CN106838180A - Actuator with the elastic element for volume balance - Google Patents

Abstract

The present invention relates to actuator（10）, with shell（20）And bracket（30）, bracket is in longitudinal axis（11）Direction on can be supported on shell to linear movement（20）Place, bracket（30）Along the direction of the longitudinal axis from the shell（20）In it is protruding, the shell and the bracket jointly define interior room（12）, the volume of the interior room is in the bracket（30）Relative to the shell（20）It is changed during motion, threaded spindle（60）By means of rolling bearing on the longitudinal axis（11）The shell can be rotatably supported at（20）Place, the threaded spindle puts in the bracket（30）Hollow chamber（31）In, the bracket（30）Nut is provided with, the nut arrangements are in the interior room（12）In and the nut be in and threaded spindle（60）Screw action in.In bracket（30）Hollow chamber（31）The middle resilient element of arrangement（70；70'）, the element is in the bracket（30）Relative to shell（20）Elastic deformation during motion.

Description

Actuator with the elastic element for volume balance

Technical field

The present invention relates to one kind according to actuator of the present invention.

Background technology

By known a kind of actuator in the A1 of DE 10 2,007 043 391.The actuator has shell and bracket, wherein, The bracket can be supported on to linear movement at the shell on the direction of longitudinal axis, wherein, the bracket is along longitudinal axis Direction is protruding from the shell.The shell and the bracket jointly define interior room, and the volume of the interior room is in the support Frame is changed when being moved relative to the shell.In addition, there is provided threaded spindle, the threaded spindle by means of rolling bearing on The longitudinal axis can be rotatably supported at the shell, wherein, the threaded spindle is stretched into the hollow chamber of the bracket.Separately Outward, the bracket is provided with nut, and the nut arrangements are in the interior room and the nut is in the screw action with threaded spindle In.

On the one hand the screw action being previously mentioned needs lubrication, so that the actuator has the life-span more long.In addition, in rotation Twist in acting on and produce heat, the heat must be derived outwards towards surrounding environment.It can be considered that, solve in the following manner Certainly described two problems, i.e., described interior room is filled using the liquid that can not be compressed, especially with oil.But, the interior room Variable volume caused by be not to be ensured that：The screw action is in each attitude of the bracket and in actuator Each installation site in incompressible fluid realize contact.

The content of the invention

An advantage of the invention that：A section, when the movement of bracket, the area are established in the interior room The constancy of volume of section.The section can almost entirely be filled corresponding to this using incompressible liquid.Thus, described Be ensured that in each attitude of bracket and in each installation site of actuator, the screw action with it is incompressible Fluid realizes contact.

According to it is proposed that, resilient element is arranged in the hollow chamber of bracket, the element is in the bracket phase It is elastically deformed when being moved for shell.By the elastic deformation being previously mentioned of the element of the elasticity, mended in movement of bracket The stereomutation of the interior room is repaid.

The nut is preferably arranged in an end of the bracket.The rolling bearing is preferably arranged in the back of the body of shell From in the end of the bracket.The nut is preferably configured to single construction package, the construction package firmly with The bracket for retaining is connected.Certainly also it can be considered that, the nut is integrally constructed with the bracket that retains.The bullet The element of property is preferably made of plastics and preferably is made up of elastomer.

Favourable modification and evolutionary approach of the invention are illustrated in preferred embodiment and other embodiments.

Can be provided that, the element of the elasticity hermetically puts the first and second section fluids of the interior room each other Open, wherein, the region of the screw action between the nut and threaded spindle is the composition portion of the second section of the interior room Point.Therefore ensure that, the incompressible fluid in the second section of the interior room in each attitude of bracket and The contact with screw action is realized in each installation site of actuator.

Can be provided that, the nut is provided with end part seal in the end towards rolling bearing of the nut only Portion, the end part seal portion is so in the sealing function of threaded spindle, i.e. the end part seal portion is by the 3rd area of interior room Put out from the second section of interior room on section Fluid Sealing ground.Through this, the necessary bullet of the element of elasticity in movement of bracket is reduced The deformation of property.Here, it is noted that the volume of the 3rd section is smaller when bracket is moved into, wherein, when bracket movement When going out, the volume increases strongly.This volume changes need not be born by the element of the elasticity.Meanwhile, it is described can not The volume of the fluid of compression only slightly reduces, and the fluid can be filled into the interior room.Additionally, somewhat smaller fluid volume subtracts The small weight of the incompressible fluid, the weight is come according to the installation site of actuator by the element of the elasticity respectively Carry.

Can be provided that, the nut is so openly constructed in two opposed ends of the nut, i.e., should Second section of interior room extends through the nut.Can be accomplished that through this, the incompressible fluid is in the bracket The nut is flowed through during motion, so as to improve the cooling effect in screw action.

Can be provided that, elastic element such crust deformation when bracket is moved relative to shell so that the firstth area The volume of section is changed, and the volume of the second section is held substantially constant.In the ideal case, the volume of the second section is protected Hold accurate constant.Obviously, this ideal situation is difficult to realize in practice, because such as inertia force causes the unit of the elasticity The deformation being not desirable to of part.But through this, do not obtain the lubricant effect on the incompressible fluid and cooling is imitated The obvious shortcoming of fruit.Importantly, the big volume of the interior room occurred in conventional actuator changes obtaining significantly Ground reduces.The volume of the 3rd section can be similarly obtained change when bracket is moved relative to the shell.

Can be provided that, the second section of the interior room is substantially completely filled using incompressible fluid. In the ideal case, the second section fully utilize incompressible fluid is filled.But the one of second section Part can be filled with bubble, and the bubble is difficult to avoid when the incompressible fluid is filled.It is described incompressible Fluid for example refer to oil, the oil is particularly suited for lubricating and/or being cooled in the screw action between nut and threaded spindle.

Can be provided that, threaded spindle has end face, wherein, the element of the elasticity be arranged in the end face that is previously mentioned and Between the bottom surface of the hollow chamber of bracket.Significant volume change is carried out in this region of interior room, the volume changes with simple Mode can be compensated directly by the element of elasticity.

Can be provided that, elasticity element by can elastically-deformable diaphragm formed, the diaphragm is fastened in bracket At the side of empty room.Preferably so select the thickness of the diaphragm so that or even only occur when flexural deformation is larger so Small stress, i.e., described diaphragm does not rupture enduringly.The thickness of the diaphragm is simultaneously, preferably so selected greatly so that institute State diaphragm shapes stabilization.Elastic deformation needed for volume balance is can be implemented as using such diaphragm, and without worrying institute State the rupture of the element of elasticity.

Can be provided that, diaphragm construction is the form of bellows, the bellows has multiple annularly around described vertical Circular, the flexible fold of axis.Such bellows can be advantageously manufactured especially in cost.Preferably, the bellows Manufactured with plastic injection molding process.The fold is arranged parallel to each other preferably along the direction of longitudinal axis.The bellows Preferably can-like it is configured with closed bottom side and unlimited rostral.Preferably, the rostral is firmly hollow with bracket The side wall of room is connected, wherein, the bottom side is departing from the threaded spindle.

Can be provided that, the element of the elasticity is formed by the foamed plastics with multiple holes, wherein, the hole definition First section of the interior room.Such actuator can be advantageously manufactured particularly simplely and in cost.

Can be provided that, the surface that the foamed plastics is closed with having Fluid Sealing.Hindered through this, it is described not Compressible fluid reaches the first section from the second section of interior room.

Can be provided that, foamed plastics has multiple holes, the hole Fluid Sealing ground is put out each other.Hindered through this, The incompressible fluid reaches the first section from the second section of interior room.

Can be provided that, the screw action between nut and threaded spindle is by being provided with the roller in outer special-shaped portion Or facilitated by being configured to spherical or tubular rolling element.Roller through heteromorphosis is preferably rabbeted using its outer abnormity portion To in the groove portion helically moved towards, the groove portion is arranged in the threaded spindle and the nut.The rolling element is excellent Selection of land is rolled in the groove portion helically moved towards, and the groove portion is arranged in the threaded spindle and the nut.It is described Rolling element is preferably circulated and is arranged in the nut continuously around ground.

Can be provided that, the bracket has at least one ventilating opening in the region of the first section of the interior room. First section of interior room is preferably filled with gas, especially air.Avoided by least one ventilating opening, in interior room The first section in there is excessive pressure change in movement of bracket.Except at least one ventilating opening and expectation situation Fluid be input into beyond mouth, the preferably Fluid Sealing ground closing interior room.

Obviously, feature that is previously mentioned and also being explained below can not only be used in correspondingly illustrated combination In, and

Can use in other combinations or be used alone, and without departing from framework of the invention.

Brief description of the drawings

Next the present invention is explained in detail by accompanying drawing.Wherein：

Fig. 1 is the sectional side elevation of the end of the transmission side of the actuator according to first embodiment of the invention；

Fig. 2 is the sectional side elevation of the end of the bracket side according to the actuator of Fig. 1；And

Fig. 3 is according to the sectional side elevation corresponding to Fig. 2 of the actuator of second embodiment of the present invention.

Specific embodiment

Fig. 1 shows the sectional side elevation of the end of the transmission side according to the actuator 10 of first embodiment of the invention.Hold Row device 10 has shell 20, and the shell is by main body 23, the first end block（It is in figs 2 and 3 No. 21）Constituted with the second end block 22.Main body 23 Preferably it is made up with extrusion process of aluminium, so that the main body has constant, tubulose cross section shape along longitudinal axis 11 Shape.Rolling bearing 63 is accommodated in the second end block 22, causes threaded spindle 60 on the longitudinal axis 11 using the rolling bearing Can rotationally support.Rolling bearing 63 is preferably configured to the form of annular bearing with rolling contact, wherein, it is being currently included multiple Oblique ball bearing, the oblique ball bearing seamlessly causes tight relative to one another.Threaded spindle 60 runs through second end block 22, wherein, The threaded spindle is protruding from the shell 20 using axle journal 62 is driven.Threaded spindle 60 is enabled to by the transmission axle journal 62 For example by means of（It is unshowned）Electro-motor enters in rotational motion.In the interior room 12 of shell 20, threaded spindle 60 is provided with one The main shaft groove portion 61 that individual or multiple is helically moved towards on longitudinal axis 11.

Nut 50 is disposed with addition in the interior room 12 of the shell 20, and the nut is in screw action with threaded spindle 60 In.The sleeve-shaped of the nut 50 ground surrounds the threaded spindle 60, wherein, the nut is provided with one or more at inner circumferential surface On the nut groove portion 51 that the longitudinal axis 11 is helically moved towards.Currently, ball screw nut is illustrated, as example from EP 1 The ball screw nut known to 132 651 B1 is such.The not shown described spherical rolling for facilitating the screw action in Fig. 1 Kinetoplast.Nut groove portion 51 and main shaft groove portion 61 shape of cross section approximate half-circular ground construction, so that they are with compact patch By being matched to the spherical rolling element.Replacing the ball-screw can also use planet nut certainly, as utilizing from DE The known planet nut is such in 10 2012212311A1.In this case, the screw action is promoted by multiple rollers Into the roller is provided with outer special-shaped portion, and the outer special-shaped portion is scarfed in nut groove portion 51 and main shaft groove portion 61.Obviously, nut groove portion 51 and main shaft groove portion 61 shape of cross section is matched to the outer special-shaped portion of the roller being previously mentioned.In this case the present invention especially Favorably, because produced heat in screw action especially efficiently can be derived outwards towards surrounding environment.

Nut 50 is provided with end part seal portion 52 at it towards the end of rolling bearing 63, the end part seal portion and the screw thread Main shaft 60 is in sealing function.End part seal portion 52 is by the second of interior room 12 and the 3rd section 14；15 Fluid Sealings ground is each other Put out.Second section 14 is preferably by incompressible fluid, such as oil to seal.Through this, should on the one hand lubricate The screw action between nut 50 and threaded spindle 60, wherein heat produced there should be derived simultaneously.Here, Different from two conventional actuators in end part seal portion, the interior room of the nut not being filled merely with oil, but also A part for the hollow chamber 31 being filled in bracket 30.Also it can be considered that, the end part seal portion 52 is saved, so that interior room 12 the best part namely except first section（In figs 2 and 3 No. 13）Outer all parts are incompressible using this Fluid fill.When the nut 50 is configured to planet screw thread nut, the alternative of the latter is preferred, wherein, During operation, big heat should be derived by the incompressible fluid.

The end part seal portion 52 firmly constructs very much currently, so that the end part seal portion can withstand the fluid Pressure.The end part seal portion 52 is preferably formed by elastomer.It is fastened on nut using single sealing keeper 53 At 50 main body 54.Obviously, it is same it can be considered that, the end part seal portion 52 is fastened directly at main body 54.The stream The pressure being previously mentioned of body is for example by the mass acceleration when actuator 10 is moved also or by especially in the execution The gravity of the fluid in the vertical arrangement of device 10 is caused.

The bracket 30 has preferably cylindrical pipe 34, and the pipe surrounds the threaded spindle 60 in the way of section. Pipe 34 is firmly connected by means of connector 37 with nut 50.Bracket 30 is for example using from the A1 of DE 10 2,007 043 391 It is known to rotate the torsion that insurance is protected from being carried out relative to the shell 20, so that when threaded spindle 60 enters rotational motion The bracket is not rotated around longitudinal axis 11 when middle.Corresponding torsion can also pass through certainly（It is unshowned）The structure surrounded Component hinders, and the actuator 10 is put into the construction package.

In addition, it is indicated that in shell 20 first is input into mouth 26 and in nut 50 second is input into mouth 55.In bracket 20 In one attitude, described first and described second is input into mouth 26；55 so alignedly arrange so that what is be previously mentioned is incompressible Fluid can be filled into the second section 14 of the interior room 12.Preferably, this second be input into mouth 55 in be disposed with（It is not shown 's）Check-valves, the check-valves allows fluid stream to enter in second section 14 only.

Fig. 2 shows the sectional side elevation of the end of the bracket side according to the actuator 10 of Fig. 1.There, first end block 21 are fastened at the main body 23 of the shell 20.The bracket 30 run through first end block 21, wherein, the bracket there by means of Slide bushing 24 can be guided to linear movement along the direction of longitudinal axis 11.The slide bushing 24 is provided preferably with along vertical To the gap that direction 11 is moved towards.In addition, being disposed with bracket sealing 25 at the first end block 21, the bracket sealing is by elastomer Formed.The bracket sealing 25 hermetically contacts the preferably cylindrical outer peripheral face of the bracket 30.Hindered through this, Dirt is reached in the interior room 12 of actuator 10, wherein hinder simultaneously, described lubricant etc. is outwards arrived at from the interior room 12.

The end of the outside of the bracket is provided with single secure component 35, can be fastened at the secure component（It is not shown 's）The construction package of higher level.The secure component 35 is provided with fastener 36, and the fastener is external screw thread in present construction.It is described Fastener 36 can also be configured to internal thread, fastening fork or ball-joint certainly.

Threaded spindle 60 has the end face 64 of plane, and the end face is preferably perpendicular to longitudinal axis orientation.In bracket 30 The bottom surface 33 of the plane of hollow chamber 31 is abreast opposed to the end face 64 being previously mentioned.Bottom surface 33 is arranged at secure component 35. In remaining situation, the hollow chamber 31 in bracket 30 is limited by side 32, the side by pipe 34 preferably cylindrical inner circumferential Face is formed.

The element 70 of the elasticity is disposed between end face 64 and bottom surface 33.In the first embodiment of actuator 10 In, this actuator is configured to the form of the diaphragm 71 of elasticity, and the diaphragm is fastened at the side 32 of hollow chamber 31.Diaphragm 71 will be interior First and second sections 13 of room 12；Put out each other 14 Fluid Sealings.As explained, second section 14 Incompressible liquid is preferably by fill.Figure 2 illustrates the shape for farthest moving into bracket 30 The bracket in state.In the diaphragm that a part for incompressible fluid is located at can-like ground, constructed in the form of the bellows 72, Wherein, the bellows 72 is maximally compressed.If now the bracket 30 is moved from the shell, the bellows 72 expansions, because incompressible fluid is from the medial compartment exclusion between threaded spindle 60 and the pipe 34 to bellows 72 In.Result is：Second section 14 of interior room 12 keeps its volume, wherein, the volume of only the first section 13 is changed.In bracket 30 When farthest moving away, bellows 72 is located in the state of its maximum extension.Above-mentioned explaination is applicable following, i.e. institute State nut and be provided with end part seal portion as described above（No. 52 in Fig. 1）.If this end part seal portion is lacked, when the bracket 30 When moving away, bellows 72 also can be along opposite direction deformation.

Bellows 72 has multiple folds 73, and the fold is arranged parallel to each other along the direction of longitudinal axis 11, wherein, should Fold is annularly moved towards around the longitudinal axis 11.The bellows 72 has unlimited rostral 75, and institute is caused by the rostral Stating incompressible fluid can reach in bellows 72 and can be flowed outwardly from this bellows.The rostral 75 is consolidated Ground is connected with the side 32 of hollow chamber 31.The rostral for example can be pressed into there.The cloth of bottom side 74 of the closure of bellows 72 Put on the sidepiece departing from threaded spindle 60 of bellows 72.Bottom side 74 can be in the elastic scope of bellows 72 freely Ground motion in bracket 30.Bellows 72 is preferably made of plastics, and preferably is made up of elastomer.

The bracket can be provided with ventilating opening 38；38', to hinder：When the bracket 30 is moved, the of interior room 12 Pressure in one section 13 excessively changes.According to the first alternative, the air vent 38 is concentric with longitudinal axis 11 through institute State secure component 36.According to the second alternative, the air vent 38' runs through the pipe 34 of bracket 30 radial to longitudinal axis 11. Air vent 38 is illustrated in Fig. 2；Two alternatives of 38', wherein preferably, using only in described two alternatives It is individual.

Fig. 3 shows the sectional side elevation corresponding to Fig. 2 according to the actuator 10' of second embodiment of the present invention.Perform The end of the transmission side of the second embodiment of device 10' constructs with being same as first embodiment, so as to ground reference relevant with this The embodiment of Fig. 1.The end of the bracket side of the second embodiment of actuator 10' is same as in addition to difference described below First embodiment ground construction, so as to the embodiment of relevant with this reference picture 2.Here, in figs 2 and 3, identical or phase The part answered is provided with identical reference.

The second embodiment of the element 70' of elasticity is formed by the foamed plastics 76 with multiple holes.Foamed plastics is preferred Be constructed so as to, i.e., described incompressible fluid can not get into the foamed plastics from the second section 14 of the interior room 76.The surface that foamed plastics 76 can be closed with having Fluid Sealing for this.Certainly also it can be considered that, foamed plastics 76 has There are multiple holes, the hole Fluid Sealing ground is put out each other.Such foamed plastics is also referred to as closed pore.Described two measures also can It is combined with each other.

First section 13 of interior room 12 is defined by the hole of foamed plastics 76.Only moved relative to the shell 20 in bracket 30 When, the volume in the hole is changed.The volume of the second section 14 is accordingly constant or approximate constant with this holding.

Fig. 3 shows the bracket in the state for farthest moving into of bracket 30.Incompressible fluid A part in free space 77 is currently located at, the free space construct threaded spindle 60 end face 64 and foamed plastics 76 Between.

Foamed plastics 76 is located in its maximum compressed state.If now bracket 30 moved away, the foam Plastics 76 are stretched.Meanwhile, the free space 77 can be bigger, because between threaded spindle 60 and the pipe 34 not A part for compressible fluid is squeezed in free space 77.This point especially to it is following be applicable, i.e., described nut as described above that Sample is provided with end part seal portion（No. 52 in Fig. 1）.If lacking this end part seal portion, when the bracket 30 is moved away, from Can be also reduced by space 77.Then also it can be considered that, the foamed plastics 76 is leaned in each attitude of bracket 30 Put at the end face 64 of threaded spindle 60.

The foamed plastics 76 is preferably directly rested at the bottom surface 33 of the hollow chamber 31 of bracket 30.In addition, the foam Plastics are rested at the side 32 of the hollow chamber 31 being previously mentioned in the way of section.

Reference numerals list

10 actuators（First embodiment）

10' actuators（Second embodiment）

11 longitudinal axis

12 interior rooms

First section of 13 interior rooms

Second section of 14 interior rooms

3rd section of 15 interior rooms

The region of 16 screw actions

20 shells

21 first end blocks

22 second end blocks

23 main bodys

24 slide bushings

25 bracket sealings

26 first are input into mouth

30 brackets

31 hollow chambers

The side of 32 hollow chambers

The bottom surface of 33 hollow chambers

34 pipes

35 secure components

36 fasteners

37 connectors

38 ventilating openings（First alternative）

38' ventilating openings（Second alternative）

50 nuts

51 nut groove portions

52 end part seal portions

53 sealing keepers

The main body of 54 nuts

55 second are input into mouth

60 threaded spindles

61 main shaft groove portions

62 transmission axle journals

63 rolling bearings

The end face of 64 threaded spindles

The element of 70 elasticity（First embodiment）

The element of 70' elasticity（Second embodiment）

71 diaphragms

72 bellowss

73 folds

The bottom side of 74 bellowss

The rostral of 75 bellowss

76 foamed plastics

77 free spaces

Claims (14)

1. actuator（10；10'）, it carries shell（20）And bracket（30）, wherein, bracket（30）In longitudinal axis（11）Direction on Can be supported on shell to linear movement（20）Place, wherein, bracket（30）Along the longitudinal axis（11）Direction from the shell（20）In It is protruding, wherein, the shell（20）With the bracket（30）Jointly define interior room（12）, the volume of the interior room is in the support Frame（30）Relative to the shell（20）It is changed during motion, wherein, threaded spindle（60）By means of rolling bearing（63）On The longitudinal axis（11）The shell can be rotatably supported at（20）Place, wherein, the threaded spindle puts in the bracket（30）'s Hollow chamber（31）In, wherein, the bracket（30）It is provided with nut（50）, the nut arrangements are in the interior room（12）In and the spiral shell Mother is in and threaded spindle（60）Screw action in,

Characterized in that, in the hollow chamber of the bracket（31）The middle resilient element of arrangement（70；70'）, the element is in the support Frame（30）Relative to shell（20）It is elastically deformed during motion.

2. according to the actuator described in claim 1,

Wherein, the element of the elasticity（70；70'）By the interior room（12）The first and second sections（13；14）Fluid Sealing Ground is put out each other, wherein, in the nut（50）And threaded spindle（60）Between screw action region（15）It is in described Room（12）The second section（14）Part.

3. according to the actuator described in claim 2,

Wherein, nut（50）Only in the direction rolling bearing of the nut（63）End be provided with end part seal portion （52）, the end part seal portion is so in and threaded spindle（60）Sealing function in, i.e. the end part seal portion is by interior room （12）The 3rd section（15）Fluid Sealing ground is from interior room（12）The second section（14）Put out.

4. according to the actuator described in claim 2,

Wherein, the nut（50）So openly constructed in two opposed ends of the nut, i.e. the interior room（12） The second section（14）Extend through the nut（50）.

5. according to the actuator described in claim 3 or 4,

Characterized in that, the element of the elasticity（70；70'）In bracket（30）Relative to shell（20）Such crust deformation during motion, So that the first section（13）Volume be changed, and the second section（14）Volume be held substantially constant.

6. according to the actuator any one of claim 2 to 5,

Wherein, interior room（12）The second section（14）Substantially completely filled using incompressible fluid.

7. according to actuator in any one of the preceding claims wherein,

Wherein, threaded spindle（60）With end face（64）, wherein, the element of elasticity（70；70'）It is arranged in the end face being previously mentioned （64）And bracket（30）Hollow chamber（31）Bottom surface（33）Between.

8. according to actuator in any one of the preceding claims wherein,

Wherein, elastic element（70）By being capable of elastically-deformable diaphragm（71）Formed, the diaphragm is fastened on bracket（30）In Empty room（31）Side（32）Place.

9. according to the actuator described in claim 8,

Wherein, diaphragm（71）It is configured to bellows（72）Form, the bellows have multiple annularly around the longitudinal axis （11）Circular, flexible fold（73）.

10. according to actuator in any one of the preceding claims wherein,

Wherein, elastic element（70'）By the foamed plastics with multiple holes（76）Formed, wherein, the hole is defined in described Room（12）The first section（13）.

11. according to the actuator described in claim 10,

Wherein, foamed plastics（76）The surface closed with Fluid Sealing.

12. according to the actuator described in claim 10 or 11,

Wherein, foamed plastics（76）With multiple holes, the hole Fluid Sealing ground is put out each other.

13. according to actuator in any one of the preceding claims wherein,

Wherein, in nut（50）And threaded spindle（60）Between screw action by being provided with the roller in outer special-shaped portion or by ball The rolling element of shape ground or tubular ground construction is facilitated.

14. according to actuator in any one of the preceding claims wherein,

Wherein, bracket（30）In interior room（12）The first section（13）Region in have at least one ventilating opening（38；38'）.