JPH10201205A - Hand-held machine tool - Google Patents

Abstract

(57) [Problem] To provide a hand-held machine tool insensitive to dust causing abrasion sucked together with cooling air. A commutator is disposed on a front casing of a motor casing, the front casing having barriers surrounding the commutator, and an end casing attached to the front casing is provided. In a completely assembled motor casing, which surrounds the barrier in a radial direction, the cooling air can be guided along the barrier, with a small part of the cooling air passing directly along the commutator 24. The abrasions are scraped so that most of the cooling air flows along the electric motor 18 without contacting the commutator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hand-held machine tool having a motor casing which can be assembled from a plurality of parts, the motor casing receiving an electric motor having a rotor together with a commutator, It concerns a type in which the electric motor can be cooled by a cooling air flow guided along its axis from an end casing, which is a rear part of the motor casing, towards a front casing, which is a front part.

[0002]

BACKGROUND OF THE INVENTION With all known hand-held tools, especially angle grinders, in which cooling air is drawn in and flows through the machine, the abrasive dust that causes wear is also removed from the interior of the machine together with the cooling air that is drawn in from the outside. Sucked into
The distance between the carbon brush and the commutator is reached, which results in significant wear of the carbon brush and the commutator.

[0003] Furthermore, the carbon brush may be fixed due to the penetration of fine grinding dust into the carbon brush guide, so that the carbon brush further follows the commutator in the radial direction when the contact surface is worn. You will not be able to move closer. In this case, arcs and consequently so-called brush fires are formed, which cause the commutator to be burned and thus destroyed over time.

If the sucked-in grinding dust consists of a conductive material, cleave sections are formed between the commutator laminates, resulting in short-circuits between different potentials and, consequently, motor failure.

[0005]

SUMMARY OF THE INVENTION In order to solve this problem, the design of the present invention improves a hand-held machine tool of the type mentioned at the outset to reduce wear-induced dust which is sucked in with the cooling air. To provide a hand-held machine tool that is less sensitive.

[0006]

SUMMARY OF THE INVENTION In order to solve this problem, according to the present invention, a commutator is disposed in a front casing of a motor casing, and the front casing has a barrier surrounding the commutator. The end casing, which is attached to the front casing, radially surrounds the barrier, so that in a fully assembled motor casing, cooling air can be guided along the barrier, whereby the cooling air A small portion rubs the commutator directly along the commutator so that most of the cooling air flows along the electric motor without contacting the commutator.

[0007]

The hand-held machine tool according to the present invention thus configured has the following advantages over the known machine tools.
This has the advantage that wear in the region of the commutator is reduced and the useful life of the carbon brush is extended. Furthermore, the prevention of disturbance is improved by the prevention of the brush fire, and no creep zones can be formed. This improves the resistance to dust to nearly 10 times the service life, increases the service life of the carbon brush by about 15 hours, and reduces commutator wear to less than about 50%.

The commutator is cooled sufficiently by the cooling air flow being guided around the commutator and a portion of the cooling air reaching the commutator, but the supply of dust particles causing wear is almost complete. To be avoided.

Due to the fact that the barrier encloses the commutator entirely in a box shape, a complete shielding of the commutator from the main cooling air flow is achieved.

The commutator is cooled sufficiently by the barrier, together with the machine casing surrounding the barrier, forming an approximately 1 mm wide gap through which a portion of the cooling air can be guided to the commutator. Is done.

Due to the through-opening in the barrier being somewhat larger than the cable diameter, a portion of the cooling air can enter through the cable passage to cool the commutator. In this case, the particles that cause wear are separated from the cooling air.

Due to the fact that the barrier is arranged at right angles to the cooling air flow, the cooling air is deflected substantially at right angles at the barrier and entrained, especially coarse dust, is separated off by strong acceleration. You. The high flow rate of the cooling air at the box-shaped barrier region by rubbing at a high velocity creates an injector action inside the region shielded by the barrier, which causes an additional supply of cooling air.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

A hand-held machine tool shown in a longitudinal sectional view in FIG.
An angle grinder 10 provided with a motor casing 12 comprising: The end casing 16 has side intake slots 17 (see FIG. 2), which are located behind an electric motor 18 acting as a drive. This electric motor 18 is a motor shaft 2
And the commutator 24 of the electric motor 18 is provided by two spiral springs.
Electric energy is supplied via two carbon brushes 22 pressed against the. Behind the compression spring 26 for the carbon brush 22 towards the right in the viewing direction, there are arranged a plurality of radially outwardly extending barriers 28, which are arranged on one side of the front casing 14. Department. Between the barrier 28 and the end casing 16 which is set in the front casing 14 in the axial direction, a slot approximately 1 mm wide in the radial direction remains open, through which the sucked cooling The air (see arrow 38 indicating the flow direction)
Rub over the two carbon brushes 22 to remove both carbon brushes 2
2 and the commutator 24 can be cooled. The main part of the cooling air is guided along the side barrier 30 on the side of the barrier 28 and can therefore be swept over the rotor 20 of the electric motor 18 without contacting the commutator 24 without being throttled, and It can be sucked in by the fan wheel 31, pass through the fan wheel 31 and the exhaust slot 35 in the front casing 14 and the transmission casing 32, and can flow out to the outside. The side barrier 30 prevents the main air flow from entering the carbon brush 22 and the commutator 24. The transmission casing 32 has an orthogonal transmission 34 for driving a working spindle 36.

FIG. 2 is a top view of the hand-held machine tool 10. FIG. 2 shows a motor casing 12 having a front casing 14 and an end casing 16, and a transmission casing 32 having an exhaust slot 35. Are clearly shown. In addition, the rear intake slot 17 through which the cooling air sucked from the outside (see arrow 38 indicating the flow of the cooling air) flows in is clearly shown. The front casing 14 is provided with the electric motor 1 shown in FIG.
8 has a side slide switch 19 for connecting / disconnecting the energy supply to the power supply 8.

The front casing 14 and the end casing 16 are shown in a perspective view in FIG. 3, and the positions of the barriers 28 and 30 can be clearly seen from FIG.
FIG. 3 also shows the arrangement of the intake slots 17 in the end casing 16.

The end casing 16 can be fitted over the front casing 14 in the axial direction, so that the end casing 16 engages with the ring collar 14 'of the front casing 14 in the front pipe region 16'.

FIG. 4 shows the front casing 14 in a perspective view from the front, in which the barriers 28, 30 are shown.
Is particularly clear. As can also be particularly clearly seen from FIG. 4, a barrier 28 arranged at right angles to the longitudinal axis of the front casing 14 and a side barrier 30 arranged parallel to the longitudinal axis,
A box-shaped chamber is formed, in which the carbon brushes 22 are shielded from the cooling air and are moved radially towards the commutator 24 by a spiral spring 26, also arranged in the box-shaped area. The cooling air is not throttled along the side barrier 30 but flows toward the rotor 20 of the electric motor 18 and can cool the rotor 20 in an advantageous manner. On the other hand, since the carbon brush 22 and the commutator 24 are shielded from the main air flow, they are sufficiently cooled by the secondary air flow of about 10% of the main air flow,
In this case, however, less than 10% of the dust that causes wear in the cooling air flow can penetrate into the box-shaped area formed by the barriers 28, 30, most of which are perpendicular to the air flow. Separated at the placed barrier 28.

FIG. 3 shows a cutout 40 provided above the barrier 28, which cutout 40 serves to clamp the electrical cable for power supply. The notch 40
It helps to reduce the tensile load on the joint between the electric cable and the carbon brush 22.

In the notch 40, one opening for air flow is still left when the electric cable is laid, and cooling air flows through this opening without the dust particles following the opening.
And dimensioned so that it can reach the carbon brush 22.

The dust separated at the barrier 28 is trapped by the main stream of cooling air, which carries it through the electric motor 18 and out of the exhaust slot 35. The main cooling air flowing relatively quickly along the longitudinally extending side barriers 30 creates a negative pressure effect inside the box-shaped space by the barriers 28,30,
This negative pressure action is caused by the barriers 28 and 30 and the end casing 1.
6 to provide a strong supply of cooling air through the slot between them. This improves the service life of the machine against dust from 10 to 100 hours, in which case the service life of the carbon brush is increased by 15 hours and the commutator wear is reduced to less than 50%.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an angle grinder according to the present invention.

FIG. 2 is a plan view of the angle grinder shown in FIG. 1 as viewed from above.

FIG. 3 is an exploded perspective view showing a machine casing according to the present invention.

FIG. 4 is a perspective view showing a front portion of a motor casing.

[Explanation of symbols]

10 angle grinder, 12 motor casing, 14 front casing, 14 'ring collar, 16 end casing, 16' pipe area,
17 intake slot, 18 electric motor, 19
Slide switch, 20 rotor, 22 carbon brush, 24 commutator, 26 compression spring, 28 barrier,
30 side barrier, 31 fan wheel, 32 transmission casing, 34 orthogonal transmission, 35 exhaust slot, 36 working spindle, 38 arrow,
40 Notch (Cable passage)

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H02K 13/00 H02K 13/00 XZ

Claims (6)

[Claims] 1. A hand-held machine tool having a motor casing (12) which can be assembled from a plurality of parts (14, 16), wherein the motor casing (12) is provided with a rotor (2).
0) together with a commutator (24), which is moved along its axis from an end casing (16), which is the rear part of the motor casing (12). In a type which can be cooled by a cooling air flow guided toward a front casing (14) which is a front part, the commutator (2)
4) is arranged in the front casing (14) of the motor casing (12), said front casing (14) being a barrier (28,3) surrounding the commutator (24).
0), and the end casing (16) attached to the front casing (14) includes a barrier (28,
30) in a radial direction, so that in the fully assembled motor casing (12), cooling air can be guided along the barriers (28, 30), with a small portion of the cooling air being Direct commutator (24)
Along with the commutator (24) so that most of the cooling air flows along the electric motor (18) without contacting the commutator (24). Hand-held machine tool. 2. A barrier (2) of a front casing (14).
8, 30) encircling the commutator (24) and the carbon brush (22) in a box shape, the barriers (28, 30) being partly perpendicular to the cooling air flow and partly cooling. A hand-held machine tool that is arranged along the air. 3. The barrier (28, 30) forms a defined air gap with respect to the end casing (16), through which about 10% of the total cooling air flow flows. A hand-held machine tool characterized in that it can be guided via a). 4. A cable passage (40) passing through the barrier (28, 30) is provided.
0) are also dimensioned to act as through-flow openings for cooling air guided towards the commutator (24), so that dust can be separated at the barriers (28, 30). The hand-held machine tool according to claim 3, wherein 5. The barrier (28) is at least partially arranged in the cooling air flow, the cooling air being diverted substantially at a right angle at the barrier (28), whereby the cooling air is entrained by the cooling air. 5. A hand-held machine tool according to claim 4, wherein particularly coarse dust particles are separated. 6. A negative pressure is formed behind the barrier (28, 30) by the cooling air flowing across the barrier (28, 30), the cooling air causing the cooling air to flow through the barrier (2, 30).
After the commutator (24) and carbon brush (2
The hand-held machine tool according to claim 5, wherein the machine tool is pulled toward (2).