Angle grinder with non-removable protective cover

Abstract

An angle grinder comprises an output shaft defining an axis of rotation, a housing from which the output shaft extends, and a flange connected to the housing and surrounding the output shaft. The angle grinder further comprises a first circumferential groove defined between the flange and the housing, a first arrangement of radially outward extending slots in the flange communicating with the first circumferential groove, and a wedge channel defined in the housing. The wedge channel is aligned with a first of the radially outward extending slots in the first arrangement. The angle grinder further comprises a guard comprising a second arrangement of radially inward extending projections and a wedge that can be positioned in the wedge channel. The radially inward extending projections engage in the radially outward extending slots.The wedge can close the first radially outward extending slot in the first arrangement to prevent the protective device from being removed from the housing.

Description

Cross-reference to related registrations

[0001] This application claims priority over the concurrently pending US Provisional Patent Application No. 63 / 468,365, filed on May 23, 2023, and the concurrently pending US Provisional Patent Application No. 63 / 483,573, filed on February 7, 2023, the entire contents of which are hereby incorporated by reference. Field of invention

[0002] The present invention relates to hand-held power tools, in particular angle grinders. Background of the invention

[0003] Power tools, such as handheld angle grinders, include rotating grinding elements or grinding wheels that produce abrasion on a workpiece during operation. Such angle grinders typically include a guard that partially surrounds the grinding wheel to protect the user from this abrasion. However, these guards are typically removable to expose the entire outer circumference of the grinding wheel for grinding. Summary of the invention

[0004] The invention relates in one aspect to an angle grinder comprising an output shaft defining an axis of rotation, a housing from which the output shaft extends, and a flange connected to the housing and surrounding the output shaft. The angle grinder further comprises a first circumferential groove defined between the flange and the housing, a first arrangement of radially outwardly extending slots in the flange that communicate with the first circumferential groove, and a wedge channel defined in the housing. The wedge channel is positioned in a row with a first of the radially outwardly extending slots in the first arrangement. The angle grinder further comprises a guard with a second arrangement of radially inwardly extending projections and a wedge that can be positioned in the wedge channel.The second arrangement of radially inward-extending projections is accommodated within the first arrangement of radially outward-extending slots. The wedge can close the first radially outward-extending slot in the first arrangement to prevent removal of the protective device from the housing.

[0005] In a further aspect, the invention provides an angle grinder comprising an output shaft defining an axis of rotation, a housing from which the output shaft extends, and a flange connected to the housing and surrounding the output shaft. The angle grinder also comprises a first circumferential groove defined between the flange and the housing, a first arrangement of radially outwardly projecting slots in the flange that communicate with the first circumferential groove, and a guard comprising a second arrangement of inwardly projecting projections. The inwardly projecting projections of the guard are configured to engage in the first arrangement of radially outwardly projecting slots.The angle grinder further comprises a first stop arranged on the housing and a second stop formed on the guard, which can be engaged with the first stop. The second stop engages with the first stop to prevent the second arrangement of radially inwardly extending projections from realigning with the first arrangement of radially outwardly extending slots, thereby preventing the guard from being removed from the housing.

[0006] In a further aspect, the invention provides an angle grinder comprising an output shaft defining an axis of rotation, a housing from which the output shaft extends, a guard connected to the housing and partially surrounding the output shaft, and a guard locking flange connected to the housing. The guard locking flange is permanently attached to the housing and configured to hold the guard axially to the housing.

[0007] Further aspects of the invention will become clear from the detailed description and the accompanying drawings. Brief description of the drawings Fig. Figure 1 is a perspective view of an angle grinder according to an embodiment of the invention. Fig. 2 is an exploded view of the angle grinder from Fig. Figure 1 shows a protective device and a wedge for axially fastening the protective device to a gearbox housing cover of the angle grinder. Fig. Figure 3 is an exploded view of the angle grinder. Fig. 1, which shows a locking plate for rotationally locking the protective device. Fig. Figure 4 is a partially composite perspective view of the gearbox housing cover, the protective device and the wedge made of Fig. 2, showing the wedge removed from the gearbox housing cover. Fig. Figure 5 is a perspective view of the gearbox housing cover. Fig. 2, showing the wedge in an installed position. Fig. Figure 6A is a partially composite perspective view of an angle grinder according to a further embodiment of the invention, showing a wedge removed from the gearbox housing cover. Fig. 6B is a perspective view of the angle grinder from Fig. 6A, which shows the wedge in an installed position. Fig. Figure 7 is a cross-sectional view of the angle grinder made of Fig. 6B, which shows the wedge in the installed position. Fig. Figure 8A is a partially composite perspective view of an angle grinder according to a further embodiment of the invention, showing a wedge removed from the gearbox housing cover. Fig. 8B is a perspective view of the angle grinder from Fig. 8A, which shows the wedge in an installed position. Fig. Figure 9A is a perspective view of an angle grinder according to a further embodiment of the invention. Fig. 9B is an enlarged view of the angle grinder from Fig. 9A, which shows a stop on a rotatable guard that engages in a counter-stop. Fig. Figure 10 is a perspective view of an angle grinder according to a further embodiment of the invention, showing a guard and a guard locking flange. Fig. Figure 11 is an enlarged cross-sectional view of an angle grinder according to a further embodiment of the invention, showing a roller pin installed in the gearbox housing cover and a rotatable protective flange.

[0008] Before embodiments of the invention are explained in detail, it should be understood that the invention is not limited in its application to the design details and arrangements of components set out in the following description or illustrated in the following drawings. The invention may have other embodiments and be practiced or implemented in various ways. It should also be understood that the terms and concepts used here serve only for descriptive purposes and should not be considered limiting. Detailed description

[0009] Fig. Figure 1 shows a handheld power tool, for example an angle grinder 100, comprising a housing 104 that together defines a motor housing section 114 and a gearbox housing section 116, which is attached to a front end of the motor housing section 114. In the illustrated embodiment, the gearbox housing section 116 comprises a gearbox housing 118 and a gearbox housing cover 120, which is attached to the gearbox housing 118 by a plurality of gearbox housing fasteners 121. The angle grinder 100 also comprises an output shaft 122 extending from the gearbox housing section 116 along a rotational axis 126 that is perpendicular to a longitudinal axis 128 defined by the motor housing section 114.The output shaft 122 is driven by a motor (not shown) positioned within the motor housing section 114, and a gear train (also not shown) is positioned within the gear housing section 116 to transmit torque from the motor to the output shaft 122. A grinding or abrasive wheel (not shown) can be attached to the output shaft 122 to rotate with it about the axis of rotation 126.

[0010] With reference to Fig. 2 The gearbox housing cover 120 comprises a flange 130 extending from it and surrounding the axis of rotation 126. In some embodiments, the gearbox housing section 116 and the motor housing section 114 can be formed integrally as a single part, with the flange 130 also being an integral part of the housing 104. In other embodiments, the flange 130 can be a separate component and optionally connected to the housing 104. The flange 130 comprises an arrangement of six radially outwardly extending slots 138 and a wedge channel 139 that coincides with or is arranged in series with a first of the slots 138. The gearbox housing cover 120 defines a circumferential groove 134 below and adjacent to the flange 130, such that the slots 138 communicate with the circumferential groove 134.One of the slots 138 has a width greater than that of the other slots 138 and is therefore used as an alignment slot 142, as explained in detail below. In other embodiments of the angle grinder 100, the flange 130 may include more or fewer slots 138. Furthermore, the wedge channel 139 is shaped to accommodate a wedge 141, which serves to hold a protective device 146 axially against the gearbox housing cover 120, as explained in more detail below.

[0011] With further reference to Fig. 2 The guard 146 partially surrounds the grinding wheel (not shown) when the wheel is attached to the output shaft 122. The guard 146 is rotatable relative to the gearbox housing 120 to adjust its orientation relative to the housing 104 and to expose different areas of the grinding wheel required for a grinding operation. The guard 146 comprises an arrangement of six radially inwardly projecting projections 150 and five openings 155 arranged radially around the guard 146. One of the projections 150 is wider than the other projections and therefore serves as an alignment projection 158, which is received in the alignment slot 142 in the flange 130.The projections 150 on the guard 146 are aligned with the slots 138 in the flange 130 and can therefore be inserted through them when the alignment projection 158 is aligned with the alignment slot 142. After the projections 150 are inserted into the slots 138, the guard 146 is lowered until the projections 150 reach the circumferential groove 134. The guard 146 can then be rotated about the axis of rotation 126 to align the projections 150 out of the slots 138, thereby securing the guard 146 axially to the gearbox housing cover 120. The protective device 146 can therefore only be removed from the circumferential groove 134 if the alignment projection 158 is aligned again with the alignment slot 142, whereby the other projections 150 are also aligned again with the respective slots 138.

[0012] With reference to Fig. 3. The angle grinder 100 further comprises a locking plate 162 for rotationally securing the guard 146 in a desired orientation relative to the gearbox housing cover 120. The locking plate 162 includes an actuating section 170 and a detent element 174. A compression spring 182 is positioned between a spring seat 186 on the gearbox housing cover 120 and presses the detent element 174 towards the guard 146. In the illustrated embodiment, the spring seat 186 is a recess and the compression spring 182 is positioned within the spring seat 186. In alternative embodiments, the spring seat can be a pin and the compression spring 182 can be positioned and seated around the pin. The detent element 174 can be received in one of the five openings 155 in the guard 146 to hold the guard 146 rotationally secured relative to the gearbox housing cover 120.The locking plate 162 is pre-tensioned by the spring 182 to position the detent element 174 in one of the openings 155 when the guard 146 is installed on the gearbox housing cover 120 as described above. The detent element 174 is removed from one of the openings 155 in the guard 146 by applying a force to the actuating section 170 of the locking plate 162 in a direction away from the guard 146. The applied force removes the detent element 174 from one of the openings 155, whereupon the guard 146 can rotate freely about the axis of rotation 126 into a different rotational position relative to the gearbox housing cover 120.When the actuating section 170 is released, the spring 182 rebounds and pushes the detent element 174 back towards the guard 146, positioning the detent element 174 in the next opening 155 that it will encounter when the guard 146 continues to rotate into a desired position.

[0013] With reference to the Fig. 4 and Fig. 5. When installed in the wedge channel 139, the wedge 141 prevents the guard 146 from being removed from the gearbox housing cover 120. In practice, the guard 146 is installed as described above and then rotated into a position where none of the projections 150 block the wedge channel 139, as shown in Fig. Figure 4 shows the wedge channel 139 aligned with a slot between two adjacent projections 150. If the wedge channel 139 is not obscured, the wedge 141 can be inserted into the wedge channel 139. Once installed in the wedge channel 139, the wedge 141 can be secured to the gearbox housing cover 120 with a fastener or pin (not shown) to make it more difficult for unauthorized users to remove the wedge 141. The fastener or pin (not shown) is inserted into a hole 184 in the gearbox housing cover 120 using a tool (e.g., a hex key). Fig. 5) inserted and in an aligned, corresponding hole 188 in the wedge 141 ( Fig. 4) secured. In some embodiments, the hole 184 is oriented transversely to the axis of rotation 126. When the wedge 141 is installed, one of the slots 138 is secured by a flanged section 190 of the wedge 141 ( Fig. 5) blocked, thus preventing one of the projections 150 from protruding through its designated slot 138. This prevents the guard 146 from being removed from the gearbox housing cover 120 at any time. However, the rotational adjustment of the guard 146 is not hindered, since the wedge 141 includes a circumferential groove 192 that aligns with the circumferential groove 134 in the gearbox housing cover 120 and has the same thickness as the circumferential groove 134. Thus, the guard 146 can rotate freely when the detent element 174 is removed from the openings 155.

[0014] An alternative embodiment of the 500 angle grinder is in the Fig. 6A, Fig. 6B and Fig. 7 shown, with the same features as in the Fig. The angle grinder 100 shown in Figures 1-5 is provided with the same reference numerals. In the illustrated embodiment, the guard 146 remains rotatable about the axis of rotation 126, but is not removable. The guard 146 is installed in a similar manner to the angle grinder 100, as described above. However, the wedge 541 does not include an opening, but rather several recesses 543 against which a corresponding number of fastening elements (e.g., adjusting screws 548) are clamped with a tool (e.g., a hex key). Each of the recesses 543 comprises an angled surface 544 and an adjacent base surface 545, as shown in Figure 1-5. Fig. Figure 7 shows that when the wedge 541 is installed in a wedge channel 539, the recesses 543 are aligned with several holes 584 formed in a gear housing cover 520. The holes 584 are threaded and each accommodates an adjusting screw 548, which is inserted into one of the recesses 543. In the illustrated embodiment, the adjusting screws 548 have a conical end 547. When the wedge 541 is not fully installed, the conical end 547 of the adjusting screw 548 contacts the angled surface 544. As the adjusting screw 548 is screwed in further, the conical end 547 moves along the angled surface 544, thereby moving the wedge 541 further into the wedge channel 539. The wedge 541 is considered fully inserted when it touches a bottom 550 of the wedge channel 539 and the conical ends 547 of the adjusting screws 548 touch both the bottom surface 545 and the chamfered surface 544.

[0015] Fig. 8A and Fig. Figure 8B shows an alternative embodiment of a wedge 541B and an alternative embodiment of a gearbox housing cover 520B. The wedge 541B comprises a single recess 543 that can accommodate an adjusting screw 548. The adjusting screw 548 can be received through a hole 584 in the gearbox housing cover 520B.

[0016] An alternative embodiment of an angle grinder 300 is described in the Fig. 9A-9B is shown, with the same features as the one in the Fig. The angle grinders 100 shown in Figures 1-5 are designated with the same reference numerals. In the illustrated embodiment, the guard 146 remains rotatable but not removable. The guard 146 is attached in a similar manner to that described above for the angle grinder 100. However, due to the interaction between a first stop 393 and the guard 146, the guard 146 is not removable from the gearbox housing cover 120. As in Fig. As shown in Figure 9B, the first stop 393 has an L-shaped cross-section and is attached to the gearbox housing cover 120 by a fastener or pin (not shown) that is not easily removable. In the installed state, a second stop 394, formed on the guard 146, for example as a radially outwardly projecting projection, contacts a notch 395 formed on the first stop 393 to prevent the guard 146 from rotating beyond a certain angle. This prevents the guard 146 from being removed from the gearbox housing cover 120, as the projections 150 cannot be aligned with their respective slots 138.

[0017] An alternative embodiment of a gearbox housing cover 420 is shown in Fig. 10 shown, with the same features as those in Fig. The gearbox housing cover 120 shown in Figures 1-5 is provided with the same reference numerals. In the illustrated embodiment, the guard 146 is held axially by a guard locking flange 498. The guard locking flange 498 holds the guard 146 on the gearbox housing cover 420 by being connected to a hub 499 on the gearbox housing cover 420 via a pair of reverse threads, an interference fit, a roller pin, or a combination of these three elements. In the illustrated embodiment, the guard locking flange 498 comprises a set of male reverse threads (not shown), while the hub 499 of the gearbox housing cover 420 comprises a set of corresponding female threads (not shown).When the guard locking flange 498 is installed on the hub 499 of the gearbox housing cover 420, the guard locking flange 498 cannot be removed and the rotatable guard 146 is held axially. In another embodiment, the guard locking flange 498 is pressed onto the hub 499 of the gearbox housing cover 420. After pressing, the guard locking flange 498 cannot be removed and thus holds the guard 146 axially.

[0018] Fig. Figure 11 shows an alternative embodiment of a gearbox housing cover 620 and an alternative embodiment of a guard locking flange 698. The gearbox housing cover 620 and the guard locking flange 698 include similar features to those shown in Figure 11. Fig.Figure 10 shows the gearbox housing cover 420 and the guard locking flange 498, which are designated with the same reference numerals. In the illustrated embodiment, the guard 146 is held axially by the guard locking flange 698. To secure the guard 146 axially, it is first inserted into a circumferential groove 634. Next, the guard locking flange 698 is pressed into the gearbox housing cover 620 over the guard 146, thereby permanently attaching the guard locking flange 698 to the housing of the angle grinder. Once the guard locking flange 698 is fully inserted into the gearbox housing cover 620, a pin 652 is pressed through a first pin opening 654 in the gearbox housing cover 620 and then through a second pin opening 656 into the guard locking flange 698.The pressed-in pin 652 then prevents the removal of the guard locking flange 698 and the guard 146, while still allowing the guard 146 to rotate in the circumferential groove 634. In other embodiments, the gearbox housing cover 620 and the guard locking flange 698 can be screwed together before the pin 652 is inserted.

[0019] Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications within the scope and spirit of one or more independent aspects of the described invention are possible.

[0020] Various features and advantages of the invention are claimed in the following claims. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 63 / 468,365

[0001] US 63 / 483,573

[0001]

Claims

[1] Angle grinders, including: an output shaft that defines an axis of rotation; a housing from which the output shaft extends; a flange that is connected to the housing and at least partially surrounds the output shaft; a first circumferential groove defined between the flange and the housing; a first arrangement of radially outward extending slots defined in the flange, each of the slots in the first arrangement being connected to the first circumferential groove; a wedge channel defined in the housing and positioned in a row with one of the radially outward extending slots in the first arrangement; a protective device comprising a second arrangement of radially inwardly extending projections configured to be received in the first arrangement of radially outwardly extending slots; and a wedge that can be positioned in the wedge channel to close one of the radially outward extending slots in the first arrangement in order to prevent removal of the protective device from the housing. [2] Angle grinder according to claim 1, wherein the second arrangement of radially inward extending projections comprises at least one alignment projection and wherein the alignment projection has a greater width than any remainder of the radially inward extending projections. [3] Angle grinder according to claim 2, wherein the first arrangement of radially outward extending slots comprises at least one alignment slot, wherein the alignment slot has a greater width than any remainder of the radially outward extending slots, and wherein the radially inward extending projections on the guard are aligned with the radially outward extending slots in the flange and can be received through them when the alignment projection is aligned with the alignment slot. [4] Angle grinder according to claim 1, wherein the wedge comprises a second circumferential groove in which the radially inwardly projecting protrusions in the second arrangement are movable when a rotational alignment of the guard relative to the housing is set. [5] Angle grinder according to claim 1, wherein the first circumferential groove in the housing and the second circumferential groove in the wedge have the same thickness. [6] Angle grinder according to claim 1, wherein the wedge comprises a flange section which is received in one of the radially outward extending slots in the first arrangement when the wedge is positioned in the wedge channel, and wherein the flange section of the wedge and the flange have the same thicknesses. [7] Angle grinder according to claim 1, wherein the housing includes a hole configured to accommodate a fastening element to secure the wedge in the wedge channel. [8] Angle grinder according to claim 7, wherein the hole is oriented transversely to the axis of rotation. [9] Angle grinder according to claim 7, wherein the fastening element is a pin and wherein the wedge comprises a corresponding receiving opening which is aligned with the hole in the housing. [10] Angle grinder according to claim 7, wherein the fastening element is an adjusting screw and wherein the wedge comprises a recess aligned with the hole in the housing. [11] Angle grinder according to claim 10, wherein the recess comprises a bottom surface and an angled surface. [12] Angle grinder according to claim 11, wherein the fastening element can be brought into engagement with the angled surface of the recess in a first position of the wedge within the wedge channel. [13] Angle grinder according to claim 11, wherein the fastening element can be brought into engagement with the bottom surface and the angled surface of the recess in a second position of the wedge within the wedge channel. [14] Angle grinders, including: an output shaft that defines an axis of rotation; a housing from which the output shaft extends; a flange that is connected to the housing and at least partially surrounds the output shaft; a circumferential groove defined between the flange and the housing; a first arrangement of radially outward extending slots defined in the flange, each of the radially outward extending slots in the first arrangement being connected to the circumferential groove; a protective device comprising a second arrangement of radially inwardly extending projections configured to be received in the first arrangement of radially outwardly extending slots; a first stop that is arranged on the housing; and a second stop formed on the protective device and capable of engaging with the first stop to prevent realignment of the second arrangement of radially inwardly projecting protrusions with the first arrangement of radially outwardly projecting slots and subsequent removal of the protective device from the housing. [15] Angle grinder according to claim 14, wherein the first stop has an L-shaped cross-section. [16] Angle grinder according to claim 14, wherein the first stop is attached to the housing after the guard is attached to the housing. [17] Angle grinder according to claim 14, wherein the second stop is a projection extending radially outwards. [18] Angle grinder according to claim 14, wherein the first stop comprises a notch configured to receive the second stop. [19] Angle grinders, including: an output shaft that defines an axis of rotation; a housing from which the output shaft extends; a protective device that is connected to the housing and partially surrounds the output shaft; and a guard locking flange connected to the housing, wherein the guard locking flange is permanently attached to the housing and configured to hold the guard axially to the housing. [20] Angle grinder according to claim 19, wherein the guard locking flange comprises a first pin opening and the housing comprises a second pin opening, and wherein the angle grinder further comprises a pin which is pressed into the first pin opening and the second pin opening and cannot be removed from it in order to permanently attach the guard locking flange to the housing.

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