Patent Description:
Wood splitters are mechanical devices for splitting wood, which are used for splitting logs or log parts into firewood suitable for use. Logs can be separately split into shorter cylindrical parts using a saw or in the splitter itself. The splitting blade may be movable or fixed, wherein in case of the latter the log or its part must be pushed towards the blade with a pushing plate or a similar element. Usually, movement of the blade or the pushing plate is achieved with a hydraulic cylinder, its path from the origin (start point, initial position) towards the end point (for example, the fixed blade) and back defines the length of the splitting cycle. The problem occurring during work is that the logs for splitting into firewood have different lengths, while the path of the hydraulic cylinder is always the same regardless of the log length. Thus, in case of shorter logs the hydraulic cylinder performs significantly longer splitting cycle than needed, which prolongs the work and decreases productivity.

The technical problem, which is solved by the present invention, is thus design of a log splitter having an improved path of the hydraulic cylinder that will allow selection of the desired path with respect to the log length, thus leading to shorter splitting cycles and increasing productivity of the wood splitter.

Patent <CIT> describes a log splitter with optimization of the splitting cycle, wherein the splitter has a fixed splitting knife in the splitting channel, said knife being at a distance from a hydraulic pushing device, wherein said distance is the length of longest log and an additional length L. In the basic position the path of the hydraulic pushing device is limited to the length L and consequently the controller performs movement of the hydraulic pushing device for the value L, which represents a reference point. Once the reference point is achieved, the pushing device is moved into the initial position. This solution includes use of a measuring rod for measuring movement of the pushing plate with regards to the reference point. This solution functions so that in the splitting channel at least two logs are placed, wherein the first log may be in contact with the splitting knife, the second log being pushed by the pushing plate, so that the first is moved through the splitting knife and consequently splits into firewood.

The same principle is also shown for a wood splitter of the company Posch, available at the address: https://www. com/watch?v=Vg5Tj0uOrzA.

Measuring rods are generally an expensive solution, whereas they are also sensitive for dirt, impacts, and deformations. Operation of the measuring rod in the solution described in <CIT> may be disrupted by several impurities. In addition, their precise operation is not needed, as adjustment to one hundred of a millimetre is not needed nor used.

Splitters S360 Turbo produced by company Posch have a mechanism for shortening the splitting movement. The mechanism comprises a handle, which can be set into two different positions using pins, wherein one position enables the usual length of the splitting cycle, while the second position allows shortened splitting cycle. A disadvantage of this solution is that only two lengths of the splitting cycle are possible, hence the splitter cannot be adjusted to any other, intermediate size of logs or firewood, respectively. Mechanical setting for changing the length of the hydraulic cylinder path is not optimal, because the user must interfere with the device and mechanical damage to the device may occur.

The essence of the wood splitter with an adjustable path of a hydraulic cylinder for setting splitting cycle length is in that it allows the hydraulic cylinder to be stopped in a certain point followed by its return into the initial position. The hydraulic cylinder is equipped with a suitable sensor or a switch, which sends to a controller information about the position of the cylinder. The controller then with an electromagnetic hydraulic valve adjusts the path of the hydraulic cylinder based on the user's selection of the cylinder movement path, which depends on the length of the logs or resulting firewood, respectively. The electromagnetic valve then changes oil flow and thus changes the direction of movement of the cylinder. The suitable sensor is selected in the group comprising inductive sensors, end switches, a Hall sensor, optical sensor, encoder, or any other suitable electric element. The preferred choice is the inductive sensor. Said sensor or switch is arranged to detect reference points provided on a sheath attached to the hydraulic cylinder and moves forwards and backwards with the cylinder. The sensor itself is mounted on a suitable holder in a fixed manner, so that the sensor is not moved when the sheath moves. Reference points on the sheath may be holes, cat eyes, detections on steel and similar elements. It is important that the reference points can be detected with the chosen sensor or switch. Preferably, the sheath is provided with holes as reference points, as this option has the lowest price. The shape of said holes is arbitrary, usually circular or oval.

Sensors may be installed on one holder or each sensor has its own holder, wherein in case of the latter the holders are installed one next to the other or close to each other.

The material for the sheath of the cylinder is metal, suitably steel. In the preferred embodiment the sheath is an open hexagon, whereas also open circle (tube) or only sheet metal (tin plate) in the shape of letter V on top could be used, but the latter options are not preferred.

In the preferred embodiment two sensors and three reference points are used and the description of operation will be made based on this preferred embodiment. Operation has the same principle for all variants and embodiments of reference points. In the basic (closed) position of the hydraulic cylinder the first sensor is active and the second sensor is inactive, which means that under one of them a reference point, preferably hole, is located, and under the second the material of the sheath is located. The first sensor sends the position that the piston of the hydraulic cylinder is in the null (basic, initial, closed) position, wherein preferably an additional hole is provided nearby to allow smooth stopping of the cylinder. Namely, when the cylinder is returning with a high speed, every splitting movement could impact the cylinder and the sheath. This is prevented by activating sensor a bit earlier to partly close the valve and thus decreases the speed of the cylinder's return movement.

Activity of the second sensor, which is provided for the shortened splitting cycle (movement path of the cylinder), is detected at the hole in the sheath. The sensor is removed from the sheath for approximately <NUM> to <NUM>, while the threshold value for its inactivity is <NUM>. When it reaches the hole, the distance to the sensor is increased above the threshold and thus the sensor gains information about the position of the cylinder, which is sent to the controller, which then sends a signal to the electromagnetic valve, which switches the hydraulic flow and thus changes the direction of movement of the hydraulic cylinder. During movement towards the splitting blade, the second sensor obtains a signal at each hole at lengths from L1 to L3. Lengths L1, L2, L3 are lengths, where the cylinder can stop in agreement with user's settings stored in the controller. The number of required lengths is arbitrary, wherein the number of reference points is accordingly adjusted. Usually, said reference points are chosen with regards to standard lengths of firewood, which are <NUM>, <NUM>, <NUM> and <NUM>. Stopping the cylinder and its return to the initial position is thus activated with a suitably programmed controller.

The process of use of the wood splitter is performed in the following manner. The switch on a control panel is used to select the required length of movement path of the hydraulic cylinder. At selection of length L1 software of the controller waits for one signal from the second sensor. After detection of the signal, the cylinder is returned to its initial position. In case of selection of length L2 software of the controller waits for two signals from the second sensor, wherein the first signal is read as a first reference point and counted as <NUM>, after detection of the second reference point, the cylinder is returned to its initial position. In case the longest length L3 is selected, software of the controller waits for three signals from the second sensor 3b. The first signal is read as a first reference point and counted as <NUM>, the second signal is read as a second reference point and counted as <NUM>, and after detection of the third reference point, the cylinder is returned to its initial position.

Required lengths may be detected with more sensors. For example, each movement may have its own sensor and the controlled does not have to be programmed for counting signals during several different movements. Accordingly, the reference points on the sheath have to be adjusted.

The invention enables choice of shortened movement path based on the selected log length. This shortens the splitting cycle and increases productivity of the wood splitter. The process of use of the described splitter is economical and practical, as already installed equipment, i.e., sensors and controller, are used, which means that no further materials have to be installed. Thus, there is no additional costs for the material. The solution is also practical, because the sheath surrounding the cylinder is used to determine the movement path of the cylinder, wherein the sheath is a standard component of wood splitters used for protection of the piston of the hydraulic cylinder. Therefore, the invention solves the technical problem in a simple and cost-effective manner.

The wood splitter with an adjustable path of a hydraulic cylinder for optimizing the splitting cycle will be described in further detail based on exemplary embodiments and figures, which show:.

<FIG> shows a possible embodiment of an assembly of the hydraulic cylinder <NUM> and the sheath <NUM> of the cylinder <NUM> for a wood splitter according to the invention. The sheath <NUM> surrounds the cylinder <NUM>, wherein the sheath <NUM> is provided with three holes 4a, 4b, 4c, which function as reference points and are on the sheath <NUM> provided away from sensors 3a, 3b. On the holder <NUM>, installed on the framework of the wood splitter, two sensors 3a, 3b are non-movably mounted, wherein said sensors are preferably inductive sensors and are arranged one next to the other on the part of the sheath which is close to the pushing plate <NUM>. As shown in <FIG>, the distance L1 represents the length of the path from the sensor 2b to the first hole 4a, the distance L2 is the length of the path from the sensor 2b to the second hole 4b, and the distance L3 is the length of the path from the sensor 2b to the third hole 4c.

In the basic (initial, closed) position of the hydraulic cylinder the first sensor 3a is active and the second sensor 3b is inactive, which means that under it a reference point, preferably hole, is located, while material of the sheath is located under the first sensor. The first sensor 3a sends position that the piston of the hydraulic cylinder is in the null (initial) position. Further, an additional hole 4d is provided nearby, which is provided for soft stopping of the cylinder <NUM>. Namely, when the cylinder is returning with a high speed, every movement could impact the cylinder and the sheath. This is prevented by activating sensor a bit earlier to partly close the valve and thus decreases the speed of the cylinder's return movement.

The process of use in shorter logs is performed in the following manner. The switch on a control panel is used to select the required length of movement path of the hydraulic cylinder <NUM>, for example L1. At selection of length L1 software of the controller waits for one signal from the second sensor 3b. After detection of the signal, the cylinder <NUM> is returned to its initial position so that a suitable signal is sent to the electromagnetic valve <NUM>, which changes oil flow and returns the cylinder <NUM> into its initial position.

In case the longest length L3 is selected, software of the controller waits for three signals from the second sensor 3b. The first signal is read as a first reference point and counted as <NUM>, the second signal is read as a second reference point and counted as <NUM>, and after detection of the third reference point, the cylinder is returned to its initial position.

Claim 1:
A wood splitter with an adjustable path of a hydraulic cylinder (<NUM>) for optimizing the splitting cycle, said wood splitter comprising:
- a splitting channel arranged to accept at least one log and is provided with:
∘ a splitting blade on one end of the channel, and
∘ a linearly movable pushing plate on the opposite end of the channel, wherein the pushing plate is movable with a hydraulic cylinder (<NUM>),
- a controller for controlling operation of the hydraulic cylinder (<NUM>),
- an electromagnetic hydraulic valve arranged to control the hydraulic cylinder (<NUM>) based on information from the controller,
characterized in that
- the hydraulic cylinder (<NUM>) is provided with a protective sheath (<NUM>), which surrounds the cylinder (<NUM>) and said sheath (<NUM>) is equipped with at least two reference points (4a, 4b, 4c), and
- the wood splitter is provided with at least two non-movably installed sensors (3a, 3b) or switches mounted on a common holder (<NUM>) one next to another, wherein said sensors (3a, 3b) or switches are arranged to detect reference points (4a, 4b, 4c) on the sheath (<NUM>) and are connected to the controller so as to send detected reference points to the controller, on the basis of which the controller manipulates with said electromagnetic valve and consequently the hydraulic cylinder (<NUM>),
- in the basic position of the hydraulic cylinder (<NUM>) the first sensor (3a) is active and the second sensor (3b) is inactive, which means that below the first sensor (3a) the reference point, preferably a hole (4a), is located, while below the second sensor (3b) material of the sheath (<NUM>) is present,
- the reference points (4a, 4b, 4c) are arranged to define at least distances L1 and L2, preferably three lengths L1, L2, and L3, wherein the distance L1 represents the length of the path from the sensor (3b) to the first hole (4a), the distance L2 is the length of the path from the sensor (3b) to the second hole (4b), and the optional distance L3 is the length of the path from the sensor (3b) to the third hole (4c), and
- wherein based on programmed and set movement of the hydraulic cylinder (<NUM>) defined with the reference points (4a, 4b, 4c), the cylinder (<NUM>) is arranged to return to its initial position with the aid of the controller and the electromagnetic valve after detection of the suitable reference point (4a, 4b, 4c) with the sensor (3a, 3b).