# Patent

## Title
Handheld power tool, in particular handheld power saw

## Abstract

The invention relates to a handheld tool, in particular a handheld saw, with an electric drive motor (12), a serially switched gearbox (13), and a movement converter (14) that converts the driven movement of the gearbox (13) into an axial to-and-fro movement of a lifting element (15) for driving a tool (16), in particular a saw blade, inside a housing (11). The gearbox (13) and the movement converter (14) are combined into a gear unit (17). The gear unit (17) is within a robust, bending- and deformation-resistant gear housing (40), which is in turn inside the housing (11). The housing (11) is made of flexible plastic.

## Background
PRIOR ART
The invention is based on a handheld power tool, in particular a handheld power saw, as generically defined by the preamble to claim 1.
A handheld power tool that can be bent longitudinally is known that has an angular gear and a motion converter that converts the power takeoff rotary motion of the drive motor into an axially reciprocating working motion of the saw blade, and these parts are combined into a gear unit, forming a compact device. This handheld power tool can be supplied with power via cords, from the utility grid. It is still quite bulky, however.
DISCLOSURE OF THE INVENTION
The handheld power tool of the invention, in particular the handheld power saw, having the characteristics of claim 1 has the advantage that it is designed to be small, handy, and above all both robust and lightweight. The flexible plastic housing is capable of absorbing forces if the handheld power tool hits something or falls, without the risk of damage or destruction.
By the provisions in the other claims, advantageous refinements of and improvements to the handheld power tool recited in claim 1 are possible.



BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described in further detail in the ensuing description in terms of exemplary embodiments shown in the drawings. Shown are:
FIG. 1, a schematic perspective view of a handheld power tool, embodied as a handheld power saw, with a housing shell removed;
FIG. 2, a schematic side view of individual elements of the handheld power tool, together with a portion of its gearbox;
FIG. 3, a schematic perspective exploded view of the elements shown in FIG. 2 of the handheld power tool;
FIG. 4, a schematic section through the handheld power tool in the direction of the arrows IV-IV in FIG. 1, on a larger scale.



EMBODIMENTS OF THE INVENTION
In FIG. 1, an electric handheld power tool 10 is shown, which is designed as a small, handy, robust handheld power saw designed approximately like a straight-back hand saw with an open handle. This handheld power tool 10, inside a housing 11, has an electric drive motor 12, a gear 13 downstream of the drive motor 12, and a motion converter 14. By means of the motion converter 14, the power takeoff rotary motion of the gear 13 is converted into an axially reciprocating working motion of a reciprocating element 15 for driving a tool 16, especially a saw blade. The gear 13 and the motion converter 14 form a drive train and are combined into a gear unit 17.
The gear 13 is embodied as an angular gear. It has a power takeoff pinion 18, which is press-fitted onto the motor shaft 19, and a crown gear wheel 20, with which the power takeoff pinion 18 is operationally in engagement. By means of this gear 13, the power takeoff rpm of the drive motor 12 is stepped down to a lesser rpm of the crown gear wheel 20. The crown gear wheel 20 has a press-fitted-in bearing bolt 21, which protrudes to one side of the crown gear wheel 20 and is supported by means of at least one deep-groove bearing, and preferably by means of two axially adjacent deep-groove bearings 22, 23. In this way, the crown gear wheel 20 is floatingly supported. On the side diametrically opposite the deep-groove bearings 22, 23, the crown gear wheel 20 has an eccentrically located, press-fitted-in bolt 24, which engages a sleeve 25 on an end toward it of a connecting rod 26 of the motion converter 14. Via the bolt 24, the power takeoff rotary motion of the crown gear wheel 20 is converted, by means of the connecting rod 26, into a linear, reciprocating motion with a suitable stroke length. The connecting rod 26 is formed of two longitudinal struts 27, 28, parallel to one another and extending at a spacing from one another, which are connected in one piece to one another on both ends via eyelets 29, 30 located there. The sleeve 25 is received in the eyelet 29. In the region near the crown gear wheel 20, the connecting rod 26 is overlapped on both sides by pins 31, 32 oriented transversely, and in particular approximately perpendicularly, to it, which serve to guide the connecting rod 26 on both sides in the transverse direction.
The gear unit 17 formed of the above-described gear 13 and motion converter 14 by combining them is located inside a robust gearbox 40 that is resistant to bending and torsion. This gearbox 40 is in turn received in the housing 11. The gearbox 40 is formed in particular of metal, such as aluminum, and is in two parts. It comprises one molded body in the form of a housing shell 41 and a housing cap 42 that covers the housing shell 41 and that is detachably connected to the housing shell 41 via fastening means 43, such as screws. The housing 11 is formed of two housing shells 33, 34, which are detachably connected to one another inside a mold parting plane 35 that is symmetrical to the housing 11. This housing 11 advantageously comprises a flexible material. This design with regard to material is possible because of the compact structure and because of the fact that the gear unit 17 is received in the robust gearbox 40 that is resistant to bending and torsion. The thus-designed flexible plastic housing 11 is capable of absorbing forces, for instance if the handheld power tool 10 falls. The handheld power tool 10 is in this way protected to a high degree against damage on falling, even if it falls from a great height.
A ribbed body 44, which is embodied as a heat sink and as a bending- and torsion-resistant mount that is for an end plate 45 and which is in one piece with the gearbox 40, is located on the gearbox 40, in particular on the housing shell 41, in the region below the motion converter 14. The end plate 45 is seated on a holder 46, which is secured to the ribbed body 44. An electric switch 47, indicated only schematically, is located laterally beside and approximately parallel to the gear unit 17, and its actuation member 48 is coupled to an actuator 49, such as a toggle, via a lever 50. An electronic monitoring device 51, also indicated only schematically, is likewise located laterally beside the gear unit 17, for instance approximately parallel to it, and is intended to monitor the current consumption. Both the electric switch 47 and the electronic monitoring device 51 are seated on the outside of the housing cap 42 that faces away from the housing shell 41. This arrangement again makes a small, compact structure of the handheld power tool 10 possible. The location of the switch 47 and monitoring device 51 offset transversely with respect to the approximately symmetrically extending mold parting plane 35 means that the actuator 49, such as a toggle, is transversely offset relative to this mold parting plane 35 of both housing shells 33, 34, as can also be seen from the position of the through opening 52, indicated in FIG. 4, for the actuator 49. Particularly from FIG. 4, the floating support of the crown gear wheel 20 by means of the two deep-groove bearings 22, 23 that are received in the housing shell 41 also becomes clear. The gear 13 has a fan wheel 36, driven by it, which is located on the bearing bolt 21 of the crown gear wheel 20. By means of the fan wheel 36, which is provided on the drive motor 12 in addition to the motor fan, heat dissipation from the gear 13 and cooling, for instance of the electronic monitoring device 51, are possible in a simple way. For removing heated air, conduits provided in the usual way in the housing 11 and openings provided on the side of the housing toward the end plate 45 are used, by way of which the waste air is carried away; the waste air simultaneously serves as blowing air for removing particles, such as sawdust or chips, at the place being machined by the handheld power tool 10.
On the end facing away from the gearbox 40, the reciprocating element 15 has a clamping system 53, shown only schematically, for interchangeably mounting a tool 16, such as a saw blade. The clamping system 53 is designed in the usual way and makes it possible to fasten a tool 16 both in one position and in another position rotated 180° relative to it. This increases the accessibility to places that are hard to reach in working with the handheld power tool 10, and thus the handheld power tool can be used even at poorly accessible places.
The reciprocating element 15 that can be driven to reciprocate by the motion converter 14 is embodied as a rod 55 that protrudes out of the gearbox 40. A slide bearing 56 is located in the gearbox 40, and in this slide bearing the reciprocating element 15, in particular in the form of the rod 55, is supported and guided displaceably back and forth. The slide bearing 56 is received nonrotatably between the housing shell 41 and the housing cap 42 and is penetrated by the end toward it of the reciprocating element 15, in particular the rod 55. The location is moreover selected such that guide means for guiding the reciprocating element 15 are provided that are operative between the slide bearing 56 and the reciprocating element 15, in particular the rod 55. These guide means may be formed of a nonround and/or angular cross-sectional shape of the reciprocating element 15 and of the bore, penetrated by it, of the slide bearing 56. In this way, torques introduced into the reciprocating element 15 as well are absorbed by the slide bearing 56. In the exemplary embodiment shown, the guide means between the slide bearing 56 and the reciprocating element 15 are formed of longitudinal guides 57, located on the slide bearing 56, which protrude from the slide bearing 56, and at least one connecting element 58, engaging the reciprocating element 15 in the region of the eyelet 30, by means of which connecting element the motion converter 14 is connected on the power takeoff side to the reciprocating element 15; by means of the longitudinal guides 57, this connecting element 58 is supported and guided in the longitudinal and/or transverse direction. The at least one connecting element 58 for instance simply comprises a cross pin 59, which engages both the end of the connecting rod 26 remote from the gear 13 and the end of the reciprocating element 15 toward the connecting rod 26, and for instance transversely penetrates bores 60 provided in a fork, located on the end of the reciprocating element 15, that receives the eyelet 30. The longitudinal guides 57 protrude from the slide bearing 56 in the direction toward the connecting rod 26 that extends between them. The longitudinal guides 57 of the slide bearing 56 have guide pins 61 on one side and 62 on the other side of the connecting rod 26, which are approximately parallel to one another, and of which, three guide pins may for instance be provided on each side. The connecting element 58, in particular the cross pin 59, with respective end portions, protrudes on both sides out of the bores 60 of the reciprocating element 15 and is received with these two end portions on both sides between two guide pins 61 on one side and 62 on the other; these two guide pins 61 and 62 extend in planes, approximately parallel to one another, that extend approximately parallel to the plane that contains the connecting rod 26. These two guide pins 61 and 62 on both sides act similarly to respective longitudinal guide grooves for the respective end portion, located between them, of the connecting element 58. The third guide pin 61 and 62 provided for each side, respectively, extends farther outward spaced apart from the respective aforementioned plane within which the respective pairs 61 and 62 of guide pins extend. This transverse spacing is approximately equivalent to the length of the connecting element 58. It is thus attained that the connecting element 58 rests, with the respective approximately frontal end on the respective guide pin 61 and 62 and is supported and guided not only in the longitudinal direction but also in particular in the transverse direction as well. This design of the guide means is especially simple and economical. As can be seen from FIG. 2, on the side of the slide bearing 56 that faces toward the clamping system 53, pins 63 analogous to the pins 31, 32 may be provided, between which the reciprocating rod 55 is additionally guided. The support as described for the reciprocating element 15 including its guidance is simple and economical and makes fast, easy assembly possible.
The handheld power tool 10 is supplied with power by at least one battery, preferably at least one rechargeable battery, which is shown only schematically and identified by reference numeral 64. This at least one rechargeable battery 64 is a lithium-ion (Li-ion) cell for supplying the drive motor 12.
The housing 11 has a first portion 65, acting as a handle part, and a second portion 66, adjoining the first portion 65 in one piece and inclined at an obtuse angle to it. The at least one rechargeable battery 64 and the electric drive motor 12 are both received in the first portion 65, while the gearbox 40 with the gear unit 17 it contains are contained in the second portion 66.
The handheld power tool 10 is small, lightweight, handy, and robust, and because of the power supply by means of at least one battery, in particular a rechargeable battery 64, it is especially simple and easy to manipulate. Moreover, the handheld power tool 10 is highly safe in operation and is also secure against damage from any impacts or from falling.

## Claims

1. A handheld power tool comprising:
(a) a plastic housing having a handle part and another portion adjoining the handle part;
(b) a linearly reciprocating tool;
(c) an electric drive motor positioned in the housing and having a rotatable motor shaft that rotates around an axis that extends non-parallel, non-colinear and non-perpendicular to a direction of linear reciprocation of the tool;
(d) a rotating gear positioned on the motor shaft;
(e) a motion converter configured to convert rotary motion of the gear to axially linearly reciprocating motion of the tool; and
(f) a metal gear box secured to, and positioned within, the housing;
(i) the motion converter being positioned in the gear box;
(ii) the gear box including a gear wheel therein having an eccentrically located projection which engages the motion converter;
(iii) the motor shaft projecting into the gear box from the motor;
(iv) a reciprocating rod projecting outwardly from the gear box at an obtuse angle to the motor shaft;
(v) a slide bearing:
(A) surrounding the reciprocating rod;
(B) positioned in the gear box; and
(C) inhibited from rotational motion in the gear box; and

(vi) at least one pin positioned in the gear box, the at least one pin comprising:
(A) a pin in the gear box engaging the slide bearing; and
(B) a pin in the gear box limiting relative rotational motion between the slide bearing and the rod.

2. The handheld power tool as defined by claim 1, characterized in that the gearbox (40) is formed of aluminum.

3. The handheld power tool as defined by claim 1, characterized in that the gearbox (40) is in two parts and comprises a housing shell (41) and a housing cap (42) that covers the housing shell (41) and that is detachably connected to the housing shell (41).

4. The handheld power tool as defined by claim 1, characterized in that a ribbed body (44), which is embodied as a heat sink and as a mount that is resistant to bending and torsion for a an end plate (45) and is in one piece with the gearbox (40), is located on the gearbox (40) in a region below the motion converter (14).

5. The handheld power tool as defined by claim 1, characterized in that an electric switch (47) having an actuation member (48) coupled with an actuator (49) that protrudes from the housing (11), is located laterally beside the gear unit (17).

6. The handheld power tool as defined by claim 5, characterized in that the actuator (49) is located transversely offset with respect to a symmetrical mold parting plane (35) of two housing shells (33, 34) that together form the housing (11).

7. The handheld power tool as defined by claim 1, characterized in that the gear (13) has a crown gear wheel (20), meshing with a power takeoff pinion (18) of the drive motor (12), with a bearing bolt (21) which protrudes to one side and which by means of at least one deep-groove bearing (22, 23) is supported in the gearbox (40).

8. The handheld power tool as defined by claim 1, characterized in that the gear (13) has a fan wheel (36) driven by the motor (12) via the gear (13).

9. The handheld power tool as defined by claim 8, characterized in that the fan wheel (36) is located on the bearing bolt (21) of the crown gear wheel (20).

10. The handheld power tool as defined by claim 1, characterized in that the reciprocating rod (55) is connected to a clamping system (53) located on one end of the reciprocating rod (55) for interchangeably mounting the tool (16).

11. The handheld power tool as defined by claim 1, characterized in that at least one rechargeable battery (64), for supplying the drive motor (12) is received in the housing (11).

12. The handheld power tool as defined by claim 11, characterized in that the drive motor (12) and the at least one rechargeable battery (64) are received inside the first portion (65) of the housing (11), the portion acting as the handle part.

13. A handheld power tool according to claim 1 wherein:
(a) the at least one pin includes a transverse pin.

14. A handheld power tool according to claim 13 wherein:
(a) the transverse pin projects through a rod that engages the projection on the gear wheel.

15. A handheld power tool according to claim 1 wherein:
(a) the tool is a saw blade.

16. A handheld power tool according to claim 1 including:
(a) an end plate; and
(b) a clamping system releaseably fastening the tool; the clamping system being positioned between the end plate and the gear box.

17. A handheld power tool according to claim 1 including:
(a) an electric switch and electric monitoring device.

18. A handheld power tool comprising:
(a) a housing (11) within which an electric drive motor (12), a gear (13) connected downstream of the drive motor, and a motion converter (14) that converts the power takeoff rotary motion of the gear (13) into an axially reciprocating working motion of a reciprocating element (15) for driving a tool (16) are located, the gear (13) and the motion converter (14) being combined into a gear unit (17), characterized in that the gear unit (17) comprising the gear (13) and motion converter (14) is located inside a gearbox (40) that is resistant to bending and torsion and that in turn is received in the housing (11); and that the housing (11) is formed of flexible plastic;
(b) wherein the gear (13) has a fan wheel (36) driven by the motor (12) via the gear (13); and
(c) wherein the fan wheel (36) is located on the bearing bolt (21) of the crown gear wheel (20).

19. A handheld power tool comprising:
(a) a housing (11) within which an electric drive motor (12), a gear (13) connected downstream of the drive motor, and a motion converter (14) that converts the power takeoff rotary motion of the gear (13) into an axially reciprocating working motion of a reciprocating element (15) for driving a tool (16) are located, the gear (13) and the motion converter (14) being combined into a gear unit (17), characterized in that the gear unit (17) comprising the gear (13) and motion converter (14) is located inside a gearbox (40) that is resistant to bending and torsion and that in turn is received in the housing (11); and that the housing (11) is formed of flexible plastic;
(b) a slide bearing (56), in which the reciprocating element (15) is supported and guided displaceably back and forth, located in the gearbox (40); and
(c) a guide means (57, 58, 59) for guiding the reciprocating element (15), the guide means (57, 58, 59) being operative between the slide bearing (56) and the reciprocating element (15); and
(d) wherein the guide means are formed of a nonround and/or angular cross-sectional shape of the reciprocating element (15) and a bore, penetrated by the reciprocating element, of the slide bearing (56).

20. The handheld power tool as defined by claim 19, characterized in that the connecting element (58) is formed of a cross pin (59), which engages the end, remote from the gear (13), of a connecting rod (26) of the motion converter (14) as well as the end of the reciprocating element (15) toward the motion converter (14).

21. The handheld power tool as defined by claim 19, characterized in that the longitudinal guides (57) of the slide bearing (56) have guide pins (61, 62) that are approximately parallel to one another, wherein the connecting element (58) is supported and guided between the guide pins (61, 62).

22. A handheld power tool comprising:
(a) a housing (11) within which an electric drive motor (12), a gear (13) connected downstream of the drive motor, and a motion converter (14) that converts the power takeoff rotary motion of the gear (13) into an axially reciprocating working motion of a reciprocating element (15) for driving a tool (16) are located, the gear (13) and the motion converter (14) being combined into a gear unit (17), characterized in that the gear unit (17) comprising the gear (13) and motion converter (14) is located inside a gearbox (40) that is resistant to bending and torsion and that in turn is received in the housing (11); and that the housing (11) is formed of flexible plastic;
(b) a slide bearing (56), in which the reciprocating element (15) is supported and guided displaceably back and forth, located in the gearbox (40); and
(c) a guide means (57, 58, 59) for guiding the reciprocating element (15), the guide means (57, 58, 59) being operative between the slide bearing (56) and the reciprocating element (15); and
(d) wherein the guide means are formed of longitudinal guides (57) on the slide bearing (56), which protrude from the slide bearing, and at least one connecting element (58), which engages the reciprocating element (15) and by means of which the motion converter (14) is connected on the power takeoff side to the reciprocating element (15) and which is supported and guided in the longitudinal and/or tranverse direction by means of the longitudinal guides (57).