state of the hydraulic actuating device. The purpose is to provide equipment.

(Means for Solving the Problems) In order to achieve the above object, the clearance evaluation device between a piston and a cylinder in a hydraulic actuating device of the present invention is rotatably provided around a rotation axis, and the device is rotatable around a rotation axis. A cylinder of a hydraulic actuating device, comprising a cylinder having a plurality of cylinder holes formed around the rotation axis substantially parallel to the rotation axis, and a piston slidably inserted into each cylinder hole via hydraulic oil. and a device for evaluating the clearance between each piston, comprising: a holding means for holding the cylinder rotatably around the axis of one cylinder hole; a pushing means that applies a constant load (-1) to the other end of the piston in order to push the piston, one end of which is inserted into the cylinder hole while being filled with hydraulic oil, into the cylinder hole; Rotating means for rotating the cylinder around the axis of the cylinder hole;
It is characterized by comprising a measuring means for measuring a pushing speed of the piston that has a substantially constant correlation with the clearance between the piston and the cylinder, and the clearance is evaluated based on the correlation from the pushing speed.

(Operation) According to this means, when evaluating the clearance between the cylinder and each piston of the hydraulic actuating device,
First, the cylinder is held rotatably around the axis of the one cylinder hole by the holding means, and
The cylinder hole is filled with hydraulic oil, and in this state, one end of the piston is inserted into the cylinder hole.

Next, the cylinder is rotated around the axis of the cylinder hole by the rotation means, and in this state, a constant load is applied to the other end of the piston by the pushing means, thereby causing the piston to move into the cylinder. It is pushed into the cylinder hole while rotating relative to the cylinder. At this time, the pushing speed of the piston is measured by the measuring means, and the clearance between the cylinder and the piston is evaluated from the pushing speed.

Then, by repeating the above operations for each cylinder hole and each piston of the cylinder, the clearance between each piston and cylinder of the hydraulic actuator is evaluated.

(Example) An example of a clearance evaluation device between a piston and a cylinder in a hydraulic actuating device of the present invention will be described with reference to FIGS. 1 to 4. Figure 1 shows, for example, a swash plate type piston pump or a swash plate type bis I.
2 is a side view of an example of the clearance evaluation device of the present invention, FIG. 3 is an explanatory cross-sectional view of the main portion, and FIG. 4 shows an evaluation method using the clearance evaluation device. It is a line diagram for explanation.

In FIG. 1, a hydraulic actuator A includes a cylinder a and a plurality of pistons b.

Cylinder a has a shaft hole C drilled in its center,
For example, the rotation axis d of the input shaft or output shaft of H3T is connected to the shaft hole C.
It is fitted into and is rotatable integrally with the rotation axis d. A plurality of cylinder holes e are bored around the shaft hole C in parallel with the shaft hole C, and these cylinder holes e are arranged at equal intervals in the circumferential direction.

Each piston b is formed into a hollow cylindrical shape with one end closed, and is slidably inserted into each cylinder hole e of the cylinder a via a spring or the like (not shown). The hydraulic oil f is inside each cylinder hole e and each piston b.
For example, if the hydraulic actuating device A is a swash plate type piston motor, each piston b reciprocates due to the hydraulic pressure of the hydraulic oil f, and as a result, the cylinder a moves around the rotation axis d. Rotate to.

In FIGS. 2 and 3, 2 indicates a holding means for holding the cylinder a, and 2 indicates a state in which one of the cylinder holes e of the cylinder a held by the holding means 1 is filled with hydraulic oil f. 3 is a pushing means for applying a constant load to the piston b in order to push the piston b into the cylinder hole e; 3 is a rotating means for rotating the cylinder a held by the holding means 1 when the piston b is pushed; 4 is a measuring means for measuring the pushing speed of the piston b.

The holding means 1 includes a cylindrical body 7 that is vertically fitted onto a base 6 provided on a fixed frame 5, a rotation shaft 8 that is inserted through the cylindrical body 7, and The rotating shaft 8 is rotatably supported on the cylinder body 7 via a plurality of bearings 10 provided in the cylinder body 7 as shown in the third figure. has been done.

As shown in the third figure, the holding jig 9 is fixed via a port 12 on a plate Il fixed to the upper end surface of the rotating shaft 8 protruding from inside the cylindrical body 7, and is integrally attached to the rotating shaft 8. It is said to be able to rotate freely around its axis. A recess 13 into which the cylinder a can be inserted is formed on the upper surface of the holding jig 9.
At the center of the bottom surface, a holding rod 14 that can be inserted into the shaft hole C of the cylinder a is located at a position where there is a distance between the shaft hole C of the cylinder a and each cylinder hole 0 with respect to the axis of the rotating shaft 8. It is erected. Further, a pad 15 is attached to the bottom surface of the recess 13 of the holding jig 9.

This holding means 1 is constructed by inserting a holding rod 14 into a shaft hole C of a cylinder a as shown in phantom lines in FIG. By screwing a nut 16 toward the cylinder a into the threaded portion 14a formed at the upper end of the holding rod 14 protruding from the shaft hole C of the cylinder a, the cylinder a is fixed in pressure contact with the pad 15. I try to keep it. In this case, the cylinder a is fixedly held at a position where one of its cylinder holes e is concentric with the rotating shaft 8, and is integrally formed with the holding jig 9 around the axes of the cylinder hole e and the rotating shaft 8. It is said to be rotatable.

The holding jig 9, the plays 1 to 11, etc. are housed in a case body 17 fixed on the base 6 as shown in the third figure, and are inserted into the opening hole 17a formed in the top plate of the case body 17. The recess 13 of the holding jig 9 opens to the outside through the opening hole 17a, and the holding rod 14 projects upwardly from the case body 17 through the opening hole 17a.

The rotating means 3 includes a drive motor 19 that is fixed vertically below the holding means 1 at the lower end of a bracket 18 fixed to the lower surface of the base 6, as shown in the third figure. A drive shaft 19a of the drive motor 19 extends concentrically toward the rotation shaft 8 and is connected to the rotation shaft 8 via a connecting portion 20. The rotation means 3 is driven by a drive motor 19
By applying rotational driving force to the rotation shaft 8 through the drive shaft 19a, the holding jig 9 is rotated about the axis of the rotation shaft 8.

The pushing means 2 includes a pair of columns 21 and 21 erected on the base 6 with the case body 17 in between, as shown in the second figure.
and a stepped portion 21a at the upper end of both struts 21.21.

A pair of guide rods 23.23 are erected via the screw portion 21a and the threaded portion 22.22, and both guide rods 232.
3, a weight 25 of a predetermined weight mounted on the elevating plate 24, and a bushing rod 26 extending vertically from the elevating plate 24 toward the holding jig 9. and an elevating cylinder 27 that holds the weight 25 and bushing rod 26 so as to be movable up and down via an elevating plate 24.

A fixing plate 28 is fitted into the upper end of each column 21, 21, and is horizontally supported by both columns 2], 21 via their stepped portions 21a, 21a, and further includes:
The screw portion 222 protrudes above the fixing plate 28
2) 29. Both struts 2] by 29.
It is fixed at 21. And the fixed plate 28
A cylindrical body 30 is fitted therein concentrically with the rotating shaft 8 of the holding means 1.

The guide rod 23.23 is provided integrally with the support column 21.21, and its upper end is fixed to an upper frame 31a of a fixed frame 31 fixedly installed on the base 6.

The weight 25 is made up of a plurality of annular weights 32 stacked concentrically, and is mounted on the elevating plate 24 by being inserted into a fitting rod 33 erected at the center of the elevating plate 24. Further, the weight 25 is fixed to the lifting plate 24 by a pole 34, 34 inserted from the upper surface of the weight 25 toward the lifting plate 24, and is movable up and down together with the lifting plate 24.

The bushing rod 26 is connected to the lifting play 1 as shown in the third diagram.
-24 slideably penetrates the cylinder 30 from the lower surface of the holding means 1, extends toward the holding jig 9, and is movable up and down integrally with the lifting plate 24 on the axis of the rotating shaft 8 of the holding means 1. ing.

The lifting cylinder 27 is connected to the fixed frame 31 as shown in the second figure.
A telescopic piston rod 27a is fixedly installed on the upper frame 31a of the upper frame 31a, and a telescopic piston rod 27a extends toward the fitting rod 33 under the upper frame 31a. It is engaged with the upper end of the insertion rod 32. The elevating cylinder 27 is connected to a control device 36 fixed to the sides of the fixed frame 5 and the base 6, and its operation is controlled by the control device 36.

This pushing means 2 controls the lifting cylinder 27 by a control device 36.
The piston rod 2 of the lifting cylinder 27 is controlled by
By holding 7a in a non-extensible manner, the elevating plate 24, weight 25 and bushing rod 26 are held in a non-elevating manner as shown by solid lines in FIG. and,
In the pushing means 2, the cylinder a is held by the holding means 1 as described above, and the lower end of the piston b is inserted into the cylinder hole e on the axis of the rotating shaft 8 of the holding means 1. In this state, the elevating plate 24 by the elevating cylinder 27
By releasing the holding of the elevating plate 24, etc.
The bushing rod 26 is lowered toward the holding jig 9 by the weight of the weight 25 as shown by the imaginary line in the figure.

In FIG. 2, 37 is a limit switch for detecting the position of the lifting plate 24, and the limit switch 37 is fixed to the guide rod 23 via a bracket 38.

The measuring means 4 is connected to the control device f as shown in the second diagram.
When the piston b is inserted into the cylinder hole e of the cylinder a by the pushing means 2 as described later, the time from the start to the end of the insertion is measured by, for example, a pulse generator or the like (not shown). (not).

Next, the operation of such a clearance evaluation device will be explained with reference to FIGS. 2 to 4.

When evaluating the clearance between the cylinder a and each piston 75, first, as described above, the cylinder a is fixedly held on the holding jig 9 of the holding means 1, and then the rotation axis 8 of the holding means l is The hydraulic oil f is filled into the cylinder hole C located on the axis of the cylinder. In this state, the lower end of one piston b is inserted into the cylinder hole e as shown by the imaginary line in FIG. It is rotated together with the tool 9 and the rotation shaft 8 about the axis of the rotation shaft 8. At this time, the cylinder a
Since the piston b inserted into the cylinder hole e is located on the axis of the rotation shaft 8, it rotates relative to the cylinder a.

Next, the lifting cylinder 27 of the pushing means 2 releases the holding of the lifting plate 24, etc., and the bushing rod 26 is lowered together with the lifting plate 24 toward the piston b by the weight of the weight 25.

At this time, the tip end surface of the bushing rod 26 comes into contact with the top end surface of the piston b during its descent, and the bushing rod 26
As the piston b further descends, the piston b is pushed into the cylinder hole e of the cylinder a while being rotated relative to the cylinder a while a constant load is applied from the weight 25 via the bushing rod 26. Then, the bushing rod 26 is moved to the third position from the position where its tip surface abuts the upper end surface of the piston b.
When it has descended by a predetermined distance (hereinafter referred to as the pushing distance) as shown by the imaginary line in the figure, it is stopped by the lifting cylinder 27,
Therefore, the piston b is pushed into the cylinder hole e of the cylinder a by the pushing distance.

On the other hand, the measuring means 4 starts measuring the time at the same time as the piston b starts to push in, and the measurement means
This continues until the lowering of the piston b is stopped, that is, until the pushing of the piston b is completed, and as a result, the piston b is pushed into the cylinder hole e filled with the hydraulic oil f by the pushing distance. The time required for this (hereinafter referred to as push-in time) is measured.

In this case, the pushing speed of the piston b is obtained by dividing the predetermined pushing distance by the measured pushing time, but in this example, the pushing speed is simply inversely proportional to the pushing time, so the following As explained in , the clearance between the cylinder B and the cylinder 8 was evaluated based on the pushing time.

That is, the pushing time is T, the pushing distance is S, the load applied to piston b is F1, the viscosity coefficient of hydraulic oil f is μ, the diameter of cylinder hole e is D1, the clearance between piston b and cylinder a is δ, and the cylinder hole e is If the distance over which the clearance continues in the axial direction is l, then in general, the following relational expression holds: T=N/δ3 (1) However, K= (3/4)πμID3 (S/F) . Therefore, the pushing time T is 3 of the clearance δ.
When expressed in a graph, it becomes a curve as shown by the solid line in FIG.

The allowable range of the clearance δ is determined in advance by design. For example, if the allowable range of the clearance δ is δ1≦δ≦62 as shown in the fourth figure, the allowable range of the pushing time T is T ≦T≦T2. Here, T
,,T, is obtained from equation (1) above as T,=to/δ13,T2
= is given by /δ23.

Therefore, the clearance δ between the cylinder a and the piston 75
Whether or not is within the allowable range of δ1≦δ≦δ2 is evaluated by whether or not the indentation time T is within the allowable range of TI<T≦T2.For example, in the above measurement, if the indentation time T is 4 If T=Tx as shown in the figure, T,
Since ≦Tx≦T2, the cylinder a and the piston 75
The clearance δ between them is evaluated as good. Also, for example,
When the pushing time T is T=Tx' as shown in the fourth diagram, it is evaluated as defective because T2<Tx'.

In this case, the pushing time T of the piston b is the state in which the piston b is rotated relative to the cylinder a as described above, that is, the state in accordance with the operation of the hydraulic actuating device A. Therefore, the clearance δ evaluated in this evaluation is the effective clearance between the piston b and the cylinder a.

Then, by repeating the same operation as described above for other pistons b, the effective clearance between each piston b and cylinder 8 is evaluated.

In this example, the clearance between each piston b and the cylinder 8 was evaluated from the pushing time, but as is clear from equation (1), the clearance can be evaluated from the pushing speed of each piston b. Of course, it is also possible to measure the pushing distance while keeping the pushing time constant, and to evaluate the clearance from the pushing distance.

(Effect) As is clear from the above description, according to the clearance evaluation device between a piston and a cylinder in a hydraulic actuating device of the present invention, one cylinder hole of the cylinder held by the holding means is filled with hydraulic oil. and, with one end of the piston inserted into the cylinder hole, it is rotated around the axis of the cylinder hole by a rotation means, and further, in the rotation state, a constant load is applied to the piston by a pushing means. The piston is pushed into the cylinder hole, and the clearance between the piston and the cylinder is evaluated from the pushing speed of the piston measured by the measuring means. In the rotated state, that is, in the state corresponding to the operation of the hydraulic actuator,
The effective clearance between the piston and cylinder can be evaluated, and the clearance can be appropriately evaluated comprehensively, including the operability of the hydraulic actuating device.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of essential parts of an example of a hydraulic actuating device, FIG. 2 is a side view of an example of the clearance evaluation device of the present invention, and FIG. 4
The figure is a diagram for explaining the evaluation method using the clearance evaluation device. 1... Holding means 3... Rotating means A... Hydraulic actuating device b... Piston e... Cylinder hole 2... Pushing means 4... Measuring means a... Cylinder d ...Cylinder rotation axis f...Hydraulic oil 1

Claims (1)

[Claims] 1. A cylinder that is rotatably provided around a rotation axis and has a plurality of cylinder holes drilled around the rotation axis substantially parallel to the rotation axis, and hydraulic oil is supplied to each cylinder hole. A device for evaluating the clearance between a cylinder of a hydraulic actuating device and a piston that is slidably inserted through the piston, the cylinder being freely rotatable around the axis of one of the cylinder holes. a holding means for holding the cylinder in the holding means, and a piston having one end inserted into the cylinder hole while the cylinder hole of the cylinder held by the holding means is filled with hydraulic oil. A pushing means that applies a constant load to the other end, a rotating means that rotates the cylinder around the axis of the cylinder hole during the pushing, and a substantially constant correlation with the clearance between the piston and the cylinder. 1. A clearance evaluation device between a piston and a cylinder in a hydraulic actuating device, comprising a measuring means for measuring a pushing speed of the piston, and the clearance is evaluated based on the correlation based on the pushing speed.