JPH06185659A - Hydraulic type piston slider type directional control valve - Google Patents

Abstract

PURPOSE: To cause the gradual capacity flow characteristic curve of a hydraulic directional control valve having a piston slider to show a secondary function curve over the entire range of slider stroke. CONSTITUTION: The notch trailing end of a control notch 32 in a longitudinal slider 12 shows a secondary function-capacity flow rate characteristic owing to its triangular shape and the aperture cross section of the control notch has a multi-dimensionally enlarged shaped to compensate casing losses which occur during an increase in flow rate of a pressure medium, with the result that an approximate secondary function-capacity flow characteristic that rises continuously over an entire range of stroke can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic piston slider type directional control valve of the type described in the general concept of claim 1.

[0002]

2. Description of the Prior Art Direction control valves of the above type are disclosed in DE No. 2717.
384C _{2 and} DE-GM 880 1058. This hydraulic directional control valve is a so-called progressive valve (“Stetigventil”), in which the fine control function of the valve is provided with a control notch whose control edge is substantially triangular, which control notch is generally a control surface. The valve is provided by having a semi-conical shape, a half-pyramidal shape, or a similar three-dimensional shape with respect to the cross section of. With such a control notch extending over the entire travel range of the longitudinal slider, fine control of the valve is obtained with the desired accuracy. The above-described geometry of the control notch gives a quadratic profile of the volumetric flow over the stroke, especially in the region of small aperture cross sections and thus in the region of small pressure medium flow. The disadvantage of such a control notch is that as the volumetric flow rate increases, the effect of the losses in the valve casing becomes progressively greater, which results in a flatter characteristic curve. The characteristic curve of the volumetric flow rate therefore has in most cases a progressive end section which transitions into a straight section in the intermediate setpoint range and a lower rate of rise in the entire control range of the directional control valve. Such a characteristic curve is especially disadvantageous for the braking process of large masses, which are normally to be braked initially quickly and then slowly. Furthermore, the drift that normally occurs in such valves results in a relatively large relative error when the target value is relatively small.

Further, according to DE 3515563 C1, a hydraulic piston slider type directional control valve is known in which the shape of the control edge of the control slider corresponds to a sinusoidal curve. Such a control edge shape is intended to obtain a good fine control function of the valve and to prevent a drastic change in the flow force. In this case, the flow force changes progressively with respect to the cross-section of the opening, without any inflection point, but this directional control valve has the disadvantage that the volumetric flow rate does not change as a quadratic function over the entire target range. There is. In this case, the characteristic curve of the change in volumetric flow rate becomes almost linear over the target value range. Also in this case, the fine control function is limited when the volumetric flow rate is small. Because the shape of the control edge is sinusoidal, the volumetric flow characteristic curve starts with a defined slope.

[0004]

In contrast to the prior art, the hydraulic piston slider type directional control valve according to the present invention having the features of claim 1 can change the quadratic function of the volumetric flow rate over the entire stroke range. . With the inventive design of the control notch, the effect of the casing losses is compensated, so that the volumetric flow-characteristic curve exhibits a continuously increasing, almost quadratic function change in the target range of 0-100%. Show. This quadratic volumetric flow characteristic is advantageous for controlling large masses, especially for acceleration and braking. The continuously rising volumetric flow characteristic curve allows the directional control valve to be used in connection with relatively simple control electronics. Furthermore, the geometry of the control notch allows particularly precise and sensitive control at low pressure medium flow rates.

A further advantage of the directional control valve according to the invention is that the drift normally occurring in such valves in the small control stroke range of the slider has only a slight influence on the control. Furthermore, the control notch does not have the geometric discontinuity that occurs at the boundary of the notch-shaped portion in the notch shape formed by combination. Moreover, a control slider with such a control notch can be manufactured relatively easily and cost-effectively.

By means of the features having the features of the subordinate claims, a further advantageous design of the directional control valve according to claim 1 is obtained.

[0007]

1 shows a so-called main control stage of a hydraulic piston-slider progressive-direction control valve, which is controllable by a pilot control unit not shown in detail. is there. This directional control valve 10 has a casing 11
The vertical slider 12 is slidably guided in a sealed state in the casing 11. The vertical slider 12 is held in a centered position by a centering spring 13 supported by the casing 11. In this case, the centering spring 13 is provided at opposite ends of the vertical slider 12 in the casing 11. A pressure chamber 14 for receiving the is formed.
The pressure chambers 14 each have a hole 15 which serves as a connection to a hydraulic pilot control device, not shown.

An axial slider hole 16 for a vertical slider 12 is formed in the casing of the directional control valve 10. The vertical slider 12 is 3 in the illustrated embodiment.
It has two, spaced apart, annular notches 17 so that between them two piston sections 18 with a complete piston cross section are formed. The notch 17 annularly surrounds the piston core 19 so that an end face control surface 21 projecting radially from the piston core 19 is formed in the piston core section 18, the outer edge of which serves as the control edge 22. It slides along the inner surface of the axial slider hole 16 in a sealed state. Figure 1
In the arrangement according to the prior art according to the preamble of claim 1, the control edge 22 has a triangular notch 23, the plurality of notches 23 being spaced apart from one another. Located along the control edge 22 of the piston core section 18. The notch 23 has a generally semi-conical shape towards the piston core, which is known per se. The vertical slider 12 is surrounded by a control chamber 24 which is formed in the casing 11 and which surrounds the vertical slider 12 in an annular shape, the control chamber 24 being connected via connection ports 25-28 to the direction It is external to the control valve and is therefore connected to devices not shown, such as tanks, pumps, consuming devices. In this case, reference numeral 25 denotes a connection port to the tank, reference numeral 26 denotes a connection port to the pump, and reference numerals 27 and 28 denote one connection port to the consumer device. Between the control chambers 24 formed in the slider holes 16 in the casing 11 are casing webs 29, which cooperate with the control edges 22 of the longitudinal slider 12 as the longitudinal slider 12 moves axially. To work. The two outer control chambers 24 are connected to one another in the usual way via a control channel 31 and thus also to the connection port 25 leading to the tank.

FIG. 2 shows the inventive construction of the longitudinal slider 12, in which the longitudinal slider 12 is shown in a side view together with a partial sectional view of a control chamber 24 which is immovable with respect to the casing. . The control notches 32 for valves which are designed as four-way valves are designed in principle identical to one another, so that only one control notch 32 will be described below. The control notch 32 is triangular at the beginning of the notch. The control notch 32 further includes piston section 1
8 has a bottom surface 34 between the circumferential surface and the longitudinal axis of the vertical slider 12, the bottom surface 34 having a diameter slightly larger than the diameter of the piston core 19. This bottom surface 34 is no longer triangular and its legs are
It is open toward, but stays in the range of almost an acute angle. From the bottom surface 34, a side wall 35 extends outwardly toward the peripheral surface 33, in which case the control notch 32 forms a butterfly-shaped peripheral surface opening 36 in the outer peripheral surface 33, giving a quadratic volume flow curve. Has a resulting geometric shape. The side walls 35 are in this case configured in such a way that their mutual spacing gradually increases in the radial and longitudinal directions, so that the flow cross section formed by the control notch 32 is expanded in a multidimensional manner. . The peripheral aperture 36 formed in the outer peripheral surface 33 by the control notch 32 is thus formed in a hopper shape, which is located radially above the bottom surface 34 and is significantly larger than this bottom surface 34. Due to this geometry of the control notch 32, the change in volumetric flow at this control notch is of higher order,
In this case, it corresponds to at least a quartic function. As can be seen from FIG. 2 together with the perspective view of the vertical slider 12 shown in FIG.
Both control surfaces 21 on the right piston section 18
In each case, two control notches 32 are arranged diametrically opposite one another. Further left piston section 1
Four control notches 32 are equally distributed along the outer circumference on the control surfaces 21 on both sides of 8, respectively,
In this case, the cross-sections of these openings are made smaller in proportion to the greater number of control notches. In order to further improve the effect of compensating the casing resistance, one undercut portion 37 is provided on each of the control surfaces 21 on the end face side.
Are arranged in the exemplary embodiment shown as an annular turning conical surface.

The mode of operation of the directional control valve 10 will be described below with reference to FIG. In this case, the basic function of the hydraulic progressive directional control valve itself is assumed to be known. In this case, FIG. 4 shows the course of the change in volumetric flow between two adjacent control chambers 24 over one control notch 32 with respect to the desired value, here the stroke of the longitudinal slider 12.

In this case, the characteristic curve 41 is the control notch 32.
Shows the variation of the volumetric flow rate with respect to the above stroke in the longitudinal slider 12 according to the invention with the contrary, whereas the dashed characteristic curve 42 shows the variation of the volumetric flow rate in a conventional valve with a simple triangular notch 23. Is shown. As can be seen from the characteristic curve 41 for the directional control valve according to the invention, when the connection of the pressure medium between the two control chambers is controlled and opened by the control notch 32, it is first caused by the triangular shape at the beginning of the notch. A quadratic function volume flow rate change can be obtained. As the opening control of the control notch 32 gradually progresses, and thus the volume flow rate increases, even when the control slider 12 moves to the maximum value of 100%, the characteristic curve 41 gradually increases. The changes that occur are maintained. The effect of the casing loss, which is enhanced with increasing volumetric flow, is in this case compensated by the special geometry of the control notch 32. That is, the cross-section of the opening of the control notch 32 is expanded by a quartic function during opening control, so that the directional control valve 10 maintains a characteristic curve of a quadratic function with respect to the volumetric flow rate Q. On the other hand, the dashed characteristic curve 42 shows the characteristic in the prior art described in the general concept of claim 1, and the extension of the characteristic curve gradually becomes flat as the volumetric flow rate increases due to casing loss. Then, after going through a straight line section, the rate of increase decreases at the end, showing a progressive change. Casing losses are compensated for in the directional control valve 10 according to the invention as compared to the prior art valve showing the characteristic curve 42, so that a substantially quadratic extension of the characteristic curve 41 is ensured over the entire opening stroke. .

A quadratic volumetric flow change is particularly advantageous for the control of large masses, which must be braked initially rapidly and then relatively slowly during braking. This configuration of the control notch 32 makes it possible, in the most advantageous manner, to increase the ascending slope of the characteristic curve 41 linearly with the desired value.
As a result, a small volume flow can be controlled particularly finely and sensitively. As a further advantage, if the directional control valve according to the invention drifts over a small control range, the effect is smaller than in conventional notches. Furthermore, the relative error caused by drift is also equal over the entire target range. The illustrated configuration of the control notch 32 also avoids the geometrical discontinuity in the notch, so that no abrupt changes in function as in the combined notch geometry can occur.

Longitudinal slider 1 with control notch 32
2 can be manufactured relatively easily and economically. For example, the notch shape is produced cost-effectively without an apex of the triangle, by means of an automatic lathe with a main drive incorporated into the production line control system, the apex of the triangle being subsequently eroded or stamped relatively It can be easily manufactured.

The invention is not limited to the illustrated embodiment, but can be implemented in different variants.

[Brief description of drawings]

FIG. 1 is a schematic view of a conventional hydraulic directional control valve.

FIG. 2 is a side view of a longitudinal slider according to the invention with parts of control chambers which are immovable relative to a casing and which are adjacent to each other.

FIG. 3 is a perspective view of the vertical slider of FIG.

FIG. 4 is a characteristic curve diagram showing a relationship between a target value (stroke) and a volumetric flow rate regarding the directional control valve according to the present invention.

[Explanation of symbols]

 10 Directional Control Valve 11 Casing 12 Vertical Slider 13 Centering Spring 14 Pressure Chamber 15 Hole 16 Axial Slider Hole 17 Notch 18 Piston Section 19 Piston Core 21 Control Surface 22 Control Edge 23 Notch 24 Control Chamber 25 Connection Port 26 Connection Port 27 Connection Port 28 Connection Port 29 Casing Web 31 Control Passage 32 Control Notch 33 Circumferential Surface 34 Bottom Surface 35 Sidewall 36 Open Hole 37 Undercut Part 41 Process-Volume Flow Characteristic Curve 42 in the Present Invention 42 Process-Volume Flow Characteristic Curve in Prior Art

Front page continuation (72) Inventor Eckart Schuttenberg Germany Stuttgart Zuckerberg Strasse 175

Claims (14)

[Claims] 1. A hydraulic piston slider type directional control valve, wherein a longitudinal slider is slidably guided in a slider hole of a casing in a sealed state, and at least two sliders are provided in the slider hole. , Control chambers that are located in parallel with each other are formed, and the control chambers are located between
Two casing webs are formed in which the piston sections of the longitudinal sliders control the connection between the two control chambers, for which purpose the longitudinal sliders have at least one fine control switch. In the type having a geometrically constructed control notch extending over the entire travel range of the longitudinal slider, which serves as a notch, the volume flow characteristics of the control notch (32) are At the beginning of the opening stroke of the directional slider, a volumetric flow rate characteristic (41) of a quadratic function is shown based on the substantially triangular shape of the control notch (32), and as the opening stroke progresses,
On the basis of the multidimensionally expanding shape of the control notch (32), a transition to a higher-order function volumetric flow rate characteristic is achieved, so that depending on the casing loss compensation, it is continuous over the entire target range. A hydraulic piston-slider type directional control valve, characterized in that the volumetric flow rate characteristic (41) that rises rapidly and progressively is maintained. 2. The control notch (32) has a substantially triangular bottom surface (34) located between the longitudinal axis of the longitudinal slider (12) and the peripheral surface (33), the bottom surface (34) being The piston section (18) is open towards the control surface (21) on the end side and the side wall (35) extends outwardly from the bottom surface (34) towards the peripheral surface (33), the side wall being Extending with increasing mutual spacing in both radial and axial directions, this results in a circumferential surface (3) of the piston section (18).
3. A hydraulic system according to claim 1, characterized in that the control notch (32) is provided on the bottom surface (34) of the control notch (3) with a peripheral opening (36) expanded in a hopper shape. Piston slider type directional control valve. 3. The volume flow defined exclusively by the open cross section of the control notch (32) shifts to at least a quartic function with increasing travel distance of the longitudinal slider (12). The hydraulic piston slider type directional control valve according to claim 1 or 2. 4. A vertical slider (12) having a bottom surface (34).
4. A hydraulic system according to any one of claims 1 to 3, characterized in that it extends substantially parallel to the longitudinal axis of and is located on the circumferential surface of the piston core (19) in the radial direction. Piston slider type directional control valve. 5. A plurality of control notches (3, in particular 2-6).
5. A hydraulic piston-slider type directional control valve according to claim 1, wherein 2) are arranged at equal intervals on the outer circumference of the piston section (18). 6. A longitudinal slider (12) having a plurality of piston sections (18) with control notches (32),
Hydraulic piston-slider type direction according to any one of claims 1 to 5, characterized in that it has four control edges (22) especially for the function of a four-way three-position directional control valve. Control valve. 7. A hydraulic piston slider type directional control valve according to any one of claims 1 to 6, characterized in that a progressive valve is used. 8. The control surface (2) on the end face side of the bottom surface (34).
8. The hydraulic piston slider type directional control valve according to claim 1, wherein the boundary lines up to 1) form an acute angle with each other. 9. A hydraulic piston-slider type directional control valve according to claim 8, characterized in that the inner ends of the bottom surface (34) and the outer circumference (33) are significantly separated from each other in the radial direction. 10. The control notch (32), except for its triangular tip, is manufactured on an automatic lathe, the triangular tip being manufactured by erosion or stamping. The hydraulic piston slider type directional control valve according to any one of claims 1 to 9. 11. The volumetric flow rate characteristic curve (41) over the entire target value range is substantially a quadratic function curve,
The hydraulic piston slider type directional control valve according to any one of claims 1 to 10. 12. The hydraulic piston slider type according to claim 1, wherein an undercut portion (37) is provided on the control surface (21) on the end face side. Directional control valve. 13. An additional fine control notch is provided at the beginning of the control notch (32), the depth of which is smaller than the depth of the control notch (32).
13. The hydraulic piston slider type directional control valve according to any one of 1 to 12. 14. The axial discharge surface of the control notch (32) is, in the end-side control surface (21), approximately three times as large as the peripheral opening (36) for radial flow-through. The hydraulic piston slider type directional control valve according to any one of claims 1 to 13, characterized in that.