EP2445687B1 - Chainsaw - Google Patents

Description

The invention relates to a chain saw according to the preamble of claim 1, comprising a sword, a driving pinion belonging to a drive and a running over the sword and the drive pinion saw chain, by a relative movement of the sword or part of the sword, in particular at the end of a Slider arranged sword point, and the drive pinion is tensioned and relaxed.

Such a chainsaw, for example, from the DE203 19 743 U1 out.

Many materials are cut with chainsaws. These cutters experience a special burden when cutting hard materials such as rocks. Since the cutting chain of a chain saw loses tension during the cutting of very hard materials and such a cut often takes an hour or more, on the one hand the chain tension must be constantly monitored and on the other hand the loss of tension of the cutting chain should be compensated immediately to avoid damage to the device ,

Manual mechanical chain tensioning systems have been known for some time. However, in addition to the constant monitoring of the chain tension, they require recognizing that the chain tension decreases, that is, some experience of the person operating the chain saw, and interrupting the cutting operation. Since usually unskilled workers work with the devices, in many cases, the need for re-tensioning is not known, or the relaxation of the chain tension is not recognized, so that the control and maintenance of the cutting means is neglected in use, whereby the cost of replacement and Downtimes due to machine problems increase significantly.

It is therefore an object of the present invention to design a chainsaw so that the release of the chain tension is automatically detected and this change is compensated.

This object is achieved by a chain saw with the features of claim 1, i. by in the above-mentioned chainsaw between the drive pinion and the sword, preferably in the area running from the drive pinion chain, a sensor element for detecting a change in the chain tension is arranged and independent of the load on the chain based on the change in the chain tension constantly working adjusting unit is provided for generating the relative movement.

In the chain saw according to the invention, therefore, the chain tension is automatically optimized and the disadvantages of a manual Kettennachspannung the prior art and premature wear and avoid machine problems automatically.

In the dependent claims 2 to 20 preferred embodiments of the chain saw according to the invention are characterized.

In the following, the invention will be explained in more detail with reference to embodiments which are illustrated in the accompanying drawings. The figures show various solutions for adjusting the chain tension. Fig. 1 represents a chainsaw schematically. The FIGS. 2 to 11 show the exemplary readjustment of the chain tension by several solutions. The FIGS. 12 to 20 bring exemplary solutions for picking up the chain tension with the help of electronic or mechanical sensors. The FIGS. 21 to 26 represent the internal construction of the adjusting unit 3 in different variants.

The Fig.1 schematically shows a chainsaw with the drive part 1, the chain bar 2 and the adjusting unit 3. The drive part and the sword will not be discussed further, since these parts are not relevant to the invention. The drive pinion 4 is in flight with the sword 2. The chain is in the Fig. 1 not shown.

The embodiment according to the FIGS. 2 and 3 Leans on the hitherto customary type of adjustment, in which the sword 2 is moved relative to the drive motor 1. In order to enable this adjustment, the housing of the adjusting unit 3 is divided and designed to be displaceable in the direction of the sword 2. The Fig. 2 shows the top view of the adjusting unit 3, the Fig. 3 the view from the side of the drive pinion, which has been omitted in the illustration. The division of the adjusting unit 3 relates to a part 5a, which is fixed to the drive motor 1 and an exemplary carriage 5b, on which the sword 2 is fixed. Thus, the sword 2 in the longitudinal direction relative to the drive motor 1 is displaced. The attachment or support of the chain saw for guiding the cut can be performed both on the motor side 6, as well as on the side of the chain 7. The necessary fittings are not shown.

The solution is only an example, it may instead of the Nutenführung 8 in the split housing 5a and 5b, other solutions such as trapezoidal guides, linear guides with bushings, etc. are used. The mechanism for the re-enactment will be explained in a later section, since it can be used for almost all of the presented solutions.

The FIGS. 4 to 11 are concerned with the adjustment of the chain tension by changes in the geometry between the sword 2 and the sword point and the drive pinion 4. This part of the invention is based on the usual techniques for, usually manual, retightening the chain. There are the known methods of a nose, a spindle that moves the nose and thus the sword or a gear, a rack and the associated pinion used. Stand-alone developments result from dividing the housing for the adjusting unit into a fixed part and a slide.

Fig. 4 shows the readjustment by a pinion 12 which engages in a rack 12a, which in turn constitutes a part of the sword 2. The sword 2 is moved over the longitudinal holes 12b in the desired direction. The pinion 12 is moved by the adjusting unit 3 in the sense of readjusting the chain tension.

The Fig. 5 shows another form of adjustment, in which the sword tip is moved in the longitudinal direction. The mechanism for readjustment is included in the now undivided adjustment unit 3. About a nose 9, the force is introduced from the adjusting unit 3 in the sword 2, either to move the whole sword or only the sword tip. The nose 9 is latched via the opening 11 in the slide 10. The slider 10 moves the tip 10a of the sword 2.

Fig. 6 shows a cross-section A ... A of Fig. 5 The nose 9 moves over the recess 11, the slider 10, which in turn moves the tip 10a of the sword 2 in the sense of re-tensioning.

Fig. 7 shows the simpler variant in which the sword 2 on the guide pin 13 in the longitudinal direction relative to the drive motor 1 or the adjusting unit 3 remains movable. The nose 9 of the adjusting unit is inserted into the opening 11 'and causes the adjustment of the sword. 2

The FIGS. 8 to 11 bring a more complex solution in which both the sword 2, as well as the adjusting unit 3 and the drive motor 1 keep a constant position. The adjustment is done by moving the drive pinion 4 for the chain.

at Fig. 8 the drive pinion 4 is pivoted about the motor pinion 15. The center 17 of the gear 16 is rotated in a circular path about the center of the pinion 15, for example, the positions 16 'or 16 "can be taken in. Disadvantage of this solution is that the center 17 does not remain exactly in the alignment of the sword 2 but by pivoting its height can change by more than 1 mm Fig. 9 shows the side view of the solution. To the motor shaft 14, the motor pinion 15 is driven. Both the shaft 14 and the pinion 15 remain stationary. The gear 16 is guided by the rocker 19 to the pinion 15, wherein the necessary adjusting force acts on the bore 18. About the shaft 17, the pinion 4 is driven by the gear 16. Through the solution, the pinion is moved relative to the sword 2 in the sense of a Nachspannens.

Fig. 10 (Top view) and 11 (side view) more schematically indicate a solution in which the pinion 4 by a double-executed gear similar to the characters 3 to 7 is guided parallel to the line of flight of the sword 2. The motor pinion 15 is stationary in the machine and in turn drives the gear 16 at. The pinion 15 and the shaft 20 of the gear 16 are connected to each other via the rocker 22 at a fixed distance. The torque from the gear 16 is transmitted via the shaft 20 to the pinion 21, which in turn drives the gear 24. The gear 24 is seated on the shaft 25 and drives the pinion 4 for the chain. The shafts 20 and 25 are connected to each other via the 2 rocker 23 at a fixed distance. The shaft 25 is guided in addition to the mounting of the rocker 23 in a sliding block 26. The sliding block 26 is moved by the adjusting unit 3, not shown here, in the sense of re-tensioning the chain.

The FIGS. 12 to 20 bring exemplary solutions for picking up the chain tension with the help of electronic or mechanical sensors.

The recording of the tension of the chain 31 is in the Fig. 12 shown. The only place where the chain 31 is not under tension and at which the change in length can be removed unaffected, is immediately after the pinion 4 and before the entry into the sword 2. The arrows in the Figure 12 show the direction of movement of the chain 31 and the direction of rotation of the pinion 4. The sensor 30, shown here as a wheel or roller acts on or in the adjusting unit 3. The following figures relate only to this area or to a part of Pinion 4. The roller 30 has two side treads not further described and a groove in the middle to guide the saw chain as with the sword with the lateral links.

FIGS. 13 and 14 show in a non-inventive embodiment, the decrease of the chain tension by means of the aforementioned roller 30 in side view and in plan view. The roller 30 is connected via a bearing 36 with the rocker 32. The rocker 32 leads via the bearing 33 and with the shaft 34 in the interior of the adjusting unit 3. About a, fixedly connected to the shaft 34 lever 37, the force is transmitted from the roller 30 to the spring 35. The spring 35 specifies the tension of the chain 31. From the lever 37, the manipulated variable for adjusting the chain is removed. The processing of the control signal takes place in one of the following sections.

Fig. 15 brings a erfingungsgemäße variant for transmitting the manipulated variable in the adjusting unit 3. The roller 30 is mounted on the bearing 36. The bearing 36 is fixed on the angle 39, which in turn leads to the bolt 38 in the interior of the adjusting unit 3. The spring 35, which presses on the bolt 38, again provides the necessary chain tension. This variant has advantages in the decrease of the correcting variables for the readjustment, as shown in one of the following sections.

Instead of the roller 30 and a sliding member 40 can be used from the sword. This solution has the advantage that the bearing 36 is eliminated and instead a rigid connection to the rocker 32 or the angle 39 can be provided. This solution is exemplified with the Fig. 16 shown. The sliding element 40 has the advantage that the radius 41 in Fig. 17 10 to 20 times larger than the radius of the roller 30. The slider 40 has in the middle a groove for the transport teeth of a typical saw chain, the chain 31 runs with the side members on the side parts of the groove. Apart from the simpler construction, the sliding member 40 is characterized by a much greater smoothness, as constantly several chain links rest on the running surfaces.

An electronic determination of the chain tension is in Fig. 18 treated. The sensor 50 is arranged laterally from the running direction of the chain 31 because of the higher security. The chain 31 consists of the parts 31 a, the abrasive, the outer chain links 31 b and the middle chain link 31 c with the transport tooth for the drive pinion 4. The arrow h indicates the direction of disengagement in loose chain. About the distance 59, the approximation of parts of the chain 31 is measured electronically, be it capacitive or inductive. The sensor 50 provides the output signal according to Fig. 19 , a diagram of the amplitude 52 and the time t. In the wavy curve, the individual elements of the chain, depending on their distance 59 to the sensor 50 can be seen. The individual regions of the curve 53 clearly show the small distance 59 between the sensor 50 and, for example, the cutting means 31a. The individual parts of the chain are formed in the curve 53 in the steps 53a to 53d, wherein the outer chain links 31b with the curve section 53b, the middle chain link 31c with the part 53c correlate. The area 53 d shows the increasing distance of the chain 31 from the sensor 50.

After such a wavy signal still makes little sense to readjust the chain, in a further switching stage 60, the signals 51 must be smoothed directly from the sensor 50. After the switching stage 60, a smoothed signal 54 remains in the lower region of Fig. 19 left. The threshold 55a corresponds to the measurement of the cutting means 31a, the value 55b to the outer chain links 31b, the value 55c to the middle chain link 31c and the decaying value 55d to the increasing distance h of the chain 31 from the sensor 50. The smoothed signal 54 is sufficient to The signals 62 and 63 are generated by the switching stage 61 and cause a retightening of the chain via the usual amplifier 64 for the signals and the motor 65 controlled by the amplifier 64. This servo technology corresponds to the prior art , a detailed description can be omitted.

As an alternative to the electronic sensor 50 on an inductive or capacitive basis, it is also possible to use a sensor with a fixed magnet and the change in the magnetic flux as the manipulated variable. This sensor provides a comparable signal, but has the disadvantage that any magnetizable particles that are removed during cutting, adhere to the sensor and distort the measurement.

The Fig. 20 shows by way of example the preparation of an electrical signal for adjusting the chain tension. Depending on the type of sensor, for example the electronic sensor 50 with the signal conditioning 60, the switching stage 61 or the amplifier 64 can be controlled. But there may also be a mechanical circuit, for example, from the lever 37 in Fig. 14 is operated and the switching stage 61 operated directly.

The FIGS. 21 to 30 represent the internal construction of the adjusting unit 3 in different variants. After various sources of power to readjust in question, the most important solutions are held in this area.

Fig. 21 shows an exemplary mechanical solution for readjustment: The sensor 40, by way of example and identical to the position 40 in the previous figures, transmits the tension of the chain to the shaft 70 and the spring 75, which rests in a fixed support 76. By changes in the chain tension, represented by the Double arrow above the sensor 40, the shaft 70 is axially displaced against the spring 75. The shaft 70 is set in rotation via a gear 71 of no further interest, as the arrow above the gear 71 indicates. By the displacement of the shaft 70, the clutch plates 72 and 73 are brought closer to or further away from the Reibradscheibe 77. The friction wheel 77 changes the direction of rotation, depending on whether it is touched by the clutch disc 72 or 73. The Reibradscheibe 77 is mounted on the shaft 80 which is provided with a thread 82. By the thread 82, the slider 81, which is provided with an internal thread, depending on the direction of rotation of the friction wheel 77 is set in a lateral movement. At this slider 81, a coupling device is provided, for example, the nose 9 from the FIGS. 5, 6 and 7 , The shaft 80 is fixed by the bearings 78 and 79 in the position.

The force generated here can also be used to not otherwise, but obvious mechanical solutions to the other adjustment methods of FIGS. 3 to 7 to supply with the necessary manipulated variable.

Fig. 22 Instead of the friction wheel 77, an electric motor 85 with gear 86 may be provided to make the necessary corrections. It forms the actuator for the electrical and electronic solutions in the sensor technology, as in the FIGS. 18, 19, 20 shown by way of example. The drive of a pinion 12, as in the FIG. 4 shown, can be realized directly with many commercially available transmissions and should also not be shown further.

The following two solutions use the drive fluid for the readjustment of the pressure of the rinsing fluid, which is required in any case with a high-performance saw. The entire control circuit is matched to the rinsing fluid, which creates a variety of new components and solutions.

Fig. 23 shows the control required for most hydraulic adjusting units, which is controlled by the chain tension via the sensor 40. The logic of the systems corresponds to a 3/2 control valve from the hydraulics with a middle position in which all lines are closed. This technique is believed to be known and is generally available. The control valve consists of a metal or plastic body 102 with a blind hole 108. In the Blind hole is located at the bottom of the bore, a return spring 103, which presses the control pin 100 against the chain tension, which is the sensor part 40, ident identi with the earlier names recorded. Via the bore 106, the fluid is supplied under pressure to the chamber 109, which is formed by the recess 101 in the bore 108. The holes 104 and 105 pass the fluid from the chamber 109 on to a simple turbine 110, depending on the position of the control pin 100th

If the chain tension is released, the bolt 100 slides upwards and the recess 101 releases the bore 104. Thus, the turbine 110 is rotated to the right. The rotation will, like Fig. 24 shows, transmitted via an already known gear 86 to the shaft 80 and thus to the thread 82. Fig. 22 shows the sliding block for adjusting the chain tension, for example via the sword 2. If the chain is shorter, for example by cooling after the cut, then the opening 105 is released, the turbine 110 is rotated to the left and there is a decrease in the voltage , Since the fluid runs freely after moving the turbine, a more complicated return control is not required here. The entire arrangement of the turbine 110 via the gear 86 and the threaded spindle 80 and 82 are self-locking under the load of the chain saw, which is why no clamping or braking systems are required here.

The bore 107, which leads to the chamber under the control pin 100, serves primarily to relieve the chamber from the pressure of the fluid from the supply line 106. Via the bore 107, a back pressure can also be built up for further control and control purposes, e.g. to achieve an adjustment of the chain tension to certain materials or other operating parameters.

Fig. 25 brings another solution with a fluid, preferably a liquid. It is a more complex 4/2 control valve used in hydraulics, which knows a central position of the control pin 120, in which all outputs are locked. The control valve is, for example, a part of the housing of the adjusting unit 3 and by the required holes 139 for the control pin 120, the bore 126 for the pressurized fluid, the bore 125 for the passage of the pressureless fluid, the holes 127 and 128 for the Exit 140, the hole 129 for the second exit and the relief bore 130 formed for any leaks between the control pin 120 and the bore 139.

The bores 140 and 129 may be alternately connected by the control bolt 120 to the fluid under pressure 126 or to the non-pressurized drain 125. In the middle position, as in the FIG. 25 shown, all holes 127 to 129 are locked. The spring 123 specifies the actuating force of the control pin 120 and thus the tension of the chain.

The bores from the control valve are connected to a double-acting pressure cylinder 133, wherein the output 140 is connected to the input 132 of the printing cylinder and the output 129 to the input 131 of the printing cylinder. Depending on the pressure and volume ratios in the pressure cylinder 133, the piston 134 is moved to the appropriate position. The position of the piston is transmitted via the push rod 135 to the control block 137 and from this example to the nose 9, which is connected to the sword 2.

The control pin 120 is moved by the chain tension, which is received via the already known sensor 40. If the chain tension decreases, then pressure is applied via the pressure cylinder 133 through the nose 9, e.g. adjusted the sword. Likewise, if the chain is shortened, e.g. by cooling after a cut, the pressure is released from the pressure cylinder 133 and the chain is not overstretched.

The entire control unit consists of the control pin 120 with the sensor 40, the tension of the chain against the spring 123 acts. If the tension of the chain decreases, the control pin 120 is moved upwards and releases via the holes 126, the chamber 122 and the outlet 129 the pressure via the input 131 into the pressure cylinder 133. At the same time, the inlet 132 is connected via the elements 140, 121 and 125 to the non-pressurized drain, allowing the piston to move and retighten the chain.

A big advantage of this arrangement Fig. 25 is that a readjustment in the sense of relaxation in the unpressurized state, without external energy occurs.

About the hole 130 can, as to the Fig. 23 executed, again a pressure signal to be applied in order to be able to respond to special conditions such as materials, detergents, temperatures, etc. and to ensure an optimal operating point.

Since the pressure of the fluid is usually low, for example 4 to 6 bar water pressure when using the chainsaw, considerable cross sections of the piston 134 are required for the pressure cylinder 133. However, the adjusting unit 3 should be built as small as possible in order to keep the entire machine easily manageable. It is therefore in the Fig. 26 proposed to perform the printing cylinder multiple times to obtain sufficient force for the readjustment of the sword and thus the chain even at a low pressure of the fluid.

Fig. 26 shows as an example two parallel, double executed printing cylinders, thus a 4-fold acting system, which is 4 times stronger than in FIG. 25 shown system. The system after Fig. 26 is followed by a 4/2 control valve FIG. 25 controlled, whereby the feeding of all four single cylinder via the already known outputs 132 and 131 occurs. The output 132 acts on the upper inputs of the four cylinders with the designations 166 to 169, the output 131 on the lower inputs 162 to 165. According to the pressure conditions, the pistons 154 to 157 are moved to the desired position, whereby the piston rods 170 and 171 on which said pistons are mounted, move the block 137 and thus, for example, the locating lug 9.

Depending on the design of the saw, more than the two pressure cylinders shown can be connected both in succession and in parallel, with which the force can be raised very far even at very low pressures of the fluid.

The valves for the fluid after the Fig. 23 and 25 act directly on the adjusting unit, be it a pressure cylinder, a turbine, or one of the other systems shown. If there are vibrations on the chain, for example due to uneven hardening in the material to be cut, they also trigger very fast readjustment reactions. Here, a damping system in the sensor path can limit the ongoing readjustment. Suitable damping systems are:

A cross-sectional throttle in the bores 107 and 130, so that the control bolt 100 and 120 can follow only damped the movements of the chain. As a further measure, the connection 32 or 39 between the sensor part and the control pin or the electronic control can be carried out elastically, which also fast vibrations are kept away from the adjusting unit.

Other solutions are known in fluidics or hydraulics, in which the flow rate is limited by the throttling in the supply and discharge lines to the pressure cylinders 133 and 150 to 153. Likewise, it is possible to achieve by the formation of the bores 104 and 105, a progressive valve opening, which starts with low flow rates and only with larger deviations gives a larger cross-section free. Similarly, the control bolt 100 or 120 may be ground at the edges of the chambers 101 and 121 and 122 such that at low opening, a low flow occurs.

It is also possible to have the control bolt 100 or 120 act on a rotating control valve with the logic already described. With this solution, there are further possibilities of intervention in order to effect a damping of the signals.

Claims (18)

1. Chainsaw having a strut (2), a driving pinion (4) belonging to a drive mechanism (1) and a saw chain (31) running over the strut (2) and the driving pinion (4), which can be tautened and slackened by a relative mouvement of the strut (2) or a part of the strut (2), in particular the strut tip (10a) arranged at the end of a slide (10), and of the driving pinion (4), wherein a sensor element (30, 40) is arranged between the driving pinion (4) and the strut (2), preferably in the region of the chain (31) running from the driving pinion (4), to detect an alteration in the chain tension, and wherein a continuously operating adjustment unit (3) is provided, independent of the load on the chain (31) based on the alteration in chain tension, to generate the relative mouvement, characterised in that the sensor element contains a displaceable roller (30) or a displaceable slide piece (40), over which the saw chain (31) runs.
2. Chainsaw according to claim 1, characterised in that the sensor element contains an element that generates a mechanical signal, this mechanical signal being discharged from the displacement of the roller (30) or the slide piece (40), and which activates the adjustment unit (3).
3. Chainsaw according to claim 2, characterised in that the adjustment unit (3) contains a rotating coupling shaft (70) that can be displaced by the sensor element (40) along its longitudinal axis against the force of an elastic element (75), on which two coupling discs (72, 73) are provided, between which a friction wheel disc (77) is located, the shaft (80) of which is mounted in a fixed manner and is part of an actuator (80, 81, 82) for altering the relative distance between the driving pinion (4) and the strut (2) or the strut tip (10a).
4. Chainsaw according to claim 2, characterised in that the adjustment unit (3) contains an hydraulic control valve, the control pin (100, 120) of which can be displaced by the sensor element (40) along its longitudinal axis against the force of an elastic element (103, 123) and/or a counter-pressure fluid, wherein the outlets of the hydraulic valve load an hydraulic regulator (110, 134, 154, 155, 156, 157) for altering the relative distance between the driving pinion (4) and the strut (2) or the strut tip (10a).
5. Chainsaw according to claim 4, characterised in that the hydraulic regulator is a turbine (110), which is part of an actuator (110, 86, 80, 82).
6. Chainsaw according to claim 4, characterised in that the hydraulic regulator is one or more pistons (134, 154, 155, 156, 157).
7. Chainsaw according to claim 1, characterised in that the sensor element contains means for generating an electrical signal, the output of which is connected to the input of a switching stage for signal grading (60), the output signals of which activate the adjustment unit (3).
8. Chainsaw according to one of the preceding claims, characterised in that an electronic, mechanical or hydraulic damper is arranged in the sensor element or the adjustment unit.
9. Chainsaw according to claims 3 and 8, characterised in that the damper is a part (32, 39) that connects the sensor element and the control pin or the coupling shaft, said part being elastic.
10. Chainsaw according to one of claims 4 to 6 and 8, characterised in that the damper is a restrictor in one or more bore-holes or feed and off-take lines of the hydraulic control valve.
11. Chainsaw according to one of claims 4 to 6 or 10, characterised in that the edges of one or more bore-holes of the control valve have a progressively opening shape.
12. Chainsaw according to one of claims 4 to 6 or 10 or 11, characterised in that the control pin is abraded at its operating edges.
13. Chainsaw according to one of the preceding claims, characterised in that the strut (2) or the strut tip (10a) via the slide (10)is arranged displaceably on the adjustment unit (3) or the drive mechanism (1).
14. Chainsaw according to one of claims 1 to 13, characterised in that a gear rod is provided for displacing the strut (2) thereof, with which a pinion, that can be activated by the adjustment unit (3), engages.
15. Chainsaw according to one of claims 1 to 12, characterised in that the adjustment unit (3) consists of at least two parts (5a, 5b) that can move with respect to one another, and in that the strut (2) or the strut tip (10a) via the slide (10) is connected tightly to one of the parts (5b).
16. Chainsaw according to one of claims 1 to 13, characterised in that the adjustment unit (3) has a moveable projection (9), which engages with an opening (11, 11') in the strut (2), in the slide (10), in the housing of the adjustment unit (3) or in parts of the drive mechanism (1).
17. Chainsaw according to one of claims 1 to 12, characterised in that the adjustment unit (3) is in an operative connection with an oscillation crank (19) so as to alter the position of the driving pinion (4), in which the entire axis (17) of the driving pinion (4) and of a gear wheel (16) is mounted, which engages with a motor pinion (15).
18. Chainsaw according to one of claims 1 to 12, characterised in that the adjustment unit (3) is in an operative connection with a slide piece (26) so as to alter the position of the driving pinion (4), in which the entire axis (25) of the driving pinion (4) and of a gear wheel (24) is mounted, which is part of a gearing mechanism (16, 21, 24) connected to the motor opinion (15).

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