EP4622774A1

EP4622774A1 - Handheld electric tool

Info

Publication number: EP4622774A1
Application number: EP23806229.3A
Authority: EP
Inventors: Heng Shen; Desheng CAI; Sheikh SIKANDER; Henrik Walter
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 2022-11-24
Filing date: 2023-11-14
Publication date: 2025-10-01
Also published as: CN118061137A; WO2024110247A1

Abstract

A handheld electric tool, comprising a main housing in which a drive motor is installed, with a substantially D-shaped handle extending from a lower part or rear part of the main housing, the D-shaped handle comprising a gripping part for a user to hold in the hand and an auxiliary support part which is located at a front side of the gripping part and extends substantially along a handle axis (A), the bottom of the D-shaped handle having a base for installing a battery pack; the auxiliary support part is provided with a fall cushioning structure, and the auxiliary support part is able to experience compressive deformation along the handle axis (A). Thus, when the handheld electric tool falls or suffers an accidental impact, the impact force sustained by the electric tool can be cushioned, to avoid the risk of local damage, or circuit board damage due to deformation of the handle gripping part.

Description

DESCRIPTION

Handheld electric tool

TECHNICAL FIELD

The present invention relates to an electric tool, in particular to a rechargeable handheld electric tool.

BACKGROUND ART

Handheld electric tools are the most commonly used type of electric tool. A typical structure of a handheld electric tool comprises a main body housing in which a drive motor and a transmission mechanism are installed; a handle formed of joinable halfhandle shells extends from the bottom of the main body housing, with a battery pack plug-in structure at the bottom of the handle. In the case of certain high-power heavy- duty electric tools, the handle may be formed in a D shape, in order to support the main body housing more firmly while ensuring balance with respect to gravity. The D-shaped handle generally comprises a gripping part for a user to hold in the hand, and an auxiliary support part located at a front side of the gripping part. The auxiliary support part has one end connected to a front end of the main body housing and another end connected to a battery pack mounting part; thus, the electric tool has good manipulability, and the auxiliary support part provides the main body housing with ample strength.

Structural stability is an important feature of electric tools. In the case of a handheld electric tool, an operator might inadvertently drop the electric tool onto the ground or a similar place. To test the strength of electric tools, manufacturers often subject the tools to “fall tests”. In such a fall test, the electric tool falls from a specific height, then a check is carried out to ascertain whether the tool has split open or lost efficacy in some other way. The results of these fall tests are then used to quantify the structural stability of the electric tool. In many electric tools, the handle of the tool is a point of failure. This is because the diameter of the handle is generally small to better suit the ergonomics of the user’s hand, but the battery pack with its large volume and heavy weight is generally fitted to the bottom of the handle. Thus, such an ergonomically beneficial handle often sacrifices structural stability at the bottom of the electric tool handle.

Especially in the case of electric tools with D-shaped handles, the auxiliary support part of the D-shaped handle increases the strength of the main body housing, but the gripping part and in particular a base part of the gripping part that is used for connection to the battery pack becomes a weak point in fall tests, and consequently deforms or splits open. Furthermore, because the battery pack is connected to the bottom of the handle, electronic connections are generally contained inside the gripping part, e.g. from the battery to a circuit board of a trigger and the motor, so there is even a risk of damage to electronic connectors.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a handheld electric tool, such that when the electric tool falls on the ground or suffers an accidental impact, the impact force sustained by the electric tool can be cushioned, to avoid the risk of local damage, or damage to electronic connectors due to deformation of the housing or handle.

To solve the above technical problem, the technical solution of the present invention is as follows:

A handheld electric tool, comprising a main housing in which a drive motor is installed, with a substantially D-shaped handle extending from a lower part of the main housing, the D-shaped handle comprising a gripping part for a user to hold in the hand and an auxiliary support part which is located at a front side of the gripping part and extends substantially along a handle axis (A), the bottom of the D-shaped handle having a base for installing a battery pack; the auxiliary support part is provided with a fall cushioning structure, such that the auxiliary support part is able to experience compressive deformation along the handle axis (A). Thus, when the electric tool falls, the auxiliary support part experiences compressive deformation, absorbing the energy of impact, and thereby lessening the impact force sustained by the base part of the D-shaped handle, thus reducing the risk of the electric tool being damaged.

The auxiliary support part comprises a first part adjoining the main housing and a second part adjoining the base, the fall cushioning mechanism being fitted between the first part and the second part. The auxiliary support part is divided by the fall cushioning mechanism into an upper part and a lower part in the direction of the handle axis (A). It is often the main housing or battery pack that suffers an impact when the electric tool falls; the fall cushioning mechanism of the present invention can deform when acted on by a force, such that the first part and second part of the auxiliary support part move towards each other, thereby cushioning the impact force sustained by the electric tool.

According to an embodiment of the present invention, the fall cushioning mechanism comprises an elastic body formed of a material having rubber elasticity. For example, an elastic body formed of rubber material is a low-cost, structurally simple fall cushioning mechanism that is convenient to fit.

The elastic body comprises a main body extending along the handle axis (A), and a first engagement part and a second engagement part which respectively extend outwards along the handle axis (A) from the main body, the first engagement part being engaged with the first part, and the second engagement part being engaged with the second part. The elastic body is fixed relative to the auxiliary support part through the engagement of the first engagement part and second engagement part with the first part and second part respectively, ensuring that the auxiliary supporting action of the auxiliary support part is not affected when the electric tool does not suffer an impact.

The cross section of the main body of the elastic body in a direction perpendicular to the handle axis (A) is continuous, and the profile thereof has substantially the same shape as the auxiliary support part in the direction perpendicular to the handle axis (A). The main body of the elastic body clamped between the first part and second part has the same shape as the cross sections of the first part and second part, such that the auxiliary support part still has the appearance of being whole when viewed from the outside, and the solid elastic body can provide support strength similar to that of the auxiliary support part formed of another material such as plastic.

The length of the main body of the elastic body in the direction of the handle axis (A) is 3% - 25% of the length of the auxiliary support part. If the length of the elastic body is too large, the strength of the auxiliary support part will be affected; if it is too small, a good cushioning effect will be unachievable.

According to another embodiment of the present invention, the fall cushioning mechanism comprises an elastic body formed of a material having rubber elasticity, and a core shaft formed of a rigid material, the elastic body surrounding the core shaft and being movable along the core shaft. The core shaft formed of a rigid material is used to connect the elastic body to the auxiliary support part, ensuring that the function of the auxiliary support part will not be weakened due to the presence of the cushioning structure.

Two ends of the core shaft are respectively engaged inside the first part and the second part, and the elastic body is clamped between the first part and second part. Thus, the fall cushioning structure is installed on the auxiliary support part in a simple and reliable way.

The fall cushioning mechanism is arranged at a side of the auxiliary support part that is close to the base. In a fall test, the point where breakage is most likely to occur is at the base of the gripping part, so if the fall cushioning mechanism is arranged close to the base, it will produce a better result in terms of cushioning the impact force.

The handheld electric tool is an impact wrench or an impact drill. D-shaped handles are often used on high-power heavy-duty impact wrenches and impact drills. A main body part of such impact wrenches or impact drills is often heavy, and an auxiliary support part is needed to provide additional support for a main housing. Moreover, because the tool is heavy, it sustains a greater impact force when it falls. Thus, the fall cushioning mechanism of the present invention can effectively prevent damage to the electric tool when it falls.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the embodiments mentioned can be gained from the following detailed description with reference to the drawings. It is emphasized that the various components are not necessarily drawn to scale. In fact, dimensions may be increased or decreased at will for the purpose of clear description. In the drawings, the same reference numerals refer to the same elements.

Fig. 1 shows a schematic overall view of a handheld electric tool according to an embodiment of the present invention.

Fig. 2 is a schematic sectional view of the handheld electric tool shown in Fig. 1.

Fig. 3 is a partial schematic view of the auxiliary support part of the handheld electric tool shown in Fig. 1.

Fig. 4 is a partial schematic view of the auxiliary support part of the handheld electric tool according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A handheld electric tool according to embodiments of the present invention is described below with reference to Figs. 1 - 4. The terms “front”, “rear”, “above...”, “below...”, “left” and “right” in the present invention are used throughout this specification to define various components of the electric tool when arranged in an orientation in which it is to be used.

Fig. 1 shows a schematic drawing of a handheld electric tool according to the present invention, more specifically, a rechargeable impact drill 1 as an example of an impact tool. Here, the impact drill 1 merely serves as one of the embodiments of the handheld electric tool. D-shaped handles are often used on high-power heavy-duty impact wrenches and impact drills. A main body part of such impact wrenches or impact drills is often heavy, and an auxiliary support part is needed to provide additional support for a main housing. Moreover, because the tool is heavy, it sustains a greater impact force when it falls. Thus, the fall cushioning mechanism of the present invention can effectively prevent damage to the tool when it falls. Handheld electric tools according to the present invention include but are not limited to the impact drill described in this embodiment; other handheld electric tools with D-shaped handles are also included in the scope of the present invention. The electric tool 1 has a main housing 2, and a substantially D-shaped handle 3 extending from the bottom of the main housing 2. The main housing 2 is formed with a central axis D in a front-rear direction. A motor 4, a transmission mechanism 5 and a work unit 6 are provided inside the main housing 2. The main housing 2 and the D- shaped handle 3 are made of plastic or resin. Preferably, the main housing 2 and the D- shaped handle 3 are split into left and right joinable half-shells, which are then fitted together.

The D-shaped handle 3 comprises a gripping part 7 for a user to hold in the hand, and an auxiliary support part 8 located at a front side of the gripping part. For example, the gripping part 7 is formed in a downward direction from a rear end of the main housing, thereby forming a rear side of the D-shaped handle 3. A forward-protruding trigger 9 is provided at an upper end of the gripping part 7. Preferably, the gripping part 7 is located in a position slightly to the rear of the middle of the main housing 2. More preferably, an axis B running through the gripping part passes through the centre of gravity of the electric tool. Thus, the electric impact tool of the present invention has good manipulability while achieving overall balance with respect to gravity.

An upper end of the auxiliary support part 8 is formed in such a way as to extend to the main housing 2 in a bent form in front of the main housing 2 (e.g. a gearbox housing of the impact drill in this embodiment). The auxiliary support part 8 is formed in such a way as to extend downwards from the bent upper end, thereby forming a front side of the D- shaped handle 3. A main body part of the auxiliary support part 8 defines a handle axis A running through the auxiliary support part. The handle axis A is substantially parallel to the axis B running through the gripping part, or forms a certain angle with the axis B running through the gripping part, e.g. not more than 30 degrees. The auxiliary support part 8 forms a left-right width less than that of the gripping part 7.

A lower end of the gripping part 7 and a lower end of the auxiliary support part 8 are joined to form a base 11 , and the handle 3 is thereby formed as a substantially D-shaped ring. A battery pack mounting part 12 is fixedly connected to the base 11 , a battery pack (not shown) as a power source is removably fitted to the battery pack mounting part 12, and a circuit board is mounted inside the base 11 . The auxiliary support part 8 extends between a front-end bottom face of the main housing 2 and the base 11 of the D-shaped handle. Preferably, a receiving space or engagement structure is formed inside the auxiliary support part, for the purpose of installing the fall cushioning mechanism of the present invention; this is described in further detail below.

In the electric tool of the present invention, the auxiliary support part 8 of the D-shaped handle 3 thereof provides additional support for the main housing 2, increasing the strength of the main housing; therefore, during a fall test, or when a fall or accidental impact occurs during use, the weakest part of the electric tool 1 or the part of the electric tool that is most likely to suffer damage is the part of the gripping part 2 that adjoins the base 11. The reason for this is that, due to considerations of convenience of operation and ergonomics, the gripping part 2 cannot be too thick, and as the power requirements of the electric tool increase, the weights of the tool body and the battery pack also increase correspondingly. Thus, during a fall, regardless of whether the tool body or the battery pack contacts the ground first, the impact energy which it receives is concentrated at the part of the gripping part 7 and/or the auxiliary support part 8 that adjoins the base 11 . Moreover, the axis of the gripping part runs through the centre of gravity of the electric tool, so the gripping part will obviously sustain a greater impact force when a fall occurs. In the prior art, there are already many technical solutions in which a cushioning or shock absorbing structure is added to the gripping part. However, electric wires connecting the circuit board, the motor and a switch need to be arranged inside the gripping part, and a ventilating structure is also needed to prevent overheating of electronic components, so the space and structure available for installing a fall cushioning or shock absorbing structure are very limited.

The fall cushioning structure of the present invention is mounted on the auxiliary support part 8. Thus, when the electric tool falls, the auxiliary support part 8 can experience compressive deformation along the handle axis (A), thereby lessening the impact force sustained by the base 11 of the D-shaped handle and/or the battery pack mounting part 12, and reducing the risk of the electric tool being damaged.

Referring to Figs. 1 and 2, the auxiliary support part 8 comprises a first part 13 adjoining the main housing 2, and a second part 14 adjoining the base 11. The fall cushioning mechanism 10 is fitted between the first part 13 and the second part 14. That is to say, the auxiliary support part 8 is discontinuous in the direction of the handle axis A; the first part 13 and second part 14 are separate and connected by means of the fall cushioning mechanism 10. The auxiliary support part 8 is divided by the fall cushioning mechanism 10 into an upper part and a lower part in the direction of the handle axis (A). It is often the main body housing or the battery pack that suffers an impact when the electric tool falls; the fall cushioning mechanism of the present invention can deform when acted on by a force, such that the first part and second part of the auxiliary support part move towards each other, thereby cushioning the impact force sustained by the electric tool.

Preferably, the fall cushioning mechanism 10 is arranged at the side of the auxiliary support part 8 that is closer to the base 11 . That is to say, the first part 13 is longer than the second part 14. In a fall test, the point where breakage is most likely to occur is at the base of the gripping part, so if the fall cushioning mechanism is arranged at the side close to the base 11 , it will produce a better result in terms of cushioning the impact force.

According to an embodiment of the present invention, the fall cushioning mechanism 10 comprises an elastic body formed of a material having rubber elasticity. As stated above, fall cushioning or shock absorbing structures are already widely used in gripping parts or main handles, whereas the fall cushioning structure 10 installed on the auxiliary support part 8 in the present invention is expected to achieve cushioning of impacts in a structurally simple way with convenient installation. Thus, in the present invention, the fall cushioning structure 10 is an elastic body formed of rubber for example, and has the advantages of low cost, structural simplicity, and convenient fitting.

The elastic body comprises a main body 15 extending along the handle axis (A), and a first engagement part 16 and a second engagement part 17 which respectively extend outwards along the handle axis (A) from the main body; the first engagement part 16 is engaged in a receiving space or corresponding engagement structure formed inside the first part 13, and the second engagement part 17 is engaged in a receiving space or corresponding engagement structure of the second part. The elastic body is fixed relative to the auxiliary support part through the engagement of the first engagement part 16 and second engagement part 17 with the first part 13 and second part 14 respectively, ensuring that the auxiliary supporting action of the auxiliary support part is not affected when the electric tool does not suffer an impact. Referring to Figs. 2 and 3, the first engagement part 16 and second engagement part 17 may be ribs extending along the handle axis, the ribs being slightly smaller in cross section than the main body 15 of the elastic body, and a number of catches are formed inside the first part 13 and second part 14 respectively, the ribs being engaged in the catches such that the fall cushioning mechanism 10 is fixedly connected to the auxiliary support part 8. It will be understood that the first engagement part 16 and/or second engagement part 17 could also be other structures capable of fixedly connecting the elastic body to the first part 13 and/or second part 14. For example, the first engagement part 16 and/or second engagement part 17 may be a flange structure, with a recess for accommodating the flange being formed inside the first part 13; alternatively, the first engagement part 16 and/or second engagement part 17 is a number of protrusions formed on upper and lower end faces of the main body 15, with holes for accommodating the protrusions being respectively formed in the end face of the first part 13 and/or second part 14 that contacts the main body. In addition, the first engagement part 16 and second engagement part 17 may also be different engagement structures.

Preferably, the cross section of the main body 15 of the elastic body in a direction perpendicular to the handle axis (A) is continuous, and the profile thereof has substantially the same shape as the auxiliary support part in the direction perpendicular to the handle axis (A). Although the fall cushioning mechanism 10 of the present invention is already fixedly connected to the auxiliary support part 8 by means of the engagement structure described above, electric tools and especially impact tools will produce considerable vibration during use; the main body 15 of the elastic body that is continuous and solid can deform elastically to provide cushioning when the electric tool falls, and can also provide a certain degree of shock absorption when the electric tool is being used. The shaking produced by the electric tool during a job includes not only shaking in the direction of the handle axis A, but also shaking in a direction perpendicular to the handle axis A. The fact that the cross-sectional profile of the main body 15 of the elastic body in the direction perpendicular to the handle axis (A) has substantially the same shape as the auxiliary support part in the direction perpendicular to the handle axis (A), can also reduce shaking in the direction perpendicular to the handle axis (A).

More preferably, the length of the main body 15 of the elastic body in the direction of the handle axis (A) is 3% - 25% of the length of the auxiliary support part. If the length of the elastic body is too large, the strength of the auxiliary support part will be affected; if it is too small, a good cushioning effect will be unachievable. Of course, the ratio of the length of the main body of the elastic body to the length of the auxiliary support part depends on many factors, for example the thickness and material of the auxiliary support part, and the material of the elastic body, etc. In an embodiment in which the elastic body is formed of rubber, the length ratio should not be too large, otherwise the strength of the auxiliary support part will be affected.

According to another embodiment of the present invention, referring to Fig. 4, the fall cushioning mechanism 10 comprises an elastic body 18 formed of a material having rubber elasticity, and a core shaft 19 formed of a rigid material, the elastic body 18 surrounding the core shaft 19 and being movable along the core shaft 19. Unlike the previous embodiment, the fall cushioning mechanism 10 further comprises a rigid core shaft 19; the core shaft formed of a rigid material is used to connect the elastic body to the auxiliary support part, ensuring that the function of the auxiliary support part will not be weakened due to the presence of the cushioning structure, while the elastic body 15 continues to be used to deform when a fall occurs such that the auxiliary support part can experience compressive deformation along the handle axis (A), thereby cushioning the impact energy received in the fall.

Two ends of the core shaft 19 are respectively engaged inside the first part 13 and the second part 14, and the elastic body is clamped between the first part and second part. Thus, the fall cushioning structure is installed on the auxiliary support part in a simple and reliable way. The structure of engagement of the core shaft 19 with the first part 13 and the second part 14 may also be realized in various ways, such as a ring groove fit, etc. The shape of the core shaft 19 is also not limited to being cylindrical; a suitable shape may be chosen according to the structure of the auxiliary support part, as long as it is ensured that the core shaft 19 can be fixed relative to the auxiliary support part 9.

The elastic body 18 surrounds a peripheral face of the core shaft 19; at the same time, the elastic body 18 is movable relative to the core shaft 19. The elastic body 18 is clamped between the first part 13 and the second part 14, so when the electric tool falls, the first part 13 or second part 14 sustains a force, and the elastic body 18 is compressed, such that the first part 13 and second part 14 move towards each other, cushioning the energy which arises in the impact.

As described above, although exemplary embodiments of the present invention have been explained herein with reference to the drawings, the present invention is not limited to the specific embodiments described above, and may have many other embodiments. The scope of the present invention should be defined by the claims and their equivalents.

Claims

1. Handheld electric tool, comprising a main housing in which a drive motor is installed, with a substantially D-shaped handle extending from a lower part of the main housing, the D-shaped handle comprising a gripping part for a user to hold in the hand and an auxiliary support part which is located at a front side of the gripping part and extends substantially along a handle axis (A), the bottom of the D-shaped handle having a base for installing a battery pack, characterized in that the auxiliary support part is provided with a fall cushioning structure, and the auxiliary support part is able to experience compressive deformation along the handle axis (A).

2. Handheld electric tool according to Claim 1 , characterized in that the auxiliary support part comprises a first part adjoining the main housing and a second part adjoining the base, the fall cushioning mechanism being fitted between the first part and the second part.

3. Handheld electric tool according to Claim 2, characterized in that the fall cushioning mechanism comprises an elastic body formed of a material having rubber elasticity.

4. Handheld electric tool according to Claim 3, characterized in that the elastic body comprises a main body extending along the handle axis (A), and a first engagement part and a second engagement part which respectively extend outwards along the handle axis (A) from the main body, the first engagement part being engaged with the first part, and the second engagement part being engaged with the second part.

5. Handheld electric tool according to Claim 4, characterized in that the cross section of the main body of the elastic body in a direction perpendicular to the handle axis (A) is continuous, and the profile thereof has substantially the same shape as the auxiliary support part in the direction perpendicular to the handle axis (A).

6. Handheld electric tool according to Claim 5, characterized in that the length of the main body of the elastic body in the direction of the handle axis (A) does not exceed 3% - 25% of the length of the auxiliary support part.

7. Handheld electric tool according to Claim 2, characterized in that the fall cushioning mechanism comprises an elastic body formed of a material having rubber elasticity, and a limiting component formed of a rigid material, the elastic body surrounding the limiting component and being movable along the limiting component.

8. Handheld electric tool according to Claim 7, characterized in that two ends of the core shaft are respectively engaged inside the first part and the second part, and the elastic body is clamped between the first part and second part.

9. Handheld electric tool according to any one of Claims 2 - 7, characterized in that the fall cushioning mechanism is arranged at a side of the auxiliary support part that is close to the base.

10. Handheld electric tool according to any one of Claims 1- 9, characterized in that the electric tool is an impact wrench or an impact drill.