WO2018050232A1

WO2018050232A1 - Air filter

Info

Publication number: WO2018050232A1
Application number: PCT/EP2016/071879
Authority: WO
Inventors: Alexandre LUCHESI DE ALMEIDA; Edson VALDOMIRO DE AZEVEDO JUNIOR; Pedro BASSO; Marcos José DANTAS DE OLIVEIRA
Original assignee: Mahle International Gmbh; Mahle Metal Leve S/A
Priority date: 2016-09-15
Filing date: 2016-09-15
Publication date: 2018-03-22

Abstract

The present invention relates to an air filter(1) for a fresh air system of an internal combustion engine, comprising a filter housing (2) which has a housing pot (3) and a housing cover(4), and a filter element (7) which is arranged in the filter housing (2), wherein the housing cover(4) is fastened to the housing pot (3) with a bayonet lock (9). The closing of the housing cover(4) can be improved if the bayonet lock (9) has, radially on the outside of the housing pot (3), a plurality of locking elements (13) arranged distributed in the circumferential direction (10), if the bayonet lock (9) has, on the housing cover (4), a guide slot (14) for each locking element (13), said guide slot having an inlet (15) through which the respective locking element (13) can be introduced axially into the guide slot (14), a ramp (16) along which the respective locking element (13) is helically adjustable, and an end stop (17) into which the respective locking element (13) can be introduced in the circumferential direction (10) and in which the respective locking element (13) is secured axially.

Description

Air filter

The present invention relates to an air filter or to an air filter device for a fresh air system of an internal combustion engine, comprising the features of the preamble of claim 1 .

An air filter of the type in question, which may also be referred to as an air filter device, is known, for example, from DE 10 2010 009 249 A1 . It comprises a filter housing which has a housing pot, a housing cover, an untreated air inlet and a clean air outlet. Furthermore, a filter element is provided which has an annular filter body and two end plates and which, in the filter housing, separates an untreated side, which is fluidically connected to the untreated air inlet, from a clean side, which is fluidically connected to the clean air outlet. So that the filter housing can be opened and closed again in a simple manner, for example for changing the filter element, the housing cover is fastened to the housing pot with a bayonet lock, which can also be named as bayonet fastener, bayonet joint or bayonet fitting. Such a bayonet lock is distinguished by an at least two-stage movement. In the first movement stage, an axial adjustment, for example, takes place, while, in the second movement stage, an adjustment then takes place in the circumferential direction. In the case of the known air filter, the bayonet lock between housing cover and housing pot is configured in such a manner that the adjustment movement in the first movement stage takes place exclusively axially and in the second movement stage takes place exclusively in the circumferential direction. In order to be able to achieve a play-free contact between housing pot and housing cover in the axial direction, relatively large forces have to be overcome in the known air filter in order to actuate the bayonet lock. This makes the handling more difficult, in particular when changing the filter element. The present invention is concerned with the problem of specifying an improved embodiment for an air filter of the type mentioned at the beginning, said improved embodiment being distinguished in particular by simplified handling during the opening and closing of the housing cover.

This problem is solved according to the invention by the subject matter of the independent claim. Advantageous embodiments are the subject matter of the dependent claims.

The invention is based on the general concept of providing the bayonet lock with a ramp which forces a screwing movement, and therefore in total a three-stage adjustment movement is produced. When the housing cover is fitted, exclusively an axial adjustment movement takes place in a first movement stage. In a following second movement stage, a screwing movement takes place, i.e. a combined movement oriented in the axial direction and in the circumferential direction. In a third movement stage, a movement then takes place exclusively in the circumferential direction. The middle or second movement stage brings about an axial approach between housing cover and housing pot in such a manner that friction forces which may arise because of extensive axial contact between housing cover and housing pot are effective only when the third movement stage is reached. All in all, the fitting and the removal of the housing cover can thereby be facilitated.

In detail, the invention proposes that the bayonet lock has, radially on the outside of the housing pot, a plurality of locking elements arranged distributed in the circumferential direction. Furthermore, the bayonet lock has, on the housing cover, a guide slot for each locking element, said guide slot having an inlet, a ramp and an end stop. The respective locking element can be introduced axially into the guide slot through the inlet. This corresponds to the first movement stage in which exclusively axial relative adjustment between housing cover and housing pot is possible. The respective locking element can be adjusted axially and in the circumferential direction along the ramp. The ramp therefore defines the second movement stage in which exclusively a combined movement in the axial direction and in the circumferential direction or the screwing movement takes place. This means that rotation of the housing cover relative to the housing pot forces an axial adjustment of the housing cover relative to the housing pot. Finally, the end stop defines the third movement stage in which the respective locking element is adjustable exclusively in the circumferential direction in order to be able to introduce said locking element into the end stop. The locking element is then secured axially in the end stop, as a result of which the axial position between housing cover and housing pot is secured.

According to an advantageous embodiment, at least one such locking element is secured in the end stop of the respective guide slot by means of a latching connection in the circumferential direction. The locking element which is secured in the end stop with the aid of the latching connection can therefore no longer readily move out of the end stop in the circumferential direction. As a result, the housing cover is secured nonrotatably on the housing pot. Automatic release of the housing cover can thereby be substantially avoided.

According to a first variant of the latching connection, the latter on the associated locking element can have a latching lug which protrudes radially and axially from the respective locking element and which interacts in the end stop with a latching contour of the respective latching connection, which latching contour is formed on the housing cover. By means of this measure, the latching connection is constructed comparatively simply, and therefore said latching connection can be realized inexpensively and nevertheless operates reliably. In an advantageous development, the respective latching lug can engage radially over a slot edge which bounds the guide slot axially on a side facing away from the inlet. In this manner, between latching lug and slot edge an additional guide for the rotational movement between housing cover and housing pot is also provided, said guide simplifying the introduction of the locking element into the end stop.

In another embodiment, the inlet has a radial depression through which the latching lug can be guided axially when the locking element is introduced into the guide slot. This measure facilitates the detection of the relative rotational position between housing cover and housing pot that has to be present in order to be able to carry out the axial movement in accordance with the first movement stage.

In a second embodiment of the latching connection, the latching connection for the respective locking element can have a ratchet lever which is mounted on the housing cover so as to be pivotable between a securing position and a release position. The ratchet lever, in its release position, permits the locking element to move out of the end stop in the circumferential direction. By contrast, in the securing position, the ratchet lever prevents the locking element from moving out of the end stop in the circumferential direction. While another latching connection, for example the latching connection of the previously described type, has to be subjected to excessive pressure for release purposes, which may be associated with a considerable wear of the latching connection, the use of a pivotable ratchet lever permits a virtually wear-free actuation of the latching connection in order to release the rotational position. The removal of the housing cover from the housing pot, for example, is therefore simplified. A development is advantageous in which a pivot axis of the ratchet lever, about which the ratchet lever is pivotable between its securing position and its release position, runs tangentially and preferably extends in a plane which runs perpendicularly to a longitudinal center axis of the filter housing.

In another embodiment, the ratchet lever has a latching contour which, in the securing position, interacts in the circumferential direction with a mating latching contour formed on the locking element. In this manner, an efficient form-fitting connection for securing the rotational position is realized in the securing position of the ratchet lever.

In a development, the ratchet lever can have a ramp which rises radially with respect to the latching contour and which, when the locking element is introduced into the end stop, forces the ratchet lever to be adjusted from the securing position into the release position. This construction has the consequence that the ratchet lever does not have to be actuated manually in order, when the housing cover is fitted, to rotate the housing cover into its predetermined rotational position since the respective ratchet lever is automatically adjusted into the release position.

Expediently, the ratchet lever can be prestressed into its securing position by means of a resetting spring. This measure prevents an accidental adjustment of the securing lever into its release position. At the same time, this measure, for example in conjunction with the abovementioned ramp, brings about an automatic readjustment of the ratchet lever into its securing position if, when the housing cover is rotated, the respective locking element reaches its end position in the end stop. The ratchet lever then pivots automatically into its securing position in a manner driven by the resetting spring. In another embodiment, the ratchet lever is mounted pivotably on a bearing bracket which is fastened to the housing cover. The bearing bracket is

accordingly a component which is separate with respect to the housing cover and is fastened in a suitable manner to the housing cover. For example, the bearing bracket can be fastened to the housing cover by means of an adhesive

connection or a welding connection or else by means of a latching connection. The configuration of the bearing bracket as a separate component permits a preassemblable assembly which consists of the bearing bracket, the ratchet lever and the optionally provided resetting spring. By this means, the assembly of the filter housing is simplified.

The above-described embodiments of the latching connection are preferably realized as alternatives, but can also be realized in cumulative fashion. For example, a plurality of latching connections between housing pot and housing cover can be provided along the circumference of the filter housing, of which latching connections at least one is equipped with the ratchet lever, while all of the other latching connections are configured without said ratchet lever.

In another embodiment, the housing cover can have a receiving groove which is axially open, encircles in a closed manner in the circumferential direction and into which an end-side edge of the housing pot penetrates axially. By this means, a type of tongue and groove connection is provided between housing cover and housing pot, said tongue and groove connection firstly guiding the rotational movement between housing cover and housing pot and secondly also acting as a labyrinth seal. A development in which an axial seal is arranged in the receiving groove is particularly advantageous. Expediently, the end-side edge of the housing pot comes into contact axially with said axial seal when the housing cover is correctly installed, as a result of which efficient sealing can be achieved between housing cover and housing pot. The ramp in the guide slot acts particularly advantageously here, said ramp making it possible, when the housing cover is fitted, to produce a certain axial prestress between the end-side edge and the axial seal in the receiving groove.

Further important features and advantages of the invention emerge from the dependent claims, from the drawings and from the associated description of the figures with reference to the drawings.

It goes without saying that the features mentioned above and those which have yet to be explained below are usable not only in the respectively stated combination, but also in different combinations or on their own without departing from the scope of the present invention.

Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the description below, wherein the same reference signs refer to identical or similar or functionally identical components.

In the drawings, in each case schematically,

Fig. 1 shows an isometric view of an air filter,

Fig. 2 shows a side view of the air filter in the region of a bayonet lock,

Fig. 3 shows an exploded illustration of the air filter in the region of the bayonet lock,

Fig. 4 shows a side view of the housing in the region of the bayonet lock after a first adjustment movement, Fig. 5 shows a side view as in Fig. 4, but after a final adjustment movement,

Fig. 6 shows an enlarged detail VI from Fig. 5,

Fig. 7 shows a cross section of the air filter in the region of the bayonet lock, but in a different embodiment,

Fig. 8 shows a longitudinal section of the air filter in the region of the

bayonet lock with a ratchet lever in its securing position,

Fig. 9 shows a sectional view as in Fig. 8, but with the ratchet lever in its release position,

Fig. 10 shows an isometric view of the air filter in the region of the bayonet lock with the ratchet lever removed.

According to Fig. 1 , an air filter device 1 or an air filter 1 , which is used in a fresh air system of an internal combustion engine for filtering fresh air, comprises a filter housing 2 which has a housing pot 3, a housing cover 4, an untreated air inlet 5 and a clean air outlet 6. A filter element 7 which can be partially seen in Fig. 3 is arranged in the interior of the filter housing 2, said filter element in the filter housing 2 separating an untreated side, which is fluidically connected to the untreated air inlet 5, from a clean side, which is fluidically connected to the clean air outlet 6. For example, the filter element 7 is an annular filter element 7. For this purpose, the filter element 7 has an annular filter body 8 which is composed of a filter material. The filter material can be formed here by a folded web material. The annular filter body 8 can have a respective end plate on its axial end sides. The housing cover 4 is fastened releasably to the housing pot 3 with the aid of a bayonet lock 9. The bayonet lock 9 has a plurality of fastener segments 11 which are arranged distributed in the circumferential direction 10 and in their entirety form the bayonet lock 9. At least two such fastener segments 11 are provided here. In the example of Fig. 1 , four such fastener segments 11 are arranged uniformly distributed in the circumferential direction 10. It is clear that basically any number of fastener segments 11 may be provided. In the views of figs. 2 to 5, only one of the fastener segments 11 of the bayonet lock 9 having at least two fastener segments 11 can be seen in each case.

The circumferential direction 10 relates to a longitudinal center axis 12 of the filter housing 2 and rotates about said longitudinal center axis. The longitudinal center axis 12 at the same time defines an axial direction of the filter housing 2. The axial direction extends parallel to the longitudinal center axis 12. A radial direction of the filter housing 2 extends transversely with respect to the axial direction.

According to figs. 2 to 9, the respective fastener segment 11 has a locking element 13 and a guide slot 14. In particular, the respective fastener segment 11 is formed by the locking element 13 and the corresponding guide slot 14. Within the fastener segment 11 the locking element 13 and the guide slot 14 cooperate with each other to create a two-stage movement or a three-stage movement, respectively, characterizing the bayonet lock 9. The bayonet lock 9 is formed by the entirety of the fastener segments 11 , i.e. by the entirety of locking elements 13 and guide slots 14.

In the preferred embodiments the respective locking element 13 is formed radially on the outside of the housing pot 2. In the case of the examples shown here, the respective locking element 13 is configured in an elongate manner such that it extends in the circumferential direction 10 and lies here in a plane which extends perpendicularly to the longitudinal center axis 12. Furthermore, in the preferred embodiment the respective guide slot 14 has an inlet 15, a ramp 16 and an end stop 17. When the housing cover 4 is fitted on the housing pot 3, the respective locking element 13 can be introduced axially into the guide slot 14 through the inlet 15. The respective locking element 13 is adjustable axially and in the circumferential direction 10 in a helical manner along the ramp 16. From the end of the ramp 16, the locking element 13 can be introduced in the circumferential direction 10 into the end stop 17. The locking element 13 is secured axially in the end stop 17. The guide slot 14 is formed here on the housing cover 4. The housing cover 4 is therefore mounted on the housing pot 3 in three stages.

Before the housing cover 4 is fastened to the housing pot 3, the state shown in Fig. 3 is present. In this state, the respective locking element 13 is already oriented axially with the inlet 15. As a result, the housing cover 4 can be adjusted axially in the direction of the housing pot 3 in accordance with an arrow 18.

According to Fig. 4, within the scope of a first phase of the overall three-phase adjustment movement of the bayonet lock 9, the locking element 13 is now introduced axially into the guide slot 14 through the inlet 15. This first movement is a pure axial movement and is indicated by an arrow 19 in Fig. 4. Subsequently, a second movement phase takes place, during which the locking element 13 is adjusted simultaneously in the circumferential direction 9 and in the axial direction along the ramp 16 within the guide slot 14. This produces a helical movement which is indicated in Fig. 4 by an arrow 20. The position of the locking element 13 after said second movement phase is indicated by a broken line in Fig. 4. Said second movement phase is then followed by a third movement phase in which the locking element 13 is adjusted exclusively in the circumferential direction 10 and in the process is introduced into the end stop 17. A corresponding adjustment movement is indicated by an arrow 21 in Fig. 4. In Fig. 5, the locking element 13 has reached its end position in the end stop 17. As can be gathered in particular from figs. 1 and 4 to 10, a latching connection 22 can be provided at least in the case of one of the fastener segments 11 , said latching connection securing the respective locking element 13 in the

circumferential direction 10 in the end stop 17. In other words, the latching connection 22 prevents the locking element 13 from a movement in the circumferential direction 10, said movement leading out of the end stop 17.

A first embodiment of a latching connection 22 of this type is explained in more detail below with reference to figs. 4 to 6. Subsequently, a second embodiment for a latching connection 22 of this type is explained in more detail with reference to figs. 7 to 10. It is clear from the figures that at least one of the fastener segments 11 within the bayonet lock 9 can then be provided with the first variant of the latching connection 22 or with the second variant of the latching connection 22. The example of Fig. 1 shows an embodiment in which the first variant of the latching connection 22 is realized at the fastener segment 11 which faces the observer, while the second variant of the latching connection 22 is realized at the upper fastener segment 11 in Fig. 1 . The two variants of the latching connection 22 can therefore be realized simultaneously within the same bayonet lock 9, but with different fastener segments 11 .

According to figs. 4 to 6, the respective latching connection 22 can have a latching lug 23 on the respective locking element 13 in the first variant. The latching lug 23 protrudes here radially and axially from the respective locking element 13. The latching lug 23 is arranged eccentrically here in the

circumferential direction 10 between the two longitudinal ends of the respective locking element 13.

The latching connection 22 also has a latching contour 24 which is formed on the housing cover 4 and which is positioned in such a manner that the latching lug 23 interacts with the latching contour 24 in order to secure the latching connection 22 in the circumferential direction 10 as soon as the locking element 13 has reached its designated end position in the end stop 17. This state is reproduced in Fig. 5 and in the detailed view of Fig. 6. As can be seen, the latching lug 23 according to Fig. 6 has an outer contour 25 which is curved convexly toward the latching contour 24, while the latching contour 24 has, in a complementary manner with respect thereto, an inner contour 26 which is curved concavely toward the latching lug 23. For the latching connection, the latching contour 24 engages over the latching lug 23 in the circumferential direction 10 beyond the apex of the convex outer contour 25. At the same time, axial clamping between locking element 13 and guide slot 14 can be realized with the latching connection 22.

The latching lug 23 protrudes over the remaining locking element 13 laterally and axially with respect to the radial direction. The guide slot 14 and the locking element 13 are coordinated with each other here in such a manner that the latching lug engages radially on the outside over a slot edge 27. Said slot edge 27 bounds the guide slot 14 on a side facing away from the inlet 15. This results in an additional guiding effect at least during the third movement phase 21 . The inlet 15 has a radial depression 28 which is coordinated with the latching lug 23 in such a manner that, when the locking element 13 is introduced into the guide slot 14, the latching lug 23 is guided through said depression 28.

According to figs. 7 to 10, in the case of the second variant of the latching connection 22, the respective locking segment 11 can have a ratchet lever 29 which is pivotable about a pivot axis 30 between a securing position I reproduced in figs. 7 and 8 and a release position II reproduced in Fig. 9. Said pivot axis 30 lies here in a plane which extends perpendicularly to the longitudinal center axis 12. Furthermore, the pivot axis 30 forms a tangent to the circular contour of the housing 2.

In the securing position I shown in figs. 7 and 8, the ratchet lever 29 prevents the locking element 13 from moving in the circumferential direction 10 out of the end stop. For this purpose, the ratchet lever 29 has a latching contour 31 which is radially in engagement with a mating latching contour 32, which is

complementary with respect thereto, and interacts with said mating latching contour in the circumferential direction 10. The mating latching contour 32 is formed here on the locking element 13.

In the release position II according to Fig. 9, latching contour 31 and mating latching contour 32 are not in engagement with each other, and therefore the ratchet lever 29 releases the locking element 13 and accordingly permits the locking element 13 to move in the circumferential direction 10 out of the end stop 17.

The ratchet lever 29 can be adjusted manually between the securing position I and the release position II via an actuating section 33. For this purpose, the actuating section 33 and the latching contour 31 are located on mutually opposite sides of the ratchet lever 29 with respect to the pivot axis 30. In order to be able to bring about securing of the housing cover 4 on the housing pot 3 without manual actuation of the ratchet lever 29, the ratchet lever 29 is equipped here with a ramp 34 which rises radially with respect to the latching contour 31 . When the locking element 13 is introduced into the end stop 17, the interaction of the mating latching contour 32 with the ramp 34 forces the ratchet lever 29 to pivot from the securing position I into the release position II. As soon as the desired end position of the locking element 13 in the end stop 17 is then reached, the mating latching contour 32 moves over the latching contour 31 at the end of the ramp 34 such that the ratchet lever 29 can be adjusted back into the securing position I. So that said adjustment back can take place automatically, the ratchet lever 29 here also has a resetting spring 35 which prestresses the ratchet lever 29 into its closed position I. According to Fig. 9, the resetting spring 35 is tensioned or tensioned further when the ratchet lever 29 is adjusted into the release position II. In other words, the ratchet lever 29 can be adjusted into the release position II only counter to the resetting force of the resetting spring 35.

According to figs. 7 to 10, the ratchet lever 29 is mounted on a bearing bracket 36 so as to be pivotable about its pivot axis 30. In particular, the resetting spring 35, which is configured here as a leg spring, is supported on one side on the ratchet lever 29 and on the other side on the bearing bracket 36. The bearing bracket 36 is designed here as a separate component with respect to the housing cover 4 and is fastened in a suitable manner to the housing cover 4.

According to figs. 8 and 9, the housing cover 4 can have a receiving groove 37 which is axially open with respect to the housing pot 3 and encircles in a closed manner in the circumferential direction 10. In a complementary manner with respect thereto, the housing pot 3 has, on its end side facing the housing cover 4, an edge 38 which encircles in a closed manner and enters the receiving groove 37 axially. Expediently, an axial seal 39 is arranged in said receiving groove 37, said axial seal sealing the housing cover 4 within the receiving groove 37 in relation to the edge 38 and therefore in relation to the housing pot 3. Axial seal 39, receiving groove 37 and edge 38 are coordinated with the bayonet lock 9 in such a manner that, in the predetermined final rotational position between housing cover 4 and housing pot 3, axial clamping of the axial seal 29 between the edge 38 and a groove base of the receiving groove 37 is produced. Although the receiving groove 37 and the edge 38 and also the optionally present axial seal 39 are illustrated in figs. 8 and 9 only for the second variant of the latching connection 22, it is clear that the receiving groove 37 and the edge 38 and optionally the axial seal 39 can also be realized in the previously described first variant of the latching connection 22.

Claims

1 . An air filter for a fresh air system of an internal combustion engine,

- comprising a filter housing (2) which has a housing pot (3) and a housing cover (4),

- comprising a filter element (7) which is arranged in the filter housing (2),

- wherein the housing cover (4) is fastened to the housing pot (3) with a bayonet lock (9),

characterized

- in that the bayonet lock (9) has, radially on the outside of the housing pot (3), a plurality of locking elements (13) arranged distributed in the circumferential direction (10),

- in that the bayonet lock (9) has, on the housing cover (4), a guide slot (14) for each locking element (13), said guide slot having an inlet (15) through which the respective locking element (13) can be introduced axially into the guide slot (14), a ramp (16) along which the respective locking element (13) is helically adjustable, and an end stop (17) into which the respective locking element (13) can be introduced in the circumferential direction (10) and in which the respective locking element (13) is secured axially.

2. The air filter as claimed in claim 1 ,

characterized in that

at least one such locking element (13) is secured in the end stop (17) of the respective guide slot (14) by means of a latching connection (22) in the

circumferential direction (10).

3. The air filter as claimed in claim 2,

characterized in that

at least one such latching connection (22) on the associated locking element (13) has a latching lug (23) which protrudes radially and axially from the respective locking element (13) and which interacts in the end stop (17) with a latching contour (24) of the respective latching connection (22), which latching contour is formed on the housing cover (4).

4. The air filter as claimed in claim 3,

characterized in that

the respective latching lug (23) engages radially over a slot edge (27) which bounds the guide slot (14) axially on a side facing away from the inlet (15).

5. The air filter as claimed in claim 3 or 4,

characterized in that

the inlet (15) has a radial depression (28) through which the latching lug (23) can be guided axially when the locking element (13) is introduced into the guide slot (14).

6. The air filter as claimed in one of claims 2 to 5,

characterized

- in that at least one latching connection (22) for the respective locking element (13) has a ratchet lever (29) which is mounted on the housing cover (4) so as to be pivotable between a securing position (I) and a release position (II),

- in that the ratchet lever (29), in its release position (II), permits the locking element (13) to move out of the end stop (17) in the circumferential direction (10), - in that the ratchet lever (29), in its securing position (I), prevents the locking element (13) from moving out of the end stop (17) in the circumferential direction (10).

7. The air filter as claimed in claim 6,

characterized in that

the ratchet lever (29) has a latching contour (31 ) which, in the securing position (I), interacts in the circumferential direction (10) with a mating latching contour (32) formed on the locking element (13).

8. The air filter as claimed in claim 7,

characterized in that

the ratchet lever (29) has a ramp (34) which rises radially with respect to the latching contour (31 ) and which, when the locking element (13) is introduced into the end stop (17), forces the ratchet lever (29) to be adjusted from the securing position (I) into the release position (II).

9. The air filter as claimed in one of claims 6 to 8,

characterized in that

the ratchet lever (29) is prestressed into its securing position (I) by means of a resetting spring (35).

10. The air filter as claimed in one of claims 6 to 9,

characterized in that

the ratchet lever (29) is mounted pivotably on a bearing bracket (36) which is fastened to the housing cover (4).

11 . The air filter as claimed in one of claims 1 to 10,

characterized in that the housing cover (4) has a receiving groove (37) which is axially open, encircles in a closed manner in the circumferential direction (10) and into which an end- side edge (38) of the housing pot (3) penetrates axially.

12. The air filter as claimed in claim 11 ,

characterized in that

an axial seal (39) is arranged in the receiving groove (37).