GB2383007A

GB2383007A - Improvements to a hand tool machine.

Info

Publication number: GB2383007A
Application number: GB0229018A
Authority: GB
Inventors: Monika Renner
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2001-12-14
Filing date: 2002-12-12
Publication date: 2003-06-18
Anticipated expiration: 2022-12-12
Also published as: GB2383007B; DE10161615A1; GB0229018D0

Abstract

A hand tool machine (fig 1, 10) comprising a housing 12 inset with air intake slots 20 which contains a drive motor about which is disposed a sliding frame 26. The sliding frame 26 is capable of being manually actuated by a push button 27 from outside the machine. Thus resulting in debris being removed from the said air intake slots by virtue of having inter spaced knock-out wedges 30.

Description

Hand tool machine having a housing with ventilation slots Background art The present invention proceeds from an, in particular electric, hand tool machine having the features of the preamble of claim 1.

Hand tool machines are known, the housings of which carry ventilation slots to allow cooling air to pass in and out.

The stronger the cooling air stream, the better the cooling of the hand tool motors and/or gear units and the more rugged and efficient are the corresponding hand tool machines. A drawback of known hand tool machines is that-especially when carrying out work which generates chips and dust-the air inlet slots gradually become clogged and so the cross section, through which cooling air may be taken in, becomes smaller. Consequently, with progressive fouling of the ventilation slots the cooling and hence the performance of the hand tool machine is impaired.

The ventilation slots have previously had to be cleaned in a relatively laborious manner using brushes, with the risk that larger dust residues might be carried into the interior of the housing where, upon the first occasion of

use after the cleaning procedure, they might cause damage to the collector or to the winding of stator and rotor.

Advantages of the invention The electric hand tool machine having the features of claim 1 has the advantage that without an external cleaning tool, by, as it were, pressing a button on the electric hand tool machine the air inlet slots of the latter may be cleaned quickly and conveniently. Short, appropriate cleaning intervals for the air inlet slots and a consistently adequate cooling capacity are thereby secured.

The resultant effect for the hand tool machines according to the invention is greater reliability and an extended life.

The cleaning apparatus, by virtue of being disposed in the interior of the housing, may be designed as an air baffle to reduce the flow resistance, thereby enabling an improvement of the efficiency of the motor cooling.

By virtue of the fact that the cleaning apparatus is designed as a sliding frame, which carries the knock-out wedges on the one side and the operating button on the other, a part is provided, which is simple to manufacture, easy to assemble and rugged.

By virtue of the fact that the knock-out wedges are flexible and compressible, their cleaning action is both thorough and gentle because the dust is completely removed by them without deformation of the ventilation slots.

The fact that the wedge angle of the knock-out wedges lies above the self-locking range rules out their jamming during cleaning of the air inlet slots, wherein the design as a negative form of the air inlet slots ensures thorough cleaning of the entire air inlet slot periphery.

By virtue of the fact that the actuating switch for starting the electric motor for the electric hand tool machine is coupled to means of arresting the actuating button, the cleaning apparatus may not be activated during operation of the machine, i. e. in the actuated state of the switching key, thereby ensuring that the air inlet slots are always open during operation of the hand tool machine.

Overheating of the operating hand tool machine is therefore ruled out.

Drawings The invention is described below with reference to an

embodiment and the accompanying drawings. The latter show in Figure 1 a three-dimensional side view of a hand tool machine according to the invention, Figure 2 a cross section of the motor housing of the hand tool machine, the cleaning device of which is in neutral position, and Figure 3 the cross section according to Figure 2 with the cleaning device shifted into cleaning position.

Description of the embodiment Figure 1 shows an electric hand tool machine 10 in the form of an angle grinder, the motor housing 12 of which

accommodates a non-illustrated electric motor, which may be switched on and off by means of a switching key 16 and is connectable to a voltage source by means of an electric cable 18.

Adjoining the motor housing 12 in viewing direction on the left is a gear case 14, projecting down from which is an output shaft, which is not described in detail and carries for rotational coupling a grinding disc 22, which is partially enclosed by an angle grinder protective cover 24.

The motor housing 12 in the rear region carries lateral air inlet slots 20, through which a fan of the non-illustrated electric motor sucks in cooling air. The cooling air is blown through between rotor and stator of the electric motor and leaves the electric hand tool machine 10 through an air outlet opening 21 at the top of the gear case 14.

When carrying out grinding with the electric hand tool machine 10, air containing dust is sucked in through the air inlet slots 20, wherein the dust is blown with the cooling air through between rotor and stator and is expelled from the air outlet opening 21.

Upon entering the air inlet slots 20, dust contained therein collects at the edges of the air inlet slots 20 and gradually reduces the cross section of the latter. As a result, in the worst-case scenario the cross section of the air inlet slots may be reduced by 20 to 50% so that cooling of the electric motor is correspondingly impaired. The air inlet slots 20 therefore have to be regularly checked and cleaned.

Figure 2 shows a cross section of the motor housing 12 in the region of the air inlet slots 20. In the interior of the housing 12 a sliding frame, which is movable at right angles to the longitudinal axis of the hand tool machine 10, is positioned by means of rib-like counterpart guides 29 into longitudinal guides 28 of the housing 12.

The sliding frame 26 carries, in viewing direction on the right, a pushbutton 27 and, in viewing direction on the left, a number of knock-out wedges 30, which corresponds to the number of air inlet slots 20.

In viewing direction on the right, the motor housing 12 carries a recess 32, into which the pushbutton 27 of the sliding frame 26 fits in a flush manner.

Two compression springs 34 disposed in viewing direction at the top left and bottom left keep the sliding frame 26 spring-loaded in its neutral position, wherein they attempt to press the sliding frame to the right. The compression springs 34 are disposed in each case about a guide pin 36 of the housing 12 and engage with their opposite free end in each case into a guide bore of the sliding frame 26.

When the pushbutton 27 is actuated leftwards in accordance with the actuating arrow 40, the springs 34 are compressed and the knock-out wedges 30 move, in viewing direction to the left, out through the air inlet slots 20.

Figure 3 shows the sliding frame 26 according to Figure 2 in its extreme left actuated position, in which the knockout wedges 30 pass right through the air inlet slots 20.

In said position the dust is almost completely knocked off the edges of the ventilation slots 20 and expelled, thereby preventing it from passing inwards into the housing 12.

When the pushbutton 27 is released, the sliding frame 26 automatically shifts to the right into its neutral position, in which the knock-out wedges 30 clear the full cross section of the air inlet slots 20.

The housing 12 according to Figure 3 differs from that according to Figures 1 and 2 in that it comprises two housing half-shells 11,13, which in a latch-over joint 15 are pressed together so as to be flush and latch over one another.

Given such a housing configuration, assembly of the sliding frame 26 is particularly simple. Given the construction according to Figures 1 and 2, the sliding frame has to be fitted as a quasi-elastic/flexible part into the cylindrical part of the housing 12.

According to Figures 2 and 3 the knock-out wedges 30 are provided with flow radii, which in the neutral position according to Figure 2 reduce the flow resistance when intake cooling air flows against them and hence improve the cooling efficiency.

The invention is advantageous also for hand tool machines with a compressed-air or i. e. engine drive as it improves and/or safeguards cooling of their motor and/or gear unit.

Claims

Claims 1. Hand tool machine (10), in particular with an electric drive, shaving a housing (12), which contains a drive motor for driving an, in particular chip-forming, tool and which has air inlet slots (20) for the intake of cooling air, characterized in that in the interior of the housing (12) a cleaning apparatus (25) is integrated, which is manually actuable from the outside and by means of which the air inlet slots (20) are to be cleaned.
2. Electric hand tool machine according to claim 1, characterized in that the cleaning apparatus chas knock-out wedges (30), which are movable to and fro between a neutral and an operating position.
3. Electric hand tool machine according to claim 1 or 2, characterized in that the cleaning apparatus (25) in its neutral position clears the cross section of the air inlet slots and in the operating position acts upon their edges.
4. Electric hand tool machine according to one of the preceding claims, characterized in that the knock-out wedges (30) of the cleaning apparatus (25) are

<Desc/Clms Page number 8>

designed as an air baffle with flow radii (31) and reduce the flow resistance of the cooling air.
5. Electric hand tool machine according to one of the preceding claims, characterized in that the cleaning apparatus is a carrier part in the form of a sliding frame (26), which carries the knock-out wedges (30) on the one side and an operating pushbutton on the opposite side.
6. Electric hand tool machine according to one of the preceding claims, characterized in that the sliding frame (26) is movable-in a direction perpendicular to the air inlet slots (20)-at opposite sides in longitudinal guides.
7. Electric hand tool machine according to one of the preceding claims, characterized in that the sliding frame (26) is holdable spring-loaded in neutral position by spring-elastic means.
8. An electric hand tool machine substantially as herein described with reference to the accompanying drawings.