The invention relates to a high-pressure pump for the overload protection of a crusher unit of a crusher, in particular of a jaw crusher.
Jaw crushers of the type mentioned above are used for crushing rock material, such as natural stone, concrete, bricks or recycled material. The material to be crushed is fed to a feed unit of the material crusher plant, for instance in the form of a hopper, and fed to the crusher unit via transport devices. In a jaw crusher, two crusher jaws arranged at an angle to each other form a wedge-shaped shaft into which the material to be crushed is introduced. While one crusher jaw is stationary, the opposite crusher jaw can be moved by means of an eccentric and is supported by a pressure plate on a control unit. The latter is articulated in relation to the swingarm holding the movable crusher jaw and the actuator unit. This results in an elliptical motion of the movable crusher jaw, which crushes the material to be crushed and guides it downwards in the shaft into a crushing gap. A control unit can be used to adjust the gap width of the crushing gap.
The crusher is exposed to high mechanical loads during the crushing process. These result from the feed size, the grain distribution and the crush resistance of the fed material and from the desired crushing ratio and the filling level of the material to be crushed in the crushing chamber of the crusher. Incorrect operation of the material crusher plant, in particular if a non-crushable element, e.g. a steel element, enters the crushing chamber, can result in an overload of the crusher. This can damage or wear out components of the crusher prematurely.
In the event of an overload, the pressure plate can also serve as a predetermined breaking point. If a non-breakable object in the crushing chamber blocks the crusher jaws, the forces acting on the movable crusher jaw increase. These forces are transferred into the pressure plate. If the forces are excessive, the pressure plate buckles. This causes the movable crusher jaw to move out of the way and the crushing gap to increase. In this way the unbreakable object can then fall out of the crushing chamber. This reliably prevents damage to important system components of the jaw crusher. Clearly this procedure can only be used sensibly if the frequency of foreign elements entering the crushing chamber is very low because the pressure plate is damaged every time. Therefore, ways to avoid damage to the pressure plate based on the state of the art were sought. For this reason, EP 2 662 142 B1 proposes a jaw crusher, in which the moving crusher jaw is again supported by a pressure plate. The pressure plate itself is supported by a hydraulic cylinder on its side facing away from the movable crusher jaw. A high-pressure valve is assigned to the hydraulic cylinder. If an overload situation now occurs, the valve opens and the hydraulic cylinder is triggered. Then the movable crusher jaw can move out of the way, which increases the crushing gap. The disadvantage of this design is that the hydraulic cylinder no longer provides rigid support for the moving crusher jaw during the crushing process. The hydraulic cylinder brings too much elasticity into the system affecting the crushing result.
The invention addresses the problem of providing a means of effectively acting on the support system of the crusher jaws in the event of an overload to permit the uncrushable or difficult to crush object to escape from the crushing jaws by letting the crusher jaws move away from each other.
This problem is solved by the high-pressure pump in accordance with claim 1. Accordingly, the high-pressure pump for the overload protection of a crusher unit has an actuator unit, which adjustably accommodates an actuation element in a housing. The actuation element has at least one piston or it is coupled to at least one piston. Furthermore, at least one actuator and one pressure accumulator are provided. The actuator unit is connected in a fluid-conveying manner to the actuator such that in a pump stroke of the actuator unit a transfer medium is pumped into a second chamber of the actuator and during the pump stroke a quantity of transfer medium displaced from a further first chamber of the actuator is temporarily stored in a pressure accumulator. Hydraulic oil can be the preferred transfer medium in such a case. Such a high-pressure pump can be used to act on one or several actuators of the crusher unit. For instance, it may, in particular, be used to pressurize an actuator, which, in conjunction with an actuator unit of the jaw crusher, opens the crushing jaw of the jaw crusher when a non-crushable object enters the crushing jaw. The invention may also comprise one or more actuators to assist in the opening motion of the crushing jaw. For instance, an actuator designed as a tensioning cylinder can be supplied by the high-pressure pump, wherein the tensioning cylinder preloads a pressure plate during the opening movement. The high-pressure pump according to the invention can be integrated into an at least partially closed fluid circuit, which effectively supports a simple design.
For this purpose it may also be provided that in a return stroke of the actuator unit, the pressure accumulator conveys the transfer medium to the pump chamber of the actuator unit.
If provision is made that the first chamber of the actuator has at least the same cross-sectional area as the second chamber of the actuator, the pump chamber supplying the actuator is always completely filled with transfer medium.
In a preferred variant of the invention, the actuator unit can be blocked in a rest position and after the actuator unit has been released, it is in a position from which it is ready to perform the pump stroke. This can be implemented in a simple manner, for instance, by blocking the actuator unit in the rest position by pressurizing transfer medium in a chamber, in particular in a pump chamber designed as a blocking chamber.
To be able to implement a closed circuit system, a variant of the invention provides that the pump chambers are interconnected in such a way that during the pump stroke the blocking chamber is supplied from the actuator by a return quantity of the transfer medium and in the return stroke the blocking chamber delivers transfer medium to a further pump chamber.
According to a preferred variant of invention it may be provided that a deflector element is provided, which is designed to drive the actuator unit, and that in the rest position of the actuation element, a possible contact between the deflector element and the actuation element or the parts attached thereto is avoided. The actuation element can, for example, be adjusted by a deflector element attached to a drive shaft. The drive shaft can be part of the crusher drive, resulting in high forces being available to operate the high-pressure pump. This makes for a particularly effective crushing gap adjustment. In this way, wear can be optimized by connecting a connection piece to the actuation element, which holds a rolling element outside the housing. The rolling element can, for instance, run along a radial cam to adjust the actuation element.
A particularly preferred variant of invention is such that the pressure accumulator has a housing, in which a piston can be adjusted against the pretension of a spring and that transfer medium in the housing can be pressurized by means of the piston and the spring. Such pressure accumulators are of simple design and have no or only minor approval requirements. In this respect, they offer advantages over conventional gas accumulators.
The actuation element has a simple and pressure-stable design, if it is provided that the pistons are coaxially interconnected in the pumping direction, in particular integrally interconnected.
For the high-pressure pump, a simple design results if provision is made that a piston of the actuation element has two active sides arranged opposite from each other and that each active side is assigned to a pumping chamber.
It is conceivable to use the high-pressure pump in systems where different types of actuators are used. To be able to meet the different needs of these actuators, provision may be made that when the pistons are adjusted during the pump stroke, different volumes of a transfer medium are delivered from the pump chambers and/or that different pressures are generated in the pump chambers during the pump stroke.
The invention is explained in greater detail below based on an exemplary embodiment shown in the drawings. In the Figures:
The material flow not screened out on the first screen deck 12.1 is fed into the crusher unit 20. The crusher unit 20 has a stationary crusher jaw 21 and a movable crusher jaw 22. A crushing chamber 23 is formed between the two crusher jaws 21, 22. At their lower ends, the two crusher jaws 21, 22 define a crushing gap 24. The two crusher jaws 21, 22 thus form a crushing chamber 23 converging towards the crushing gap 24. The stationary crusher jaw 21 is firmly mounted to the crusher frame 17. An eccentric drive 30 drives the movable crusher jaw 22. The crusher drive 30 has a drive shaft 31, on which a flywheel 30.1 is mounted for co-rotation. This will be explained in more detail below. As
Finally,
The control unit 60 is used to adjust the crushing gap 24 between the two crusher jaws 21, 22.
A tensioning cylinder 40 is provided in order to be able to maintain a defined allocation of the pressure plate 50 to the control unit 60 on the one hand and to the movable crusher jaw 22 on the other hand during the crushing process. The tensioning cylinder 40 has a piston rod 41, which bears a fastening element 42 at one end. The fastening element 42 is pivotably attached to the movable crusher jaw 22. The piston rod 41 is connected to a piston 45. The piston 45 can be linearly adjusted in the tensioning cylinder 40. A beam 44 bears the housing of tensioning cylinder 40. The beam 44 is supported by at least one, preferably two, compression springs 43 on a component of the crusher frame 17. A spring preload is applied accordingly. The spring preload causes a tension, which pulls the housing of the tensioning cylinder 40 and with the latter the piston 45 and the piston rod 41. In this way a tensioning force is applied to the movable crusher jaw 22, which tensioning force is transferred to the pressure plate 50. Accordingly, the pressure plate 50 is held in a clamped and preloaded manner between the movable crusher jaw 22 and the control unit 60.
As
According to a preferred invention variant, the actuators 80 act bidirectionally. They are used to allow the adjustment of the crushing gap 24 during normal crushing operation. Accordingly, they can be controlled via a controller, for instance. Because both actuators 80 are permanently coupled to the control elements 60.1, 60.2, the control elements 60.1, 60.2 can be moved linearly with the actuators 80. The gap width of the crushing gap 24 is determined depending on the control position of the control elements 60.1, 60.2. The tensioning cylinder 40 follows the adjustment motion, i.e. it is guaranteed that the pressure plate 50 is always held securely between the two pressure plate bearings 51, 52.
While a small crushing gap 24 is set in
As
As the illustration in
The actuation element 110 can be linearly adjusted in the housing 100.1. The actuation element 110 has a first piston 110.1 and a second piston 110.2. Embodiments, in which only one piston 110.1 is used, are also conceivable. The first piston 110.1 has a relatively smaller diameter than the second piston 110.2.
A connection piece 110.3 is connected to the second piston 110.1. The connection piece 110.3 is used to guide the actuation element 110 out of the housing 100.1, the connection piece 110.3 bears a head 120. A rolling element 130 is connected to the head 120 for rotation. The rolling element 130 can have the shape of a wheel, as shown here. The rolling element 130 has an outer circumferential running surface 131.
As the drawings show, the actuation element 110 is supported in the housing 100.1 against the preload of a spring 140. The spring 140 acts on the actuation element 110 preferably in the area of one of the pistons 110.1, 110.2 and can be accommodated in a space-saving manner in one of the pump chambers, preferably in the first pump chamber 102.
The actuator unit 100 is spatially assigned to the deflector element 33 (see
If an overload occurs, the operating position as shown in
As mentioned above, it is advantageous if not only one actuator 80, but both actuators 80 are adjusted simultaneously. In this way, the crushing gap 24 can be enlarged within a very short time. In this case, both actuators 80 are connected to the first pump chamber 102.
As a result of an adjustment of the two actuators 80, the two control elements 60.1 and 60.2 are displaced relative to each other. Consequently, the movable crusher jaw 22 can move out of the way, increasing the crushing gap 24. The tensioning cylinder 40 is activated to prevent the pressure plate 50 from falling down, as mentioned above. The tensioning cylinder 40 pulls the movable crusher jaw 22 against the pressure plate 50 to keep the latter always tensioned.
In particular, it may be preferable to have the actuator(s) 80 of the actuator unit 100 pressurized two or more times within one overload cycle to open the crushing gap 24. Then the actuator unit can be designed having a relatively manageable installed size. For instance, it may be intended that the actuation element 110 of the actuator unit 100 described above performs two or more pump strokes. The actuator 80 and/or the tensioning cylinder 40 is/are in such a case not moved along its/their entire length of travel per pump stroke, but only along a partial length of travel. After the deflector element 33 is attached to the drive shaft 31, the pump strokes can be performed in short succession, one after the other, enabling the crushing gap 24 to be opened quickly.
It is also conceivable that the invention could be designed in such a way that the deflector element 33 is designed such that two or more pump strokes can be achieved per revolution. Similarly, a configuration of the invention is conceivable in which two or more actuator units are used, all of which act on the actuators simultaneously or with a time delay.
The position of the deflector element 33 on the drive shaft 31 determines the point at which the pumping action of the actuator unit 100 is initiated. The deflector element 33, which operates the rolling element 130, is arranged at an angular offset to the eccentric, which is responsible for the eccentric motion of the movable crusher jaw 22. Because of the angular offset, the opening motion of the control unit 60 can be synchronized with the motion of the moving crusher jaw. Particularly preferably, the deflector element 33 is set in such a way that the opening motion of the crushing gap 24 by the control unit 60 begins shortly before the closing motion of the crushing gap 24, which is performed by the rotation of the drive unit of the crusher. This prevents uncrushable material from being further pressed in the crusher jaw and reduces the load on the crushing mechanism. However, any other adjustment of the deflector element 33 relative to the eccentric is also conceivable. In principle, it would also be possible to adjust the position of the deflector element 33 relative to the eccentric during operation.
If a pump stroke is performed from the position shown in
In
As
A pressure accumulator 150 is also provided. The pressure accumulator 150 is used to keep hydraulic oil pressurized. In this exemplary embodiment, a housing, in which a piston 152 is preloaded against a spring 151, can be used to form the pressure accumulator 150. The housing is used to hold hydraulic oil, which is preloaded via the piston 152 and the spring 151. The spring chamber can be atmospherically balanced or have a gas pressure.
As
If now an overload occurs, the situation shown in
When the deflector element 33 meets the rolling element 130, the pumping motion starts, which pushes the actuation element 110 back from its extended position as shown in
Firstly, a pump pressure is generated in the pump chamber 103. The fluid port 100.3 is used to connect the pump chamber 103 to the chamber 40.1 of the tensioning cylinder 40. Accordingly, a pressure is introduced into the chamber 40.1, which acts on the piston 45 and thus activates the tensioning cylinder 40. Accordingly, the piston 45 moves the piston rod 41 (chamber 40.2 must be de-pressurized to do so). Simultaneously, the fluid port 100.2 is used to connect the first pump chamber 102 to the chamber 80.2 of the actuator 80. This pump pressure causes a displacement of the piston 82 in the actuator 80. This adjustment results in the coupling 81 being entrained from the right to the left. To prevent the actuator 80 from blocking, the chamber 80.1 on the other side of the piston 82 is de-pressurized into the pipe leading away from the accumulator 150. The hydraulic oil is thus de-pressurized into this accumulator pipe and fills the accumulator 150 until the pressure exceeds the pressure set in valve 187. Particularly preferably, the accumulator pressure at maximum filling quantity and the set pressure value of valve 187 are balanced. At the same time, the oil returning via the check valve 193 refills the front chamber 80.2, which gains volume during the pumping process. For this purpose, the actuator 80 has to have a certain area ratio or the return oil quantity of the tensioning cylinder 40 is used for this purpose.
If this process causes the pressure in the pipe to rise above a preset limit, the pressure is discharged into the tank 160 via the relief valve 187.
As mentioned above, the first pump stroke may be followed by a second or more pump strokes. Two unidirectional valves 184, 185 are used to secure the pressure in the tensioning cylinder 40 and in the actuator 80 after the first pump stroke (see
If the pressure rises above the value set in the valve 186, the discharged oil fills the accumulator 150. If the pressure rises above the value set in the valve 190, the oil is transferred from the chamber 103 to 104. In doing so, the oil remains in the system and is always ready for use in the next pump stroke, even after long periods at pressure limitation.
When the overload has ended, i.e. the crushing gap 24 has been opened and the uncrushable object has left the crushing chamber 23, the valves 181 and 183 are moved to their original position. In this case the actuator unit 100 is also moved back to its prepared waiting position, as shown in
Number | Date | Country | Kind |
---|---|---|---|
10 2018 110 267.4 | Apr 2018 | DE | national |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/EP2019/059215 | 4/11/2019 | WO | 00 |