Improved system for generating vibrations

Abstract

A compactor comprising: a roller (125, 135) driven in motion by a drive system (100), a vibrating element (225, 235) comprising a mass eccentric with respect to the roller, adapted to generate vibrations of the roller, and an electric motor adapted to drive the vibrating element (225, 235), in which a controller (400) is configured to selectively drive the electric motor so that the vibrating element (225, 235) is driven in the same direction of rotation as the roller (125, 135). Figure for the abbreviation: Fig. 1.

Description

Title of the invention: Improved system for generating vibrations technical field

[0001] The present invention relates to a system for generating vibrations for a compactor. Previous technique

[0002] The generation of vibration in a machine or device such as a compactor responds to specific constraints, which lead to the creation of dedicated circuits.

[0003] Conventional circuits for vibration generation commonly employ a hydraulic pump supplying one or more hydraulic motors to drive one or more eccentric rotating masses forming an imbalance, via an on / off selector.

[0004] However, integrating such a dedicated circuit into a compactor poses problems, particularly in terms of volume, weight, and also in terms of energy transmission to power such a circuit.

[0005] The present invention thus aims to address at least partially these problems. Description of the invention

[0006] The present invention thus relates to a compactor comprising: - a roller driven in movement by a drive system, - a vibrating element comprising a mass eccentric with respect to the roller, adapted to generate vibrations of the roller, - an electric motor, adapted to drive the vibrating element, in which a controller is configured to selectively drive the electric motor so that the vibrating element is driven in the same direction of rotation as the roller.

[0007] According to one example, the compactor comprises two rollers and two vibrating elements, each vibrating element being associated with a roller.

[0008] According to one example, the controller is adapted to obtain information relating to the direction of rotation of the roller.

[0009] According to one example, the compactor further includes a sensor adapted to deliver information relating to the direction of rotation of the roller to the controller.

[0010] According to one example, the drive system comprises a primary motor, a hydraulic pump, and a hydraulic motor adapted to drive the rotating roller, the primary motor being adapted to drive the hydraulic pump. rotation, so as to power the hydraulic motor.

[0011] According to one example, the electric motor and a variator associated with said electric motor are configured so as to perform a current generator function by the electric motor during a deceleration phase of the rotation of the vibrating element.

[0012] According to one example, the electric motor is associated with a reducer, so that the rotational speed of the vibrating element is less than a rotational speed of the electric motor.

[0013] The eccentric mass of the vibrating element is then typically mobile in rotation about a pivot axis perpendicular to a rotation axis of the roller, and in which the compactor includes a control element adapted to vary the eccentricity of the mass of the vibrating element so as to vary the amplitude of the vibrations.

[0014] The reducer may for example have a central passage along the axis of rotation, which allows for example to pass an actuator of the control element.

[0015] According to one example, the electric motor is associated with a control unit mounted on a fixed chassis of the compactor and may include a position or rotation sensor for the electric motor. A fixed chassis is understood here to be a stationary element, as opposed to the moving parts of the compactor, which are mobile.

[0016] The present invention also relates to a method for controlling an electrical drive system for generating vibration within a compactor, the compactor comprising: - an electric motor adapted to rotate a vibrating element, - a drive system adapted to rotate a roller, the process being characterized in that the electric motor is controlled so that the vibrating element is selectively driven in the same direction of rotation as the roller.

[0017] According to one example, during the deceleration of the vibrating element, the electric motor is driven in rotation so as to generate an electric current and to charge a current storage means. Brief description of the drawings

[0018] The invention and its advantages will be better understood upon reading the detailed description below of various embodiments of the invention given by way of non-limiting examples.

[0019] [Fig.1] Fig.1 is a schematic representation of an example circuit according to one aspect of the present invention.

[0020] [Fig.2] Fig.2 is a schematic representation of another example circuit according to one aspect of the present invention.

[0021] [Fig.3] Fig.3 schematically represents an example of an embodiment of the present invention.

[0022] In the figures, the common elements are identified by identical numerical references. Description of the implementation methods

[0023] An example of an embodiment of the present invention is described below with reference to figures 1, 2 and 3.

[0024] The circuit as shown in these figures includes a traction system 100 and a vibration system 200.

[0025] The traction system 100 comprises two motors 120 and 130 adapted to drive the rotation of moving parts of a vehicle or machine, 125 and 135 respectively, for example, balls or rollers. The nature of the moving parts varies depending on the type of machine, in particular whether it is a simple compactor, i.e., with a single roller and an axle equipped with wheels, or a tandem compactor with two rollers. It is understood that although the examples represent two moving parts driven by two motors, these examples are not limiting, and that the present description can be directly transposed to an embodiment comprising one or more motors driving one or more moving parts, which typically include at least one roller or a ball.

[0026] The 120 and 130 motors can, for example, be hydraulic, thermal or electric motors.

[0027] Figure 2 illustrates an example in which the motors 120 and 130 are hydraulic motors, and therefore in which the traction system includes, in particular, a hydraulic circuit comprising a primary motor M1 associated with a hydraulic pump 110. The hydraulic pump 110 is connected to the hydraulic motors 120 and 130. In operation, the primary motor M1 drives the hydraulic pump 110 in rotation so as to deliver a flow rate. The hydraulic pump 110 thus supplies the hydraulic motors 120 and 130, which generate torque to drive the drive elements 125 and 135 in rotation.

[0028] The traction circuit 100 as shown is a closed-loop hydraulic circuit.

[0029] The vibration system 200 comprises two electric motors 220 and 230, adapted to drive in rotation vibrating elements 225 and 235, adapted to generate vibrations, for example, eccentric masses. The embodiment shown typically corresponds to a tandem compactor comprising two rollers. It is understood that in the case of a compactor comprising a single roller, the vibration system 200 may then comprise only a single motor driving a single vibrating element in rotation. Each vibrating element is supported by the rotating structure of the associated roller.

[0030] A schematic representation of a current storage means 250, for example an electric accumulator such as a battery which provides an electrical supply to electric motors 220 and 230.

[0031] The electric motors 220 and 230 are controlled by a controller 400, typically an electronic control unit commonly referred to by the acronym ECU, and also includes a converter (also called a variable frequency drive) that controls the frequency and the switching of the electric current to drive the motors. Particularly in the case of permanent magnet motors, the converter shapes the current that supplies the motors to control their torque and speed. The controller 400 is typically configured to individually drive each of the electric motors 220 and 230 in order to control the rotational drive of the vibrating elements 225 and 235. The system as shown in [Fig. 2] also includes a feed circuit 300, adapted to deliver feed pressure via a feed pump 310. The feed circuit 300 is typically an open circuit.It delivers pressure via the feed pump 310, this feed pressure being used in particular to provide feed pressure in the low pressure line of the traction system 100 in the case where the latter is a hydraulic circuit, but it can also be used for piloting a brake 320 or for applying pilot pressures.

[0032] The feed circuit 300 is thus connected to the traction system 100 via a safety block 150. The safety block performs a feed function and prevents overpressure. A feed element 152 and a discharge element 154 are defined for the safety block 150. The feed element 152 typically comprises one or more check valves and calibrated relief valves forming a pressure limiter adapted to provide feed at the inlet of the associated hydraulic pump 110, as well as overpressure protection.

[0033] The safety block 150 thus ensures a minimum pressure in the traction system 100 via the feed valve 152 as soon as the feed pump 310 is activated, and provides a pressure relief when the pressure in the hydraulic circuit of the traction system 100 exceeds a set value via the relief valve 154. By way of example, the relief valve 154 associated with the traction system 100 can be calibrated to a pressure of approximately 350 bar. The relief valve 154 typically comprises a valve or calibrated valve, configured as follows: in order to vent fluid to reservoir R when the pressure in one of the lines of the associated circuit exceeds the set pressure threshold. The set pressure of the set pressure element 154 is typically defined according to the permissible pressures of the various components of the hydraulic circuit under consideration, for example, where applicable, according to the maximum permissible pressures of the hydraulic motors 120, 130.

[0034] The fuel supply circuit 300 as illustrated includes a calibrated valve 330 upstream of the safety block 150, which allows the pressure applied to the brake 320 to be set as needed. The brake 320 can be connected to the wheels or the vibrating elements 225 and 235. Typically, a brake 320 is incorporated into each motor 125 and 135. Typically, the brake can be a negative brake which is applied in the absence of control pressure, and which is released when pressure is applied. The fuel supply circuit 300 is connected to a reservoir R via two calibrated valves 340 and 345 mounted in series, downstream of the calibrated valve 330 and in parallel with the exchange block 150. An exchange block 350 is typically interposed between the two calibrated valves 340 and 345. The calibrated valve 345 can be integrated into the exchange block 350.

[0035] The exchange block 350 typically contains a selector for the lower of the two pressures in the two lines of the traction circuit 100, and provides a calibrated leak from the lower-pressure branch of the circuit to replenish the oil towards the reservoir R. The calibrated valve 345 is located on the outlet line of the lower-pressure selector. When oil exits through the exchange block 350, an equal amount of oil enters through the safety block 250, via the feed valve 257. The minimum pressure in the closed-loop lines is therefore defined by the calibration of the outlet valves of the exchange blocks. The calibration of the two calibrated valves 340 and 345 defines the feed pressure applied via the exchange block 150 to the traction circuit 100.

[0036] By way of example, if we consider that the pressure relief valve 345 is set to a pressure of approximately 4 bar, the feed pressure during system operation will be approximately 5 bar, i.e., 4 bar plus the pressure setting of the feed element 152, typically around 0.5 bar, as well as the various pressure losses in the circuit, which are also, for example, around 0.5 bar. However, feed pressures of approximately 10 to 20 bar can also be chosen depending on the requirements and the choice of components.

[0037] The valve 340 operates if the pump 110 is not activated. In this case, the heat exchanger is not activated because there is no pressure difference between the lines of the closed-loop circuit. The valve 345 provides an oil outlet, acting as a pressure limiter on the feed circuit, which returns to the reservoir R via the calibrated valve 345. The feed pressure at this time is defined by the sum of the calibrated valves 340 and 345, and the closed-loop circuits are filled with oil at this pressure. through valve 152

[0038] The heat exchanger 350 provides fluid exhaust from the traction system 100, notably to renew the fluid in the circuits, particularly for filtration and cooling. The set pressure of the calibrated check valve 345 determines the fluid exhaust from the circuit 100 and therefore the fluid flow rate through the heat exchanger 350. In the illustrated example, a single calibrated valve 345 regulates the fluid exhaust for the traction system 100.

[0039] In addition, the calibration of the calibrated valve 345 will impact the feed pressure applied in the traction system 100; the pressure drop caused by the oil exhaust in the low pressure line of the traction circuit 100 will be compensated by the feed.

[0040] The controller 400 is typically configured so that the vibrating elements 225 and 235 are driven in the same direction of rotation as the displacement members 125 and 135, which reduces energy consumption and limits friction. Indeed, if the vibrating elements are rotating masses located inside the compactor cylinders and suspended within the cylinders by bearings or bushings, the relative speed of the bearing races will be lower if the vibrating elements rotate in the same direction as the compactor cylinder. Furthermore, the bearing friction will be oriented in such a way that it contributes to the vehicle's forward movement.

[0041] In the case where the controller 400 drives the traction system 100, the controller 400 then has direct information regarding the direction of rotation of the drive elements 125 and 135, and can therefore drive the electric motors 220 and 230 so that the vibrating elements 225 and 235 are driven in the same direction of rotation as the drive elements 125 and 135. In this case, the controller 400, or a human-machine interface such as a driving joystick, is considered to constitute a sensor of the rotation status and the direction of rotation of the drive elements 125 and 135. Alternatively, the compactor may include sensors adapted to provide information to the controller 400 regarding the direction of rotation of the drive elements 125 and 135, for example, a rotation sensor for the motors 120 and 130 or for the drive elements 125 and 135, or any other suitable sensor depending in particular on the nature of the traction system 100..

[0042] A vibrating part, connected to the roller, can be distinguished on the compressor from a non-vibrating part, particularly if the roller or wheels are isolated from the frame by a damping element such as a shock absorber, for example, rubber pads. The parts connected to the roller are considered vibrating parts, while the frame and the various elements mounted on the frame are considered non-vibrating.

[0043] As previously stated, the electric motors 220 and 230 are typically controlled by a controller 400 and a control unit, typically a variable frequency drive (VFD), also referred to as a "converter," which includes a motor control board and a power board for switching the current. The VFDs can be separated from the electric motors and placed in a vibration-protected environment, for example, attached to the compressor frame or another non-vibrating part. In the figures, the VFDs associated with the electric motors 220 and 230 are represented by the numerals 222 and 232, respectively. In a particular manner, depending on the motor technology chosen, each electric motor includes a rotation or position sensor connected to the associated control board by a harness to control the motor's supply current by the associated VFD and power board.The position or speed sensor is therefore of a type that can withstand vibrations. Alternatively, if the motor technology used is sensorless, the power board or the drive control board is adapted to determine the speed or position of the associated motor rotor by the shape of the supply currents. For this type of motor, there is no speed or rotation sensor remaining on the 220 and 230 electric motor. The electrical harness connecting the motor to the drive is typically configured, supported, and fixed to protect it from vibration stresses.

[0044] A speed reducer, for example a gear reducer, more particularly an epicyclic reducer, can be positioned between the electric motor and the shaft of the vibrating masses to be driven. A structure with parallel gear trains can also be considered.

[0045] The speed reducer can for example be center-pass, that is to say it has a clearance at the level of the axis of rotation, to allow passage of shafts or controls.

[0046] An additional control can be provided to vary the vibration amplitude. This variation is achieved by a greater or lesser eccentricity of the mass of a vibrating element relative to its axis of rotation. An eccentricity system is then integrated and adapted to operate in the same way in both directions of rotation, so that it can rotate in both directions without changing the eccentricity.

[0047] Figure 3 presents an example of such a command.

[0048] In the illustrated example, the pivot axis ZZ of the mass of the vibrating element 225 under consideration intersects the axis of rotation of the associated roller XX and is perpendicular to it. The eccentricity is achieved, for example, by pivoting the center of gravity of the mass away from the axis of rotation of the roller XX. The mass is then, for example, articulated on the pivot axis ZZ. A 90° pivot of the mass makes The amplitude of the vibration can be varied from zero to maximum. A control element 227, such as an axial control (for example, a cylinder, rod, or cable), allows the eccentricity to be varied from outside the roller. The control element 227 can, for example, pass through the central opening of the motor or the center-bore gearbox.

[0049] The electric motor 220 which drives the vibrating element 225 is shown here associated with a reducer 221, and is for example offset to the side of the associated reducer 221.

[0050] Alternatively, an output pinion of the electric motor 220 can be tangent to the toothed ring of the reducer 221, which creates an eccentricity of the electric motor 220 with respect to the axis of rotation of the output of the reducer 221. Such a configuration frees up the central part to facilitate the passage of control elements.

[0051] The system as proposed is particularly advantageous due to the use of electric motors for driving the vibrating elements.

[0052] Indeed, the use of electric motors allows for simplified integration compared to hydraulic or pneumatic systems commonly used for such applications.

[0053] Furthermore, electric motors can be controlled directly via the controller 400, and the direction of rotation is controlled by applying a command to the electric motor in question. Thus, the vibration system is flexible and responsive.

[0054] Furthermore, the use of electric motors to drive the vibrating elements allows for a direct connection, which is advantageous in terms of efficiency and energy balance compared to a system using an intermediate circuit. This allows for greater compactness by limiting the number of components to be installed and the size of the battery for a given operating time, while maintaining the operator's visibility of the machine's surroundings.

[0055] The system as proposed is also reversible, and allows for an energy recovery function to be performed when the vibration system 200 is stopped, as explained below.

[0056] Advantageously, the electric motors 220 and 230 of the vibration system 200 can operate as generators when the vibration circuit 200 is stopped. When the vibration circuit 200 is to be stopped, the vibrating elements 225 and 235 will temporarily continue to rotate due to their inertia. They will thus drive the shaft of the electric motors 220 and 230, which will then perform the function of an electric generator, enabling the charging of a current storage device such as the current storage device 250, for example, an electric accumulator such as a battery. Thus, all or part of the energy of the The vibration of the vibrating elements is recovered during braking. The braking time of the vibrating elements 225 and 235 can be predetermined based on their inertia, thus allowing the control unit to control the shutdown of the vibration circuit 200 to achieve vibration cessation at a desired time. If necessary, a braking device can be activated to accelerate the stopping of the vibrating elements 225 and 235.

[0057] Advantageously, the control system may include a control for activating or deactivating the function of rotating the vibrating masses in the same direction as the rotation of the moving parts. The controller 400 may, for example, include a control allowing a user to disengage this function.

[0058] For example, if the working length is very short, such as for a repair on a construction site, and if the material to be compacted is ballast, sand, or gravel, excluding asphalt, it may be preferable not to stop and restart the vibrating masses. In a more sophisticated manner, by specifying the working length, the system can determine whether or not it is preferable to reverse the direction of rotation of the vibrating masses with each pass, by comparing the energy required to stop and restart the masses, taking into account energy recovery, with the energy required to let the masses rotate in the same direction without stopping them. For example, it may be possible to specify that for a working length of less than 5 meters, the masses are allowed to rotate without changing the direction of rotation.

[0059] Although the present invention has been described with reference to specific embodiments, it is evident that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various embodiments illustrated / mentioned can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than a restrictive sense.

[0060] It is also evident that all the characteristics described with reference to a process are transposable, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device are transposable, alone or in combination, to a process.

Claims

Demands

1. Compactor comprising: - a roller (125) driven in movement by a drive system (100) comprising a primary motor (Ml), a hydraulic pump (110) and a hydraulic motor (120) adapted to drive the roller (125) in rotation, the primary motor (Ml) being adapted to drive the hydraulic pump (110) in rotation, so as to supply the hydraulic motor (120), - a vibrating element (225) comprising a mass eccentric with respect to the roller, adapted to generate vibrations of the roller, - an electric motor (220), adapted to drive the vibrating element (225) in rotation, in which a controller (400) is configured to control the electric motor so that the vibrating element (225) is driven in the same direction of rotation as the roller (125).

2. Compactor according to claim 1, comprising two rollers (125, 135) and two vibrating elements (225, 235), each vibrating element (225, 235) being associated with a roller (125, 135).

3. Compactor according to any one of claims 1 or 2, wherein the controller (400) is adapted to obtain information relating to the direction of rotation of the roller (125, 135).

4. Compactor according to claim 3, further comprising a sensor adapted to deliver information relating to the direction of rotation of the roller (125, 135) to the controller (400).

5. Compactor according to any one of claims 1 to 4, wherein the electric motor (220, 230) is configured to perform a current generator function by the electric motor (220, 230) during a deceleration phase of the rotation of the vibrating element (225, 235).

6. Compactor according to any one of claims 1 to 4, wherein the electric motor (220, 230) is associated with a reducer (221), such that the rotational speed of the vibrating element (225, 235) is less than a rotational speed of the electric motor (220, 230).

7. Compactor according to claim 6, in which the reducer (221) has a central passage along the axis of rotation (XX).

8. Compactor according to any one of claims 6 or 7, wherein the eccentric mass of the vibrating element is rotationally mobile about a pivot axis (ZZ) perpendicular to a rotation axis (XX) of the roller, and in which the compactor includes a control element adapted to vary the eccentricity of the mass of the vibrating element (225, 237) so as to vary the amplitude of the vibrations.

9. Compactor according to any one of claims 1 to 8, wherein the electric motor (220, 230) is associated with a control unit mounted on a fixed chassis of the compactor.

10. Method of controlling an electric drive system for generating vibration within a compactor, the compactor comprising: - an electric motor (220) being adapted to rotate a vibrating element (225), - a drive system (100) adapted to rotate a roller (125), the drive system (100) comprising a primary motor (Ml), a hydraulic pump (110) and a hydraulic motor (120) adapted to rotate the roller (125), the primary motor (Ml) being adapted to rotate the hydraulic pump (110) so as to supply the hydraulic motor (120), the method being characterized in that the electric motor is controlled so that the vibrating element is selectively driven in the same direction of rotation as the roller (125).

11. A method according to claim 10, wherein during the deceleration of the vibrating element (225), the electric motor (220) is driven in rotation so as to generate an electric current and to charge a current storage means (250).

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