EP1920887B1 - Tool with hydraulic percussion mechanism - Google Patents

Abstract

The tool such as an impact wrench has a pulse unit (6) having a hydraulic impact mechanism (7), a hydraulic rotor (26), a cylinder and hydraulic vanes (23), which together are driven by a compressed air motor as the drive unit. A working volume within the hydraulic impact mechanism is connected to an additional volume formed outside of it. The additional volume can be varied independently of the pressure. The hydraulic impact mechanism is arranged between the drive unit and a tool holder. The additional volume has a setting part (2) limiting at one end.

Description

The invention relates to a tool and in particular a screwdriver, with a hydraulic impact mechanism and a drive unit, wherein a working volume within the hydraulic impact mechanism can be connected to an additional volume formed outside this.

Such a tool is from the DE 202 10 453 U1 (Cooper ), wherein the working volume is connected within the hydraulic impact mechanism with an additional volume within the hydraulic cylinder through a small bore which is closed during the pulse of a blade. A lid sealed with O-rings closes the hydraulic cylinder and thereby locks the entire working volume of the impulse unit, since it is not adjustable for setting different working volumes. A spacer presses the lid against the cylinder wall and a retaining ring fixes the lid permanently. Due to the fixed mounting position of the locking ring and the distance between the hydraulic cylinder and the lid and thus the working volume is fixed and unchangeable. The space for the working fluid is not adjustable, and the required amount of the working fluid can be done only by the addition or removal via a filling opening. Conventionally, the chamber is first completely filled with a working fluid and then the removal is done with syringes, which pull the fluid from the interior until a desired volume is reached. This filling process is very complex and imprecise. Furthermore, a change in the workload is not possible.

From the document DE 40 18 084 C1 is known a pulse wrench whose hydraulic impact is closed on one side with a Hydraulikschlagwerkdeckel which is fixed against rotation by means of a positioning pin. A cover then closes the entire assembly. The working volume remains constant in this hydraulic impact mechanism.

From the DE 698 07 013 T2 For example, there is known a tool showing a screwdriver having a motor that rotates a drive member within a fluid chamber, the drive member being provided with a variable volume fluid collection chamber. With an expansion of the hydraulic fluid, the collection chamber takes the additional Fluid volume on. As the expansion decreases, the collection chamber returns the fluid to the fluid chamber. The compensation is provided by an elastically deformable membrane, which consists of two areas. The first region communicates with the fluid chamber via a channel and the second membrane layer is intended to protect against destruction by the chemically aggressive hydraulic fluid. The volume increase within the fluid collection chamber leads to a deformation of the membrane and thus to an increase in the working volume. As the temperature of the hydraulic fluid decreases, the excess fluid previously entering the collection chamber returns to the collection chamber via the channel and the membrane is relieved. The working volume can therefore only be changed depending on the pressure of the working fluid. A targeted volume adjustment is not possible.

Accordingly, it is the object of the present invention, a tool of the type mentioned in such a way that the working volume within the hydraulic impact mechanism without regard to the consistency of the working fluid and is adjustable at any time.

This object is achieved in that the associated with a working volume additional volume is independent of pressure variable.

According to the invention, a tool is provided with a hydraulic impact mechanism with a working volume and an additional volume formed outside this hydraulic impactor, wherein at least the additional volume is variable so that it does not depend on the consistency of the working fluid and not on the pressure ratios within the hydraulic impact mechanism. Rather, the adjustment of the additional volume takes place independently of the ambient conditions. Thus, a change in the additional volume can be carried out when the pressure conditions have not changed due to the operations within the pulse unit. Likewise, a change in the equalizing volume may occur as the volume of the working fluid changes. And further, an adjustment of the additional volume can be made, although the volume of the working fluid has changed.

A particularly advantageous embodiment of the invention provides that the hydraulic impact mechanism between the drive unit and a tool holder is arranged to ensure a low-loss power transmission as possible. Furthermore, can be designed particularly advantageous by this arrangement, the size of the tool.

In an advantageous embodiment of the invention, the hydraulic impact mechanism may have a one-sided limiting adjustment means. As a result, the hydraulic impact mechanism is closed at least on one side with a means that is adjustable or adjustable.

In a particularly advantageous embodiment of the invention, the additional volume can be increased and / or reduced with the adjusting means. Thus, the precise volume requirements of the user for the reserve oil, oil balance and pulse frequency change can be time-saving set to a required size.

Advantageously, the adjustment means may be a manually adjustable piston. This embodiment ensures a rapid change of the additional volume within the hydraulic impact mechanism. The adjustable piston has a particularly advantageous for the manual operation surface, which prevents by their rough nature slipping of the fingers or the hand. This can e.g. be realized by a knurling or with a grip-safe additionally applied surface coating or other suitable means.

In a further embodiment of the invention, the piston may be adjustable relative to the hydraulic cylinder via an external and / or internal thread. The adjustment via a thread offers a particularly precise way to adjust the translational travel and thus the volume change within the hydraulic impact mechanism. The use of an external and / or internal thread increases the possible applications and adapts the piston to the different installation conditions. In a preferred embodiment, the thread is a fine thread with which due to the small thread pitch even the smallest changes in volume can be realized.

In an advantageous embodiment of the invention, the additional volume between the hydraulic cylinder and the piston may be arranged. This construction ensures a direct influence on the volume when the hydraulic cylinder or piston is adjusted.

Advantageously, the piston for the volume change relative to the tool via a thread can be adjusted. Thus, a fine adjustment of the piston can take place and also precise volume changes can be carried out in small steps.

In an advantageous embodiment of the invention, the piston can be made of a resilient, stiff and low-mass material. In particular, hard anodized aluminum provides favorable characteristics for use of the piston in a pressurized and oil wetted environment. Even external loads can be absorbed very well by a piston made of coated aluminum.

In an advantageous embodiment of the invention, the piston may be sealed relative to the hydraulic cylinder with O-rings. These seals offer a good seal of the piston, especially in the pressurized and oil-wetted environment. Other suitable seals can be used.

In a particularly advantageous embodiment of the invention, the piston can be fixed in at least one rotational position. As a result, the piston can be fixed after it has reached the desired setting position. An undesirable displacement during use of the tool is thereby prevented.

In an advantageous embodiment of the invention, the hydraulic cylinder may have at least four offset by 90 ° arranged fixed rotational positions. By arranging at least four rotational positions, a sufficient, flexible fixing possibility can be provided.

Alternatively, more grooves on the piston are possible, advantageously an odd number to the number of slots on the hydraulic cylinder, e.g. 3 to 4 results in 12 positioning options per revolution of the piston.

In a further embodiment of the invention, the piston can be fixed in at least one rotational position with the hydraulic cylinder connecting. As a result, a secure positioning of the piston during use of the tool can be ensured.

Advantageously, the piston can be fixed in at least one rotational position with the hydraulic cylinder by means of a locking element. In this case, the locking element is a particularly reliable anti-rotation.

In a variant of the invention, the locking element may be a pin, sleeve or threaded pin. Due to its high shearing resistance as well as the simple and quick installation, this can be a good fixation option.

In a further embodiment of the invention, the piston for volume change with an auxiliary tool can be rotated several times. The tool is particularly easy to transfer the force required for the rotation of the piston. In addition, a tool can also be used in hard to reach mounting situations.

In a variant of the invention, the piston may have a substantially L-shaped profile. As a result, the weight of the piston can be reduced and a smaller design can be realized.

In a favorable embodiment of the invention, the piston may have an outer leg, which forms a chamber for reserve oil with the outer surface of the hydraulic cylinder. Thus, the chamber for the reserve oil can be molded with few components. The entire assembly can be made very small by this compact arrangement.

Advantageously, the piston can have an internal thread, which essentially corresponds to the external thread of the hydraulic cylinder. As a result, a perfect and jam-free connection of the piston can be ensured with the hydraulic cylinder.

In an advantageous embodiment of the invention, the piston may have two different sized cylindrical inner diameter. As a result, the piston can be adapted to the shape of the hydraulic cylinder and represents a particularly space-saving installation variant.

In an advantageous embodiment of the invention, at least one of the inner diameter of the piston may have a groove for an O-ring. By placing the O-ring within the piston, it can be sealed particularly well.

In a variant of the invention, at least one of the inner diameter of the piston may have a running surface for an O-ring. This allows a built-O-ring fit particularly well on the inner diameter and seal the system.

In a particularly advantageous embodiment of the invention, the piston may have at least one receiving opening for the locking element. Thus, the locking element can be placed securely and secure the piston against rotation.

In a favorable embodiment of the invention, the piston can be factory preset to a predetermined number of pulses, which is for example 10 to 40 Hz. This allows the user of the tool to adjust the pulse frequency range to their own needs.

In a particularly advantageous embodiment of the invention, the piston can be fixed relative to the hydraulic cylinder with the locking element after setting the number of pulses. As a result, the preset number of pulses of preferably 30 Hz can be securely fixed and secured against undesired adjustment.

Fig. 1

eine schematische Darstellung eines erfindungsgemäßen Werkzeugs,

Fig. 2

eine Schnittansicht des Hydraulikschlagwerks,

Fig. 3

eine Seitenansicht des in Fig. 2 dargestellten Hydraulikschlagwerks,

Fig. 4

eine Funktionsdarstellung des Hydraulikschlagwerks mit einem voreingestellten Zusatzvolumen für das Reserveöl vor der eigentlichen Ölbefüllung,

Fig. 5

eine Funktionsdarstellung des Hydraulikschlagwerks mit vergrößertem Zusatzvolumen zur Aufnahme des Expansionsöles nach der Befüllung und verschließen des Hydraulikschlagwerks,

Fig. 6

eine Funktionsdarstellung des Werkzeugs mit weiterem Zusatzvolumen zur Erhöhung der Impulsfrequenz. Die Impulsfrequenz erhöht sich deshalb, weil wegen des größeren Volumens gegenüber der Ölbefüllung die Impulsphase später einsetzt und die Beschleunigungsphase dadurch früher beginnt.

A preferred embodiment of the present invention will now be described with reference to the accompanying drawings. In detail show:

Fig. 1

a schematic representation of a tool according to the invention,

Fig. 2

a sectional view of the hydraulic impact mechanism,

Fig. 3

a side view of the in Fig. 2 shown hydraulic impact mechanism,

Fig. 4

a functional representation of the hydraulic impact mechanism with a pre-set additional volume for the reserve oil before the actual oil filling,

Fig. 5

a functional representation of the hydraulic impact mechanism with increased additional volume for receiving the expansion oil after filling and closing the hydraulic impact mechanism,

Fig. 6

a functional representation of the tool with additional additional volume to increase the pulse frequency. The pulse frequency increases because because of the larger volume compared to the oil filling the pulse phase starts later and the acceleration phase begins earlier.

Identical components are denoted by the same reference numerals throughout the drawings.

The Fig. 1 shows a schematic side view of a tool 1, which has a drive unit 24, a hydraulic impact mechanism 7 connected thereto and an output. The drive unit 24 is a conventional motor with compressed air supply. A valve allows the pressure to be switched on individually by the user.

The hydraulic impact mechanism consists essentially of a hydraulic rotor 26, a hydraulic cylinder 11 and hydraulic blades 23, which are driven together by a pneumatic motor as the drive unit 24. By located in a pulse chamber 18 of the hydraulic cylinder pressure medium, such as hydraulic oil, the hydraulic rotor 26 is taken with the tool holder 25 rotating. This will screw a bolt or nut into a component. As long as the screw head or the nut is not resting, the hydraulic rotor 26 and the hydraulic cylinder 11 is rotated further by the drive unit 24. However, as soon as the screw head or the nut are seated, the hydraulic rotor 26 experiences a counterforce. To tighten the screw or nut, it is now necessary that the hydraulic rotor 26 continues to apply torque to the screw. During the screwing operation, the space in the cylinder housing 11 eccentric to the hydraulic rotor 26 causes different pressure ratios on the hydraulic rotor 26 and higher compression in the narrowed housing space 11. The pulse unit 6 has a hydraulic impact mechanism 7, which has four sealing areas on the hydraulic cylinder 11 and four fins 23 on the hydraulic rotor 26. During a pulse phase, the lamellae 23 fastened in the cylinder 11 at the web-shaped sealing regions 9 of the hydraulic cylinder 11 seal the four spaces formed in the pulse chamber 18. Two opposite rooms are high pressure chambers and the other two opposite rooms are low pressure chambers. The resulting pressure acts on the slats 23 and generates a hydraulic pulse, which occurs in rapid succession by the motor rotation and corresponds to the hitting of a mechanical impact wrench. After the pulse has been delivered, the drive unit 24 must again accelerate the hydraulic cylinder 11 for the next pulse over a full revolution. In order for the pulses to be able to reach each other quickly, a short transit time of the sealing regions 9 after the last impulse applied is necessary.

A connection to the additional volume is sealed by a lamella during the pulse phase, see Fig. 2 ,

For simplicity, for example, a screw attachment for the tool holder or the compressed air supply was not shown.

Fig. 2 shows a sectional view of the hydraulic impact mechanism 7 with a drive spindle 26 which extends from the drive unit 24 through the hydraulic impact mechanism 7. At the free end of the tool protruding end of the drive spindle 26, the desired tool for the work is used. The lateral cover of the hydraulic impact mechanism 7 takes place on the output side of the hydraulic rotor 26 through a bearing cap 27, which has a filling opening for the hydraulic oil. The other side of the hydraulic impact mechanism 7 is closed by a rotatable piston 2. The assembly of the pulse unit 6 before introduction into the screwdriver 1 proceeds as follows. The already assembled hydraulic impact mechanism 7 is closed on one side with the bearing cap 27 and on the other side with the rotatable piston 2 and the round O-rings 13, 14 associated therewith. Before filling the pulse unit 6 with the working fluid, the rotatable piston 2 is screwed axially onto the hydraulic cylinder 11 until it reaches the stop position. If the piston is rotated counterclockwise before filling, for example 1 turn when filling this additional volume also filled with working fluid and is available as a useful reserve fluid later when needed. Then the working fluid, in particular hydraulic oil, can be introduced through the filling opening into the pulse unit 6. If the working volume within the pulse unit 6 has been completely filled with hydraulic oil, the filling opening in the bearing cap 27 is tightly closed. Within the pulse unit 6 is now no more air.

The rotatable piston 2, which is still in reserve position ( Fig. 4 ) is located with the hydraulic cylinder 11, can now be rotated and thus moved axially on the hydraulic cylinder 11, so that between the end faces of the piston 2 and the hydraulic cylinder 11, a chamber 3 with a corresponding additional volume 4 is formed. The size of the chamber can be increased and reduced in limits by turning the piston 2. In this case, the additional volume goes to zero when the piston abuts the end face of the hydraulic cylinder 11 and reaches its maximum volume when it is axially displaced so far from the end face of the hydraulic cylinder 11 until the last possible sealing position is reached. This sealing position is determined by the O-ring 13 on the outer periphery of the hydraulic cylinder 11. Advantageously, a stop limits the axial movement possibility.

During operation of the tool, the working fluid within the hydraulic impact mechanism 7 heats up and expands. If no sufficiently large additional volume is made available, the pulse unit will possibly stop until the working fluid has cooled down again and the entire working fluid has been reduced. With the rotatable piston 2, the necessary additional volume is provided. For this purpose, the piston is rotated counterclockwise and by the axial displacement increases the space between the end faces of the piston 2 and the hydraulic cylinder 11. As in Fig. 5 to see, so the fluid compensation volume can be adjusted.

If the working fluid is filled in the hydraulic impact mechanism 7, when the rotatable piston 2 in the in Fig. 4 is shown, a volume around the chamber 3 larger volume of the working fluid (reserve fluid) can be filled.

The tool can be factory filled with working fluid so that it reaches a pulse frequency of about 30 Hz. During use of the tool, the reduction of the pulse frequency due to the heating of the working fluid can be counteracted be rotated by the rotatable piston 2 counterclockwise and thus the additional volume 4 is increased. Thus, in the further course of the rotatable piston 2 can not turn independently, a locking element 15, which is in particular a pin, sleeve or a threaded pin, inserted for axial securing between the hydraulic cylinder 11 and the rotatable piston 2. This locks the two parts together. Another O-ring can additionally secure the inserted locking element axially.

The adjustment of the rotatable piston 2 to increase the additional volume 5 and thereby increasing the pulse frequency can be carried out as often, until the additional volume is either too large and the working fluid thereby does not provide enough pressure for the pulse structure or the rotatable piston due to its dimensions pushes its limits.

If the additional volume 5 is to be reduced because the working fluid has been consumed and to restore the pressure within the pulse chamber or reduce the pulse frequency, the reserve oil must be activated and the piston 2 rotated clockwise so that it shifts axially on the hydraulic cylinder 11 , For this purpose, the elastic ring 22 and the locking element 15 of the piston must first be removed and after the adjustment has been completed both are reused.

The axial rotation of the rotatable piston 2 can also be performed with other axially or radially arranged fastening means, such as a split pin.

Furthermore, the axial displacement of the rotatable piston 2 is also possible by other suitable measures, such as a splined connection. For sealing, all other sliding seals can be used instead of O-rings.

Claims (24)

1. Tool (1), in particular an impact wrench,
   with a pulse unit (6) having a hydraulic impact mechanism (7) and a drive unit (24),
   wherein a working volume (5) within the hydraulic impact mechanism (7) can be connected to an additional volume (4) formed outside of it,
   characterised in that,
   at least the additional volume (4) can be varied independently of the pressure.
2. Tool (1) according to Claim 1, characterised in that the hydraulic impact mechanism (7) is arranged between the drive unit (24) and a tool holder (25).
3. Tool (1) according to one of the aforementioned claims, characterised in that the additional volume (4) has setting means (2) limiting at one end.
4. Tool (1) according to Claim 3, characterised in that the additional volume (4) can be enlarged and reduced by means of the setting means (2).
5. Tool (1) according to claim 3 or 4, characterised in that the setting means (2) is a manually adjustable piston (2).
6. Tool (1) according to claim 5, characterised in that the piston (2) can be set via an external and / or internal thread relative to the hydraulic cylinder (11).
7. Tool (1) according to claim 5 or 6, characterised in that the additional volume (4) is arranged between the hydraulic cylinder (11) and the piston (2).
8. Tool (1) according to one of the claims 5 to 7, characterised in that the piston (2) is manufactured from a resilient, stiff and low-mass material, in particular hard anodised aluminium.
9. Tool (1) according to one of the claims 6 to 8, characterised in that the piston (2) is sealed relative to the hydraulic cylinder (11) with O-ring seals (13, 14).
10. Tool (1) according to one of the claims 5 to 9, characterised in that the piston (2) can be fixed in at least one rotary position (16).
11. Tool (1) according to claim 6, characterised in that the hydraulic cylinder (11) has at least four fixable rotary positions (16) which are arranged offset, in particular by 90°.
12. Tool (1) according to one of the claims 6 to 8 or 11, characterised in that the piston (2) is fixed in at least one rotary position (16) relative to the hydraulic cylinder (11).
13. Tool (1) according to one of the claims 6 to 8 or 11, characterised in that the piston (2) is fixed in at least one rotary position (16) relative to the hydraulic cylinder (11) by means of a locking element (15).
14. Tool (1) according to Claim 13, characterised in that the locking element (15) is a pin, sleeve or threaded stud.
15. Tool (1) according to one of the claims 5 to 14, characterised in that the piston (2) can be rotated with an auxiliary tool to change the volume.
16. Tool (1) according to one of the claims 5 to 15, characterised in that the piston (2) has an essentially L-shaped profile.
17. Tool (1) according to one of the claims 6 to 8, 11 or 13 characterised in that the piston (2) has an outer limb profile which forms a chamber (3) and (4) with the hydraulic cylinder (11) for reserve oil and compensating oil.
18. Tool (1) according to claim 6, characterised in that the piston (2) has an internal thread, which can be screwed onto an external thread of the hydraulic cylinder (11).
19. Tool (1) according to one of the claims 5 to 18, characterised in that the piston (2) has two cylindrical internal diameters of different size.
20. Tool (1) according to claim 19, characterised in that at least one of the internal diameters of the piston (2) has a groove for an O-ring seal (13, 14).
21. Tool (1) according to claim 19 or 20, characterised in that at least one of the internal diameters of the piston (2) has a mounting surface for an O-ring seal (13, 14).
22. Tool (1) according to claim 13, characterised in that the piston (2) has at least one receptacle opening or groove for the locking element (15).
23. Tool (1) according to one of the claims 5 to 22, characterised in that the reserve oil, the oil compensating volume and the increase in pulse frequency can be set simultaneously with the piston (2).
24. Tool (1) according to claims 13 or 22, characterised in that the piston (2) can be fixed relative to the hydraulic cylinder (11) with the locking element (15) after setting the pulse rate.

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