JP3136041B2 - Cylinder device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder device suitable for operating a working device provided on, for example, a hydraulic excavator.

[0002]

2. Description of the Related Art FIGS. 5 to 8 show a hydraulic cylinder device as an example of a conventional cylinder device.

[0003] In the drawings, reference numeral 1 denotes a hydraulic cylinder device.
And so on.

[0004] First, reference numeral 2 denotes a cylinder main body constituting an outer shell of the hydraulic cylinder device 1. The cylinder main body 2 includes a cylindrical tube 3, a bottom cover 4 for closing one end of the tube 3, A tube guide is formed at the other end of the tube 3 and has a stepped cylindrical shape and is closed at both ends from a rod guide 5. One end of the bottom cover 4 fixes the cylinder body 2. It is a mounting bracket 4A. The rod guide 5 and the bottom cover 4 have supply / discharge ports 6 communicating with oil chambers A and B, which will be described later.
7 are provided.

[0005] Reference numeral 8 denotes one end inserted into the cylinder body 2.
Is, the other end shows the piston rod projecting outside the cylinder body 2 through a rod guide 5, the piston rod 8
Has a small-diameter portion 8B via a shoulder 8A, and the other end has a mounting bracket 8 for fixing the piston rod 8.
C. Further, the distal end side outer periphery of the small diameter portion 8B, as shown in FIG. 6, the female screw portion 11B is screwed to become male threaded portion 8D of the fixing nut 11 to be described later, the male screw portion 8
On one end side of D, a fixing groove 8E with which the tip of a set screw 12 described later abuts is formed over the entire circumference. Further, a cylindrical one-side cushion 8F protruding toward one side is integrally formed at the tip of the small-diameter portion 8B, and the one-side cushion 8F is inserted into the bottom cover 4 when the piston rod 8 is reduced at its minimum. The flow resistance is applied to the oil liquid that enters and flows out of the supply / discharge port 7 to reduce the impact at this time.

Reference numeral 9 denotes a cylindrical other cushion located on the outer peripheral side of the small diameter portion 8B of the piston rod 8 and disposed between the shoulder 8A and the piston 10.
Is fixed to the piston rod 8 by a fixing nut 11 together with the piston 10. The other-side cushion 9, like the one-side cushion 8F, gives flow resistance to the oil liquid that enters the rod guide 5 and flows out of the supply / discharge port 6 when the piston rod 8 is fully extended. This is to reduce the impact.

Reference numeral 10 denotes a piston which is inserted into the cylinder body 2 so as to be slidable in the axial direction, and defines inside the cylinder body 2 two oil chambers A and B on the left and right sides. At the center, the small-diameter hole portion 10A of the small-diameter portion 8B of the piston rod 8 is inserted is formed through in the axial direction, on one end side of the small-diameter hole portion 10A and enlarged through the abutting end face 10B axis
A large- diameter hole portion 10C formed of a circular hole extending in the direction is formed. The other end of the fixing nut 11 is inserted into the large-diameter hole portion 10C, and the abutting end surface 11D of the fixing nut 11 abuts on the abutting end surface 10B.

Reference numeral 11 denotes a fixed nut provided on one end side of the piston rod 8. The fixed nut 11 includes a nut main body 11A formed in a stepped cylindrical shape, and a nut main body 11A.
A is formed from a female screw portion 11B formed on the inner peripheral side of A and a fixing screw hole 11C formed on one end side of the nut body 11A and formed in the radial direction so as to correspond to the fixing groove 8E of the piston rod 8. A set screw 1 for locking the fixing nut 11 is provided in the fixing screw hole 11C.
2 is screwed. The other end surface of the nut body 11A is an abutting end surface 11D which abuts against the abutting end surface 10B of the piston 10.

[0009] Thus, the fixed nut 11, the piston 10 in a state attached to the small-diameter portion 8B until it abuts against the shoulder portion 8A of the piston rod 8 through the other side cushion 9, the male threaded portion 8D of the piston rod 8 The female screw portion 11B is screwed . At this time, the fixing nut 11 is inserted into the large-diameter hole 10C while the other end is inserted into the abutting end face 11D and the piston 10.
The piston 10 is pressed to the other side by abutting the abutting end faces 10B of each other, and the piston 10 and the other-side cushion 9 are sandwiched and fixed between the shoulder 8A. Then, in this state, the set screw 12 is screwed into the fixing screw hole 11C of the fixing nut 11, and the rotation is stopped.

The hydraulic cylinder device 1 according to the prior art has the above-described configuration, and supplies pressure oil from a hydraulic pump from a supply / discharge port 6 into an oil chamber A via a hose or the like (neither is shown). By doing so, the piston rod 8 is contracted through the piston 10 and the fixed nut 11, and the pressurized oil is supplied from the supply / discharge port 7 into the oil chamber B. , Shoulder 8
The piston rod 8 is extended through A. When the piston rod 8 is contracted and extended most, the shock at this time is buffered by the one cushion 8F and the other cushion 9 of the piston rod 8.

[0011]

[SUMMARY OF THE INVENTION Incidentally, the hydraulic cylinder device 1 according to the prior art described above, the piston 10 or the like is fixed to the piston rod 8 by screwing the fixing nut 11 to the male screw portion 8D, the piston rod 8 because of that a load during reduced operation is nest with the fixed nut 11, this reduced load during operation ends up acting all male threaded portion 8D through a fixed nut 11, cracks in the male threaded portion 8D Is liable to occur.

[0012] Further, in the hydraulic cylinder device 1 used in the working device of the construction machine, when performing digging work or the like, the male screw portion 8 of the load during the excavation piston rod 8
By acting on the rapidly concentrated in the D, the male threaded portion 8D
Threads of and there is a Ru and have <br/> cormorant problem collapse as peeling caused the shear failure.

In order to solve the above-mentioned problem, pressure oil is supplied from each of the supply / discharge ports 6 and 7 with the mounting bracket 4A of the bottom cover 4 and the mounting bracket 8C of the piston rod 8 fixed at an arbitrary width. feeding, discharge is caused by the male screw portion 8D
The state of the load (stress) applied to was measured. As a result, as shown in FIGS.
On There are joined by large stress to the first and second crest th male threaded portion 8D other end of the piston rod 8 is screwed, the percentage of load that nest in the first and second crest th other It was much larger than the thread.

The reasons for these are that the abutting end face 10 B of the piston 10 and the abutting end face 11
D, the female thread 11B of the fixed nut 11
To the other end is deformed by being pressed, a large stress to the first and second crest th male screw portion 8D located in this part is considered that act, from these facts, in FIG. 6 or by tensile stress concentrated near C of this part C only crack occurs, the male threaded portion 8D is elucidated that result in broken by the growth of the crack.

Therefore, the piston rod 8 as described above is used.
To prevent damage to the male threaded portion 8D of the male screw portion 8
It is conceivable to increase the D diameter of, increasing the diameter of the male threaded portion 8D, the surface pressure of the abutting surfaces abutting area is reduced between the shoulder portion 8A and the other side cushion 9 excessive And the other-side cushion 9 is damaged. As a countermeasure for this, it is conceivable to increase the diameter of the piston rod 8 to increase the abutment area between the shoulder 8A and the other cushion 9, but with the increase in the diameter of the piston rod 8, the cylinder is increased. The main body 2 must also be formed with a large diameter, and as a result, there is a problem that the entire hydraulic cylinder device 1 becomes large.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art, and has a male thread portion of a piston rod and a fixing nut.
To prevent the the stress concentration in the female threaded portion occurs, and an object thereof is to provide a cylinder apparatus capable of preventing the occurrence of cracks.

[0017]

In order to solve the above-mentioned problems, a cylinder device employed by the present invention comprises a cylinder body having both ends closed, and one end inserted into the cylinder body serving as a male thread portion. The other end side has a piston rod protruding out of the cylinder main body, and is provided slidably in the cylinder body in the axial direction, and has a small-diameter hole portion into which the piston rod is inserted and one end side of the small-diameter hole portion is provided. A piston having a large-diameter hole through a step portion, and a fixing nut having a female screw portion on the inner peripheral side and being fastened to a male screw portion of the piston rod to fix the piston to the piston rod. . The first aspect of the present invention is characterized in that the large-diameter hole of the piston has a circular shape extending in the axial direction.
Formed as a shaped hole, the fixing nut is located on one end side and has a larger diameter than the large diameter hole portion of the piston, and the other end of the large diameter cylinder is A small-diameter cylindrical portion formed with an outer diameter smaller than the large- diameter hole of the piston and inserted into the large-diameter hole is formed as a stepped cylindrical body. The other end surface of the large-diameter cylindrical portion is configured to be abutted against the large-diameter hole-side end surface of the piston when fastened to the male screw portion.

[0018] According to the second aspect of the present invention, small diameter tubular portion of the fixing nut, the axial length dimension of the female screw portion
It is configured to have more than a quarter of the axial length for
You .

Furthermore, the configuration of the invention of claim 3, between the small diameter cylinder portion and the other end face of the fixing nut and the stepped portion of the piston, which forms a gap upon securing the piston to the piston rod in the locking nut And

[0020]

With the above construction, the small-diameter cylindrical portion of the fixed nut is pierced.
With the fixing nut inserted into the large diameter hole of
When tightened to the male thread of the ston rod, the fixing nut
The end face of the large-diameter cylindrical part of
Because if, load applied to the fixing nut during reduction operation of the piston is nest in <br/> end surface of the large diameter cylindrical portion serving as the abutting end face of the fixing nut, the internal thread from the end face of the large diameter cylindrical portion Distributed throughout the department. Also, at this time, the small-diameter cylindrical part of the fixed nut
Can be held at a distance from the step of the piston.
It can be prevented from being deformed by a load and nest with the female screw portion Gapi piston located inside parts. As a result, it is possible to load is prevented from concentrating on a portion of the male threaded portion of the piston rod.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In the embodiment, the same components as those in the prior art shown in FIGS. 5 to 8 are denoted by the same reference numerals, and description thereof will be omitted.

First, FIGS. 1 to 3 show a first embodiment of the present invention.

In the drawing, reference numeral 21 denotes a piston according to the present embodiment which replaces the conventional piston 10, and a small diameter portion 8B of the piston rod 8 is provided at the axial center of the piston 21.
Diameter but smaller diameter bore portion 21A to be inserted are formed through the axial direction, on one end side of the small-diameter hole portion 21A is made of a circular hole which is elongated in diameter and axially through the stepped portion 21B Hole 21
C is formed. On one end side of the piston 21, there is formed an annular projection 21D which is located on the outer peripheral side of the large-diameter hole 21C and projects annularly toward one side, and one end face of the annular projection 21D is And an abutting end surface 21E which abuts against an abutting end surface 22D of a fixing nut 22 described later. Further, the axial dimension of the large-diameter hole 21C is the same as that of the fixing nut 2.
The size is set such that a gap S can be formed between the other end surface of the small-diameter cylindrical portion 22B and the stepped portion 21B in a state where the second abutting end surface 22D is abutted against the abutting end surface 21E.

Reference numeral 22 denotes a fixing nut according to the present embodiment provided at one end of the piston rod 8 in place of the fixing nut 11 according to the prior art. The fixing nut 22 is located at one end and formed to have a large diameter. A cylindrical large-diameter cylindrical portion 22A,
The piston 21 is located at the other end of the large-diameter cylindrical portion 22A.
It is formed with an outer diameter smaller than the diameter hole 21C and is large.
It is formed as a stepped cylindrical body from a small-diameter cylindrical portion 22B inserted into the radial hole portion 21C, and the inner peripheral side of the cylindrical portions 22A and 22B is a female screw portion 22C screwed to the male screw portion 8D of the piston rod 8. ing. Further, the other end surface of the large-diameter cylindrical portion 22A becomes an abutting end surface 22D which abuts against the abutting end surface 21E of the piston 21, and the axial length L1 of the small-diameter cylindrical portion 22B.
That is, the distance L1 from the other end of the small-diameter cylindrical portion 22B to the abutting end face 22D is the axial length L of the female screw portion 22C.
2 is set to 1/4 to 1/2. Further, one end of the large-diameter cylindrical portion 22A is provided with the fixing nut 2.
A fixed screw hole 22E into which the set screw 12 for stopping the screw 2 is screwed is formed in the radial direction.

The fixed nut 22 is connected to the piston 2
1 in a state attached to the small-diameter portion 8B until it abuts against the shoulder portion 8A of the piston rod 8 through the other side cushion 9, a smaller-diameter tubular portion 22B to the large-diameter hole portion 21C to the male threaded portion 8D of the piston rod 8 While inserting , the female screw portion 22C is screwed to make the abutting end surface 22D and the abutting end surface 21E of the piston 21 abut against each other. It is configured to be clamped and fixed between the portion 8A. Then, in this state, the set screw 12 is screwed into the fixing screw hole 22E of the fixing nut 22, and the rotation is stopped.

The hydraulic cylinder device 1 according to the present embodiment has the above-described configuration, and its basic operation is not particularly different from that of the prior art.

In this embodiment, however, the fixing nut 22 is provided with a large-diameter cylindrical portion 22A at one end and a small-diameter tube which is positioned at the other end of the large-diameter cylindrical portion 22A and enters the large-diameter hole 21C of the piston 21. formed from a cylindrical portion 22B as stepped cylinder, pairs other end surface of the large diameter cylindrical portion 22A to the abutting end face 21E of the piston 21
The small-diameter cylindrical portion 22B
And the step 21B of the piston 21 are separated by a gap S. Therefore, the fixing nut 22 is
The load from the piston 21 received by the abutting end face 22D can be dispersed throughout the female screw portion 22C, and the female screw portion 22C of the fixed nut 22 can be prevented from being pressed and deformed. As a result, the characteristic line shown by a solid line in FIGS.
Piston portion of the male threaded portion 8D of the rod 8 can be prevented stress concentration from occurring, the load is dispersed can be distributed over the male screw part 8D as (It should be noted that FIG. 2, in FIG. 3 The characteristic line shown by the two-dot chain line in FIG.

Thus, according to the present embodiment, the load received by the abutting end face 22D of the fixing nut 22 is applied to the female screw portion 22C.
Because it can be dispersed throughout, the piston rod 8
Load the (stress) can be uniformly distributed to the male threaded portion 8D, to prevent the stress on a portion of the male threaded portion 8D is concentrated, cracks and breakage may or occurs in the male threaded portion 8D, thread is stretched life and prevented from or is collapsed, it is possible to greatly improve the reliability.

Further, a quarter to one side with the separation dimension L1 of 1/2 abutting end surface 22D from the other end of the small diameter cylinder portion 22B with respect to the axial direction length L2 of the female screw portion 22C of the fixing nut 22 The contact end face 22D
Since the so that sufficiently spaced from the internal thread portion 22C and the other end, can be dispersed throughout more effectively internally threaded portion 22C of the load and nest in該衝engagement end face 22D, the male threaded portion of the piston rod 8 8D can be more reliably prevented from being damaged by stress concentration.

[0030] In addition, the male threaded portion 8D of the piston rod 8
Since it is possible to prevent the stress concentration occurs in, for example, the oil chamber A, through the use to increase the pressure of the hydraulic fluid supplied to the B, without increasing the diameter of the cylinder body, Shin of the piston rod 8, The output during compression can be increased. Further, on the one hand, it is possible to reduce the diameter of the male threaded portion 8D, on which it is possible to diameter of the said hydraulic cylinder device 1, the piston rod 8 can be formed from inexpensive material, the cost Can be reduced.

Next, FIG. 4 shows a second embodiment of the present invention. The feature of this embodiment is that the abutting end face of the fixing nut is extended from the other end of the small-diameter cylindrical portion to the axial length of the female screw portion. In a position spaced apart from each other.

In the drawing, reference numeral 31 denotes a piston according to the present embodiment which replaces the conventional piston 10, and a small-diameter portion 8B of the piston rod 8 is provided at the axial center of the piston 31.
Diameter but smaller diameter bore portion 31A to be inserted are formed through the axial direction, on one end side of the small-diameter hole portion 31A is made of a circular hole which is elongated in diameter and axially through the stepped portion 31B Hole 31
C is formed. And one end side of the piston 31
, The large-diameter hole portion 31C cylindrical annular projection 31D becomes to increase projecting toward the one side so as to cover the external thread portion 8D outer periphery of the piston rod 8 located on the outer peripheral side of, of the annular projection 31D One end surface is an abutting end surface 31E which abuts against an abutting end surface 32D of the fixing nut 32 described later. Further, the axial dimension of the large-diameter hole portion 31C is the same as that of the fixing nut 3.
The size is set such that a gap S can be formed between the other end surface of the small-diameter cylindrical portion 32B and the step portion 31B in a state where the second abutment end surface 32D abuts on the abutment end surface 31E. Also,
The through hole 3 for screwing the set screw 12 to the fixing nut 32 located at one end side is formed in the annular projection 31D.
1F is bored in the radial direction.

Numeral 32 denotes a fixing nut according to the present embodiment provided at one end of the piston rod 8 in place of the fixing nut 11 according to the prior art. The fixing nut 32 is located at one end and is formed to have a large diameter. A cylindrical large-diameter cylindrical portion 32A,
A small-diameter cylindrical portion 32B extending from the inner peripheral side of the large-diameter cylindrical portion 32A toward the other side is formed in a stepped cylindrical shape, and the inner peripheral side of the small-diameter cylindrical portion 32B is a male screw portion 8D of the piston rod 8. The female screw portion 32C is screwed into the female screw portion 32C. And small diameter cylinder
The portion 32B is smaller than the large-diameter hole portion 31C of the piston 31.
Formed with a large outside diameter and inserted into the large diameter hole 31C
Is what is done. Further, the other end surface of the large-diameter cylindrical portion 32A has an abutting end surface 3 which abuts against an abutting end surface 31E of the piston 31.
2D, and the abutting end face 32D is
Of the small-diameter cylindrical portion 32B, which is larger than the axial length L4 of the female screw portion 32C. Have been. Further, the small-diameter cylindrical portion 32B
A fixing screw hole 32 </ b> E into which the set screw 12 for locking the fixing nut 32 is screwed is formed in a radial direction on one end side of the fixing screw 32.

Thus, in this embodiment constructed as described above, the same operation and effect as those of the first embodiment can be obtained. However, in this embodiment, particularly, the abutting end face 32D of the fixing nut 32 is provided. Is disposed at a position separated from the other end of the small-diameter cylindrical portion 32B by one distance L3, which is larger than the axial length L4 of the female screw portion 32C, on one side. Overall length L of internal thread 32C
Can be more effectively distributed across 4, the stress concentrated on the male threaded portion 8D of the piston rod 8 from occurring can be reliably prevented.

In each of the above embodiments, the hydraulic cylinder device 1 has been described as an example of a cylinder device. However, the piston devices 21 and 31 are fixed to the piston rod 8 via fixing nuts 22 and 32. If so, the present invention may be applied to other cylinder devices such as a pneumatic cylinder device.

[0036]

As described in detail above, according to the first aspect of the present invention, one end of the small diameter hole of the piston is axially
A large-diameter hole portion formed of a circular hole extending in the direction is provided, and the fixing nut is located on the other end side of the large-diameter cylinder portion on one end side and smaller than the large-diameter hole portion of the piston. With outer diameter
And a small-diameter cylindrical portion inserted into the large- diameter hole portion to form a stepped cylindrical body, and when the female screw portion formed on the inner peripheral side is fastened to the male screw portion of the piston rod, Since the other end surface of the large-diameter cylindrical portion is configured to be an abutting end surface and abut against the large-diameter hole side end surface of the piston, the other end surface of the large-diameter cylindrical portion serving as the abutting end surface of the fixed nut is received. The load can be dispersed from the abutting end face of the large-diameter cylindrical portion to the entire internal thread portion, and cracks and breaks due to stress concentration are prevented from being generated in the external thread portion of the piston rod, thereby extending the life,
Reliability can be improved.

[0037] According to the invention of claim 2, the small-diameter cylindrical portion of the fixing nut with respect to the axial length of the female threaded portion 1 /
Fixed because it has a configuration with an axial length of 4 or more
It is possible to sufficiently separate the other end of the small-diameter cylindrical portion with respect to the other end surface of the large diameter cylindrical portion serving as abutting end face of the nut, the load was nest with pistons be effectively dispersed throughout the internal thread portion it can.

[0038] Further, the invention of claim 3, female thread by the load from being configured to form a gap, which is fixed the nut and nest between the step portion of the piston and the small diameter cylinder portion and the other end face of the fixing nut part prevents the other end (the other end of the small diameter cylinder portion) to side is deformed, it is possible to load is reliably prevented from being concentrated on a portion of the male threaded portion of the piston rod.

[Brief description of the drawings]

FIG. 1 shows a piston rod according to a first embodiment of the present invention,
FIG. 7 is an enlarged vertical sectional view of a position similar to FIG. 6 showing a piston and a fixing nut.

2 is a characteristic diagram showing the stress applied to the Flip ne male piston rod in FIG.

[3] Although Flip ne male piston rod in FIG. 1 is a characteristic diagram showing a sharing state of the load that nest.

FIG. 4 is an enlarged longitudinal sectional view showing a piston rod, a piston, and a fixing nut according to a second embodiment at the same position as in FIG. 6;

FIG. 5 is a longitudinal sectional view showing a hydraulic cylinder device according to the related art.

FIG. 6 is an enlarged vertical sectional view showing a piston rod, a piston, and a fixing nut in FIG. 5;

7 is a characteristic diagram showing the stress applied to the Flip ne male piston rod in FIG.

[8] Although Flip ne male piston rod in FIG. 5 is a characteristic diagram showing a sharing state of the load that nest.

[Explanation of symbols]

1 hydraulic cylinder device 2 cylinder body 8 piston rod 8D male threaded portion 21, 31 the piston 21A, 31A small diameter hole 21B, 31B stepped portion 21C, 31C large-diameter hole portion 21E, 31E abutting end faces 22 and 32 fixing nut 22A, 32A Large-diameter cylindrical part 22B, 32B Small-diameter cylindrical part 22C, 32C Female thread part 22D, 32D Abutment end face (other end face of large-diameter cylindrical part ) L1, L3 Axial length L2, L4 Small-diameter cylindrical female screw Axial length of section S Clearance

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F15B 15/00-15/28

Claims (3)

(57) [Claims] 1. A cylinder body having both ends closed and one end inserted into the cylinder body serving as a male screw part,
The other end side has a piston rod protruding out of the cylinder main body, and is provided slidably in the cylinder body in the axial direction, and has a small-diameter hole portion into which the piston rod is inserted and one end side of the small-diameter hole portion is provided. A piston having a large-diameter hole through a step portion, and a fixing nut having a female screw portion on the inner peripheral side and being fastened to a male screw portion of the piston rod to fix the piston to the piston rod. In the cylinder device, the large-diameter hole of the piston is a circular hole extending in the axial direction.
The fixed nut is located at one end side and has a larger diameter than the large diameter hole of the piston, and the other end of the large diameter cylinder is located at the other end of the piston. Outer diameter smaller than large diameter hole
A small-diameter cylindrical portion formed with dimensions and inserted into the large- diameter hole portion to form a stepped cylindrical body, and when the fixed nut is fastened to a male screw portion of a piston rod, the large-diameter cylindrical portion has A cylinder device, wherein the other end surface is configured to be an abutting end surface with respect to an end surface on the large-diameter hole side of the piston. Wherein said small diameter cylindrical portion of the fixing nut is 1/4 or more the axial length of the axial direction length of the female I <br/> Ji unit
Formed by a structure having a cylinder device according to claim 1. 3. A gap is formed between the step portion of the piston and the other end surface of the small-diameter cylindrical portion of the fixing nut when the piston is fixed to the piston rod with the fixing nut. The cylinder device according to item 1.