In barking machines having a rotating barking ring throu which logs to be barked are transported, and a number of barking arms pivσtally mounted on this ring to be able to vary their extension towards the center of the ring and application against the periphery of the logs, a pressure fluid apparatus is known, which has the purpose to, by means of a piston cylinder mechanism, hold the barking arm against the bark and to absorb the irregu¬ larities of the log by allowing the piston-cylinder me¬ chanism to oscillate because of these irregularities and to vary the position of the barking arm and the applicati pressure against the bark by means of a pump.

A draw back in this known apparatus is that the pump dem a motor, which, if it is placed at the side of the rotat barking ring must be coupled to a pump via some sort of rotation coupling or which, if it is placed on the rotat barking ring causes further load for rotation of the bar ring, which also can cause unbalance at the rotation of the barking ring. Since the motor is necessary, it is also necessary with energy supply to this motor. This entails expenses for bringing forward electricity to the motor in case it is an electrical motor. In case a com¬ bustion engine is used the bringing forward of electrici is not necessary, but this is done at the expense of hav the motor, of practical reasons, in continuous opera¬ tion, which in its turn causes an unnecessarily high ene consumption apart from a number of draw backs on the environment.

By the Swedish specification 380 211 an apparatus in accordance with the preamble of the following claim 1 is previously known. In this apparatus a pumping device is arranged to modify the volume and the pressure of fluid in a spring chamber for the purpose of ootaining control of the level in a resilient arrangement in vehicles. In increasing the load an essential operation time is required for the pumping device to be able to transmit pressure fluid to the spring chamber in a necessary extent.

SUMMARY OF THE INVENTION

The object of the present invention is to further deve¬ lop the known technique according to the preamble of claim 1 so that the possibility is obtained to almost immediately carry out, depending on changed operation conditions, necessary adjustments of the mutual position between the parts, between which the piston-cylinder mechanism is acting, or modification of the pressure of the working space of the piston-cylinder mechanism.

The present invention fullfils the aimed object by the characterizing features in the following claim 1. Since the pumping device is arranged to achieve formation of fluid pressure in an energy accumulator, in which the fluid pressure normally is essentially higher than the fluid pressure in the working space of tne pisron-cyiinder mechanism, an excess of fluid is permanently present under such pressure that by means thereof necessary increases of the volume and/or the pressure in the working space of the piston-cylinder mechanism may be carried out almost immediately in correspondence with the changed operation conditions. In application to vehicles the invention re¬ sults in possibilities to carry out a gradual instant level control as the load of the resiliently suspended part of the vehicle increases. In application in barking machines the mounting is essentially facilitated since the need of an exter-

nal power supply to the motor for driving pumps is totally eliminated. Further, advantages with energy savings as a consequence of absence of the need of an external power supply to such motors, arise.

Other objects and advantages will appear from the fol¬ lowing dependent patent claims.

SHORT DESCRIPTION OF THE DRAWINGS

The present invention will now be described by means of an example of an embodiment during reference to the drawing showing:

Fig 1 an embodiment of the pressure fluid apparatus, accor¬ ding to the invention, used in connection with a barking machine, more precisely in connection with one of the barking arms of the barking machine.

Fig 2 an embodiment of the pressure fluid apparatus, accor¬ ding to the invention, used as a spring device for e.g. a vehicle.

Fig 3 an enlarged partial viwe of the piston-cylinder mechanism with a built-in pumping device and damping member

Fig 4 a further embodiment of the pressure fluid appa¬ ratus according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In fig 1 a pressure fluid apparatus is shown in connection with a barking arm 1 , which is pivotably journalled at a rotating (not shown) barking ring. At this barking ring several barking arms 1 are pivotably journalled.

The pressure fluid apparatus comprises a piston-cylinder mechanism 2 connected between two in relation to each other movable parts 1, 38, said piston-cylinder mecha¬ nism 2 being by its relative movement between the piston 3 and the cylinder 4 arranged to resiliently yieldingly counteract movement between the parts 1 , 38 in one direction, more precisely in the direction when the parts 1, 38 are approaching each other, by letting the fluid in the piston-cylinder mechanism 2 communicate with a first reservoir 5, which is divided by means of a displaceable member 6 and provided with a spring member 7 on the side of the displaceable member 6, which is opposite the side of the member 6 against which the fluid of the piston-cylinder mechanism is acting.

The pressure fluid apparatus comprises also a pumping device 8 which is arranged to put the first fluid under pressure by allowing said relative movement between the piston 3 and ^' the cylinder 4 to drive the pumping device ^" 8.

The volume and/or the pressure of the fluid in the piston-cylinder mechanism 2, which is constituted of either said first fluid, which is the case in the em¬ bodiments shown in fig 1 and 2 , or a second fluid, is con¬ trolled by means of a fluid control device 9, which also is comprised in the pressure fluid apparatus.

In the embodiments in fig 1 and 2 the pumping device

8 is arranged to by, via the one-way valve 11 arranged in the supply conduit 10 leading to the pumping device

8, supplied with the first fluid from the fluid sump 12, which is put under pressure by means of a displaceable member 13 in the sump 12, which is pressed against the first fluid by means of a spring member 14, which is arrang on the opposite side of the member 13 in relation to the first fluid.

The pumping device 8 in fig 1 and 2 is further arranged to pump the first fluid supplied to the pumping device 8, via a one-way valve 16 arranged in a discharge conduit 15 leading away from the pumping device 8 to a second reservoir 17, which operates as an energy accumulator, and which is constituted in the same way as the first reservoir 5 and as the fluid sump 12, i.e. with a spring member 18 acting on a displaceable member 19, which is pressed against the first fluid.

The first reservoir 5 has a pressure which essentially lies below the pressure in the second reservoir 17 and which essentially lies above the pressure in the sump 12 during operation. The second reservoir 17 shall be dimensioned to that the pressure therein is enough to set the maximum pressure in the first reservoir at least one time.

The second reservoir 17 is, via a val ^' ve 9a included in the fluid control device 9, in connection with the working space 39 included in the piston-cylinder mecha¬ nism 2, or more precisely with the first reservoir 5 being in mutual connection with the working space 39 of the piston-cylinder mechanism 2 to, by means of the spring member 7, which is shown in fig 1 and 2 as an ordinary spring, achieve an expansion of the piston-cylinder mechanism 2 and to, by means of the spring member 7, achieve a resilient yielding resistance at compression of the piston-cylinder mechanism, which compression is achieved by an external load on the piston 3 of the piston-cylinder mechanism 2. In the embodiment according to fig 1 this external load is provided on the piston 3 by the barking arm 1 when the barking arm 1 , depending on a projection on the log, is pivoted in the anti-clockwise direction, observed in fig 1.

The pumping device 8 is in the embodiment shown in

fig 1 and 2 built into the piston-cylinder mechanism

2 by that a tube 20 being concentrically firmly arranged at the end of the cylinder, which is opposite the end through which the piston rod 21 of the piston 3 extends, and by that the tube 20 is received in a hole 22 arranged in the piston 3 so that the volume of the hole 22 is varied at relative movement between the piston 3 and the cylinder 4 since the tube extends into the hole

22 dependent of the relative movement between the piston

3 and the cylinder 4.

The hole 22 is fluidly sealed in relation to the working space 39 of the piston-cylinder mechanism 2.

The piston 3 and its piston rod 21 are in fig 1 and 2 integrated to an equally thick part.

In the fluid control device 9 a valve 9B is also besides the valve 9A included, which is arranged in the conduit

23 connecting the sump 12 with the piston-cylinder mechanism 2, which valve 9B is designed to decrease the volume and pressure in vthe piston-cylinder mechanism 2.

In the fluid control device an additional valve is included ^' , namely the valve 9C which is arranged between the piston-cylinder mechanism 2 and the reservoir 5. This valve 9C shall be closed when the volume and the pressure in the piston-cylinder mechanism shall be decreased so that the reservoir in opening of the valve 9B need not be unloaded of the pressure.

The invention according to fig 1 operates in the follo¬ wing way:

The barking arm 1 transmits the forces arising from the irregularities of the log to the piston 3, which is carried by the fluid in the working space 39 so that a part of the fluid in the cylinder 4 now and then

is pressed out into the conduit 36 and into the reservoir 5 and so that the spring member 7 now and then presses out a part of the fluid from the reservoir 5 to the wor¬ king space 39 of the piston-cylinder mechanism 2. During this movement of the piston 3 fluid is sucked and pressed by means of the spring member 14 in the sump 12 from the sump 12 via the one-way valve 11 in through the tube 20 and into the hole 22 to then be pressed out into the dis¬ charge conduit 15 via the one-way valve 16 to the energy accumulator 17. When the pressure in the energy accumula¬ tor 17 has reached a certain value, the one-way valve 11 is manoeuvred, e.g. by means of a pilot pressure through the conduit 37 from the discharge conduit 15, to an open position so that the fluid under both expansion and com¬ pression of the piston-cylinder mechanism is allowed to pass the one-way valve 11. The pressure in the energy accumulator 17 can, if desired, then be used to expand the piston-cylinder mechanism since the fluid by opening the valve 9A is brought from the energy accumulator 17 to the reservoir 5 so that the volume and/or the pressure in the piston-cylinder mechanism 2 increases. An increase of the volume is desirable when the barking arm 1 shall be app¬ lied against a log with smaller diameter, while an in¬ crease of pressure is desirable when the disbarking has not been performed in a sufficiently high extent. The pressure in the energy accumulator 17 can also be trans¬ mitted in a desired extent to the sump 12 via a valve 9D. In a decrease of the volume and/or the pressure in the piston-cylinder mechanism 2 to be able to pivot away the barking arm 1 , the valve 9C is closed and the valve 9B is opened so that a discharge of fluid takes place to the sump 12. The pivoting away of the barking arm 1, i.e. pi¬ voting of the barking arm anti-clockwise in fig 1 to a position out of operation, is achieved by means of a not shown spring or the like.

The invention according to the embodiment in fig 2 is used as a spring device for e.g. cars and operates in the same way as the embodiment in fig 1 , with the addi¬ tion that a sensor 25 is arranged to sense the relative position between the piston 3 and the cylinder 4 and that a processing unit 34 is arranged to actuate the fluid control device 9 so that the sensed present value will be the same as the desired value 24 ordered by the driver of the vehicle. This is done by either opening the valve 9A so that additional fluid is pressed into the reservoir 5 from the energy accumulator 17 and closing it when the desired increased distance between the parts 38, 40 is reached, or by opening the valve 9B so that fluid is dis¬ charged from the working space 39 and the reservoir 5 and closing it when the desired decreased distance between the parts 38, 40 is reached. Preferably a pressure fluid apparatus is arranged at each wheel unit. The piston- cylinder mechanism at each wheel is arranged between the chassis 40 and the carrying arm 38 of the wheel of the car. The sensing and the processing of the present value should be done when the relative movement between the piston 3 and the cylinder 4 is as little as possible, i.e. when the car stands still. A sensing and a processing of the present value must not be done for each individual mo¬ mentary value of the present value, since such a sensing pro¬ cessing of the present value will lead to an unusable spring device since it would be elevated and lowered res¬ pectively all the time. The sensing of the present- value must therefore be done during a longer period of time during which small variations in the present value can be accepted. Should however a larger variation appear under a sensed time no processing at all of the sensed value will take place but a new sensing period must be awaited. The pressure fluid apparatus according to fig 2 can thus be elevated and lowered respectively to in¬ crease and decrease respectively the belly clearance of

the car. Since a pressure fluid apparatus is arranged at each wheel, uneven load of the vehicle can be absor¬ bed by the piston-cylinder mechanisms respectively since they are adjusted individually.

To increase the damping of the piston-cylinder mechanism 2, the piston 3 can, as shown in fig 3, at the end ex¬ tending into the cylinder 4, be provided with a damping member 26, which is provided with holes, and which extends circumferentially from the evenly thick part constitu¬ ting both piston 3 and piston rod 21 and abuts against the inner periphery of the cylinder 4. In this way the flow of the fluid back and forth through the dam¬ ping means 26 is restricted and causes a damping.

In fig 4 an additional embodiment of the pressure fluid apparatus according to the invention is shown. In this embodiment the piston-cylinder mechanism 2 comprises in itself a displacable member 27, which with its one side faces against the fluid of the piston-cylinder mechanism, preferably being liquid, and which with its other side faces against a spring member 28, consisting of a spring or gas to achieve the resilient yielding counteraction of the relative movement between the piston 3 and the cylinder 4.

In this embodiment the pumping device is separately arran¬ ged and pneumatic and communicates with the surroundings via the one-way valve 33 and via another one-way valve 32 with an energy accumulator 29 being divided by a displacable member 30, which on its one side is in con¬ tact with air and on its other side is in contact with the fluid of the piston-cylinder mechanism 2, which is pressed into the piston-cylinder mechanism via a valve 31. The valve 31 is in normal operation totally closed and operates as a control for the fluid supply to

the piston-cylinder mechanism 2. Another valve 41 is ar¬ ranged for the discharge of the fluid from the piston- cylinder mechanism 2 to a sump 42 which is divided in the same way as the energy accumulator 29, i.e. by means of a displacable member 43, which divides the fluid of the piston-cylinder mechanism 2, which in this case is a liquid, from the air of the fluid device 8, which via the one-way valve 32 and the energy accumulator 29 is suppliable to the sump 42 by means of a valve 45 arranged in a conduit 44 extending from the energy accumulator 29 to the sump 42. The sump 42 and the energy accumulator 29 are on the air side provided with a valve 35, 46 eachof which shall unload the pressure from the reservoir 29, 42 respectively. Of these valves 46 and 35 at least the valve 35 shall be able to be adjusted so that it automa¬ tically opens at the desired pressure, while the valve 46 only needs to be opened and closed. The valve 46 is however in fig 4 shown as a similar valve as the valve 35.

The embodiment according to fig 4 operates in the following way:

The barking arm transmits the forces arising from the irregularities of the log to the piston 3, which is car¬ ried by a fluid in the cylinder 4 so that the spring mem¬ ber 28 is reciprocally compressed and expanded respec¬ tively. During this movement of the piston 3 air is suc- tioned via the one-way valve 33 and p esspr' via the one¬ way valve 32 from the environment to the energy accumu¬ lator 29, which thus obtains an increased pressure. This pressure, which shall be higher than the pressure in the piston-cylinder mechanism 2, presses, at opened valve 31 the liquid into the cylinder 4. In putting the barking arm out of operation, i.e. in compressing of the piston-cylinder mechanism 2, the valve 31 shall

be closed and the valve 41 be opened to get the fluid in the cylinder 4 to flow out into the sump 42. For the pressure on the air side in the sump 42 not to be too high the valve 46 must be openedwhen the liquid in the sump 42 increases. When the barking arm again shall be applied against a log, i.e. when the piston-cylinder mechanism shall be expanded, the valve 45 is opened so that the pressure in the energy accumulator 29 can be transmitted to the sump 42 and at the same time the valve 46 is closed. The member 43 then presses back the liquid into the cylinder 4. Then the valve 41 and the valve 45 are closed while the valve 31 is opened in case addi¬ tional volume and/or pressure is desired in the cylinder 4.

This separate pumping device can unlike the pumping device built into the piston-cylinder mechanism, which is shown in fig 1 to 3, be formed double acting so that pumping is performed both when the pumping device is compressed and expanded respectively.

The pressure fluid apparatus is here described within different application areas. This shall not be considered as limiting. It can e.g. be used in connection with a seat on a tractor.

It is also obvious that the invention is not only limited to the above described embodiments but that many modi¬ fications are possible within the scope of the invention. The above described barking means could of course, within the scope of the invention, be replaced by delimbing means or other wood working means.