DE102017110380A1 - Drain valve for high pressures - Google Patents

Abstract

The present invention relates to a discharge valve for discharging a hydraulic fluid from a high-pressure region into a low-pressure region, in particular for a hydraulic drive circuit of a VCR connecting rod, comprising a base body, a sleeve-shaped housing inserted into the base body with a valve seat, a closing body movably guided in the housing, a valve spring biasing the closing body against the valve seat, a valve seat upstream upstream throttling point and a closing body from a closed to an open position, arranged on the low pressure side, arranged actuating device. To improve such a drain valve is provided according to the invention, that the throttle point upstream of the closing body is arranged such that the throttle point is formed in the transition region of the base body and the sleeve-shaped housing and / or in the wall of the sleeve-shaped housing and the valve spring as part of the actuator the low pressure side is arranged downstream of the valve seat. Furthermore, the invention relates to a corresponding insert for a drain valve and to a VCR connecting rod with at least one drain valve formed in this way.

Description

The present invention relates to a discharge valve for discharging a hydraulic fluid from a high-pressure region into a low-pressure region, in particular for a hydraulic drive circuit of a VCR connecting rod, comprising a base body, a sleeve-shaped housing inserted into the base body with a valve seat, a closing body movably guided in the housing, a valve spring biasing the closing body against the valve seat, a valve seat upstream upstream throttling point and a closing body from a closed to an open position, arranged on the low pressure side, arranged actuating device.

There are hydraulic applications in which the function of a directional control valve, such as a 3/2-way valve, must be represented, with the blocked lines are under very high pressure and to the high tightness of the system must be ensured. Such an application is e.g. the hydraulic drive circuit of a VCR (variable compression ratio) connecting rod, that is, a length-adjustable connecting rod for an internal combustion engine. The hydraulic drive circuit used for this purpose uses drain valves, which are to discharge hydraulic fluid from a previously closed pressure chamber. Usually, the adjustment of the connecting rod from the short to the long position or vice versa due to mass and gas forces occur, with a hydraulic blocking of the respective position takes place. This hydraulic lock is released by opening the discharge valve associated with the respective blocking pressure chamber. The VCR connecting rod is constantly loaded with tension and pressure. Accordingly, in the Druckkamer and the associated lines to the drain valve and the closing body a swelling pressure of over 300 bar. This results in very high demands on the components of the hydraulic control circuit, in particular the drain valves. These must be sufficiently durable and yet be accommodated in the available small space. The weakening of the VCR connecting rod should be as low as possible due to the space required for the drain valve. Furthermore, the leakage of the sealed line or the sealed pressure chamber should be as low as possible. Gap seals, such as those used in control valves with gate valves, are therefore rather impractical for the required blocking of a VCR connecting rod. However, it must be possible to be able to reasonably open the closing body in spite of the high pressure forces occurring in the closed line or in the blocked pressure chamber.

It is therefore an object of the present invention to provide a drain valve of the type mentioned, which is robust and is very easy to operate even at high pressures or pressure differences.

For this purpose, the invention provides that the throttle point is formed in the transition region of the base body and the sleeve-shaped housing and / or in the wall of the sleeve-shaped housing, and the valve spring is arranged as part of the actuating device on the low pressure side downstream of the valve seat. First of all, a throttle point is provided as part of the drain valve, which automatically arises by inserting the sleeve-shaped housing in the base body. This throttle point is tuned to the expected maximum system pressure so that at the throttle point such a large pressure drop arises that the closing body can be very easily opened against this reduced pressure. As a result, much lower holding forces are required to open the closing body. A special feature is therefore that very high pressure differences, which can also act swelling on the drain valve, are reduced. In order to reduce the force on the closing body and to prevent large volume flows, a throttle point is connected upstream of the actual valve seat and the associated valve opening. If the drain valve is opened, advantageously only a small part of the pressure drops on the closing body. The advantage becomes the greater, the greater the pressure difference, which drops at the upstream throttle point. It is also advantageous that the actuating device, including the valve spring, is arranged on the low-pressure side downstream of the valve seat. As a result, the most diverse controls can be used and trained. The actuating device accordingly controls the closing body, the actuating force depends on the design and direction of movement of the actuating device. A single actuator may also be associated with multiple drain valves. The arrangement of the valve spring on the low pressure side also opens the possibility to couple the closing body with the sleeve-shaped housing captive. Then, the closing body, the housing and the valve spring can form a preassembled unit (e.g., an insert) that can be tested by itself. This pre-assembly unit can then be inserted into a bore in the base body and e.g. be sealed tight with a screw cap. The term "actuator" should be understood as wide as possible and for all types of control of the closing body from the low pressure side.

As already mentioned, it is of particular advantage if the valve spring with the closing body the sleeve-shaped housing captively coupled so that they form a mounting unit.

Furthermore, on the low-pressure side on the closing body as part of the actuating device, an actuating tappet may be provided with a supporting surface spaced from the closing body, wherein the valve spring is arranged between a low-pressure side of the sleeve-shaped housing and the end surface. Since the valve spring is now supported between the housing and the support surface, it pulls the closing body on the valve seat and closes it with a predetermined spring force. At the same time, this spring force is also the holding force with which the coupling of these parts takes place.

According to a variant, the throttle point may be configured such that the pressure difference that occurs at the throttle point is at least three times greater than the pressure difference between the open closing body and the valve seat or associated valve opening. The pressure therefore falls mainly before the closing body. For this purpose, a narrowed flow cross-section is provided, which throttles the flow of oil. The closing body experiences thereby only a relatively small pressure load and the holding force for holding the closing body in the open position is low. This difference is achieved by a suitably selected aspect ratio. The loss factor of the throttle point is much higher than that of the actual valve on the valve seat. The throttle point can be generated in the interaction between the base body and the sleeve-shaped housing or by the housing itself.

In one embodiment, the restriction may e.g. be formed by an annular gap between the sleeve-shaped housing and the base body. Accordingly, the hydraulic fluid must flow through this annular gap and then a possibility must be created that the hydraulic fluid flows into the sleeve-shaped housing. For this, e.g. an inlet bore in the base body terminate on the outer surface of the valve housing. At this point, then the valve housing has a change in the outer diameter, so that at the top of said annular gap forms with the receiving bore in the base body. When flowing through the annular gap, the hydraulic fluid undergoes a pressure loss. The hydraulic fluid may then flow into the housing through the end openings (e.g., grooves) and over the opened closing body.

But there is also the possibility that the throttle point is formed by at least one opening, in particular a precision bore, in the wall of the sleeve-shaped housing. Such precision bores can be produced very accurately, which is why the throttle effect can be determined very precisely beforehand. With e.g. the sleeve-shaped housing can be installed undirected with respect to its rotational position, the distribution of hydraulic fluid from the inlet bore can be made via a groove. This groove may be in the base body or in the sleeve-shaped housing, or both, attached. Usually, the variant with the groove on the outside of the valve housing is easier to manufacture, but leads to a larger overall diameter of the valve housing, which in turn is disadvantageous at very high pressure values.

Of course, the sleeve-shaped housing must also be sealed relative to the base body such that an outflow of the hydraulic fluid takes place mainly or completely via the valve seat or the valve opening.

The closing body is guided longitudinally displaceable in the sleeve-shaped housing. So that there is no tilting of the closing body at the high load present here, according to a further embodiment, the closing body is guided on at least two guide surfaces arranged at an axial distance from each other. As a rule, there is a guide surface within the sleeve-shaped housing, while the other guide surface does not necessarily have to be arranged in the housing. Preferably, these guide surfaces are not located on a portion of the closing body with the same diameter.

Conveniently, the closing body may have a conical closing surface and the valve seat a corresponding conical shape. For high-pressure lines in particular such closing body and valve seats with conical seats are. Compared with other types of seats, both the sealing effect and the load capacity are good. It also occurs on a self-centering of closing body and valve seat.

The sleeve-shaped housing with the closing body and the valve spring are usually configured as a plug-in or plug-in part. In a further advantageous embodiment, therefore, a separate housing cover for closing and sealing the sleeve-shaped housing may be provided, which is inserted and fixed in the base body and by means of a, preferably elastic, compensation device (eg, a spring bias applying compensation device) on a front side of the sleeve-shaped Housing presses. The housing is thus constructed at least in two parts, wherein the attachment of the housing cover is not directly on the sleeve-shaped housing, but on the base body. As a result, can be applied by means of the housing cover a spring preload on the sleeve-shaped housing, whereby This example, in a sealing seat, preferably also a conical seat is pressed. Also, the housing cover should preferably seal to the base body with a sealing seat. Between the housing cover and the sleeve-shaped housing, for example, a plate spring, a wave spring, or another body can be placed, which deforms elastically under pressure. This ensures that both the sleeve-shaped housing and the housing cover are in contact with the base body and seal. A conical seat can also be used for the housing cover. But it is also possible to postpone or plug a seal on the housing cover. This also prevents a multiple fit, since the housing cover in the axial direction does not need to be positioned exactly. The seal, with eg a sealing ring, may even have some axial play, eg a groove.

In addition, the base body may have a guide section for guiding one of the guide surfaces of the closing body, preferably a guide surface on the actuating tappet. Usually, then, the leadership of the closing body takes place both within the sleeve-shaped housing and outside of the sleeve-shaped housing in the base body on the low pressure side. The guide surfaces then have the desired distance from each other for a tip-safe guidance of the closing body. In addition, the engagement of a separate actuating element as part of the actuating device in the low-pressure region and the existing there guide surface can be arranged at a small distance to the point of initiation of the actuating force in the actuating plunger.

In a further variant, it is provided that the guide surfaces on the closing body have regions which are arranged at a distance from the associated guide sections in the sleeve-shaped housing and / or in the base body such that, with the drain valve open, an axial flow along the hydraulic fluid at the closing body in the form of at least one Bypass channel is enabled. For example, the closing body may have flats, wherein these flattened areas are not in contact with the housing and thus formed between this bypass channel. But it is also possible, a part of the closing body, e.g. likewise to be guided in the housing on the actuating tappet, this can then likewise be flattened or longitudinal grooves can be introduced into the housing in this area, through which the hydraulic fluid can flow. These could be e.g. by making rooms.

In a variant, it can be provided that the housing cover has a guide section for guiding one of the guide surfaces of the closing body. The guide then takes place upstream of the valve seat. This variant has the advantage that the hydraulic fluid on the low pressure side could flow around the end of the closing body through a large bore, since no further guidance has to be provided here. However, the tolerance chain is very long. The housing cover should also be sufficiently centered in the base body in such a configuration.

When using a guide surface on the actuating tappet must be ensured that the hydraulic fluid can flow. This can e.g. by longitudinal grooves or by an eccentrically positioned bore, which creates a connection to the oil drain passage done.

An attachment of the valve spring can be carried out well in particular if, according to a variant of the confirmation plunger has an actuating head on which the support surface is arranged for the valve spring. When mounting, e.g. the closing body inserted through the housing and then the valve spring, in particular a conical valve spring, pushed over the end of the closing body until it rests behind the actuating head on the support surface. The outermost spring coils are slightly bent. The valve spring and the actuator head should be dimensioned so that the deformation of the valve spring takes place in the elastic range. Should this design be so impractical, there would be several alternative mounting options that would be compatible with the basic concept of the drain valve. It would be possible, e.g. a split closure body in which e.g. the actuator head is subsequently connected to the actuating tappet (glued, pressed, screwed, etc.). As an operating head to use a locking ring is also possible. The actuator head may also have a spiral groove on the outer periphery for attachment of the lower end of the valve spring. The valve spring of the dump valve could also be designed as a truncated cone spring having a rectangular cross section (e.g., sheet metal wound).

The invention relates to an insert for a drain valve according to one of the claims 1 to 13 with a sleeve-shaped, a valve seat-forming housing for insertion into an opening in the base body and a displaceably guided in the housing and by a valve spring with this captive coupled closing body, and a formed on the outer circumference or in the wall of the sleeve-shaped housing throttle means for forming a valve seat upstream upstream throttle with arranged in the base body insert. This insert is therefore designed as a key component of the drain valve pre-assembled, allowing a prior component test is possible, and an assembly in the base body, for example, the lower rod part of a VCR connecting rod, is facilitated. This insert is inserted into the base body and optionally fixed and sealed by a further element, eg housing cover.

Moreover, the invention relates to a VCR connecting rod for an internal combustion engine having a hydraulic drive circuit, the at least one drain valve according to one of the claims 1 to 13 includes. A VCR connecting rod is exposed to high loads and high pulsating pressures of over 300 bar occur in a hydraulic control circuit. All components must be designed to be durable. The demands on a drain valve used for this purpose are high.

The high pressure has a swelling effect on the drain valve and its closing body. Preferably, the closing body should be opened with little force in the low-pressure phases. As part of the confirmation device, e.g. an actuator may be used, which may include a cam disc disposed below the bleed valve which raises the closure body and thus opens the conduit. When repressurized, the drain valve is open. The hydraulic fluid flows off. The pressure drops mainly before the closing body. Due to the throttling, the holding force for the closing body is very low. But it is also possible the design of an actuating element, so that no holding power is required. For example, in the case of a rotated cam, which has an area which is cylindrical and whose axis coincides with the axis of rotation of the cam, this is the case (no change in stroke when turning). However, there are other forms of design as well.

There are applications where high accelerations act on the drain valve. In order to prevent the closing body tipping in his seat, it is therefore advantageous to place the center of gravity of the closing body in the region of the valve seat. Favorable here is e.g. the variant with the guide in the housing cover. This solution automatically results in more mass on the high pressure side, which at least partially offsets the mass of the actuating pin. A corresponding shape of the closing bodies could also be used if e.g. For technical reasons, no guidance at the top is possible.

The closing bodies could consist of metallic or ceramic materials. The mass of the closing body should be as low as possible in order to reduce the acceleration forces. In addition, the material must have a high wear resistance (hardness) and a high strength.

In addition, the actuating device can be designed such that it acts on several similar discharge valves simultaneously and thus enables the function of a control valve.

• 1 eine erste Ausführungsform eines erfindungsgemäßen Ablassventils im Vollschnitt,
• 2 eine zweite Ausführungsform eines erfindungsgemäßen Ablassventils im Vollschnitt,
• 3 eine dritte Ausführungsform eines erfindungsgemäßen Ablassventils im Vollschnitt,
• 4 eine vierte Ausführungsform eines erfindungsgemäßen Ablassventils im perspektiven Vollschnitt,
• 5 das Ablassventil aus 4 in einer perspektivischen Außenansicht,
• 6 eine vergrößerte Darstellung des hülsenförmigen Gehäuses aus 4 und 5 in einer vergrößerten perspektivischen Draufsicht,
• 7 eine Variante eines Schließkörpers in einer vergrößerten perspektivischen Darstellung,
• 8 eine weitere Ausführungsform eines erfindungsgemäßen Einsatzes im Vollschnitt und
• 9 eine weitere Ausführungsform eines erfindungsgemäßen Einsatzes im Vollschnitt.

In the following, embodiments of the present invention will be explained in more detail with reference to drawings. Show it:

• 1 a first embodiment of a discharge valve according to the invention in full section,
• 2 a second embodiment of a discharge valve according to the invention in full section,
• 3 a third embodiment of a discharge valve according to the invention in full section,
• 4 A fourth embodiment of a drain valve according to the invention in the perspective full section,
• 5 the drain valve off 4 in a perspective exterior view,
• 6 an enlarged view of the sleeve-shaped housing 4 and 5 in an enlarged perspective plan view,
• 7 a variant of a closing body in an enlarged perspective view,
• 8th a further embodiment of an insert according to the invention in full section and
• 9 a further embodiment of an insert according to the invention in full section.

In the 1 shown first embodiment of a drain valve 1 is used as part of a hydraulic drive circuit of a VCR connecting rod whose center distance between the small and the large connecting rod eye is changeable. By means of the drain valve 1 a pressure chamber of the hydraulic control circuit can be hydraulically closed or opened. The VCR connecting rod is thus locked in a desired length position or released for transfer to another length position. The VCR connecting rod of an internal combustion engine is alternately loaded with tension and pressure during operation. Accordingly, in the high-pressure region of the hydraulic control circuit, swelling pressures of more than 300 bar arise (in the closed state of the drain valve 1 ). The drain valve 1 is in the present case in the lower, connected to the crankshaft part of the VCR connecting rod, thus the base body 2 for the drain valve 1 applies, integrated. The drain valve 1 comprises a sleeve-shaped housing 3 , a slidably guided therein closing body 4 , a conically shaped valve spring 6 , A designed as a sealing plug housing cover 5 and a spring element designed as a plate spring 16 between the housing cover 5 and the sleeve-shaped housing 3 , In the base body 2 there is a the high-pressure area associated supply 7 , By the hydraulic fluid, in particular engine oil, the sleeve-shaped housing 3 is forwarded.

The closing body 4 is with a closing cone 8th provided in the closed state accurately to the likewise conically shaped valve seat 9 suppressed. Above the closing cone 8th there is a cylindrical guide surface 10 with which the closing body 4 in a corresponding guide section 10a of the sleeve-shaped housing 3 is guided. Below the closing cone 8th is on the closing body 4 an actuating tappet 11 arranged to form an annular gap through the valve opening 13 of the sleeve-shaped housing 3 extends and protrudes down from this. The actuating tappet 11 is with an operating head 14 provided at its free end. The actuating head 14 forms a support surface 15 for the lower end of the valve spring 6 out. At the free end is the actuator head 14 with a cam surface 17 Mistake. The upper, larger diameter end of the valve spring 6 is in a drilling stage 18 on the lower end side of the sleeve-shaped housing 3 added. Above the closing cone 8th and the cylindrical guide surface 10 there is a cylindrical pin attachment 19 in a corresponding receiving hole 20 in the lower end of the housing cover 5 is guided. The peripheral surface of the pin approach 19 thus forms a second guide surface 21 of the closing body 4 in the distance to the guide surface 10 is arranged and smaller in diameter. The closing body 4 is due to the spring force of the valve spring 6 in his in 1 shown closed position pressed.

The closing body 4 is by means of an unspecified actuator 22 (eg a cam mechanism acting on the cam surface 17 of the actuating head 14 acts) axially moved, in particular moved to its open position. The actuating device 22 , which also includes the actuating tappet 11 and the valve spring 6 can be configured in a variety of ways. It would be conceivable, for example, a cam, which is the closing body 4 raising. It is also possible a design, so that no holding power is required. This is the case, for example, with a rotated cam having an area which is cylindrical and whose axis coincides with the axis of rotation of the cam (no change in stroke during rotation). A hydraulically actuated slide with cam is conceivable.

The sleeve-shaped housing 3 has at its front end a sealing cone 23 on top of a complementary sealing surface at the end of a receiving bore 24 for the sleeve-shaped housing 3 is arranged. The receiving bore 24 is in the base body 2 formed.

The housing cover 5 has a threaded portion 25 on, with this in the base body 2 is screwed. At the upper end of the housing cover 5 there is a sealing cone 26 which is in a complementary conical sealing surface 27 in the base body 2 is pressed. At the upper end is located on the housing cover 5 a centering surface 28 , so that an exact alignment of the receiving bore 20 and leadership of the Stift approach 19 is possible. The housing cover 5 has a suitable tool holder 29 to perform screwing in with a predetermined tightening torque. For tolerance compensation and for secure pressing and thus sealing of the sleeve-shaped housing 3 is between the front end face of the housing cover 5 and the upper end surface of the sleeve-shaped housing 3 said spring element 16 interposed in the form of a plate spring. As a result, the necessary contact pressure of the housing 3 with the sealing cone 23 against the base body 2 guaranteed.

The drain valve 1 has a valve seat 9 upstream upstream throttle point 30 , This is in the present case by a precision opening in the side wall of the sleeve-shaped housing 3 formed in the closed state of the closing body 4 on the cylindrical guide surface 10 opens and is closed by this. So that the sleeve-shaped housing 3 can be installed undirected, is in the receiving bore 24 an annular groove 31 at the height of the supply line 7 incorporated. Alternatively, this could also be on the outside of the sleeve-shaped housing 3 be present, but which would increase its diameter. The pressure drop across the throttle 30 is dimensioned such that it is at least three times larger than the pressure drop in the area of the valve seat 9 and the valve opening 13 in the open state. Both the valve spring 6 as well as the actuator 22 are thus located on the low pressure side of the drain valve 1 , The valve opening 13 stands above a bore section 32 with the drain line 33 in fluid communication. The actuating device 22 is designed so that this flow connection with open drain valve 1 given is. The described drain valve 1 is in operation with locked supply line 7 exposed to a very high pressure and must ensure a high tightness, which is preferred by the closing cone 8th and the correspondingly shaped valve seat 9 and also the sealing cone 23 he follows. The chosen construction of the drain valve 1 and the use of a plunger-driven, provided with a valve spring, actuator on the low pressure side, opens the possibility to produce a highly loaded component, with the least possible weakening in the base body 2 gets along, since the dimensions of all components are as small as possible. This arrangement also allows the installation of the drain valve 1 in such a way that the function is not affected by occurring accelerations in the VCR connecting rod. This allows the axis of the closing body 4 Arrange parallel to the crankshaft axis.

Due to the design and the specially shaped sealing surfaces, it is also possible to keep the leakage in the closed state as low as possible, whereby a very good blocking of the length position of the VCR connecting rod is possible. In addition, the key components of the drain valve 1 be executed pre-assembled. This is the sleeve-shaped housing 3 , the closing body 4 and the valve spring 6 , The valve spring 6 fixes the closing body 4 on the housing 3 or couples this captive with this. As a result, a prior component test is possible and an assembly in the base body 2 facilitated. Due to the throttle point used 30 falls when the drain valve is open 1 the pressure mainly already before the closing body 4 from. The closing body 4 experiences a relatively low pressure load and also the holding force to keep it in the open position, is therefore low.

A special feature of a VCR connecting rod is that very high pressure differences, the swelling on the drain valve 1 act, be degraded. The throttle point is used for this purpose 30 when installing the sleeve-shaped housing 3 is automatically formed or formed. Due to the swelling pressure, the actuator 22 be formed so that a force sufficient, the drain valve 1 opens in the lower pressure phases. Is the drain valve 1 open, only a small part of the pressure falls on the closing body 4 or in the valve seat 9 from. The majority of the effective pressure difference falls at the upstream throttle point 30 from. This is achieved by a suitably selected aspect ratio.

In the 1 selected design also serves for applications when high accelerations on the drain valve 1 Act. To prevent the closing body 4 in his seat tilts, results from the pin approach 19 a counterweight to the actuating tappet 11 with operating head 14 because the center of gravity of the closing body 4 in the region of the valve seat 9 falls. The chosen solution automatically leads to more mass on the high pressure side, even if a guide in the range on the low pressure side is not possible, this variant is appropriate.

The closing body 4 could consist of metallic or ceramic materials. The mass of the closing body 4 should be as low as possible to reduce the acceleration forces. In addition, the material must have a high wear resistance (hardness) and a high strength.

The valve spring 6 is dimensioned to fit over the actuator head 14 can be pushed onto the actuating tappet. The narrower spring turns are bent slightly. The valve spring 6 and the actuator head 14 are dimensioned so that the deformation of the Endwindungen takes place in the elastic region.

The spring element used 16 automatically leads to a tolerance compensation, but nevertheless to the execution of a very well-sealed solution.

The closing body 4 is supported by the operating head 14 in an open position on a surface of an actuator of the actuator 22 from. Advantageously, the embodiment can be made so that no holding force must be exerted in the open state by means of the actuating element, but this automatically remains in the assumed switching position. In the usual VCR connecting rod are usually two of these drain valves 1 in use. The actuating device 22 can be designed so that its actuator on these two drain valves 1 or acts on several drain valves simultaneously and thus has the function of a directional control valve.

The following is based on the 2 a further embodiment of a drain valve according to the invention 1 explained in more detail. It will be discussed in the following only to the essential differences from the previous embodiment, which is why reference is made by using the same reference numerals to the above structural and functional description.

At the in 2 version shown becomes the throttle point 30 by means of a diameter jump, ie a throttle gap between the base body 2 and the lateral surface of the sleeve-shaped housing 3 educated. So that the hydraulic fluid from this throttle gap in the sleeve-shaped housing 3 can flow in, must be on the upper front side of the sleeve-shaped housing 3 Breakthroughs (not shown, eg grooves) may be provided so that the hydraulic fluid from above into the sleeve-shaped housing 3 flows. It is also a longitudinal groove 34 provided so that the hydraulic fluid on the cylindrical guide surface 10 of the closing body 4 can flow by.

Another difference is that the closing body 4 no pen approach 19 has, but the actuator head 14 on its lateral surface, the second guide surface 35 having. The actuating head 14 is therefore in a correspondingly shaped bore section 36 in the base body 2 guided. But also here has a corresponding longitudinal groove 37 be provided so that the hydraulic fluid in the low pressure region and the drain line 33 flows. As an actuator of the actuator 22 Again, various embodiments can find application, the actuating tappet 11 can move axially.

Due to the lack of pin attachment, the housing cover needed 5 no receiving bore 20 , The tolerance chain for guiding the closing body 4 is smaller and the distance between the two guide surfaces 10 and 35 is a bit bigger, which can have advantages.

Based on 3 Now, another embodiment of a drain valve according to the invention 1 explained in more detail. It will be discussed in the following only on the differences from the preceding embodiments, so reference is made by using the same reference numerals in addition to the previous description in terms of structural design and function.

The main difference is solely in the sealing on the housing cover 5 and the waiver of a spring element between the housing cover 5 and the sleeve-shaped housing 3 , The function of the spring element 16 takes over in this embodiment, the sealing ring 16a , This serves as a tolerance compensation and seals the drain valve 1 outwards with screwed-in housing cover 5 from. In addition, the centering of the housing cover is also 5 possible over a larger section, because a larger sealing cone 26 on the housing cover 5 not used, but a straight sealing surface 38 on the sealing ring 16a suppressed. However, an exact axial positioning is not mandatory. The sealing ring 16a could even be arranged with some play. Due to the unilaterally acting pressure, the sealing ring is used during operation 16a hike up and at the sealing surface 38 of the housing cover 5 and on the lateral surface of the bore in the base body 2 issue.

When using a hole as a throttle point 30 could also be a seal between sleeve-shaped housing 3 and the base body 2 respectively. However, the sealing solution appears more practical on the housing cover 5 ,

Based on 4 to 6 Now, a further embodiment of a drain valve according to the invention 1 explained in more detail. In the figures was based on the representation of the base body 2 waived. The design is very similar to the embodiment according to the 1 For this reason, only the essential differences will be discussed below and reference is additionally made to the above description. The main difference is that also the actuating tappet 11 in the sleeve-shaped housing 3 to be led. However, the guidance takes place only in some places by means of webs 39 , so that between the webs drain grooves 40 are formed. The in 4 shown section is exactly through two diametrically opposed webs 39 guided. From the 6 can also be seen that the drain grooves 40 only slightly with the conical valve seat 9 to cut.

Another difference is that instead of a pronounced actuating head a groove 41 in the actuating tappet 11 is arranged, in which a circlip 42 is arranged, the top of the support surface 15 for the valve spring 6 forms. Due to this configuration, it is not necessary, the valve spring 6 when mounting the sleeve-shaped housing 3 , the closing body 4 and the valve spring 6 as well as the circlip 42 existing use 43 elastically deform. This allows other valve springs 6 come into use. For example, the valve spring could also be designed as a truncated cone spring with a rectangular cross-section.

Based on 7 now becomes an alternative closing body 4 described in more detail. This has both in the area of its cylindrical guide surface 10 as well as in the area of the guiding surface 35 flats 44 and 45 on, so in the open state hydraulic fluid to the closing body 4 can flow by. The closing body 4 can of course with a longer actuating tappet 11 be configured for receiving the valve spring and in the previous embodiments.

Alternatively, it is now based on the 8th a further embodiment, in particular of the closing body 4 explained in more detail. In this embodiment, the closing body 4 split executed. The actuating head 14 is retrofitted with the actuating tappet 11 connected, for example by gluing, pressing or screwing or welding. This also allows the valve spring 6 mount easily and then the actuator head 14 Put on and with the rest of the closing body 4 connect.

According to the embodiment of the 9 is a further variant of the design of the closing body 4 and the attachment of the valve spring 6 explained in more detail. The outside of the actuator head 14 has a spiral groove 46 on, over which the valve spring 6 threaded, with the lower turns anchored therein.

LIST OF REFERENCE NUMBERS

1

drain valve

2

base body

3

sleeve-shaped housing

4

closing body

5

housing cover

6

valve spring

7

supply

8th

closing cone

9

valve seat

10

cylindrical guide surface

10a

guide section

11

actuating ram

12

annular gap

13

valve opening

14

actuating head

15

supporting

16

spring element

16a

sealing ring

17

cam surface

18

bore step

19

pin projection

20

location hole

21

cylindrical guide surface

22

actuator

23

sealing cone

24

location hole

25

threaded portion

26

sealing cone

27

conical sealing surface

28

centering

29

tool holder

30

restriction

31

ring groove

32

bore section

33

drain line

34

longitudinal groove

35

guide surface

36

bore section

37

longitudinal groove

38

sealing surface

39

web

40

drain groove

41

groove

42

circlip

43

commitment

44

flattening

45

flattening

46

spiral

Claims (15)

Discharge valve (1) for discharging a hydraulic fluid from a high-pressure region into a low-pressure region, in particular for a hydraulic drive circuit of a VCR connecting rod, comprising a base body (2), a sleeve-shaped housing (3) with valve seat (9) inserted into the base body (2) ), a closing body (4) movably guided in the housing (3), a valve spring (6) biasing the closing body (4) against the valve seat (9), a throttle point (30) upstream upstream of the valve seat (9) and a closing body (30). 4) from a closed into an open position convertible, arranged on the low pressure side actuator (22), characterized in that the throttle point (30) upstream of the closing body (4) is arranged such that the throttle point (30) in the transition region of the base body (2) and the sleeve-shaped housing (3) and / or in the wall of the sleeve-shaped housing (3) is formed, and the valve spring (6) is arranged as part of the actuating device (22) on the low-pressure side downstream of the valve seat (9). Drain valve (1) to Claim 1 , characterized in that the valve spring (6) the captive body (4) with the sleeve-shaped housing (3) captively coupled. Drain valve (1) to Claim 1 or 2 , characterized in that on the low pressure side on the closing body (4) as an integral part of the actuating device (22) an actuating plunger (11) with a closing body (4) spaced support surface (15) is provided and the valve spring (6) between a low pressure side of the sleeve-shaped Housing (3) and the support surface (15) is arranged. Drain valve (1) after one of Claims 1 to 3 , Characterized in that the throttle point (30) is designed such that the resulting difference in pressure at the throttle point (30) is at least three times greater than the difference in pressure between the opened closing body (4) and valve seat (9) and the associated valve port ( 13). Drain valve (1) after one of Claims 1 to 4 , characterized in that the throttle point (30) of an annular gap between the sleeve-shaped housing (3) and the base body (2) is formed. Drain valve (1) after one of Claims 1 to 4 , characterized in that the throttle point (30) of at least one opening, in particular precision bore, in the wall of the sleeve-shaped housing (3) is formed. Drain valve (1) after one of Claims 1 to 6 , characterized in that the closing body (4) is guided on at least two guide surfaces (35) arranged at an axial distance from one another. Drain valve (1) after one of Claims 1 to 7 , characterized in that the closing body (4) has a conical closing surface (8) and the valve seat (9) has a corresponding conical shape. Drain valve (1) after one of Claims 1 to 8th , characterized in that a separate housing cover (5) for closing and sealing of the sleeve-shaped housing (3) is provided, which is inserted and fixed in the base body (2) and by means of a, preferably elastic, compensation device on an end face of the sleeve-shaped housing ( 3) presses. Drain valve (1) after one of Claims 7 to 9 , characterized in that the housing cover (5) has a guide portion for guiding one of the guide surfaces (35) of the closing body (4). Drain valve (1) after one of Claims 7 to 10 , characterized in that the base body (2) has a guide section for guiding one of the guide surfaces (25) of the closing body (4), preferably a guide surface of the actuating tappet (11). Drain valve (1) after one of Claims 7 to 11 , characterized in that the guide surfaces on the closing body (4) have regions which are arranged at a distance from the associated guide sections in the sleeve-shaped housing (3) and / or in the base body (2) such that when the drain valve (1) is open, an axial flow along of the hydraulic fluid on the closing body (4) in the form of at least one bypass channel is made possible. Drain valve (1) after one of Claims 3 to 12 , characterized in that the actuating tappet (11) has an actuating head (14) on which the support surface (15) for the valve spring (6) is arranged. Insert (43) for a drain valve (1) according to one of Claims 1 to 13 , with a sleeve-shaped, a valve seat (9) forming the housing (3) for insertion into an opening in the base body (2) and a displaceably guided in the housing (3) and by means of a valve spring (6) with this captive coupled closing body (4) and a, on the outer circumference or in the wall of the sleeve-shaped housing (3) shaped throttle device for at least forming a valve seat (9) upstream upstream throttle body (30) in the base body (2) arranged insert (43). VCR connecting rod for an internal combustion engine with a hydraulic drive circuit, the at least one drain valve (1) according to one of Claims 1 to 13 includes.

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