JP2004019793A - Vibration-proof structure of hydraulic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a permanent countermeasure for reducing or eliminating a noise and vibration in a hydraulic apparatus without remarkable increase the cost. <P>SOLUTION: This vibration-proof structure includes a throttle passage 43 and an expansion chamber 44 having a larger sectional area than the sectional area of the throttle passage 43 and communicated with the throttle passage 43, wherein damper (d) is integrated with a transmission case 6c, and the throttle passage 43 is connected and communicated with supply and discharge oil passages 29, 30 near relief valves 34, 35 in a hydraulic continuously variable transmission. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an anti-vibration structure for a hydraulic device, and more particularly, to a technology for preventing noise and vibration of a hydraulic device used for a working machine such as a tractor or a wheel loader, such as a hydrostatic continuously variable transmission for traveling. Things.
[0002]
[Prior art]
For example, a hydrostatic continuously variable transmission for traveling disclosed in Japanese Patent Application Laid-Open No. 11-59210 is provided with a relief valve for setting an upper limit of a circuit pressure. When the circuit pressure exceeds the limit, the relief valve opens to release the pressure and operate. As described above, a hydraulic device is generally equipped with a relief valve for protection of the device, setting of the maximum pressure, and the like.
[0003]
[Problems to be solved by the invention]
As described above, the opening operation of the relief valve is a high-pressure state in which a pressure equal to or higher than the upper limit acts on the circuit. This is considered to be caused by noise caused by resonance of the movable part such as the valve element and the return spring or the valve box part due to the pulsating pressure fluctuation during the relief operation.
[0004]
For this reason, noise was eliminated by changing the dimensions and weight of each part of the relief valve or changing the shape within a range that did not affect the function.However, such measures caused noise. It was a dedicated one for each relief valve at the location where it was used. Permanent countermeasures to eliminate resonance are difficult to find, and at inconvenient locations where noise is generated, there is no choice but to take dedicated measures by trial and error, which requires troublesome and inefficient work. was there.
[0005]
On the other hand, trochoid pumps used for lubrication and replenishment, such as for charging a hydrostatic continuously variable transmission, are often used because of their advantages of being compact and inexpensive, but on the other hand, they have large pulsation, For example, there is a problem that the pipe on the pump discharge side resonates with pulsation and vibrates greatly. In addition, it was difficult to increase the pressure. Therefore, there is a disadvantage in that the discharge-side pipe is set to be excessively strong so as to withstand vibration caused by pulsation.
[0006]
As described above, in a hydraulic device, noise and vibration are easily generated due to resonance, and there is no permanent countermeasure against them. Therefore, means for effectively preventing noise and vibration are desired. It was actual. Therefore, an object of the present invention is to provide and provide a permanent countermeasure for reducing or eliminating the above-described noise and vibration in a hydraulic device without significantly increasing the cost.
[0007]
[Means for Solving the Problems]
〔Constitution〕
According to a first aspect of the present invention, in the vibration damping structure of the hydraulic device, there is provided a throttle channel, and an expansion chamber communicating with the throttle channel in a state having a cross-sectional area larger than a cross-sectional area of the throttle channel. A damper is configured, and a throttle flow path is connected to a pressure oil flow path in the hydraulic device.
[0008]
[Action, effect]
According to a first aspect of the present invention, there is provided a damper formed by connecting a throttle passage that is connected to a pressure oil flow passage of a hydraulic device and an expansion chamber having a cross-sectional area larger than a cross-sectional area of the throttle flow passage. Means. When vibrations and pulsations generated in the pressure oil flow path are transmitted to the expansion chamber via the throttle flow path, the cross-sectional area increases at a stretch, so that the effect of reducing the impedance near the resonance frequency is created, and the vibration wave is short-circuited. Thus, the resonance phenomenon due to the natural vibration can be reduced.
[0009]
Since the vibration reducing action can always be exerted by the presence of the damper, it is possible to obtain the vibration damping action by performing a single remodeling of connecting the damper in communication. Therefore, it is possible to eliminate the troublesome and inefficient conventional anti-vibration work of performing various countermeasures on a portion where the inconvenience due to resonance occurs and selecting and setting the best means.
[0010]
As a result, in the vibration damping structure of the hydraulic device according to the first aspect, the damper provided with the throttle passage and the expansion chamber is connected to the oil passage near the location where the resonance phenomenon occurs, so that the damper can be connected at any location. Since it is possible to avoid inconvenience due to resonance such as noise and vibration, it is possible to provide a permanent anti-vibration means while providing a simple and inexpensive single type of measure simply by connecting a damper.
[0011]
〔Constitution〕
According to a second aspect of the present invention, in the configuration of the first aspect, the damper is connected to the pressure oil flow passage near the relief valve.
[0012]
[Action, effect]
According to the configuration of the second aspect, the vibration of the movable portion such as the movable valve element and the relief spring is suppressed or eliminated when the relief valve is opened by the vibration reducing action of the damper. The generation of noise as described above can be avoided. As a result, by providing a damper having a simple structure, it was possible to eliminate the noise generated when the relief valve operated in relief.
[0013]
〔Constitution〕
According to a third aspect of the present invention, in the first aspect, the damper is connected to the discharge-side flow path of the trochoid pump.
[0014]
[Action, effect]
According to the configuration of the third aspect, the pulsation generated in the discharge side flow path of the trochoid pump is suppressed or eliminated by the vibration reducing action of the damper, and the vibration of the hydraulic pipe which is the discharge side flow path is eliminated. Can be. Therefore, there is an advantage that the pipe diameter can be reduced because it is not necessary to withstand the vibration, and the piping space can be reduced because there is no movement due to the vibration.
[0015]
〔Constitution〕
According to a fourth aspect of the present invention, in the configuration of the first to third aspects, the damper is formed integrally with a casing for forming a hydraulic device.
[0016]
[Action, effect]
According to the fourth aspect of the present invention, since the damper is integrally formed in the casing which is an essential member for constituting the hydraulic device, the vibration damping structure can be provided compactly and economically by combining the members. Was completed. For example, when the casing is made of a cast alloy such as cast iron as in a transmission case, it is easy to integrally form a space such as a flow path and an expansion chamber.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an agricultural tractor, where E is an engine, 1 is a front wheel, 2 is a rear wheel, 3 is a hood, 4 is a driving unit, 5 is an engine, 6 is a driving mission, 7 is a vehicle body, and 8 is a driving seat. Reference numeral 9 denotes a PTO shaft, 10 denotes a rear working device, 11 denotes a rear wheel fender, and g denotes a guard member.
[0018]
2 and 3 show an HST 12 which is a main part of the traveling mission 6, and FIG. 4 shows a hydraulic circuit diagram thereof. The HST 12 transmits the engine power input to the input shaft 13 to the pump shaft 15 of the variable displacement hydraulic pump P via the spur gear interlocking mechanism 14, and the two HSTs 12 are operated by the hydraulic oil of the hydraulic pump P. The output shafts 16 and 17 of the hydraulic motors M1 and M2 are directly connected and linked using a coupling 18 (an example of an output merging mechanism A), and are configured as a one-pump two-motor type. In FIG. 4, a portion surrounded by a dashed line is the transmission case 6c, and the portion drawn outside thereof (the discharge-side oil passage 19a of the charge pump 19, the electromagnetic switching valve 39 described later, etc.) is an external piping. And external parts of the case.
[0019]
The pump shaft 15 is equipped with a charge pump 19 for the HST 12, and its tip is projected outside the transmission case 6c to form a projected tip shaft portion 20 that can be used for a live PTO shaft or the like. The transmission case 6c includes a main case portion 21 that mainly covers the hydraulic pump P and the first hydraulic motor M1, a lid case portion 22 that supports the input shaft 13 and the like, a motor case portion 23 that covers the second hydraulic motor M2, and An oil passage block 24 is provided between the main case 21 and the motor case 23.
[0020]
As shown in FIG. 4, the plunger type hydraulic pump P is of a variable displacement type, the axial piston type first hydraulic motor M1 is of a constant displacement type, and the axial piston type second hydraulic motor M2 is of a variable displacement type. The two hydraulic motors M1 and M2 are connected to each other, and the hydraulic oil input ports 25 and 26 and the oil drain ports 27 and 28 are connected to each other to form a parallel circuit h. It is connected to a hydraulic pump P via oil supply / discharge passages 29 and 30. Reference numerals 34 and 35 denote traveling relief valves for setting the maximum load pressures on the forward and reverse sides, and reference numeral 36 denotes a main relief valve for setting the upper limit of the circuit pressure. The functions of the input-side and oil-discharge-side ports 25 to 28 are opposite to each other when the output rotation direction of the HST 12 is forward rotation and reverse rotation.
[0021]
By operating the hydraulic transmission cylinder 31 interlocked with the swash plate operation unit 33 of the hydraulic pump P by switching the transmission valve 32, the swash plate angle of the hydraulic pump P changes, and the pressure oil per unit time changes. The discharge amount is changed, and the energy of the discharged pressure oil is converted into rotational force by the first and second hydraulic motors M1 and M2, and the rotational power from the input shaft 13 can be switched between the forward side and the reverse side. In addition, the HST 12 functions so that the speed is changed steplessly on both the forward side and the reverse side, taken out of the output shaft 17, and transmitted to the rear wheels 2 via a not-shown auxiliary transmission mechanism or the like.
[0022]
The second hydraulic motor M2 is configured to be a two-state switching type in which a swash plate angle of the second hydraulic motor M2 is equal to the swash plate angle of the first hydraulic motor M1 and a second speed state in which the swash plate angle is 0 degree. . As shown in FIG. 4, a switching cylinder 38 acting on the swash plate operating portion 37a of the swash plate 37 of the second hydraulic motor M2, a two-position switching type electromagnetic switching valve 39 for switching the switching cylinder 38, A button switch 40 is provided. That is, by operating the button switch 40 and switching the electromagnetic switching valve 39 to extend and retract the switching cylinder 38, the first speed state in which the swash plate 37 is inclined (the state shown in FIG. 3) and the swash plate 37 are The second speed state (state shown in FIG. 2) in which the vehicle stands vertically and has a tilt angle of 0 can be selectively switched.
[0023]
The switching cylinder 38 is configured by arranging an operation unit 41 including a cylinder chamber 41a and a piston rod 41b and a return unit 42 including a return spring 42a and a push rod 42b in the motor case 23 in opposition. If the pressure oil is supplied to the cylinder chamber 41a and the piston rod 41b is forcibly pushed out against the urging force of the return spring 42a, the first speed state shown in FIG. 3 is reached, and if the oil is discharged from the cylinder chamber 41a, The push rod 42b pushes the swash plate operating portion 37a back to the 0 degree position by the urging force of the return spring 42a, and returns to the second speed state as shown in FIG.
[0024]
The second hydraulic motor M2 is arranged such that the axis of its output shaft 17 coincides with the axis X of the output shaft 16 of the first hydraulic motor M1, and is aligned on a straight line. Therefore, when viewed as a motor unit, it is long in the axial direction X (front-back direction), but can be formed compactly in the up-down and left-right directions. It has become.
[0025]
In the first speed state, since both hydraulic motors M1 and M2 have the same swash plate angle, it is possible to generate almost twice the torque as in the case of the first hydraulic motor M1. Theoretically, the torque is doubled, but actually, there is an energy loss such as mechanical friction loss, so that the torque taken out from the output shaft 17 is "almost twice". Therefore, if the hydraulic pump P is operated at the lowest speed in the first speed state, a maximum torque almost twice as large as that of the conventional case can be generated, which is suitable for work traveling in which the load torque such as plowing work on muddy land becomes extremely large. It will be. Further, in the second speed state in which the inclination angle is 0, the hydraulic oil passes through the second hydraulic motor, so that it is used as an HST in a one-motor state in which substantially only the first hydraulic motor M1 is provided. can do.
[0026]
Next, a description will be given of an anti-vibration mechanism B that reduces noise during operation of the relief valve and discharge pulsation of the charge pump.
[0027]
As shown in FIG. 4, respective oil passages (pressure oils) are provided near a branch point of each of the oil supply / discharge oil passages 29 and 30 to the relief valves 34 and 35 and a total of three locations on the discharge-side oil passage 19 a of the charge pump 19. An anti-vibration mechanism B communicating with an example of the flow path r) is provided. The two anti-vibration mechanisms B, B near the relief valves 34, 35 prevent noise such as "P" from being generated from the relief valves 34, 35 during the relief operation, and are provided in the discharge-side oil passage 19a. The anti-vibration mechanism B absorbs pulsation of the charge pump 19 composed of a trochoid pump to prevent vibration.
[0028]
As shown in FIGS. 5 to 7, the vibration isolating mechanism B for noise prevention includes a throttle channel 43 and a throttle channel 43 with a cross-sectional area larger than the cross-sectional area of the throttle channel 43. A damper d is provided with an expansion chamber 44 communicating therewith, and a throttle channel 43 is connected to supply / discharge oil passages (an example of a pressure oil passage in a hydraulic device) 29 and 30. A throttle channel 43 having a diameter of 1.5 mm and an expansion chamber 44 having a diameter several times that of the throttle channel 43 are integrally formed in a transmission case 6c made of cast iron, and the expansion chamber 44 is sealed. When the stopper 45 is screwed, the volume of the expansion chamber 44 is set to be about 1.5 cubic centimeters.
[0029]
The pair of relief valves 34 and 35 are the same, and if one relief valve 34 is described, this relief valve 34 also has the function of a check valve. Is formed in a composite valve which exerts a check function of passing the flow with almost no resistance. In FIG. 5, reference numeral 46 denotes a relief spring, 47 denotes a damping chamber, 48 denotes a valve body, 49 denotes a plug, 50 denotes a valve seat, 59 denotes a support body for slidably moving the relief valve body 48, 60 denotes a spring receiver, and 61 denotes a spring receiver. Is a winding spring for closing and urging the valve element 48 very lightly.
[0030]
That is, when the pressure of the introduction oil passage 29b communicating with the supply / discharge oil passage 29 becomes equal to or higher than a predetermined value, the relief valve 34 is opened against the urging force of the relief spring 46, and the pressure of the supply / discharge oil passage 29 is reduced. Until the pressure becomes lower than the predetermined pressure, a relief action of releasing the pressure to the discharge-side oil passage 19a via the discharge oil passage 29a is exerted. When the hydraulic oil as the HST 12 becomes insufficient due to a leak or the like, the relief valve 34 is opened against the extremely light urging force of the winding spring 61, and the charge pressure can be supplied to the HST 12 with almost no resistance. is there.
[0031]
The throttle passage 43 is communicated with the damping chamber 47 in each of the relief valves 34 and 35 via each of the introduction oil passages 29b and 30b. The throttle channel 43 and the expansion chamber 44 can be formed by machining such as drilling from the end of the transmission case 6c. Further, the relief valve 34 can also be configured inside a hole formed by machining to drill from the end of the transmission case 6c (an example of a casing).
[0032]
The anti-vibration mechanism B for preventing vibration shown in FIG. 4 is exactly the same in structure as the above-described anti-vibration mechanism for preventing noise B, and is also formed integrally with the transmission case 6c. The throttle passage 43 communicates with the discharge-side oil passage 19 a of the trochoid-type charge pump 19.
[0033]
[Another embodiment]
As shown in FIG. 8, an anti-vibration mechanism B having an external structure may be used. That is, a cylindrical damping case 51 having an open end, a throttle passage 52 formed by a fine hole at the distal end, and a plug 54 to which a connection fitting 53 for an oil passage hose 56 is screwed at the proximal end. Is screwed to form a damper d having an expansion chamber 55 in the damping case 51. An oil passage hose 56 communicating with an oil passage 58 of a hydraulic device 57 is connected to the connection fitting 53 so as to form an external vibration damping mechanism B using a dedicated damper d. .
[0034]
Various types of hydraulic devices, such as a device for raising and lowering a tractor working device and a power steering device, are conceivable.
[Brief description of the drawings]
FIG. 1 is a side view of a tractor. FIG. 2 is a side view showing a structure of an HST in a second speed state. FIG. 3 is a side view showing a structure of the HST in a first speed state. FIG. 4 is a hydraulic circuit of the HST. FIG. 5 is a sectional view showing a relief valve and a vibration isolating mechanism for noise prevention. FIG. 6 is a front view of a transmission case at a portion where the vibration isolating mechanism is mounted. FIG. 7 is a sectional view of the vibration isolating mechanism. Sectional view showing damper with external structure
6c Casing 19 Trochoid pump 19a Discharge side flow path 43 Restriction flow path 44 Expansion chamber A Output merging mechanism Y Hydraulic device d Damper r Pressure oil flow path

Claims (4)

A damper comprising a throttle channel and an expansion chamber communicating with the throttle channel in a state having a cross-sectional area larger than the cross-sectional area of the throttle channel; An anti-vibration structure for a hydraulic device in which the throttle channels are connected to each other. The vibration damping structure for a hydraulic device according to claim 1, wherein the damper is connected to a pressure oil flow passage near a relief valve. The vibration damping structure for a hydraulic device according to claim 1, wherein the damper is connected to a discharge-side flow path of a trochoid pump. The vibration damping structure for a hydraulic device according to any one of claims 1 to 3, wherein the damper is formed integrally with a casing for constituting the hydraulic device.

Images