DE102017001540B4 - Filter device, filter device housing and their use - Google Patents

Abstract

Filter device with a filter element (3) and a bypass device (5) which has a spring-loaded valve body (43) which opens from a predeterminable bypass opening pressure and a fluid-carrying connection between an unfiltrate (15) and a filtrate side (26) of the filter element (3 ) creates this filter element (3) by at least partially bypassing the filter material (21), a control device (79) being provided by means of which the bypass opening pressure can be changed in a temperature-controlled manner, the control device (79) increasing the bypass opening pressure from a high one upon reaching a predeterminable temperature threshold Pressure value drops to a lower pressure value, the control device having a bimetal element (79) which, under temperature control, produces a fluid-carrying connection between the unfiltrate side (15) and a control chamber (35) accommodated in the bypass device (5) and below this Tempe raturschwellenwerts is connected to the filtrate side (26) of the filter element (3), and wherein in a closed state of the valve body (43), in which this rests against housing parts (29, 65) of the bypass device (5), the control chamber (35) of these housing parts (29, 65) is limited, characterized in that an unfiltrate (75) and a filtrate connection (71) open into the control chamber (35), which can be closed alternately by the bimetal element (79) depending on the fluid temperature.

Description

The invention relates to a filter device with the features in the preamble of claim 1.

Filter devices, especially when they are used for mobile applications, such as in motor vehicles or mobile work equipment, for example for filtering transmission oils or hydraulic oils, there are operating phases that take place under different temperature conditions. The resulting changes in viscosity between low cold start temperatures and significantly higher operating temperatures lead to different differential pressures regardless of the operating state of the filter material of the filter element, i.e. whether it is functional or blocked, so that the response of the bypass device is influenced to an undesirable extent by the viscosity. With regard to this problem is in the document WO 01/55563 A2 discloses a filter device of the type mentioned, which provides a closing spring loading the valve body as a control device for the temperature-controlled change of the bypass opening pressure, the spring stiffness of which changes depending on the temperature in such a way that the spring stiffness is low at low cold start conditions and low at a higher temperature, such as the operating temperature , is harder. In the case of a closing spring that only provides the spring stiffness for the desired bypass function with the usual bypass opening pressure of three bar in normal operation at temperature, this means that with the closing spring, which is weak in the low temperature range, the bypass in low temperature operation, such as with a cold start, is due to the increased Viscosity of the fluid pending high differential pressure is open, regardless of the condition of the filter material. The opened bypass leads to contamination of the system despite the presence of a functional filter element.

The U.S. 4,388,196 A discloses a filter device with a filter element and a bypass device which has a spring-loaded valve body which opens from a predeterminable bypass opening pressure and creates a fluid-carrying connection between an unfiltrate and a filtrate side of the filter element while at least partially bypassing the filter material of this filter element, a control device being present , by means of which the bypass opening pressure can be changed in a temperature-controlled manner, the control device reducing the bypass opening pressure from a high pressure value to a low pressure value when a predeterminable temperature threshold value is reached, the control device having a bimetal element which, under temperature control, establishes a fluid-carrying connection between the unfiltrate side and a Establishes the control chamber received in the bypass device, which is below this temperature threshold to the filtrate side of the filter elements is connected, and wherein in a closed state of the valve body, in which this rests against housing parts of the bypass device, the control chamber is limited by these housing parts.

On the basis of this prior art, the object of the invention is to provide a filter device whose bypass device is characterized by a particularly advantageous operating behavior.

According to the invention, this object is achieved by a filter device which has the features of claim 1 in its entirety.

According to the characterizing part of claim 1, the filter device according to the invention is characterized in that an unfiltrate and a filtrate connection open into the control chamber, which can be closed alternately by the bimetal element depending on the fluid temperature.

As a result, depending on the control position of the bimetal element, the valve body is loaded with different opening forces that act against the closing force of the spring and are generated by the fluid pressure.

Furthermore, an essential feature of the invention is that the control device lowers the bypass opening pressure from a high pressure value to a low pressure value when a predefinable temperature threshold value is reached. This control behavior of the control device, which is contrary to the known solution mentioned, enables a particularly advantageous operating behavior of the filter device according to the invention. When specifying the temperature threshold value for the transition temperature between cold operation with high fluid viscosity and the range in which the viscosity of the warm fluid is in the normal range, and when the bypass device is designed for the usual opening pressure of, for example, three bar, the bypass device works in the entire range of Optimum operating temperature, with the bypass being opened in the desired manner only as a function of a malfunction (blocking) of the filter material. Since the control device in the invention prescribes a high pressure value at temperatures below the threshold value for opening the bypass, the disadvantage of the known solution that the high viscosity during cold start operation opens the bypass regardless of the functional state of the filter element is avoided. Due to the high pressure value provided in the invention at high viscosity, it also remains Cold start conditions, the bypass is closed when the filter element is functional, i.e. permeable, as long as there is no blockage of the filter material and the bypass opens despite the increased opening pressure value. In the invention, therefore, the bypass function is also dependent on the state of the filter element in the area of cold operation, thus ensuring safe operation of the filter device under all operating conditions, ie without the risk of contamination of the system under cold start conditions.

The control device has a bimetallic element which, under temperature control, produces a fluid-carrying connection between the unfiltrate side and a control chamber accommodated in the bypass device, which is connected to the filtrate side of the filter element below this temperature threshold. The change in the bypass opening pressure therefore advantageously takes place by means of a switching process controlled by the fluid pressure at a clearly specified switching temperature.

The arrangement can advantageously be made such that the temperature threshold is 20 ° C. and / or that the control device lowers the bypass opening pressure from the high value of 5 bar (five bar) to the low pressure value of 3 bar (three bar).

The bimetallic element can advantageously be designed in the form of a plate-like round control disk which forms a snap-in element and which, fixed at the edge in the control chamber by means of a fixing device, in its position blocking the filtrate side, releases a fluid path from the unfiltrate side into a subspace of the control chamber in which otherwise the filtrate connection opens. Such a bimetallic disk can be designed in such a way that, depending on the temperature, it bulges abruptly to one side or the other and, depending on the bulge, assumes a blocking position or a release position.

The arrangement can furthermore advantageously be made such that the control chamber has a further subchamber adjoining one subchamber into which the unfiltrate connection opens in a fluid-carrying manner as soon as it is released by the bimetal element. The control chamber can be encompassed on the edge side by a further control chamber which is separated from the one control chamber when the valve body is closed and is adjacent to the housing parts of the bypass device and which is permanently connected to the unfiltrate side in a fluid-conducting manner.

The unfiltrate connection can advantageously be accommodated in a cover of the control chamber which is permanently connected to the housing parts of the bypass device, the filtrate connection being passed through the valve body. With this design, the bypass device can be integrated into the filter device with little space requirement.

To seal against the housing parts of the bypass device, the valve body can carry a sealing cap and be permanently acted upon by a compression spring which extends between a housing for the valve body and the latter, the interior of the housing being permanently connected to the filtrate side of the filter element via at least one passage is.

In this case, the receiving housing for the valve body can be connected with particular advantage as an additional housing part to the other housing parts of the bypass device, which are part of an end cap of the filter element.

With this arrangement of the bypass device on an end cap, the bypass device can project at least partially into the hollow cylindrical filter element, which is provided on the bottom with a further end cap which has a filtrate outlet. During operation, the flow through the filter element is from the outside of the filter material inwards.

The invention also relates to a filter device housing for receiving a filter device according to one of claims 1 to 10, the filter device housing having the features of claim 11.

According to claim 12, the subject matter of the invention is also the use of a filter device according to one of claims 1 to 10 and a filter device housing according to claim 11.

• 1 einen zentralen Längsschnitt eines Ausführungsbeispieles der erfindungsgemäßen Filtervorrichtung;
• 2 einen gegenüber 1 vergrößert gezeichneten Teillängsschnitt lediglich des der Bypasseinrichtung benachbarten Bereichs des Filterelements der Filtervorrichtung, wobei der Betriebszustand der Bypasseinrichtung bei einer Temperatur unterhalb eines Temperaturschwellenwertes gezeigt ist;
• 3a, 3b die Projektion von oberer bzw. unterer Druckfläche des Ventilkörpers der Bypasseinrichtung, wobei die Druckverteilung beim Betriebszustand unterhalb des Temperaturschwellenwertes angegeben ist;
• 4 einen der 2 entsprechenden Teillängsschnitt, wobei der Betriebszustand der Bypasseinrichtung oberhalb des Temperaturschwellenwertes dargestellt ist; und
• 5a, 5b den 3a, 3b entsprechende Darstellungen, wobei die Druckverteilung beim Betriebszustand oberhalb des Temperaturschwellenwertes dargestellt ist.

The invention is explained in detail below with reference to an exemplary embodiment shown in the drawing. Show it:

• 1 a central longitudinal section of an embodiment of the filter device according to the invention;
• 2 one opposite 1 enlarged partial longitudinal section only of the region of the filter element of the filter device adjacent to the bypass device, the operating state of the bypass device being shown at a temperature below a temperature threshold value;
• 3a , 3b the projection of the upper or lower pressure surface of the valve body of the bypass device, the pressure distribution is specified for the operating state below the temperature threshold value;
• 4th one of the 2 corresponding partial longitudinal section, the operating state of the bypass device being shown above the temperature threshold value; and
• 5a , 5b the 3a , 3b corresponding representations, the pressure distribution being shown in the operating state above the temperature threshold value.

The 1 shows an embodiment of the filter device according to the invention including a device housing, designated as a whole by 1, which accommodates the filter device according to the invention, which is a filter element 3 and a bypass device 5 having. The case 1 has a housing main part 7th in the form of a circular cylindrical pot, on the bottom part 9 a centrally located filtrate outlet 11 is located. At the upper open end of the main part 7th is the case 1 through a housing head 13th closed, on which there is a lateral unfiltrate inlet 15th is located. As a holder for the filter element 3 is located on the bottom part 9 , to the filtrate outlet 11 concentric, a stub protruding inwards 17th . This forms with its outside the seat for a lower end cap 19th which, in the usual way, form an enclosure for a filter material forming a hollow cylinder 21st forms. The end cap 19th has a central opening 23 on, the edge of the opening from an axially downwardly protruding connection piece 25th is surrounded by the built-in filter element 3 the outer surface of the nozzle 17th of the bottom part 9 overlaps. This is over the opening 23 the end cap 19th the fluid passage from the inner filter cavity 26th of the filter element 3 to the filtrate outlet 11 educated. When the unfiltrate flows in via the inlet 15th to the outside of the filter material 21st of the filter element 3 forms the inner filter cavity 26th the clean side (filtrate side), during which the filter material 21st surrounding space within the housing forms the dirt side (unfiltrate side).

The bypass device 5 forms part of the top end cap 27 that is the bezel for the top of the filter material 21st forms. This end cap 27 has an upper housing part 29 on that, from the outer peripheral edge 31 offset radially inward, extending axially upward in stepped form. This upper case 29 forms a centrally located passage opening 33 the end cap 27 as well as a first control chamber 35 and a second control chamber 37 . Through a housing cover 39 at the top of the upper housing part 29 are the control chambers 35 , 37 completed at the top. The end cap 27 has a lower, second housing part 41 on which the housing for a movable valve body 43 forms. The lower case 41 extends from that between the opening 33 and the filter material 21st located area of the end cap 27 away axially into the inner filter cavity 26th inside and has the shape of a down to the case back 45 conically tapering pot, in the side wall of which fluid passages 47 are formed.

From the central area of the floor 45 of the lower part of the housing 41 a hollow pin extends 49 axially upwards towards the upper housing part 29 . The hollow pin forms on the inside 49 the guide for the valve body movable in the axial direction 43 . This has on the whole the shape of a mushroom with a head part forming the closing body 51 and a hollow shaft adjoining its underside 53 , the one in the hollow pin 49 is movably guided. The shaft 53 has deep grooves on the outside 55 the fluid connection between the filter cavity forming the clean side 26th and the entrance opening 57 of the hollow shaft 53 form. The outside of the valve body 43 leading hollow pin 49 forms the centering body for a closing spring in the form of a helical compression spring 50 that between the floor 45 of the housing part 41 and the underside of the headboard 51 of the valve body 43 is tense. The top of the headboard 51 forms in the inner passage 56 of the shaft 53 adjoining central area 59 a surface extending in a radial plane, which is adjoined radially on the outside by a conical part that has the shape of a stepped cone made up of two flat surface parts 62 and 63 educated. Of these forms the outer surface part 63 the valve sealing area with which the valve body 43 at the in 2 and 4th shown closed position on a sealing line 65 at a step of the upper housing part 29 is applied.

On the top of the headboard 51 of the valve body 43 , more precisely on the central area 59 and part of the first lateral surface part 61 , is a sealing cap 67 arranged from an elastomer. In the shown closed position ( 2 and 4th ), forms the sealing cap 67 by resting on the edge of an upper housing part 29 axially protruding ring body 69 the seal between the inner first control chamber 35 and the outer control chamber 37 . The latter is over in the upper case 29 located slots 85 with which the housing part 29 surrounding, dirt-side space connected so that in the second control chamber 37 the pressure on the unfiltrate side is permanently effective. The sealing cap 67 faces coaxially to the shaft 53 a tubular body 71 on, which is with its lower pipe section in the passage 56 of the shaft 53 extends and with its upper tube section in the first control chamber 35 protrudes. With its end 73 forms the upwardly protruding tubular body 71 a valve opening. Coaxial to the pipe body 71 is in a central opening of the upper housing cover 39 a short piece of pipe 75 used, like the sealing cap 67 is formed from an elastomer and like the tubular body 71 with his in the control chamber 35 located end 77 forms a valve opening. The through the pipe ends 73 and 77 The valve openings formed can alternately be released or closed depending on the temperature by a bimetal element.

The bimetal element has the shape of a membrane-like, thin, circular disc 79 which, depending on the temperature, is curved to one side or the other like a plate. If the temperature changes above a temperature threshold, the curvature changes suddenly. The bimetal disc 79 thereby forms a kind of snap element. If the temperature is below the threshold, the disk is 79 arched upwards, like this in 2 is shown in which the operating state of the bypass device 5 shown below the temperature threshold. The 4th shows the operating state above the temperature threshold, with the disc 79 is curved downwards. In the control chamber 35 is the disc 79 stored so that when arching upwards they pass through the end 77 of the pipe section 75 formed valve opening closes (see 2 ) and if it is curved downwards (see 4th ) the valve opening at the end 73 of the tubular body71 closes. The bimetal disc is used for this control or valve function 79 in the first control chamber 35 with their disc edge on wall parts of the upper housing part 29 not stored in full contact, but rather are on the edge-side suspension of the bimetal disc 79 Passage points 82 formed, the fluid connections between the upper subspace 80 and lower subspace 81 the control chamber 35 form (see 4th ).

When operating both below the temperature threshold, this operating state is in 2 , 3a and 3b shown, as well as when operating above the temperature threshold value, this operating state is in 4th , 5a and 5b shown, prevails in the second control chamber 37 permanent the pressure of the unfiltrate side, because the control chamber 37 over the slots 85 in the housing part 29 is in communication with the outer unfiltrate side. The same applies to the pipe section open to the outside 75 the pressure on the unfiltrate side. When operating below the temperature threshold ( 2 , 3a and 3b) closes the bimetal disc 79 the valve opening at the end 77 of the pipe section 75 and opens the valve opening at the end 73 of the pipe body 71 . On that by the compression spring 50 in the closed position biased valve body 43 therefore results in the pressure distribution, which in 3a and 3b is made clear. As the action of the compression spring 50 reinforcing additional closing force acts on the in 3b with A1 designated area of the entire underside of the closing body 43 pending pressure on the filtrate side.

With the valve opening closed at the end 77 of the pipe section 75 and simultaneous opening of the end 73 of the pipe body 71 works via the connection of the control chamber 35 with the passage 56 of the valve stem 53 the pressure on the filtrate side also on the top of the valve body 43 in the area of the in 3a with A3 designated area as the force that the valve body 43 applied in the opening direction. At the same time acts on the top of the valve body 43 in the outer area in the area marked with a line pattern A2 also the pressure of the unfiltrate side, that in the outer, second control chamber 37 is present and generates a force in the opening direction. In combination of this pressure distribution with the closing force of the compression spring 50 an increased bypass opening pressure of, for example, five bar can thereby be specified.

When operating above the threshold temperature, this condition is in 4th , 5a and 5b shown, the valve opening is at the end 77 of the pipe section 75 open while the valve opening at the end 73 of the pipe body 71 closed is. About the pipe section 75 therefore prevails in the control chamber 35 the unfiltrate pressure. Since this is also permanently in the outer, second control chamber 37 is effective, the entire area of the top of the valve body is now available as a differential pressure area during warm operation A2 to disposal ( 5a) , while in cold operation the differential pressure area A2 ( 3a) , only by the edge area outside the surface A3 is available. The opposite 3a enlarged differential pressure area A2 of 5a leads to an increased force generated by the fluid pressure in the opening direction and thus to a reduction in the bypass opening pressure, which can be designed, for example, to three bar in warm operation compared to the opening pressure of five bar in cold operation. It then opens the bypass valve device and releases the flow from the unfiltrate side via the valve body 43 in its open position to the filtrate side free, which depends on an increasing blockage of the filter material 21st takes place steadily increasing, with a part of the fluid flow still over unblocked parts of the filter material up to the complete blocking and up to then only partially opening of the bypass device 21st can be further cleaned.

mit

p₁ =

Druck auf der Filtratseite 26;

p₂ =

Druck auf der Unfiltratseite 15;

A1 =

druckwirksame Fläche des Ventilkörpers 43 auf der Filtratseite 26;

A2 =

druckwirksame Fläche des Ventilkörpers 43 auf der Unfiltratseite 15 innerhalb der zweiten Steuerkammer 37;

A3 =

druckwirksame Fläche des Ventilkörpers 43 auf der Unfiltratseite 15 und innerhalb der ersten Steuerkammer 35;

F_c =

Kraft der auf den Ventilkörper 43 einwirkenden Druckfeder 50.

For the forces acting on the valve body 43 act in cold operation, in which by means of the bimetal disc 79 the unfiltrate connection on the pipe section 75 is closed, the following applies: $$0=\text{p}1\cdot \text{A.}1+\text{Fc}-\text{p}2\cdot \text{A.}2-\text{p}1\cdot \text{A.}3$$

With

p ₁ =

Pressure on the filtrate side 26;

p ₂ =

Pressure on the unfiltrate side 15;

A1 =

pressure-effective surface of the valve body 43 on the filtrate side 26;

A2 =

pressure-effective surface of the valve body 43 on the unfiltrate side 15 within the second control chamber 37;

A3 =

pressure-effective surface of the valve body 43 on the unfiltrate side 15 and within the first control chamber 35;

F _c =

Force of the compression spring 50 acting on the valve body 43.

Claims (12)

Filter device with a filter element (3) and a bypass device (5) which has a spring-loaded valve body (43) which opens from a predeterminable bypass opening pressure and a fluid-carrying connection between an unfiltrate (15) and a filtrate side (26) of the filter element (3 ) creates this filter element (3) by at least partially bypassing the filter material (21), a control device (79) being provided by means of which the bypass opening pressure can be changed in a temperature-controlled manner, the control device (79) increasing the bypass opening pressure from a high one upon reaching a predeterminable temperature threshold Pressure value drops to a lower pressure value, the control device having a bimetal element (79) which, under temperature control, produces a fluid-carrying connection between the unfiltrate side (15) and a control chamber (35) accommodated in the bypass device (5) and below this Tempe raturschwellenwerts is connected to the filtrate side (26) of the filter element (3), and wherein in a closed state of the valve body (43), in which this rests against housing parts (29, 65) of the bypass device (5), the control chamber (35) of these housing parts (29, 65) is limited, characterized in that an unfiltrate (75) and a filtrate connection (71) open into the control chamber (35), which can be closed alternately by the bimetal element (79) depending on the fluid temperature. Filter device according to Claim 1 , characterized in that the temperature threshold is 20 ° C and / or that the control device (79) lowers the bypass opening pressure from the high value of 5 bar to the low pressure value of 3 bar. Filter device according to Claim 1 or 2 , characterized in that the bimetallic element is designed in the manner of a round control disk (79) which forms a snap element and which, fixed at the edge in the control chamber (35) by means of a fixing device, forms a fluid path (82) in its position blocking the filtrate side (26) from the unfiltrate side (15) into a subspace (81) of the control chamber (35) into which the filtrate connection (71) otherwise opens. Filter device according to Claim 3 , characterized in that the control chamber (35) has a further subchamber (80) adjoining the one subchamber (81) into which the unfiltrate connection (75) opens in a fluid-conducting manner as soon as it is released by the bimetal element (79). Filter device according to one of the preceding claims, characterized in that the control chamber (35) is surrounded on the edge by a further control chamber (37) which, when the valve body (43) is closed and resting on housing parts (29, 65) of the bypass device (5), is separated from the a control chamber (35) is separated and which is permanently connected to the unfiltrate side (15) to carry fluid. Filter device according to one of the preceding claims, characterized in that the unfiltrate connection (75) is received in a cover (39) of the control chamber (35) which is firmly connected to the housing parts (29, 65) of the bypass device (5), and that the filtrate connection (71) is passed through the valve body (43). Filter device according to one of the preceding claims, characterized in that the valve body (43) has a sealing cap (67) for sealing against the housing parts (26, 65) of the bypass device (5) and is permanently acted upon by a compression spring (50) which is between a receiving housing (41) for the valve body (43) and this, and that the interior of the receiving housing (41) is permanently connected to the filtrate side (26) of the filter element (3) via at least one passage (47). Filter device according to Claim 7 , characterized in that the receiving housing (41) for the valve body (43) is connected as an additional housing part with the other housing parts (29) of the bypass device (5), which are part of an end cap (27) of the filter element (3). Filter device according to one of the preceding claims, characterized in that when the unfiltrate connection (75) is closed by means of the bimetal element (79), the following force formula applies to the valve body (43): $$0=\text{p}1\cdot \text{A.}1+\text{Fc}-\text{p}2\cdot \text{A.}2-\text{p}1\cdot \text{A.}3$$

With: p ₁ = pressure on the filtrate side (26); p ₂ = pressure on the unfiltrate side (15); A1 = pressure-effective area of the valve body (43) on the filtrate side (26); A2 = pressure-effective area of the valve body (43) on the unfiltrate side (15) within the second control chamber (37); A3 = pressure-effective area of the valve body (43) on the unfiltrate side (15) and within the first control chamber (35); F _c = force of the compression spring (50) acting on the valve body (43). Filter device according to one of the preceding claims, characterized in that the bypass device (5) protrudes at least partially into the hollow cylindrical filter element (3) which is provided on the bottom with a further end cap (19) which has a filtrate outlet (23). Filter device housing for accommodating a filter device according to one of the preceding claims, characterized in that it has an unfiltrate supply (15) and a filtrate discharge (11, 17), which is designed in a step-like manner and has a receptacle (17) for the bottom side (19) of the filter element (3) forms that the bypass device (5) as part of the filter element (3), which is designed to be exchangeable in the housing (1), protrudes with a protrusion into a housing head (13) of the housing (1) with the unfiltrate supply (15), which has a housing pot (7 ), which encloses the filter element (3) received in the housing (1) at a radial distance. Use of a filter device according to one of the Claims 1 to 10 and a filter device housing (1) according to Claim 11 , characterized in that when hydraulic machines, such as mobile machines, start cold, a higher opening pressure is allowed for the bypass device (5) in order to bring fluid at a lower temperature through the filter material (21) of the filter element (3) and that with increasing fluid temperature by means of a control device (79) the opening pressure of the bypass device (5) is reduced from a higher pressure value to a lower pressure value, at which, with increasing blockage of the filter material (21) of the filter element (3), the bypass device (5) at least partially bypassing the filter material ( 21) of the filter element (3) connects the unfiltrate side (15) with the filtrate side (26).

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