EP2750835B1 - Hand-held power tool - Google Patents

Description

State of the art

The invention relates to a handheld power tool.

With the coming into force of legal requirements that include limiting the vibration behavior of hand-held power tools, this topic is becoming increasingly important in the industry. Especially with heavy drill and demolition hammers, vibration is very pronounced due to the high individual impact force. The standard or law now stipulates how long the user may continue to work with the machine, depending on the vibration level. If the load from the vibration exceeds specified limit values, the permissible service life per day is reduced accordingly. As a result, product development is increasingly working on measures to reduce vibration. The primary goal is to further increase the ease of use and to maintain a practical level for the associated usage time per day. To reduce vibrations in hammers, part of the machine movement is usually decoupled directly for an operator via handles. The market uses fundamentally different concepts for the type of decoupling. In addition to a double-shell housing, the most common method is a handle with an elastic connection to the hammer to decouple the vibrations that occur from the operator via suspension and damping.

the US 5,697,456A discloses a handheld power tool according to the preamble of claim 1 with a handle,
which is connected at a first end via a joint to a housing of the hand-held power tool. A second end of the handle is connected to the housing via an isolator. For this purpose, the isolating device has a spring element, via which the second end of the handle is supported on the housing in a vibration-decoupled manner. For this purpose, the isolating device is arranged in a holder of the handle, which has a guide element. The spring element and a braking element are supported on the guide element.

the EP 1 674 210 A1 teaches a tool with a main handle, which is vibration-decoupled via a decoupling device connected to a drive arrangement of the tool. The decoupling device has two oscillating elements formed by leaf springs and a stop body.

Of the DE 100 36 078 A1 For example, a handheld power tool can be taken that has a handle that is connected at a first end via a joint to a housing of the handheld power tool. A second end of the handle is connected to the housing via an isolator. For this purpose, the isolating device has two helical compression springs, via which the second end of the handle is supported on the housing in a vibration-decoupled manner.

the EP 1 303 383 B1 shows an electric combination hammer with a bow-shaped handle that is vibration-decoupled connected to a housing of the electric combination hammer. A ratchet is arranged on the handle. The pawl can be set to two different switching modes using a rotary knob and a locking device. The latching device includes a pivoting lever, which is supported against a compression spring, and a latching clip.

the U.S. 3,297,514 discloses a drawstring having a first layer and a second layer. Between the first layer and the second layer there is also a network of interwoven threads arranged perpendicular to one another.

• Der Antivibrationshandgriff muss trotz seiner elastischen Anbindung zur Entkopplung weiterhin eine präzise Führung der Handwerkzeugmaschine ermöglichen.
• Anbindung und Führung des Antivibrationshandgriffs sollten den Hammer in seiner Größe/Länge ergonomisch nicht beeinflussen.
• Bei der Auslegung der im Antivibrationshandgriff innen liegenden Teile ist die zusätzliche Bewegung aus der Entkopplung von der Handwerkzeugmaschine zu berücksichtigen.
• Staubschutz muss sichergestellt werden.
• Die Umschaltung vom Hammerschalter in Abhängigkeit von einer Betriebsart des Hammers, insbesondere die Umschaltung der Schalterfunktion und die Arretierbarkeit des Hammerschalters, soll weiterhin erhalten bleiben.

Anti-vibration handles with an elastic connection to the hammer also cause relative movements between the hammer and the handle itself as a side effect due to the required rigidity. From this, new requirements for the interface between a hammer and an anti-vibration handle can be derived:

• Despite its elastic connection for decoupling, the anti-vibration handle must still enable precise guidance of the hand-held power tool.
• Connection and guidance of the anti-vibration handle should not affect the size/length of the hammer ergonomically.
• When designing the parts inside the anti-vibration handle, the additional movement resulting from the decoupling from the hand-held power tool must be taken into account.
• Dust protection must be ensured.
• The changeover from the hammer switch depending on an operating mode of the hammer, in particular the changeover of the switch function and the lockability of the hammer switch, should continue to be retained.

Starting from the state of the art, the task arises of achieving a design of a handle device for a hand-held power tool that is structurally simple and preferably easy to assemble.

Disclosure of Invention

The invention is based on a handheld power tool, in particular a rotary and/or chipping hammer, with a machine housing and with a handle device, the handheld power tool having an operating mode switchover device and a drive device for driving an insert tool in different operating modes. The handle device has at least one spring element and a handle unit which is attached to the machine housing so that it can move at least to a limited extent and which is at least partially vibration-decoupled from the machine housing via the at least one spring element, and at least one secondary spring element. To solve the defined task, an intermediate plate that accommodates the spring element on one side is proposed, which is provided in the machine housing and which serves as a receptacle for or as a stop for the at least one secondary spring element.

The hand tool according to the invention with the features of the main claim solves the task in a way that is easy to install and inexpensive. It fulfills all the requirements placed on it. As a result, in particular the spring element formed by the leaf spring can be advantageously supported in a spring action and the handle device can be used in particular in larger and more powerful hand-held power tools.

The measures listed in the dependent claims and in the following description of the exemplary embodiments result in advantageous developments and improvements of the features specified in the main claim.

It is also proposed that the secondary spring element is formed by an elastomer spring element. As a result, a simple and cost-effective design of the handle device can be achieved.

In addition, it is proposed that the secondary spring element is only acted upon after a certain compression travel. It is proposed that the spring stiffness of the spring element formed by the leaf spring is adjusted in such a way that with a compression travel of between 2 mm and 10 mm, preferably between 3 mm and 7 mm, particularly preferably between 4 mm and 5 mm, there are minimum operating pressure points for most of the important use cases can be achieved. From this pressure threshold, the secondary spring element begins to act. The more the volume of the elastomer spring element is deformed during deflection, the stiffer a characteristic curve of the secondary spring element becomes.

It is therefore further proposed that a volume compression of the elastomer spring element is designed in such a way that with an additional compression of 2 mm to 5 mm, in particular of 3 mm to 4 mm beyond a minimum operating pressure point, the elastomer spring element is compressed to 70% of its initial volume. With a further deflection of 1 mm up to 2 mm, almost the entire volume of the elastomer spring element is acted upon, so that the spring stiffness increases relatively quickly. This has the advantage that if the anti-vibration handle falls, a great deal of energy can be absorbed, so that the components that are impacted are less stressed.

Furthermore, it is proposed that the handle device of the hand-held power tool includes a switch actuator for starting up the drive device, with the switch actuator being able to be switched both monostable and bistable between two switching positions. In this context, “bi-stable” is to be understood in particular as meaning that the switch actuator has two stable switch positions into which the switch actuator can be switched. The switch actuator is preferably in the form of an on/off switch for the hand-held power tool. As a result, the handle device can be designed in a way that is easy to assemble and inexpensive.

In addition, it is proposed that the hand-held power tool has a control means via which the switch actuator interacts with the operating mode switching device in such a way that the switch actuator cannot be switched to bistable mode in certain operating modes. In this context, "monostable" is to be understood in particular as meaning that the switch actuator has only one stable switch position into which the switch actuator can be switched or into which the switch actuator preferably automatically falls back, while the switch actuator is in at least one other switch position of a Operator must be kept in particular. As a result, the handle device can be designed in a way that is easy to assemble and inexpensive.

It is also proposed that the control means be designed as a drawstring. The drawstring can preferably be made of a plastic or some other material that appears sensible to a person skilled in the art. The drawstring preferably has an at least substantially rectangular cross section with an at least essentially circular, in particular circular central fiber. It is also conceivable that the central fibres, at least essentially, have a quadrilateral or hexagonal cross-section or another cross-section that a person skilled in the art deems appropriate. The central fiber is preferably intended to serve at least partially as a filling channel, in particular in an injection molding process, and/or to form an advantageously narrow contact line with the leaf spring. As a result, an advantageously cost-effective configuration can be achieved.

In addition, it is proposed that the at least one spring element is formed by a leaf spring. In this way, in particular, a preferably cost-effective implementation and an advantageously simple assembly of the handle device can be achieved.

Further advantages result from the following description of the drawings. Several exemplary embodiments of the invention are shown in the drawing. The drawing, the description and the claims contain numerous features in combination.

Fig. 1a

eine Handwerkzeugmaschine mit einer Handgriffvorrichtung in einer schematischen Seitenansicht,

Fig. 1b

einen Ausschnitt der Handgriffvorrichtung in einer Schnittdarstellung,

Fig. 2

eine Baugruppe der Handgriffvorrichtung in einer perspektivischen Darstellung,

Fig. 3a

einen Ausschnitt der Handgriffvorrichtung in einer Schnittdarstellung,

Fig. 3b

die Baugruppe der Handgriffvorrichtung in einer Schnittdarstellung,

Fig. 4a

einen Ausschnitt der Handgriffvorrichtung in einer Schnittdarstellung,

Fig. 4b

einen alternativ ausgestalteten Ausschnitt der Handgriffvorrichtung in einer Schnittdarstellung,

Fig. 4c

einen Ausschnitt der Handgriffvorrichtung in einer Schnittdarstellung,

Fig. 5

einen Ausschnitt der Handgriffvorrichtung in einer Schnittdarstellung,

Fig. 6a

einen Teil der Baugruppe der Handgriffvorrichtung in einer perspektivischen Darstellung,

Fig. 6b

einen Teil der Baugruppe der Handgriffvorrichtung in einer Seitenansicht,

Fig. 6c

einen Teil der Baugruppe der Handgriffvorrichtung in einer Seitenansicht,

Fig. 7a

ein Steuermittel der Handgriffvorrichtung in einer schematischen Darstellung,

Fig. 7b

das Steuermittel der Handgriffvorrichtung in einer Schnittdarstellung,

Fig. 7c

das Steuermittel der Handgriffvorrichtung in einer Schnittdarstellung,

Fig. 8a

einen Ausschnitt der Handgriffvorrichtung in einer Schnittdarstellung,

Fig. 8b

einen Ausschnitt der Handgriffvorrichtung in einer Schnittdarstellung,

Fig. 8c

einen Ausschnitt der Handgriffvorrichtung während einer Montage in einer Schnittdarstellung,

Fig. 9

einen Ausschnitt der Handgriffvorrichtung in einer schematischen Darstellung,

Fig. 10

einen Ausschnitt der Handgriffvorrichtung in einer Schnittdarstellung,

Fig. 11

einen Ausschnitt der Handgriffvorrichtung in einer Schnittdarstellung entlang der Schnittlinie XI-XI,

Fig. 12a

einen Ausschnitt der Handgriffvorrichtung in einer Schnittdarstellung,

Fig. 12b

einen Ausschnitt der Handgriffvorrichtung in einer Schnittdarstellung,

Fig. 13

einen Ausschnitt der Handgriffvorrichtung in einer Explosionsdarstellung,

Fig. 14a

einen Ausschnitt der Handgriffvorrichtung in einer Schnittdarstellung,

Fig. 14b

einen Ausschnitt der Handgriffvorrichtung in einer Schnittdarstellung entlang der Schnittlinie XIVb-XIVb und

Fig. 15

einen Ausschnitt der Handgriffvorrichtung in einer Schnittdarstellung.

Show it:

Fig. 1a

a hand tool with a handle device in a schematic side view,

Fig. 1b

a detail of the handle device in a sectional view,

2

an assembly of the handle device in a perspective view,

Figure 3a

a detail of the handle device in a sectional view,

Figure 3b

the assembly of the handle device in a sectional view,

Figure 4a

a detail of the handle device in a sectional view,

Figure 4b

an alternatively designed section of the handle device in a sectional view,

Figure 4c

a detail of the handle device in a sectional view,

figure 5

a detail of the handle device in a sectional view,

Figure 6a

a part of the assembly of the handle device in a perspective view,

Figure 6b

part of the assembly of the handle device in a side view,

Figure 6c

part of the assembly of the handle device in a side view,

Figure 7a

a control means of the handle device in a schematic representation,

Figure 7b

the control means of the handle device in a sectional view,

Figure 7c

the control means of the handle device in a sectional view,

Figure 8a

a detail of the handle device in a sectional view,

Figure 8b

a detail of the handle device in a sectional view,

Figure 8c

a detail of the handle device during assembly in a sectional view,

9

a section of the handle device in a schematic representation,

10

a detail of the handle device in a sectional view,

11

a section of the handle device in a sectional view along section line XI-XI,

12a

a detail of the handle device in a sectional view,

Figure 12b

a detail of the handle device in a sectional view,

13

a section of the handle device in an exploded view,

14a

a detail of the handle device in a sectional view,

Figure 14b

a detail of the handle device in a sectional view along the section line XIVb-XIVb and

15

a detail of the handle device in a sectional view.

Description of the exemplary embodiments

figure 1 shows a schematic view of a rotary and/or chipping hammer as an example of a hand-held power tool 10 with a machine housing 20, a tool holder 54 which is movably arranged on the machine housing 20 for exchangeably receiving an insert tool 16 and with a A drive device 14 having a drive unit and a gear unit for driving the application tool 16 in different operating modes. The tool holder 54 is preferably rotatably arranged on an end face of the machine housing 20 . In the example shown in FIG figure 1 a handle device is also provided. In the present example, the handle device comprises a switch actuator 24 for starting up the rotary and/or chipping hammer. The switch actuator 24 can be switched both monostable and bi-stable between two switching positions. Furthermore, an auxiliary handle device 56 is arranged on the machine housing 20 of the rotary and/or chipping hammer, in particular arranged adjustably. The hand-held power tool 10 has an operating mode switching device 12 . In addition, an operating lever for switching the operating mode is arranged on the machine housing 20, with which an operator can choose between different types of drive for the insertion tool 16 inserted in the tool holder 54.

The handle device for handheld power tool 10 comprises a spring element 18 and a handle unit 22, which is attached to machine housing 20 so that it can move at least to a limited extent, which is vibration-decoupled from machine housing 20 via spring element 18 and comprises switch actuator 24 for starting drive device 14. The handle unit 22 includes an anti-vibration handle 58. The handheld power tool device also has a control means 28 via which the switch actuator 24 interacts with the operating mode switching device 12 in such a way that the switch actuator 24 cannot be switched bistable in certain operating modes. The control means 28 is designed as a drawstring 30 . The ua in figure 2 The assembly shown is composed of the following functional units: an intermediate plate 26, the spring element 18 and a slide switch assembly. The intermediate plate 26 is the central component of this assembly. Their structure allows a number of options for the simple implementation of existing functions in the handheld power tool 10 formed by the hammer when using the anti-vibration handle 58 and a mechanical switch actuation with switching.

One of the central tasks of the intermediate plate 26 is to accommodate and guide the spring element 18, as shown in FIGS Figures 3a and 3b shown. The spring element 18 is clamped by the intermediate plate 26 in the anti-vibration handle 58 and fixed at the clamping point via a contour. The contour is preferably realized in a contact surface on the intermediate plate 26, on which the spring element 18 can be supported. The curve of this contour determines the rigidity, bending line and path of the spring element 18. The spring element 18 is designed as a leaf spring 32.

Furthermore, the intermediate plate 26 serves to accommodate or as a stop for one or more secondary spring elements 34, 34', 34", which can serve as damping elements Figures 4a to 4c conceivable variants and configurations of the secondary spring elements 34, 34', 34" are shown Figures 4a to 4c Pockets with support ribs 60 and a frame 62 for the introduction of damping elements in the intermediate plate 26. The secondary spring elements 34, 34', 34" can preferably be made of foam, cellular rubber, foam rubber, another synthetic or natural foam, elastomer, TPE , rubber, a gel or a similar elastic material. The degree of damping or springing can also be adjusted via the volume of individual chambers. The frame 62 prevents jamming with other surrounding components.

Suspension and damping are consequently adjusted to each other centrally via the accommodation of the spring element 18 and the secondary spring elements 34, 34', 34" in the intermediate plate 26. The result is the compact assembly, which is intended for pre-assembly and which contains all the essential components for the functional relationship of the The principle makes it easier to coordinate the components for decoupling and also opens up the possibility of deriving a rigid handle of the handle unit 22 without switching from it without great effort by omitting the assembly.

The special design of the intermediate plate 26 also enables improved guidance of the handheld power tool 10 and in particular improved transmission of operating forces on the anti-vibration handle 58 to the machine housing 20 of the handheld power tool 10. After figure 5 Support points and receptacles of the intermediate plate 26 are designed in the upper area of a handle housing 64 and at the connection to the drive device 14, which includes a motor assembly, in such a way that operating forces can be transmitted unfiltered or unsprung to the handheld power tool 10 along the power flow from the anti-vibration handle 58. This results in good operator guidance for the handheld power tool 10.

The intermediate plate 26 is provided in the machine housing 20 and accommodates the spring element 18 on one side. Finally, the slide switch assembly is accommodated in the intermediate plate 26. The slide switch assembly consists in accordance with the Figures 6a to 6c consists of a switch slide 66, the tie rod 30 and a compensation spring 68. In addition to the intermediate plate 26, it forms another important unit especially in the transmission of switching or switching paths to the switch actuator 24. The control means 28 designed as a tie rod 30 is made of plastic.

As a result, dimensional dependencies that affect the ways in which the operating mode is switched over by the switch actuator 24 can be regulated in just one component. Little space is required. Assembly is easy. The broadened head support on the slide switch 66 paired with jumps/steps in the guide prevents dust from being trapped between the sliding surfaces. As a result, a malfunction due to jamming on the switch slide 66 can be avoided in principle.

The Z-shaped, cranked switch slide 66 can be pushed into the intermediate plate 26 with a simple sliding movement and latches in the intended installation position via a snap hook connection (not shown in detail). It is also conceivable that the Z-shaped, cranked slide switch 66 can be rotated into the intermediate plate 26 with a simple pivoting movement. The length ratio of the guide surfaces to each other ensures sufficient pre-centering during the entire pre-assembly. This rules out incorrect assembly.

For a mode-dependent changeover from the hammer switch according to the publication DE 197 20 947 A1 , the disclosure of which is explicitly referred to at this point, the path and the force must be mechanically transmitted from an operating lever to a changeover switch from the switch actuator in the handle without any problems. In combination with an anti-vibration handle, solution approaches similar to the publication are revealed DE 10 2010 038 753 A1 , in which a drawstring is placed in the neutral axis of the handle movement.

However, friction losses, deformation of the spring element 18 and aspects of the manufacturing process make it difficult to implement this concept in practice.

For this reason, the material and geometry are particularly decisive for the design of the tie rod 30 . As a material, plastic offers a wide range of variations in order to combine low coefficients of friction with good emergency running properties and low susceptibility to dust. Therefore, a plastic is fundamentally a very suitable material for this application.

In order to achieve sufficient rigidity for the transmission of tensile forces without at the same time losing flexibility for entrainment via the spring element 18, cross-sectional ratios are decisive.

A band cross section of the tension band 30 must be very flat in height and long in width. In the present construction, a rectangular cross-section with an aspect ratio of 1:10 was chosen combined with a substantially circular, in particular circular, central fiber (see Fig Figures 7a to 7c ), but cross-sections with rounded corners and/or different aspect ratios, in particular in the range from 1:2 to 1:20, particularly preferably from 1:5 to 1:15, can also be advantageous.

Surface areas can be variably adjusted over the entire length of the drawstring 30, but must remain balanced overall. As a result, a constant tension in the drawstring 30 is maintained despite the eyelets and deflection during use. A uniform stress on the material can be ensured.

Varying the surface area also helps between rigidity and flexibility. The substantially circular, in particular circular portion is used to fill the mold in the manufacturing process and at the same time advantageously increases the strength.

Due to manufacturing tolerances, thermal-elastic changes in length, shrinkage/post-crystallization and the pronounced flow behavior of plastic under load on the tension band 30, differences accumulate when the tensile forces and distances are transmitted on the tension band 30, which is made of plastic, which ensure a safe and ensure satisfactory function of the switch actuator 24 mechanically only to a limited extent.

With the help of the compensation spring 68 (see Figure 6a ) these difficulties can easily be solved.

In the prestressing of the compensating spring 68, a buffer is created by the installation situation in the switch slide 66, which can compensate for all the imprecisions from production and mechanical behavior of the drawstring 30, which is made of plastic.

For this purpose, the drawstring 30 must have a body to accommodate the compensation spring 68 and must be securely accommodated/guided in the switch slide 66 with the aid of two rotary receptacles. The slide switch 66 supports the compensation spring 68 on the opposite side and determines the degree of compensation via the installation length.

When the changeover is actuated, the path from the switch slide 66 is now transmitted to the drawstring 30 and the switch actuator 24 as a function of the force (see Figures 8a and 8b ). The coupling is no longer rigid but linear-elastic. The paths between the switch slide 66 and the changeover lever on the switch actuator 24, which forms a hammer switch, are designed so that a reserve is always maintained in the compensation spring 68. This reserve from the length of the compensation spring 68 during operation can be used to compensate for tolerances and thermal, elastic and also plastic changes in length on the drawstring 30, which is made of plastic. Overload protection is ensured and defined tensile forces are now applied to the tension band 30 via the compensation spring 68 .

For easy assembly, an opening was left in the guide at the front of the slide switch and a snap connection was provided for the tie rod 30 (see Fig Figure 8c ). The width of the drawstring 30 is matched to the receptacle in the slide switch 66 . As a result, the drawstring 30 together with the compensation spring 68 can be easily threaded through the receptacle in the slide switch 66 . The components are then automatically pulled into their installation position by the force in the intended pulling direction and remain secured there.

For effective dust protection, a labyrinth 70 is also provided via the intermediate plate 26, which is used to cover the machine housing 20, which includes a percussion mechanism housing and a housing cover, the drive device 14, which includes a motor assembly, and the anti-vibration handle 58 inwards reached (see figure 9 ). The labyrinth 70 reaches into the surrounding parts at the transitions and, especially when switching over the switch actuator 24 formed by the hammer switch, effectively protects against dust and ensures safe operation. Additional sealing elements are therefore not required.

Another aspect relates to the fact that with larger and more powerful handheld power tools 10, such as heavy drill and chisel hammers, for example, the fixing of the leaf spring 32 between the anti-vibration handle 58 and the machine housing 20 as described above is no longer sufficient. For example, the leaf spring 32 is no longer sufficient as the sole spring element. Additional secondary spring elements 34 must still be introduced between the machine housing 20 and the leaf spring 32 in order to support the spring effect of the leaf spring 32 which is too soft. The secondary spring elements 34 are each formed by an elastomer spring element 36 .

According to the pamphlet DE 10 2006 029 630 A1 the leaf spring can only be loaded functionally or with forces on the back by means of a clamping piece and the screw plate. No holding or fixing functions or forces can be introduced on the side of the leaf spring facing the device side. The invention thus represents an extension of that from the publication DE 10 2006 029 630 A1 well-known solution to be able to implement the anti-vibration handle concept presented there in larger and more powerful handheld power tools.

The anti-vibration handle 58 held by the operator includes the switch actuator 24 designed as an on/off switch and is closed by screwing a grip shell of the anti-vibration handle 58 towards the rear.

The leaf spring 32 is clamped between the anti-vibration handle 58 and two screw plates 48 at the top. The two screw plates 48 are pushed onto the leaf spring 32 on both sides in the transverse direction. The screw plates 48 thus enclose an upper clamping area 50 of the leaf spring 32 in all spatial directions except for the contact zone for the anti-vibration handle 58 . This ensures a permanent and stable enclosing of the leaf spring 32 . Screw bosses 52 are located in the screw plates 48 , which serve to screw the screw plates 48 and thus fasten the leaf spring 32 to the anti-vibration handle 58 . The screw plates 48, the leaf spring 32, the anti-vibration handle 58 and a braced bellows 72 form a fastening system that is advantageously held together by positive and non-positive locking. The form fit is formed by holding domes and ribs that support and penetrate one another, so that the force fit only has a fixing function and the main forces are absorbed by the form fit of the components.

A significant advantage of the screw plates 48 pushed on on both sides is the creation of additional functional surfaces in front of an area and on the side of an area of the screw plates 48 of the leaf spring 32.

In the front area, the screw plates 48 are designed in such a way that they can accommodate the additional secondary spring elements 34 . In addition to spring mounts, the screw plates 48 have additional functions. In order to prevent the anti-vibration handle 58 from being torn out and thus also an overloading of the leaf spring 32, the screw plates 48 have lateral contact surfaces which are supported on the rear on two rear plates 38 designed as housing rear plates. As a result, the anti-vibration handle 58 has a stable and defined rear stop. Another function of the screw plates 48 is the lateral guidance and covering of the control means 28 formed by the tie rod 30 in relation to the secondary spring element 34 made of an elastomer , so that the operator does not have to constantly press the switch actuator 24. The drawstring 30 must be able to slide easily on the leaf spring 32 and must not be jammed or pinched.

While the two screw plates 48 are being pushed together onto the leaf spring 32, the drawstring 30 is chambered in a shaft of the screw plates 48. The bellows 72 is also chambered in the anti-vibration handle 58 by the screw plates 48 . Furthermore, the screw plates 48 also form the end stop in the longitudinal and vertical direction of the anti-vibration handle 58.

The lower leaf spring clamp has been advantageously integrated into the system of screwing the back plates 38 to the machine housing 20 (see Figures 14a and 14b ). The previously one-piece back plate was divided into two mirror-symmetrical back plates 38 in order to be able to fulfill all the required functions, favorable assembly and tool end formability.

As with the print DE 10 2006 029 630 A1 the bellows 72 and rocker arms (not shown) already mounted on the anti-vibration handle 20 are chambered during assembly by pushing the two back plates 38 together. Due to the required prestressing of the leaf spring 32, the leaf spring 32 then protrudes a little from the back plates 38 designed as housing back plates. In order to be able to simply press the leaf spring 32 into its operating position during assembly, a spring plate 40 is inserted at the top with its two retaining ribs 42 into two corresponding retaining grooves 44 of the rear plates 38 designed as housing rear plates and then folded backwards against a leaf spring tension in the direction of the rear plates 38 . In order to be able to hold this position, two snap hooks 46 are integrated into the rear plates 38, which snap into the spring plate 40 and hold it in the assembly position. The complete handle device, designed as a handle assembly, preassembled in this way can then be applied to the core device in an assembly line.

Both non-positive and positive elements are used to clamp the leaf spring 32 . The leaf spring 32 has two openings and a fold 74 at its lower end as a form fit. Furthermore, the spring plate 40 also encompasses the two screw domes of the machine housing 20. The fold 74 of the leaf spring 32 is braced between the back plates 38 and the spring plate 40. By screwing the back plates 38 formed by the housing back plates to the machine housing 20, all parts are clamped together. The advantageous nesting of the components into one another results in a permanent connection that also withstands the high vibration load in the hand-held power tool 10 formed by a percussive electric tool.

Even in the event of a loss of preload in the screw connection due to setting or loosening processes, the connection is maintained due to the form fit. The height contour of the spring plate 40 is such that the leaf spring 32 is clamped firmly at the bottom over approximately 25% of its length. The remaining length can freely protrude during compression.

A further aspect is the combination of the leaf spring 32 as the primary spring element and the at least one further secondary spring element 34, which, however, is only acted upon after a certain compression travel.

figure 15 shows a cross section through the upper area of the anti-vibration handle 58 with the leaf spring 32 and the secondary spring element 34. The screw plates 48, with which the leaf spring 32 is enclosed, are designed at the front in such a way that they can still accommodate one or the additional secondary spring elements 34. In the embodiment shown, for example, a foamed elastomer molding is introduced between the screw plate 48 or the leaf spring 32 and the spring plate 40 . The elastomer molded part is designed as the elastomer spring element 36 and forms the secondary spring element 34.

Foamed elastomer moldings have the advantage of being inexpensive to manufacture using a continuous extrusion process with subsequent cutting to the required length. Furthermore, they act in almost all spatial directions, i.e. they do not have a preferred direction like e.g. a helical compression spring.

The advantageous secondary spring element 34, designed as an elastomer spring element 36, supports the leaf spring 32 under loads that are above an optimum operating pressure point. The optimum operating pressure point is the minimum pressure that the operator just needs to apply so that the hand-held power tool 10 formed by the hammer drill carries out a regular and clean percussion operation. This operating pressure depends on the performance class of the hand-held power tool 10 and the respective application.

That is to say, by providing a certain amount of play in the elastomer spring element 36 between the contact surfaces, an at least two-stage spring characteristic is produced. Up to the operating pressure point, only the leaf spring 32 acts, so that a very good decoupling of the anti-vibration handle 58 can be achieved with a low level of vibration. Good decoupling is also achieved in this area primarily because the leaf spring 32 has a very low damping constant. In the event of excessive pressure or if the hand-held power tool 10 falls onto the anti-vibration handle 58, the elastomer spring element 36 then absorbs the majority of the loads.

It is proposed that the spring stiffness of the leaf spring 32 be set such that the minimum operating contact pressure points for most important applications are achieved with a compression travel of between 2 mm and 10 mm, preferably between 3 mm and 7 mm, particularly preferably between 4 mm and 5 mm . From this pressure threshold, the secondary spring element 34 begins to act. The more the volume of the elastomer spring element 36 is deformed during deflection, the stiffer the characteristic curve of the secondary spring element 34. It is therefore also proposed that a volume compression of the elastomer spring element 36 be designed in such a way that with an additional deflection of 2 mm to 5 mm, in particular from 3 mm to 4 mm beyond the minimum operating pressure point, the elastomer spring element 36 is compressed to 70% of its initial volume. With further deflection of 1 mm to 2 mm, virtually the entire volume of the elastomer spring element 36 is acted upon, so that the spring stiffness increases relatively quickly. This has the advantage that if the anti-vibration handle 58 falls, a great deal of energy can be absorbed, so that the components that are impacted are less stressed. A deflection characteristic described can also be brought about or supported by a targeted shaping of the elastomer spring element 36 . Tubular or other contours that can be produced in a strand process can also be installed. The elastomer spring element 36 is preferably made of foamed elastomer (foam rubber), which is produced in a continuous extrusion process with subsequent cutting to length

Claims (7)

1. Hand-held power tool (10), in particular hammer drill and/or chipping hammer, having a machine housing (29) and having a handle device, wherein the hand-held power tool has an operating-mode switching device (12) and a drive device (14) for driving an application tool (16) in different operating modes, wherein the handle device has at least one spring element (18) and a handle unit (22) which is attached to the machine housing (20) so as to be movable at least to a limited extent and is at least partially vibrationally decoupled with respect to the machine housing (20) via the at least one spring element (18), and at least one secondary spring element (34), characterized by an intermediate plate (26) that receives the spring element (18) on one side, is provided in the machine housing (20) and serves to receive or acts as a stop for the at least one secondary spring element (34).
2. Hand-held power tool according to Claim 1, characterized in that the secondary spring element (34) is formed by an elastomer spring element (36).
3. Hand-held power tool according to either of the preceding claims, characterized in that the secondary spring element (34) is acted upon only after a particular deflection travel.
4. Hand-held power tool according to one of the preceding claims, characterized in that the handle device has a switch actuator (24) for switching on the drive device (14), wherein the switch actuator (24) can be switched both monostably and bistably between two switching positions.
5. Hand-held power tool according to Claim 4, characterized by a control means (28) via which the switch actuator (24) cooperates with the operating-mode switching device (12) such that, in particular operating modes, the switch actuator (24) cannot be switched bistably.
6. Hand-held power tool according to Claim 5, characterized in that the control means (28) is in the form of a tie member (30).
7. Hand-held power tool according to one of the preceding claims, characterized in that the at least one spring element (18) is formed by a leaf spring (32) .

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