JP2013228005A - Pilot hydraulic piping - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pilot hydraulic piping that reduces pulsation due to a pump and can secure sufficient durability without over-engineering.SOLUTION: A pilot hydraulic piping 1 disposed between a pump device 8 and a manipulation lever 9 is specified to a use pressure of 6 MPa to 8 MPa, to have an inner diameter of 6 mm to 12 mm, a breakage pressure of 6 to 9 times as large as the specified use pressure. A rubber hose part 2 having an embedded fiber-reinforced layer comprising braided fibers is disposed in at least a part thereof, and an expansion amount in the rubber hose part 2 is set to 5.0 ml/m to 11.0 ml/m at the specified use pressure.

Description

  The present invention relates to pilot hydraulic piping, and more particularly to pilot hydraulic piping that can reduce pulse pressure due to a pump and ensure sufficient durability without over-spec.

  Generally, hydraulic piping of hydraulic equipment can be classified into operation hydraulic piping in which hydraulic oil flows at high pressure and pilot hydraulic piping in which hydraulic oil flows at low pressure. The operating hydraulic pipe is supplied with hydraulic oil from a drive hydraulic pump or the like driven by an engine, and directly operates a hydraulic mechanism that is a main function of the hydraulic equipment. On the other hand, the pilot hydraulic piping is supplied with hydraulic oil from a small gear pump or the like, and performs valve control of the operating hydraulic piping. For example, in a construction machine such as a hydraulic excavator or a bulldozer, a pilot hydraulic pipe is connected to a control valve to which a control lever is attached, and the operator controls the valve of the operating hydraulic pipe by operating the lever.

  In this pilot hydraulic piping, there is a pulse pressure due to a pump device such as a gear pump that supplies hydraulic oil, and this causes vibration in the steering lever. Since the operator operates the lever while always holding the control lever, there is a problem that the operator feels uncomfortable due to vibrations and vibration sounds transmitted from the lever.

  Conventionally, pulse pressure is not considered at all for pilot hydraulic piping, and fiber reinforced resin hoses and steel wire reinforced rubber hoses have been used. The resin hose has a smaller expansion amount when the fluid is pressurized than the rubber hose, and is disadvantageous for reducing the pulse pressure. In addition, a hose reinforced by embedding a steel wire reinforcing layer has a disadvantage in that the amount of expansion at the time of fluid pressurization is smaller than that of a hose reinforced by embedding a fiber reinforced layer and the pulse pressure is reduced. .

  Although it is not pilot hydraulic piping, the rubber hose which embed | buried the reinforcement layer which consists of synthetic resin yarn is proposed (refer patent document 1). In the rubber hose proposed in this document, a reinforcing layer is formed by braiding a thread of a material with low elongation at low tension in order to increase the expansion amount when the fluid is low pressure and suppress the expansion amount when the fluid pressure is high. ing. However, braiding synthetic resin yarns with low tension tends to vary the structure of the reinforcing layer, which is disadvantageous in ensuring stable quality. Moreover, the use regulation pressure of pilot hydraulic piping is about 7 MPa, and is different from a general low pressure hose (5 MPa or less) and a power steering hose for automobiles (about 10 MPa to 12 MPa). For this reason, it is necessary to make the specification suitable for the usage conditions (such as the specified use pressure) of the pilot hydraulic piping so as not to become overspec while ensuring sufficient durability.

JP-A-3-157599

  An object of the present invention is to provide a pilot hydraulic pipe that can reduce pulse pressure due to a pump and can ensure sufficient durability without over-spec.

  In order to achieve the above object, the pilot hydraulic pipe of the present invention is a pilot hydraulic pipe for performing valve control of the hydraulic pipe for operation of hydraulic equipment. The specified use pressure of the pipe is 6 MPa to 8 MPa, the inner diameter is 6 mm to 12 mm, The pressure is 6 to 9 times the specified use pressure, and at least part of the rubber hose portion has a fiber reinforcing layer in which fibers are braided. The expansion amount of the rubber hose portion is 5. It is 0 ml / m-11.0 ml / m.

  According to the pilot hydraulic piping of the present invention, the specified operating pressure of the pipe is 6 MPa to 8 MPa, the inner diameter is 6 mm to 12 mm, and the breaking pressure is 6 to 9 times the specified operating pressure, so that the specifications are suitable for the pilot hydraulic piping. ing. Furthermore, it has a rubber hose part in which a fiber reinforcing layer braided with a fiber is embedded at least partially, and the expansion amount of the rubber hose part is 5.0 ml / m to 11.0 ml / m at the specified use pressure. The rubber hose portion is provided in the minimum necessary portion, and the pulse pressure can be sufficiently reduced. Thereby, sufficient durability can be ensured without over-specifying the pilot hydraulic piping.

  Here, for example, the fiber reinforcing layer has a specification in which nylon fiber or polyester fiber is braided at a braid angle of 54 ° ± 3 °. It can also be set as the specification with which the piping full length is comprised by the said rubber hose part. In this specification, since the number of rubber hose portions that can obtain a large expansion amount increases, the pulse pressure reduction effect is improved. When the hydraulic device is a construction machine and the pilot hydraulic pipe of the present invention is connected to the steering lever via the control valve, the steering lever is suppressed by suppressing the vibration of the steering lever. Worker discomfort can be reduced.

It is explanatory drawing which illustrates the whole outline | summary of pilot hydraulic piping. FIG. 2 is a partially cutaway view illustrating a rubber hose portion of the pilot hydraulic piping in FIG. 1. It is a longitudinal cross-sectional view of the rubber hose part of FIG.

  Hereinafter, the pilot hydraulic piping of the present invention will be described based on the embodiments shown in the drawings.

  The pilot hydraulic piping of the present invention is for performing valve control of hydraulic piping for operation of hydraulic equipment including construction machines such as power shovels and bulldozers. As in the embodiment illustrated in FIG. 1, the pilot hydraulic piping 1 (hereinafter referred to as piping 1) is configured by connecting a rubber hose portion 2 and a resin hose portion 7. One end of the pipe 1 (end of the rubber hose part 2) is connected to a pump device 8 such as a gear pump that supplies hydraulic oil to the pipe 1. The other end of pipe 1 (the end of resin hose portion 7) is connected to a control valve 10 to which a control lever 9 is attached. The length of the pipe 1 is about 2 to 5 m in the case of a power shovel.

  The use specified pressure of the pipe 1, that is, the maximum use pressure is about 7 MPa (6 MPa to 8 MPa), which is lower than that of the hydraulic pipe for operation. The inner diameter of the pipe 1 is about 6 mm to 12 mm. Since only valve control is performed by hydraulic fluid flowing through the inside, a large flow rate is unnecessary, and such a small diameter is obtained. Further, by making the diameter as small as this, it is advantageous to extend a narrow gap or bend it with a small radius. The outer diameter of the pipe 1 is, for example, about 10 mm to 20 mm.

  The breaking pressure of the pipe 1 is 6 to 9 times the specified operating pressure in order to ensure sufficient durability against the repeated pressure of the hydraulic fluid flowing inside. Since the overpressure occurs when the burst pressure exceeds 9 times the specified operating pressure, the burst pressure is set within this range. If the burst pressure is over-specification, there arises a problem that the flexibility of the pipe 1 is impaired.

  As illustrated in FIGS. 2 and 3, the rubber hose portion 2 has a fiber reinforcement layer 4 embedded between an inner rubber layer 3 and an outer rubber layer 6. A line segment CL in FIG. 2 is a center line of the rubber hose portion 2. The fiber reinforcement layer 4 is formed by braiding the fibers 5 at a predetermined braiding angle A. As the fiber 5, nylon fiber, polyester fiber, or the like can be used. The layer thickness of the fiber reinforcement layer 4 is, for example, about 1.0 mm to 3.0 mm.

  The inner rubber layer 3 has a layer thickness of about 1.0 mm to 2.0 mm, for example, and NBR synthetic rubber or the like is used as a rubber type in consideration of oil resistance. The outer rubber layer 6 has a layer thickness of, for example, about 0.7 mm to 1.5 mm. As a rubber type, a synthetic rubber of CR type, SBR type, EPDM type is used because of weather resistance and wear resistance.

  The expansion amount of the rubber hose portion 2 is 5.0 ml / m to 11.0 ml / m at the specified use pressure. If it is less than 5.0 ml / m, a sufficient pulse pressure reduction effect cannot be obtained, and if it exceeds 11.0 ml / m, the durability tends to have an adverse effect. The value of the expansion amount is a measured value obtained by measuring the change in the internal volume at the time of opening by accumulating a specified pressure in the rubber hose portion 2 and then releasing it.

  A specific measuring method is to attach an open / close valve to both ends of the rubber hose part 2, close one valve, fill the rubber hose part 2 with no pressure, and use the pressure pump from the other valve side to fill the solution. After pressurizing up to the pressure for measuring the expansion amount of the rubber hose part 2, the rubber hose part 2 is filled in a pressurized state by closing the pressure side valve. Thereafter, the pressure side valve is opened and the volume of the solution filled in the rubber hose part 2 is compared before and after pressurization to measure the change in the internal volume of the rubber hose part 2.

  The piping 1 of the present invention has specifications for use specified pressure, inner diameter, and burst pressure suitable for pilot hydraulic piping. Furthermore, by burying the fiber reinforcement layer 4 and having the rubber hose part 2 whose expansion amount at the specified use pressure is set to 5.0 ml / m to 11.0 ml / m in at least a part, the necessary minimum part is obtained. A rubber hose portion 2 is provided to sufficiently reduce the pulse pressure. Therefore, sufficient durability can be ensured without over-specifying the pilot hydraulic piping.

  The braid angle A is preferably 54 ° ± 3 °. By setting this braid angle A, flexibility can be easily obtained while ensuring the necessary expansion amount and breaking pressure (durability) of the rubber hose portion 2.

The braid density coefficient K calculated by the following equation (1) is, for example, 1.0 to 4.5.
K = (the number of fibers 5 constituting the fiber reinforcing layer 4/2) / (P × sinA) (1)
P is the braid pitch of the fibers 5 constituting the fiber reinforcement layer 4, and A is the braid angle of the fibers 5 constituting the fiber reinforcement layer 4.

  When the braid density coefficient K is more than 4.5, it is difficult to obtain a necessary breaking pressure (durability) and a necessary expansion amount.

  The resin hose portion 7 is formed by embedding a fiber reinforcing layer in a resin hose such as polyester resin or nylon resin. Unlike the rubber hose portion 2, the resin hose portion 7 can hardly be expected to expand, but can be manufactured at a lower cost than the rubber hose portion 2.

  The rubber hose portion 2 may be provided in a part of the pipe 1 as in this embodiment. In that case, if the rubber hose part 2 is provided as close to the pump device 8 as possible, the pulse pressure is immediately reduced at that position, which is advantageous in reducing vibration and noise caused by the pulse pressure.

  Depending on the length of the rubber hose portion 2, the frequency of the pulse pressure to be reduced can be adjusted. Accordingly, when there is a pulse pressure frequency to be reduced in particular, the optimal length of the rubber hose portion 2 is set according to the frequency.

  The rubber hose portion 2 can be provided not only at one place of the pipe 1 but also at a plurality of places. Alternatively, the entire length of the pipe 1 can be constituted by the rubber hose portion 2. When the total length is the rubber hose part 2, the rubber hose part 2 having a larger expansion amount than the resin hose part 7 is increased, so that the pulse pressure reduction effect is improved.

  When the pipe 1 is connected to the control lever 9 of the construction machine via the control valve 10, the pulse pressure generated by the pump device 8 is reduced by the rubber hose portion 2. Therefore, it is difficult for the operator who holds the steering lever 9 to transmit vibration and noise caused by the pulse pressure through the steering lever 9, thereby reducing discomfort.

  As shown in Table 1, 10 types of rubber hose test samples (Examples 1 to 6 and Comparative Examples 1 to 4) with different specifications were prepared. The pressure reduction effect (vibration level) was measured. The results are as shown in Table 1. Each test sample had a specification in which one fiber reinforcing layer was embedded, and the braided angle of the fiber was 54.7 °. The fiber material PET in Table 1 means polyester.

[Destruction pressure]
About each test sample, the pressure at the time of destruction was measured based on the method prescribed | regulated to the hose test method of rubber | gum and resin of JISK6330-2: 1998-2nd part: pressure resistance test. If the breaking pressure is 6 times or more than the specified working pressure, it can be evaluated that there is sufficient durability. On the other hand, if the breaking pressure is more than 9 times the specified operating pressure, it can be said that the breaking pressure is excessive (overspec).

[Expansion at the specified operating pressure]
For each test sample, the specified pressure was stored in the rubber hose and then released to measure the change in the internal volume at the time of opening.

[Vibration level]
Each test sample was installed as a pilot hydraulic pipe (total length: 4.8 m) on the same power shovel, and at that time, the vibration level of a control lever connected to the test sample via a control valve was evaluated. This evaluation is a sensory index evaluation by an operator, and is evaluated with an index of 0 to 10 points. The larger the value, the better the pulse pressure reduction effect.

  From the results of Table 1, it can be seen that Examples 1 to 6 have the necessary durability and the effect of reducing the pulse pressure without being over-spec as pilot hydraulic piping.

DESCRIPTION OF SYMBOLS 1 Pilot hydraulic piping 2 Rubber hose part 3 Inner surface rubber layer 4 Fiber reinforcement layer 5 Fiber 6 Outer surface rubber layer 7 Resin hose part 8 Pump device 9 Control lever 10 Control valve

Claims (4)

  In the pilot hydraulic piping for performing valve control of the hydraulic piping for operating hydraulic equipment, the specified use pressure of the pipe is 6 MPa to 8 MPa, the inner diameter is 6 mm to 12 mm, and the breaking pressure is 6 to 9 times the specified use pressure. And a rubber hose portion in which a fiber reinforcing layer braided with a fiber is embedded at least in part, and the expansion amount of the rubber hose portion is 5.0 ml / m to 11.0 ml / m at the specified use pressure. And pilot hydraulic piping.   2. The pilot hydraulic pipe according to claim 1, wherein the fiber reinforcing layer is formed by braiding nylon fibers or polyester fibers at a braiding angle of 54 ° ± 3 °.   The pilot hydraulic piping according to claim 1 or 2, wherein a total length of the piping is constituted by the rubber hose portion. The pilot hydraulic piping according to any one of claims 1 to 3, wherein the hydraulic device is a construction machine and is connected to a control lever via a control valve.

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