CN1248934A - Motor-driven hand unit - Google Patents

Abstract

The invention relates to a motor-driven hand unit comprising a shaft (10) driven by a motor, which shaft is mounted by means of a bearing (13) in a recess (16) of a housing part (12) and carries a fan wheel (14) at an axial distance thereto. The bearing (13) is sealed on the axial side facing the fan wheel (14) in relation to said fan wheel (14) by means of an axial sealing element (30) rotating with the shaft (10), whereby said sealing element is embodied as a circular, rubber-elastic shaft seal, the flexible sealing lip (32) of which contacts the outside of the bottom part (17) of the housing (12) and seals the outlet (19) of same.

Description

Motor-driven hand-held device

Technical merit

The present invention relates to motor-driven hand-held device according to claim a kind.

Known this motor-driven hand-held device (DE-40 38 634 A1), in this device, draught fan impeller axially is installed in above the bearing of axle across a certain distance.For example, this hand-held device is constructed to the super grinding device.When the motor connection is driven in rotation by this with axle, by means of the draught fan impeller grinding dust that will in Surface Machining, produce of rotation by on grinding plate and the opening in the sand paper fixed thereon be drawn in the dust room, and be transported in the container that is connected by an outlet from this dust room.Directly be subjected to dust in the dust room at the bearing on the draught fan impeller axial side here.Thus, this bearing faster on the cloth dust, so bearing be difficult near and greatly reduce bearing service life.

Advantage of the present invention

In contrast, have following advantage according to the motor-driven hand-held device with claim 1 feature of the present invention: the axial seal element by rotation makes bearing seal with respect to dust room, dust promptly can not arrive in the bearing like this, the bearing lubrication grease can not take place unexpectedly flow out in bearing.Improved bearing service life significantly by this.

From dependent claims, can obtain other favorable structure of the present invention.Adopt feature in the claim 2 and 3 can obtain that cost is low, the simple and axial seal element of excellent sealing.Adopt the feature in the claim 7 to 9, adopt simple device just can reach the good dust sealing of bearing, here, the surface accuracy of flexible seal lip balance tolerance, angular deviation, concentricity and lower surface has so also guaranteed lasting sealing contact.Because the pliability of seal lip, housing parts, particularly its bottom, seal lip need not handle near superincumbent surface, for example need not process, and can not be damaged to good sealing function.Exactly, the surface needn't be polished.Adopt favourable mode, can be by reducing rubbing action at contact range apply oil fat.

If with the axial seal element, particularly flexible, the contacted lower surface of at least one seal lip is not processed, for example not processed, preferably scribbles lubricant grease, then is favourable.In addition, advantageously, bearing, particularly radial ball bearing have contact or integrated non-contiguously within it gasket seal in both sides, gasket seal particularly sit put on outer shroud and with respect to inner axle to end face inwardly continue and therewith at interval a determining deviation stretch.In bearing, the particularly radial ball bearing axial side of axial seal element dorsad, can on axle, install one with this pad that together rotates, radially cover on the gasket seal of in bearing, adorning on the end face of ring and with very little at least axial spacing in this pad abuts against.If if pad be by thin plate constitute and pad and the inner axle that makes bearing by means of a safety collar by pad to being fixed on the axle, then also be favourable.Simply to produce bearing seal in relative axial side,, in the hand-held device that constitutes as grinding attachment, produce less dust by this here with the mode of lower cost.

In addition, for example be eccentric axle sleeve if axle has one in the axial side of the element of axial seal dorsad of draught fan impeller, a grinding plate is rotatably installed on the interior ring of a sleeve shaped that matches by a bearing, also is favourable.The bearing of grinding plate can be made of a unlimited needle bush, towards the axial side of draught fan impeller by means of at least one potted component axial seal, the sealing element constitutes as the radial axle sealing ring.If two radial axle sealing rings are installed on axial series ground, also are favourable.At least one potted component of bearing can be constructed to cross section and roughly be equivalent to the U-shaped that keeps flat, the sealing ring with two seal lips of having alarmmed.Making in the axial side towards dust room in simple mode by this is that the bearing that grinding plate disposes has reached dust seal.

Accompanying drawing

Describe one embodiment of the present of invention in detail by means of affiliated accompanying drawing in the following description.Wherein:

Fig. 1: the axial sectional side elevation of super grinding device;

The local enlarged diagram of Fig. 2: Fig. 1.

The explanation of embodiment

A motor-driven handheld tool 1 has been shown in Fig. 1 and Fig. 2, grinding attachment particularly, super grinding device for example, it has a housing 2, motor 3 is contained in the upper case portion 12, and this motor passes through 10 grinding plate 11 that drive as the vibrating member formation of coaxial line therewith.Axle 10 is bearing in 12 li of housing parts by means of a bearing 13.In this handheld tool, housing 12 has surrounded a draught fan impeller 14, and impeller is positioned at the dust room 15 that surrounded by housing parts 12 and is installed on the axle 10 by means of an axle sleeve 18, does not have with axle 10 to relatively rotate, and like this, it is along with axle 10 rotations.Bearing 13 is positioned at outside the dust room 15 and is contained in 16 li of the receiving members of about bowl-type of housing parts 12 like this, make the bottom 17 of receiving member 16 live bearing 13 towards a side cover of draught fan impeller 14, here, bottom 17 has a through hole 19, and the axle 10 that axle sleeve 18 is housed passes this through hole.

Bearing 13 for example is constructed to radial ball bearing, its outer shroud 20 be not fixed on rotatably about bowl-type 16 li of receiving members and can be on bottom 17 by axial support.Interior ring 21 does not have to sit with the relative rotation to be put on axle 10.Bottom 17 is determined size like this, makes it radially approximately extend to interior ring 21.Bearing 13, the particularly bearing that constitutes as radial ball bearing, in the axial side towards draught fan impeller 14, by means of 30 sealings of an axial seal element, sealing element coaxial 10 and axle sleeve 18 move together with respect to draught fan impeller 14.Potted component 30 is made of a sealing annular, flexible and that have caoutchouc elasticity here especially and has a seal 31 and a flexible seal lip 32, and their are one each other mutually.Seal lip 32 is towered and can be with respect to seal 31 resilient movement from seal 31 somewhat anti-truncated cone shapes in axial side.Potted component 30 is enclosed within on axle 10 or the axle sleeve 18 with certain bias voltage and elasticity is fixedly clamped.The radial dimension of potted component 30 is selected like this, and potted component 30 makes through hole 19 relative dust room 15 sealings of bottom 17.Potted component 30 flexibly abuts against on the bottom 17 with its axial side towards bottom 17.Therefore through hole 19 is hermetically enclosed, can not leave contingent space.Because contact, coaxial 10 together rotation potted components 30 institute towards the surface 22 of bottom 17 on rub.Seal lip 32 is protruded in the direction that arrives bottom 17 and its surface 22, and here seal lip 32 preferably rests on the surface 22 of bottom 17 with less prestressing force.Adopt this mode to produce less at least seal lip 32 thrusts.Mobility owing to seal lip 32 can remedy tolerance, concentricity, angular deviation or other similar errors, particularly the error of bottom 17.Seal lip 32 plays good sealing function at axial direction, promptly bearing 13 with respect to the sealing of dust room 15.When axle 10 rotation, seal lip 32 is because centrifugal force has an off-load, thereby can reduce with the friction of 17 contacts site, bottom and reduced the wearing and tearing of seal lip 32 by this.

Housing parts 12 is preferably by light metal, here particularly be made up of die casting aluminium.The surface 22 that contacts with flexible seal lip 32 of bottom 17 is untreated, and is for example unprocessed, casts out, and exactly, this surface 22 needn't be polished.If surface 22 is coated with a grease then is favourable, by this can reduce with seal lip 32 contact-making surface scopes in friction.

Adopt axial seal element 30 to reach the excellent sealing of bearing 13 and dust room 15 in illustrated mode, and with simple and mode that cost is low, particularly at axial seal element 30 during as the parts popular use of this form.

That bearing 13, particularly radial ball bearing have in both sides is integrated, at Fig. 2 only with the gasket seal shown in the schematic diagram 23 and 24, they are particularly sat and put on outer shroud 20, with respect to the stretching, extension that further inwardly and therewith keeps at a certain distance away of the axial end 25 or 26 of interior ring 21.On axle 10, in the axial side of the element of axial seal dorsad 30 of bearing 13, promptly in the drawings above, do not have a pad 27 of for example being made by thin plate be installed with the relative rotation, this pad coaxial 10 rotates together.Pad 27 does not rub between pad 27 that rotates and non-rotary gasket seal 24 like this by radially covering on integrated gasket seal 24 on the end face 26 of ring 21 in contacting and with less at least axial spacing.Employing does not have the shim liner of grinding to carry out that this sealing can be assembled simply and cost is low.Here, the gasket seal 24 of interior ring 21 end faces 26 dress in axially protruding in a little, narrow slit of generation between pad 27 and gasket seal 24 like this can be with lubricator, for example lubricant grease fills this slit, and this is favourable.

Be mounted with a safety collar 28 on axle 10, pad 27 is axially fixed on the axle 10 by pad 27 reliably by the interior ring 21 of this safety collar and bearing 13.When axle 10 rotation, pad 27 plays the back-up ring effect, it enough at this side shaft to sealed bearing 13.

Axle 10 draught fan impeller 14 dorsad the axial side of axial seal element 30 have a for example eccentric axle sleeve 40, grinding plate 11 can be rotated to support on the axle sleeve 40 by a bearing 42 by means of ring in the axle sleeve shape 41.In shown embodiment, the bearing 42 of grinding plate 11 is made of a unlimited needle bush, in the axial side towards draught fan impeller 14, by means of at least one potted component 43 axial seal, the sealing element works encircle 41 in grinding plate 11 and axle sleeve shape between.Potted component 43 constitutes as the radial axle sealing ring,, in shown embodiment, is provided with two identical radial axle sealing rings here, and their axial series are installed.In the embodiment that another does not illustrate, at least one potted component 43 sealing ring that roughly take the shape of the letter U as the cross section, that have two seal lips of towering constitutes, one of them seal lip works as the seal lip of sealing usefulness, and another seal lip works as dustproof lip.By at least one potted component 43 bearing 42 is sealed in simple mode with respect to dust room 15 and with respect to the dust that produces there at the position towards draught fan impeller 14.

Claims (10)

1. Motor-driven hand-held devices, especially grinding devices, such as superfinishing devices, have a housing in which is housed a motor for driving a shaft (10), which is mounted by means of a bearing (13) In the housing part (12) and at an axial distance from the bearing (13) there is a fan impeller (14), characterized in that The bearing (13) is sealed against the fan wheel (14) on the axial side facing the fan wheel (14) by means of an axial sealing element (30) which rotates coaxially with the shaft (10). 2. The handheld device according to claim 1, characterized in that, The axial sealing element (30) is formed by an annular, flexible, in particular rubber-elastic, shaft seal. 3. The handheld device according to claim 1 or 2, characterized in that, The axial sealing element (30) has a sealing body (31) and at least one flexible sealing lip (32), which protrudes from the sealing body (31) approximately in the shape of an inverse frustum on one axial side and can be Elastic movement relative to the sealing body. 4. Hand-held device according to one of claims 1 to 3, characterized in that The axial sealing element ( 30 ) is prestressed onto the shaft 10 or a bushing ( 18 ) on the shaft ( 10 ), for example the bushing ( 18 ) of the fan wheel ( 14 ), and is fastened in an elastically clamped manner. 5. Hand-held device according to one of claims 1 to 4, characterized in that The housing part (12) surrounds the fan impeller (14) and encloses a dust chamber (15). ) and is fixed in such a way that the bottom (17) of the holder (16) essentially covers the bearing (13) on the side facing the fan wheel (14). 6. Hand-held device according to one of claims 1 to 5, characterized in that The bearing (13) is designed as a radial ball bearing and the base (17) of the housing part (12) extends radially approximately to the inner ring (21) of the bearing (13). 7. Hand-held device according to one of claims 1 to 6, characterized in that The axial sealing element (30) axially seals the through hole (19) of the bottom (17) relative to the dust chamber (15). 8. Hand-held device according to one of claims 1 to 7, characterized in that The axial sealing element (30) bears elastically against the base (17) with its axial side facing the base (17). 9. Hand-held device according to one of claims 3 to 8, characterized in that At least one flexible sealing lip (32) of the axial sealing element (30) bears against the base (17), in particular with a small prestress. 10. Hand-held device according to one of claims 1 to 9, characterized in that The housing part 12 is made of light metal, in particular die-cast aluminum.

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