US20130059508A1

US20130059508A1 - Electric power device with integrated cooling system for controlling tools

Info

Publication number: US20130059508A1
Application number: US13/440,340
Authority: US
Inventors: Marc BOTTAZZI
Original assignee: MBH Developpement SARL
Current assignee: MBH Developpement SARL
Priority date: 2011-09-02
Filing date: 2012-04-05
Publication date: 2013-03-07
Also published as: FR2979562A1; FR2979562B1; EP2564992B1; EP2564992A1

Abstract

A device is provided that includes at least one motor part having a housing surrounding an electric motor for driving an active head part accommodating a tool such as a tool for grinding, sanding or the like, and a suction pipe intended to be connected to a suction device. The suction pipe leads to the housing of the motor part and the motor comprises a sealed high-frequency electric motor positioned in the central part of said housing in such a way that the sucked-in air circulates around the body of the motor.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority of French application no. 1157767 filed on Sep. 2, 2011, the entire contents of which is hereby incorporated herein.

FIELD OF THE INVENTION

This invention relates to the technical field of electric power tools used in the building and construction industries and relates more specifically to long arm sanders.

BACKGROUND TO THE INVENTION

Long arm sanders are known that include, with reference to FIG. 1, a grip and carrying arm (1) to which is fitted a motor part (2) in the median portion thereof, an active head part (3) at the free end thereof and a grip handle (4) between the motor part (2) and the active head (3). The active head part is in the shape of a curved neck and accommodates at the end thereof a sanding grind wheel (5).
This type of equipment is commonly referred to in the relevant professional circles by the colourful term of “giraffe sander (trademark)” due to the particular shape of the active head accommodating the hinged sanding plate. This type of sander can be used for working on ceilings and on the upper part of walls, up to a height of about 3 metres.
These long arm sanders also comprise a suction pipe (6) for the waste produced by the sanding operation, such as dust for example, said suction pipe (6) passing through the grip arm, a first end leading to the active head (3) and the opposite end being connected to a suction device (7) for collecting the waste.
In the prior art, as shown in FIG. 2, the motor part (2) consists of a housing (8) rigidly connected to the grip arm (1) and defining two compartments, a first so-called upper compartment (9) in which the suction pipe (6) extends and a second so-called lower compartment (10) in which a motor (11) is placed, and commonly a universal electric motor. The output shaft of the motor (11) is connected to a planetary gearbox (12) whereof the output shaft is connected to a flexible drive (13).
In order to cool the motor (11), the housing (8) comprises in the lower compartment, on either side of the longitudinal cutting plane of the housing (8), a first cooling air scoop (14 a) positioned in the air inlet of the motor (11) in order to direct an air flow towards the manifold of the universal motor (11), between the rotor and the stator thereof, and a second air discharge vent (14 b) positioned in the air outlet of the motor (11), in proximity to the planetary gearbox (12).
Prior art long arm sanders thus have the drawback of having a bulky motor part.
Furthermore, the motor may well overheat causing permanent damage thereto should the vents for circulating the cooling air of the motor become blocked.
Moreover, the working dust may move inside the motor and cause the rotor or stator of said universal motor to short-circuit. Indeed, the drawback of the motor part of prior art devices is that they allow the intake of air charged with abrasive dust or conductive dust which may well burn the rotor either by short-circuiting the blades of the manifold or by abrasion of the copper coil of said rotor.
Portable electric power tools are also known, such as a portable electric sander, for example, shown diagrammatically in FIG. 4. This portable electric sander consists of a motor part (2), an active head (3) and a suction pipe (6) for the waste produced by the sanding operation, said suction pipe (6) comprising a first end leading to the active head (3) and the opposite end being connected to a suction device (7) for collecting the waste. The motor part (2) consists of a housing (8), which is intended to be taken in hand by the user, in which is placed a universal motor (11) connected to the mains (15), the output shaft of the motor (11) being connected to a planetary gearbox (12) whereof the output shaft is engaged with the active head (3). In order to cool the motor (11), the housing (8) comprises cooling air scoops (14 a) positioned in the air inlet of the motor (11) and air discharge vents (14 b) positioned in the air outlet of the motor (11), in proximity to the planetary gearbox (12).
This type of electric power tool has the same drawbacks as prior art long arm sanders. This type of prior art tool has the drawback in particular of comprising a universal motor which has low efficiency, under 40%, is particularly noisy, the noise generated by the motor being about 90 db, gets very hot with a risk of insufficient cooling, and has a significant pressure loss, has life expectancy of about 3,000 hours, i.e. the wear time of the motor brushes.

DISCLOSURE OF THE INVENTION

One of the purposes of the invention is therefore to overcome these drawbacks by proposing in particular a long arm sander of straightforward and inexpensive design that has a motor part that does not take up much space and that prevents any risk of the motor being damaged by overheating.
To this end, and in accordance with the invention, a device is proposed of the type that includes at least one motor part comprising a housing in which an electric motor is positioned suitable for driving an active head part accommodating a tool such as a tool for grinding, sanding or the like, and a suction pipe intended to be connected to a suction device; said long arm sander is remarkable in that the suction pipe leads to the housing of the motor part and in that the motor comprises a so-called sealed high-frequency electric motor positioned in the central part of said housing in such a way that the sucked-in air circulates around the body of the motor.
It will be understood that, unlike prior art long arm sanders in which the motor cooling system is independent, the motor is cooled by circulation of the air of the waste suction system. Thus, the motor is cooled as soon as the sander is turned on by the air flow sucked in at the sander head, preventing any risk of overheating. The rate of airflow of the suction system cooling the motor is very much greater than the airflow needed to cool said motor.
Furthermore, the central positioning of the motor in the housing and the absence of an independent system for cooling the motor means that the space requirement of the motor part is considerably reduced.
Moreover, a high-frequency electric motor of this kind has the advantage of being particularly silent, having no pressure loss, having efficiency in excess of 70% and having long life expectancy, upwards of 12,000 operating hours, unlike the electric motors of prior art devices.
According to one particularly advantageous feature, said inventive device comprises means for guiding the sucked-in air around the body of the motor. These guide means increase the time the sucked-in air is in contact with the body of the motor in order to cool said motor sufficiently.
Preferably, said guide means comprise at least one fin whereof the longitudinal axis is merged with the longitudinal axis of the body of the motor.
In one implementation alternative, said guide means comprise a plurality of longitudinal fins extending perpendicularly to the longitudinal axis of the housing from the body of the electric motor to the inner wall of the housing.

BRIEF DESCRIPTION OF THE FIGURES

Other advantages and characteristics will become clearer from the following description of a single implementation alternative of the inventive long arm sander, given as a non-restrictive example, with reference to the appended drawings wherein:

FIG. 1 is a perspective view of a long arm sander according to the prior art,

FIG. 2 is a diagrammatic longitudinal cross-section view of the motor part of a long arm sander according to the prior art,

FIG. 3 is a side view of the motor part of a long arm sander according to the prior art,

FIG. 4 is a diagrammatic view from above of a portable electric sander according to the prior art,

FIG. 5 is a longitudinal cross-section view of the motor part of a long arm sander according to the invention,

FIG. 6 is a longitudinal cross-section view of the motor part wherein the motor is not shown in order to display the waste suction flow of the inventive long arm sander,

FIG. 7 is a perspective view of the motor part cut along a transverse cutting plane of the inventive long arm sander,

FIG. 8 is a diagrammatic view from above of an inventive portable electric sander,

FIG. 9 is a longitudinal cross-section view of the motor part of the inventive portable electric sander,

FIG. 10 is a transverse cross-section view of the motor part of the inventive portable electric sander.

DETAILED DESCRIPTION OF THE INVENTION

In the interests of clarity, in the remainder of the description, the same elements have been denoted using the same reference numbers in the various figures. Moreover, the various cross-section views are not drawn to scale.
The long arm sander according to the invention comprises in the same way as prior art sanders, as shown in FIG. 1, a grip and carrying arm (1) to which is fitted a motor part (2) in the median portion thereof, an active head part (3) at the free end thereof and a grip handle (4) between the motor part (2) and the active head (3). The active head part (3) is in the shape of a curved neck and accommodates at the end thereof a sanding grind wheel (5).
Said long arm sander also comprises a suction pipe (6) for the waste produced by the sanding operation, such as dust for example, said suction pipe (6) passing through the grip arm, a first end leading to the active head (3) and the opposite end being connected to a suction device (7) for collecting the waste.
Moreover, the motor part (2) consists of a housing (8) rigidly connected to the grip arm (1) wherein there extends the suction pipe (6) and a motor (11), commonly a so-called high-frequency electric motor. The output shaft of the motor (11) is connected to a planetary gearbox (12) whereof the output shaft is connected to a flexible drive (13) connected to the active head part (4).
According to the invention, with reference to FIGS. 5 to 7, the suction pipe (6) leads to the housing (8) of the motor part (2) and the motor (11) is positioned in the central part of said housing (8) in such a way that the sucked-in air circulates around the body of the motor (11). Thus, the motor (11) is cooled by circulation of air of the waste suction system. It will be noted that the motor is cooled as soon as the sander is turned on by the air flow sucked in at the sander head, preventing any risk of overheating. Said sucked-in airflow cooling the motor (11) has a flow rate very much greater than the airflow rate needed to cool said motor (11) sufficiently. Moreover, the central positioning of the motor in the housing and the absence of an independent motor cooling system mean that the space required by the motor part is considerably reduced.
It will be noted that the suction device (7) comprises to advantage a known automatic start-up system so that, when the high-frequency motor (11) is turned on, the suction device (7) is automatically activated and the suction flow cools the motor (11).
The motor (11) comprises a so-called sealed high-frequency electric motor, i.e. a motor which has, in particular, an airtight body. Alternatively, the electric motor (11) and the planetary gearbox (12) may be placed in a sealed enclosure without departing from the framework of the invention.
It will be seen that said electric motor has the advantage of being particularly silent, having no pressure loss, having efficiency in excess of 70% and having long life expectancy, upwards of 12,000 operating hours.
To increase the time the sucked-in air is in contact with the body of the motor and to cool said motor sufficiently even in the event of a low suction flow rate, the inventive long arm sander comprises means for guiding the sucked-in air around and along the body of the motor (11). These guide means comprise a fin (16) whereof the longitudinal axis is merged with the longitudinal axis of the body of the motor (11).
It goes without saying that the inventive long arm sander may include one or more concentric fins (16) that may or may not have the same pitch, without departing from the framework of the invention.
In this particular embodiment example, the fin (16) is helical in shape with the pitch thereof being substantially equal to a third of the length of the housing (8).
Preferably, the fin (16) extends from the body of the motor (11) which is cylindrical in shape to the inner wall of the housing (8) which is also substantially cylindrical in shape.
It goes without saying that the housing (8) may have a transverse cross-section of any shape such as an oblong, polygonal or cylindrical shape without departing from the framework of the invention.
In this particular embodiment example, the housing (8) consists of two substantially hemi-cylindrical parts assembled by any appropriate means, such as screws for example, and the helical fin (16) is rigidly connected to the inner wall of said housing (8), the fin and the housing being obtained all in one piece by moulding for example.
With reference to FIGS. 8 to 10, showing a portable electric tool according to the invention of the portable electric sander type, said portable electric sander consists of a motor part (2), an active head (3). The motor part (2) consists of a housing (8), which is intended to be taken in hand by the user, in which is positioned a so-called sealed high-frequency electric motor (11) connected to the automatic start-up system of a suction device (7), the output shaft of the motor (11) being connected to a planetary gearbox (12) whereof the output shaft is engaged with the active head (3).
The motor (11) is positioned in the central part of said housing (8) in such a way that the sucked-in air circulates around the body of the motor (11), the space formed between the motor and the inner wall of the housing (8) forms a suction pipe (6) whereof one end leads to the active part (3) and whereof the other end is connected to the suction device (7). Thus, as previously, the motor (11) is cooled by circulation of the air of the waste suction system.
Preferably, with reference to FIGS. 9 and 10, the housing (8) comprises means (16) for guiding the sucked-in air around and along the body of the motor (11). These guide means (16) comprise a plurality of longitudinal fins extending perpendicular to the longitudinal axis of the housing (8) from the body of the motor (11) to the inner wall of the housing (8). In this embodiment example, the housing (8) and the body of the motor (11) are cylindrical in shape, the body of the motor (11) extending coaxially to the housing (8), and the guide means consist of four radial fins uniformly distributed around the body of the motor (11).
It goes without saying that the guide means may comprise any number of fins without departing from the framework of the invention.
Lastly, it is quite obvious that the invention may be applied to any electric power tool, whether or not it is portable, and that the examples that have just been given are only particular illustrations, and are under no circumstances restrictive in terms of the fields in which the invention may be applied.

Claims

1. Device including at least one motor part comprising a housing surrounding an electric motor for driving an active head part accommodating a tool, and a suction pipe connected to a suction device, wherein the suction pipe leads to the housing of the motor part and the motor comprises a sealed high-frequency electric motor positioned in a central part of said housing in such a way that sucked-in from the suction pipe air circulates around a body of the motor.

2. Device as claimed in claim 1, further comprising means for guiding the sucked-in air around and along the body of the motor.

3. Device as claimed in claim 2, wherein said guide means comprise a plurality of longitudinal fins extending perpendicularly to a longitudinal axis of the housing from the body of the motor to an inner wall of the housing.

4. Device as claimed in claim 2, wherein said guide means provide a laminar flow of the sucked-in air around and along the body of the motor.

5. Device as claimed in claim 2, wherein the guide means comprise at least one fin having a longitudinal axis merged with the longitudinal axis of the body of the motor.

6. Device as claimed in claim 5, wherein the fin extends from the body of the motor to an inner wall of the housing.

7. Device as claimed in claim 1, wherein the housing is substantially cylindrical in shape.

8. Device as claimed in claim 6, wherein the at least one fin is rigidly connected to the housing.

9. The device as claimed in claim 1, in combination with a long arm sander that includes a carrying arm, a grip handle, and an active head part accommodating a grinding or sanding tool.

10. Device as claimed in claim 7, wherein the guide means comprises at least one fin rigidly connected to the housing.

11. Device as claimed in claim 1, in combination with an active head part accommodating a grinding or sanding tool.