CH713983A1 - Hydraulic device, in particular hydraulic valve or hydraulic regulator. - Google Patents

Abstract

The present invention relates to a hydraulic device, in particular hydraulic valve or hydraulic regulator, comprising a housing and a piston (10) axially displaceably mounted in a piston bore, wherein at least one volume chamber of the device through the piston bore and an axial portion (10a) of the tapered diameter piston is formed, wherein the at least one volume chamber is connected to at least one fluid inlet of the device, wherein a introduced into the piston skirt groove (16) fluidly connects the volume chamber with at least one volume chamber of the device, in particular an end face (11) of the piston.

Description

Description: The invention relates to a hydraulic device, in particular a hydraulic valve or a hydraulic regulator, with a housing and a piston mounted axially displaceably in a piston bore, wherein in the hydraulic device at least one volume chamber is tapered by the piston bore and an axial section of the piston Diameter is formed, wherein at least one volume chamber is connected to at least one fluid connection of the hydraulic device.

The object of the invention relates to hydraulic valves and hydraulic regulators, in which at least one control surface of the piston is to be acted upon by a pressure level supplied via a fluid connection of the hydraulic valve or hydraulic regulator.

The features of the invention can be applied to different types of hydraulic regulators e.g. Pressure regulators, power regulators, volume flow regulators etc. and on different types of hydraulic valves e.g. Pressure relief valves, proportional valves etc. To clarify the general applicability of the features of the invention, the content aspect contained in the previous sentence should be emphasized that the features of the invention are applicable to hydraulic regulators and hydraulic valves regardless of whether the hydraulic device has additional control inputs or not. The term control input is to be understood here as an additional possibility of intervention to apply a further force effect to the piston which is axially displaceably mounted in its piston bore. This could e.g. an additional fluid connection to another control surface of the piston, an actuator (for example a proportional magnet) with which a force effect can also be exerted on the piston etc.

As an example of a possible use of the invention, the structure of an existing hydraulic pressure regulator is discussed. For the functioning of the hydraulic controller, reference is made to the sectional view shown in FIG. 1, which shows a longitudinal section through the hydraulic controller in the area of the main stage. For example, the high-pressure outlet of a hydraulic pump can be connected to the connection of the high-pressure bore 1. The pressure level there is fed to the main stage and the preliminary stage, not shown here. The pressure level present in the actuating pressure bore 2 serves to adjust the helix angle of a hydraulic motor or a hydraulic pump. The fluid connection of the preliminary and main stage to the hydraulic oil tank takes place via corresponding bores 3a in the interior of the regulator housing and is led to the outside via the so-called tank bore 3. The pressure level of the control pressure set by the preliminary stage reaches the annular control surface 4b in the shoulder region of the control piston 4 via the so-called control pressure bore 5a and, together with the restoring force of the compression spring 5, exerts a force on the control piston 4 which assumes a position in which one Fluid connection between the high pressure bore 1 and the signal pressure bore 2 is present, counteracts. The oil pressure applied to the control surface 4a exerts a force opposing this. Depending on the ratio of these three forces, one of the three following cases occurs:

a) The signal pressure bore 2 is connected to the tank bore 3.

b) The signal pressure bore 2 is neither connected to the tank bore 3 nor to the high pressure bore 1.

c) The signal pressure bore 2 is connected to the high pressure bore 1.

An individual perspective view of the control piston 4 is shown in FIG. 2. The control piston 4 has an axial section 6a with a tapered diameter, as a result of which there is a corresponding volume chamber 6 between the outer surface of the control piston 4 and the piston bore in the regulator housing. There is a permanent fluid connection between the volume chamber 6 and the high pressure bore 1 regardless of the position of the control piston. The transverse bore 7 creates a fluid connection between the volume chamber 6 and the control chamber, which consists of the axial bore 8 and the section 9 of the piston bore located beyond the control piston 4. The control surface 4a, which extends over the entire cross section of the control piston 4, is consequently subjected to an oil pressure, the pressure level of which is lower than that in the high-pressure bore 1. The reason for this pressure reduction is the fact that the diameter of the cross-bore 7 extending through the control piston 4 in the real implementation is significantly smaller than in the not-to-scale longitudinal sectional view of FIG. 1. As a result, there is a pressure loss along this cross-bore 7 in front. In terms of switching technology, the transverse bore 7 results in two parallel channels, each of which extends from the outer surface of the actuating piston 4 in the tapered region 6 of the control piston 4 to the longitudinal bore 8 there. To provide the control pressure within the control chamber, the required precise throttling action of the fluid connection must therefore be achieved along a comparatively short length.

With regard to the geometry, the nature of this throttle resulting from the transverse bore 7 appears to be quite simple, but this does not apply to the production technology. For the functioning of the hydraulic controller, a highly precise setting of the transverse bore 7 is imperative and with this difficult starting constellation, a precise adherence to the target mass is necessary, since otherwise very small deviations lead to extremely high deviations of the desired controller characteristic. Due to a usual bore diameter of approx. 2.5 mm with a total material diameter of approx. 5 mm, radial drilling through the control piston 4 is very demanding. Likewise are

CH 713 983 A1 the deburring, the removal of all chips produced during production and the control over it is quite complex. However, these steps are extremely important, since otherwise a drilling chip remaining in the control piston 4 could get into the hydraulic oil circuit and cause secondary damage there. In addition, the construction is extremely susceptible to contamination within the hydraulic fluid flowing through, because even the slightest blockage of the throttle or. the transverse bore 7 can cause a massive influence on the hydraulic controller characteristic.

What is therefore sought is a solution for a piston which, in addition to better reliability, is characterized by less manufacturing effort.

This object is achieved by a hydraulic device according to the features of claim 1. Advantageous embodiments of the device are the subject of the dependent subclaims.

It is assumed that a hydraulic device, in particular a hydraulic valve or a hydraulic controller, with a housing and a piston axially displaceably mounted in a piston bore. Over an axial section with a tapered diameter, this forms, together with the piston bore, a volume chamber which is connected to at least one fluid inlet of the device. According to the invention, the piston in its jacket region has a groove made therein, which forms a fluid channel between the volume chamber and at least one control chamber of the device.

The application of the groove-shaped channel on the outer circumference of the control piston offers not only manufacturing advantages, but also the positive effect that this results in significantly greater flexibility in the technical design of that section of the fluid connection via which the throttling effect is achieved. The resulting flexible design space for the groove, in particular with regard to its groove width and / or groove length, and / or profile shape, permits flexible dimensioning of the throttling effect which can be achieved, but without adversely affecting the associated production outlay. In particular, the fluid connection along which the required throttling effect can be achieved can be made significantly longer in the form of a groove than in the form of a radial bore according to the prior art. The length of the fluid connection obtained through its design as a groove is accompanied by an overall greater channel width (groove width). An extension of the oil connection along the section over which the throttling effect is to be achieved creates a higher reproducibility of the existing throttling effect after manufacture and better durability over the service life. Increasing the channel width reduces the susceptibility to clogging of the fluid connection.

It when the groove is designed helically, for example with one turn, particularly preferably with several turns, it being particularly advantageous, the number of turns not having to be an integer. The associated increased channel length makes larger groove profile widths possible.

The slope of the helix can also be freely selectable. In this way, on a length section of the control piston available for placing the groove, e.g. half or 1.4 etc. threads of the groove are applied.

It is preferred if the helical groove is designed to be clockwise. A left-handed configuration is also conceivable. A multi-course design of the helical groove is also conceivable, in particular regardless of its direction of rotation.

The cross-sectional profile of the groove, in particular the helical groove, can be chosen as desired, depending on the application and the throttling effect to be achieved. An n-angular, in particular triangular or quadrangular, or round profile shape of the groove is preferred.

The manufacture of the helical groove, in particular, is comparatively simple and can be done, for example, by means of turning, milling, grinding, rolling or embossing. In this case, only material is removed from the outer surface of the piston blank, which makes deburring and the final quality control comparatively simple by visual inspection. In addition, the introduction of the groove, in particular the helical groove, can take place without further reclamping of the piston blank, since the introduction of a transverse bore required according to the prior art requires repeated clamping and unclamping of the workpiece.

[0016] According to an advantageous embodiment, the pressure inlet corresponds to the high-pressure connection of the hydraulic device. Here, the throttled pressure level supplied to the control chamber serves to displace the piston against a force acting in the axial direction of the piston, this force being generated, for example, by a compression spring and / or an oppositely directed control surface of the device.

According to an advantageous embodiment, the hydraulic device can be designed as a hydraulic regulator, the piston in this case representing the control piston of the regulator. Such a hydraulic controller is used, for example, to cut off pressure for a hydraulic pump. The pressure cut-off of a hydraulic displacement unit means that its actuating piston and thus its helix angle and consequently the stroke of the engine cylinders do not exceed a certain dimension, as a result of which the maximum pressure is determined. There is a certain pressure level in the actuator cylinder of the displacement unit. Depending on the level of the pressure within the control chamber and consequently the position of the actuating piston, there is either a fluid connection between the high-pressure and actuating pressure bores or between the tank and actuating pressure bores, or the actuating pressure bore is closed. The latter applies as soon as the hydraulic pump is in the stationary operating state.

CH 713 983 A1 In a further embodiment, the hydraulic device can be a hydraulic valve, for example a pressure relief valve. The piston therefore serves as a slide valve. Due to the desired pressure loss along the groove of the slide valve installed in the valve housing, a reduced pressure level acts on its control surface, i.e. if, for example, the pressure difference has almost reached the opening pressure of the pressure limiting valve, the groove is designed to have a comparatively low control pressure. This offers the advantage that pressure relief valves, which are designed for high opening pressures, can be equipped with comparatively weak return springs and comparatively large control surfaces. Weak return springs simplify the handling of an adjustable return spring and reduce the manufacturing costs of a pressure relief valve. Avoiding very small control surfaces is useful to achieve a high accuracy of the pressure relief valve.

It is conceivable that the device, in particular the hydraulic controller, is designed in several stages, wherein a with the groove made on its lateral surface, i. H. a control piston according to the invention is used in the main and / or preliminary stage of the device, for example a hydraulic controller.

Further advantages and properties of the invention are explained in more detail below with reference to an embodiment shown in the figures. Show it:

1 shows a cross-sectional illustration of a hydraulic regulator according to the prior art with a control piston having a transverse bore;

FIG. 2: a perspective view of the conventional control piston according to FIG. 1;

3: an embodiment of a piston according to the invention in a perspective view;

4: a side view of the piston according to the invention according to FIG. 3;

5: an alternative embodiment of the control piston according to the invention and

FIG. 6: a detailed view of a main stage of a hydraulic regulator in which a control piston according to FIG. 5 is used.

Fig. 3 shows a perspective view of the piston 10 according to the invention for use in a hydraulic device according to the invention. It can be seen from the side view shown in FIG. 4 that in the exemplary embodiment shown, the non-tapered regions of the piston 10 all have a diameter of the same size.

Exemplary use of the piston 10 according to the invention in a hydraulic valve:

Such a piston 10 could, for example, be used as a slide valve in a pressure relief valve. Due to the desired pressure loss along the helical groove 16 of the slide valve 10 installed in the valve housing, a reduced pressure level acts on the control surface 11, i.e. If the pressure level at the external connection of the pressure limiting valve has almost reached the opening pressure, for example, the helical groove 16 is designed to have a comparatively low control pressure. This offers the advantage that pressure relief valves, which are designed for high opening pressures, can be equipped with comparatively weak return springs and comparatively large control surfaces. Weak return springs simplify the handling of an adjustable return spring and reduce the manufacturing costs of a pressure relief valve. Avoiding very small control surfaces is useful to achieve a high accuracy of the pressure relief valve.

Exemplary application examples of the piston according to the invention in a hydraulic controller:

The piston 10 according to the invention according to FIG. 3 can be used as a control piston and could, with a corresponding dimensioning in the main stage shown in FIG. 1, directly replace the control piston 4 corresponding to the prior art. In the case of such an exchange, the only difference is that when the control piston 10 according to the invention is used according to FIG. 3, the desired pressure drop, starting from the pressure level in the high-pressure bore 1 to the reduced pressure level acting on the control surface 11, via the throttle effect of a pressure introduced into the control piston jacket Groove 16, preferably a helical groove, does not take place via the throttling action of the transverse bore, as in a control piston 4 according to the prior art according to FIG. 2. If the piston 10 according to the invention according to FIG. 4 is used as a control piston in a regulator axis, in which the annular shoulder 20 is not used as a control surface or this area is not developed in such a way that it is suitable as a control surface and, apart from parasitic forces such as frictional forces on the control piston 10, only the restoring force of the compression spring and that caused by the appendix act on the reduced high pressure level on the control surface 11, the hydraulic device in which the piston 10 according to the invention according to FIG. 3 is used is a pressure cut-off.

CH 713 983 A1 If such a controller axis as described in the previous exemplary embodiment is additionally equipped with a proportional magnet, an electrically proportional controllable pressure controller with pressure cut-off can be constructed.

The compression spring 5 exerts a force on the control piston 10 which counteracts the assumption of a piston position in which there is a connection between the high pressure bore 1 and the actuating pressure bore 2. The oil pressure applied to the control surface 11, the so-called control pressure, exerts a force directed in the opposite direction. Depending on the ratio of these two forces, one of the three following cases is present:

a) There is a fluid connection between the steep pressure bore 2 and the tank bore 3.

b) Between the signal pressure bore 2 there is neither a fluid connection with the tank bore 3 nor is there such a connection to the high pressure bore 1.

c) There is a fluid connection between the control pressure bore 2 and the high pressure bore 1.

With a correspondingly high preload of the compression spring 5, a comparatively high control pressure is required until there is a connection from the high pressure bore 1 to the signal pressure bore 2. With a correspondingly high preload of the compression spring 5, a comparatively small reduction in the control pressure leads to an oil connection from the actuating pressure bore 2 to the tank return 3.

Fig. 5 shows another embodiment of a control piston 10 according to the invention for use in a hydraulic controller, in which the supply of an additional control pressure is provided, which is supplied through an additional outer bore 17 integrated in the control piston 10. If a corresponding pressure reduction is required, the outer bore 17 can be made with a very small diameter according to the prior art and thus serve as a throttle. FIG. 6 shows the installation position of the control piston 10 of FIG. 5 in one exemplary embodiment the control chamber of a main stage of a multi-stage hydraulic regulator.

The control piston 10 comprises the control surface 11, which is composed of the annular region 11a and the circular region 11b. A fluid connection from the high-pressure bore 1 to the control surface 11a, 11b is established via the helical groove. In the axial direction, the control piston 10 has sections a, b, each with a tapered diameter, which are used to form different volume chambers 6a, 6b together with the piston bore of the regulator housing 18. The first section a with a reduced diameter is used to form a volume chamber 6a which, according to FIG. 6, is connected to the high-pressure bore 1 of the hydraulic regulator 100. The second section b with a reduced diameter forms a volume chamber 6b connected to the tank bore. Depending on the position of the actuating piston 100 in the piston bore, a fluid connection is established between the high pressure and the actuating pressure bore via the volume chamber 6a or there is a connection between the tank and actuating pressure bore above the volume chamber 6b or the actuating pressure bore is from both the tank and the high pressure bore 1 separated. The latter applies as soon as the actuating piston of the hydraulic displacement unit to be set via the hydraulic controller has assumed a stationary position.

The last section c with a reduced diameter forms the end of the control piston 10. Depending on its axial position in the piston bore, a certain proportion of this section c projects into the spring chamber. The outer surface of the control piston 10 between the end facing the screw plug 21 and the adjoining region a also provides the helical groove 16 according to the invention, via which the desired pressure reduction of the pressure level existing in the high-pressure bore 1 to that pressure level which is the result of the the entire cross section of the control piston 4 extending control surface.

5 corresponds essentially to the embodiment shown in FIGS. 3 and 4, additionally has an axial longitudinal bore 19 which extends from the end of the control piston facing the screw plug 21 into the opposite last section c extends with a reduced diameter. Between the axial longitudinal bore 19 and a region separated from the spring chamber there is a fluid connection via a radial bore 17. From this region separated from the spring chamber there is a fluid connection via a preliminary stage, not shown here, for tank return acting as a variable throttle. A pressure level can thus be set in the region separated from the spring chamber via the preliminary stage. This is a control pressure, since an annular control surface 20 is acted upon in the shoulder region of the control piston 10 with this pressure level.

Alternatively, an embodiment of this throttle 17 as a radial bore, this could also be designed in the form of a groove made in the outer surface of the control piston.

Claims (10)

claims 1. Hydraulic device, in particular hydraulic valve or hydraulic controller, with a housing and a piston axially displaceably mounted in a piston bore, at least one volume chamber of the device CH 713 983 A1 is formed by the piston bore and an axial section of the piston with a tapered diameter, at least one volume chamber being connected to at least one fluid inlet of the device each, characterized in that a groove made in the piston jacket surrounds the volume chamber with at least one volume chamber Device fluidly connects, in particular an end face of the piston. 2. Hydraulic device according to claim 1, characterized in that the groove is introduced helically on the piston skirt. 3. Hydraulic device according to claim 2, characterized in that the helical groove has one or more turns. 4. Hydraulic device according to one of the preceding claims, characterized in that the helical groove is right-handed or left-handed. 5. Hydraulic device according to one of the preceding claims, characterized in that the cross-sectional profile of the groove is n-angular or round. 6. Hydraulic device according to one of the preceding claims, characterized in that the groove is applied to the jacket of the piston by turning and / or milling and / or grinding and / or rolling and / or embossing processes. 7. Hydraulic device according to one of the preceding claims, characterized in that the pressure supply corresponds to the high pressure connection of the device. 8. Hydraulic device according to one of the preceding claims, characterized in that the device is a hydraulic valve and the piston forms the control slide of the valve, the pressure level present in the volume chamber and acting on the control surface of the control slide preferably acting against an axial direction of the control slide Force acts, which can be generated in particular by a compression spring of the valve and / or an opposing control surface of the control slide. 9. Hydraulic device according to one of the preceding claims 1 to 8, characterized in that the device is a hydraulic controller and the piston forms the control piston of the hydraulic controller, the pressure level present in the volume chamber and the control surface of the control piston preferably acting against a force acting in the axial direction of the control piston acts, which can be generated in particular by a compression spring of the hydraulic regulator and / or an opposing control surface of the control piston. 10. Hydraulic device according to one of the preceding claims, characterized in that the device is designed in several stages, the main and / or preliminary stage comprising the piston having the groove.