Method for controlling rotational speed of motor and operator vehicle

Abstract

The invention relates to a method for controlling a rotational speed of a motor and an operator vehicle. The method comprises the steps of: preparing a first function that correlates a flow rate that can be delivered by the pump with a rotational speed of the pump; preparing a second function that correlates the flow rate delivered by the flow control valve with the level of the received control signal; at a given time: detecting the presence of one or more control signals and the level of each control signal; calculating, using a second function, a flow rate that can be delivered by each flow control valve from the level of the received control signal; calculating a total demand flow, i.e., the sum of the flows that can be delivered by each flow control valve; calculating a required rotational speed of the pump using the first function; the rotational speed of the motor is adjusted according to the required rotational speed of the pump.

Description

Technical Field

[0001] The invention relates to a method for controlling the rotational speed of a motor and to an operator vehicle.

[0002] The term "speed" refers to the number of revolutions per minute performed by the motor.

[0003] The motor may be an electric motor or an internal combustion engine.

[0004] In more detail, the present invention relates particularly (but not exclusively) to a telescopic handler. Background Art

[0005] Prior art telehandlers comprise a vehicle provided with a frame or "carriage" moveable on wheels housing an operator's cab and an operating arm which can be extended to lift and lower a load.

[0006] In some models the operating arm is hinged directly to the carriage, while other models are provided with a platform or "turntable" rotatably mounted on the carriage which has the cab and to which the operating arm is hinged.

[0007] At the distal end of the arm is attached a device for lifting or moving a load, such as, for example, a fork, a cage, a winch, etc. Figure 2 An example of an operator vehicle on which the method according to the invention can be employed is schematically shown in FIG.

[0008] The hydraulic actuators are supplied by means of a control circuit comprising valves and distributors directing the operating fluid to a plurality of actuators, according to specific activation commands which may be automatic or applied by an operator by means of suitable control elements.

[0009] The control circuit of the hydraulic actuator is connected to a pump, which in turn is driven by the engine of the vehicle. In addition to the operation of the pump, the engine of the vehicle can also be designed to generate the driving force of the vehicle using a transmission system known in the art.

[0010] Currently, the motor rotation speed is not subject to any specific control method. Usually, depending on the operating conditions of the vehicle, the motor is maintained in a steady state sufficient to ensure that the pump delivers the flow necessary to supply all actuators present on the vehicle at maximum flow. In this case, most of the flow delivered by the pump is recirculated into the tank without generating useful work, except in rare cases when the pump requires maximum flow. This leads to a large amount of unnecessary energy consumption. Summary of the invention

[0011] The main object of the present invention is to provide a method that allows reducing the energy consumption of the motor while guaranteeing the functionality of the actuator supplied by the pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Other features and advantages of the invention will become more apparent from the following detailed description of embodiments of the invention illustrated by way of non-limiting example in the accompanying drawings, in which:

[0013] - Figure 1 A schematic diagram is shown representing a system including some components on which the method according to the invention is operated;

[0014] - Figure 2 A schematic diagram of a vehicle is shown, on which the method according to the invention can be used. DETAILED DESCRIPTION

[0015] The method for controlling the rotational speed of a motor according to the invention is particularly effective for controlling the rotational speed of a motor associated with an operator vehicle provided with one or more hydraulic actuators for actuating movable parts and / or tools of the vehicle, such as one or more lifting arms, a stabilizer system, a system for rotating a turntable, etc. These movable parts and tools are known in the industry and will not be described in detail.

[0016] By means of this control circuit comprising valves and distributors directing the operator fluid to the various actuators, the hydraulic actuators are supplied according to specific activation commands which may be automatic or applied by the operator by means of suitable control elements.

[0017] In the following description, the term "valve" means a valve of the distributor type, that is to say a flow control valve designed to regulate the flow of a fluid along a pipeline by direct electrical control, electrohydraulic control, electromechanical control or other control. Even if not explicitly stated, it is understood that the valve comprises at least one valve movable in a valve seat between a closed position, in which the valve prevents flow through the valve and thus prevents flow through the pipeline in which the valve is installed, and at least one open position, in which the valve allows flow through the valve and thus allows flow through the pipeline in which the valve is installed.

[0018] Indicating an open position or configuration of a valve means one of a plurality of configurations in which the valve is in an open position.

[0019] Indicating the closed position or configuration of a valve means the configuration in which the valve is in the closed position.

[0020] A command to open refers to an action that moves the valve toward the open position.

[0021] The command to close refers to the action of moving the valve toward the closed position.

[0022] The expression "valve with electromechanical actuation" means a valve provided with an electromechanical actuator which acts on the valve or on a control element which determines the movement of the valve in order to move the valve towards an open position or towards a closed position. In the absence of an action exerted by the electromechanical actuator, the elastic means acts in opposition to the electromechanical actuator in order to move the valve in the opposite direction.

[0023] The control circuit of the hydraulic actuator is connected to a pump, which in turn is driven by the engine of the vehicle. In addition to the operation of the pump, the engine of the vehicle can also be designed to generate the driving force of the vehicle using a transmission system known in the art.

[0024] The method according to the invention is particularly effective if it is used to control the speed of an electric motor. However, the method according to the invention is suitable for controlling the speed of an internal combustion engine.

[0025] In the following, in this description reference numerals are used for a system comprising a motor (M) connected to a pump (P). The pump is in turn connected to one or more hydraulic actuators (A1, A2, A3...) designed to actuate movable parts and / or operator tools.

[0026] At least one flow control valve (V1, V2, V3, ...) electrically activated is interposed between the pump (P) and each actuator. Each flow control valve is designed to deliver a flow rate of operator fluid proportional to the level of the control signal.

[0027] Preferably, but not necessarily, the control signals for controlling the valves are electrical signals, and the level of each control signal is the intensity of the electric current.

[0028] Control valves are known in the industry. Typically, a control valve comprises a valve or coil that is movable in a sealed manner in a valve seat made inside a valve body. The valve is movable between at least a closed position, in which the valve blocks the flow of an operator fluid, and at least a fully open position, in which the valve allows the flow of an operator fluid. The valve can also adopt any intermediate position between the fully open position and the closed position. In the maximum open position of the valve, the valve allows the flow of a maximum flow of an operator fluid. In a plurality of intermediate positions of the valve, the flow that can be transmitted by the valve is reduced, depending on the actual position adopted by the operator.

[0029] The valve is movable between a closed position and an open position by means of an electromechanical actuator, such as a solenoid, etc. The position actually adopted by the valve depends on the intensity of the current supplied to the electromechanical actuator, which acts on the valve.

[0030] As is known in the art, varying the flow supplied to a hydraulic actuator causes a variation in the speed of movement of the actuator: the greater the flow supplied to the actuator, the greater the speed of movement of the actuator.

[0031] Preferably, the level of each control signal can be adjusted by means of a control device that can be operated by an operator. This allows adjusting the flow rate that can be delivered by each flow control valve (V1, V2, V3, ...) and therefore the flow rate of operator fluid sent to each actuator, in this way adjusting the speed of movement.

[0032] In other words, in a manner known in the art, the level of each control signal to each flow control valve (V1, V2, V3, ...) is adjustable by means of a control device operable by an operator, such as a joystick or other equivalent device. By actuating the control device, that is to say by positioning the control device in a selected operating position, the speed of movement of the actuator (A1, A2, A3, ...) connected to the flow control valve (V1, V2, V3, ...) acted upon by the control device can be adjusted.

[0033] According to a possible embodiment, the joystick is of electrical type and is designed to send input signals to a control module (U). For example, the electric joystick is connected via a controller area network (Can Bus) to a control module (U) capable of processing input signals from the joystick itself.

[0034] The method according to the present invention comprises preparing a first function and a second function. The term "function" means a mathematical relationship that allows two variables to be matched in a mutually unique manner. Specifically, by using each function, when the value of one of the two known variables is known, the value of the other variable can be known.

[0035] In a known manner, the structure of each function is such that it can be processed by an electronic processor so that, by receiving as input the value of one of the two variables, the processor can provide as output the corresponding value of the other variable.

[0036] The method according to the invention comprises the steps of preparing a first function which relates the flow rate that can be delivered by the pump to the rotational speed of the pump. In other words, the first function allows relating the number of revolutions performed by the pump per unit time to the flow rate that can be delivered by the pump at this number of revolutions.

[0037] Preferably, the first function is obtained experimentally by measuring the actual flow rate that can be delivered by the pump at one or more predetermined pressure values ​​and one or more predetermined rotational speeds during delivery, and performing interpolation on the measured actual flow rate using a predetermined mathematical method. Alternatively, in the case of a positive displacement pump, the first function is obtained by the displacement of the pump, and the flow rate that can be delivered at a certain rotational speed is calculated by multiplying the displacement by the number of revolutions per unit time at the rotational speed.

[0038] In general, the first function is defined as any relationship between the flow rate that can be delivered by the pump and the rotational speed of the pump. Specifically, the first function is any function that, given a certain flow request of the pump, provides a rotational speed for obtaining the requested delivery flow rate, or vice versa, given a certain rotational speed of the pump, provides the flow rate that can be delivered by the pump at the rotational speed.

[0039] The method according to the invention further comprises preparing for each flow control valve a second function relating the flow rate that can be delivered by the flow control valve to the level of the received control signal.

[0040] According to a preferred embodiment of the method, in which the flow control valve is a direct electrical control valve, an electrohydraulic control valve, an electromechanical control valve or another control valve, each second function allows to relate the intensity of the current sent to the corresponding control valve flow to the flow that can be delivered by the valve at this current intensity. This is because, as already explained, a predetermined current intensity corresponds to a predetermined position of the valve of the flow control valve corresponding to a predetermined flow that can be delivered.

[0041] The method according to the invention comprises performing the following steps at a predetermined time:

[0042] detecting the presence of one or more control signals and the level of each control signal;

[0043] using a second function to calculate the flow rate that can be delivered by each flow control valve based on the level of the received control signal;

[0044] Calculate the total demand flow, that is, the sum of the flows that can be delivered by each flow control valve;

[0045] Use the first function to calculate the required speed of the pump;

[0046] The motor speed is adjusted according to the required speed of the pump.

[0047] In other words, the method comprises detecting the presence of one or more control signals, that is to say detecting whether an operator requests activation of one or more actuators (A1, A2, A3, ...) acting on appropriate control means, taking into account a predetermined moment in time. In the presence of one or more control signals, the method comprises detecting the level of each control signal, that is to say detecting, according to a preferred embodiment of the method, the intensity of the current sent to each flow control valve (V1, V2, V3, ...).

[0048] Then, using the second function, the method consists in calculating the flow rate that can be delivered by each flow control valve as a function of the level of the control signal received. This is possible because, for the reasons already explained, the intensity of the current sent to each flow control valve causes the corresponding valve to be positioned in a predetermined position and produces a corresponding flow rate that can be delivered by the valve.

[0049] After obtaining the flow rate that can be delivered by each flow control valve, the method comprises calculating the total demand flow rate, ie the sum of the flows that can be delivered by each flow control valve at the considered moment in time.

[0050] Given the total requested flow, the method comprises calculating the required speed of the pump by means of a first function. The required speed allows the requested flow to be delivered at the moment in question. Preferably, but not necessarily, the required speed is the minimum value necessary to deliver the total requested flow.

[0051] Finally, the method includes adjusting the speed of the motor based on the required speed of the pump.

[0052] Thus, the method according to the invention enables the motor speed to be adapted to the actual flow demand of each flow control valve, according to the command given by the operator. In particular, the method enables the motor rotation speed to be adjusted to the minimum value required to allow the requested total flow to be delivered to the pump. This makes it possible to optimize the energy consumption of the motor, avoiding rotation speeds higher than those sufficient to obtain the required flow to be delivered by the pump.

[0053] Optimization of energy consumption can be achieved both in the presence of an electric motor and in the presence of an internal combustion engine. In the first case, the speed regulation is performed in a known manner by means of an electrical circuit for powering the motor. In the second case, the speed regulation is performed in a known manner by acting on the system for feeding fuel to the engine.

[0054] Preferably, but not necessarily, the step of preparing the second function comprises: for each flow control valve, experimentally measuring the flow rates deliverable at a plurality of predetermined opening positions, and interpolating the flow rates deliverable at these predetermined opening positions using a predetermined mathematical method.

[0055] According to a possible embodiment, the method according to the invention comprises the following steps: assigning a priority index to each flow control valve, and if the requested total flow is greater than the flow that can be delivered by the pump, modifying the level of the control signal of the control valve according to the corresponding priority index to reduce the flow that can be delivered by one or more control valves.

[0056] In other words, it is possible to establish a hierarchy of importance of the actuators (A1, A2, A3, ...) and, correspondingly, of the commands issued by the operator. For example, it is possible to distinguish between actuators that must always guarantee the requested flow and actuators that allow the requested flow to be reduced or cancelled when the total demand flow of the pump exceeds the maximum flow that can be delivered. This distinction can be obtained by assigning a priority index to each flow control valve.

[0057] The method comprises checking, in the presence of several control signals, whether the total demand flow is greater than the maximum flow that can be delivered by the pump. In this case, the method comprises not modifying the level of the control signal of the control valves having a priority index of a predetermined value (that is, the valves associated with the actuators that must always be guaranteed to operate at the maximum possible speed), and reducing or cancelling the level of the control signal of the control valves having a priority index value different from the previous predetermined value (that is, the control valves associated with the actuators that do not have to be guaranteed to operate under any conditions).

[0058] According to a particularly advantageous embodiment, the method according to the invention comprises detecting one or more of the following operating conditions: the presence of an onboard operator; the use of one or more commands for the actuators; the driving or stopping state of the vehicle. These operating conditions can be detected by sensors of a type known in the industry.

[0059] The method comprises increasing the speed of rotation of the motor (M) in the presence of at least one of these operating conditions. The increase in speed allows to reduce the response time at the command present for all actuators (A1, A2, A3, ...), but only in the presence of one or more of the above operating conditions. In the absence of said operating conditions, the motor speed can be kept at a predetermined minimum value, making it possible to reduce energy consumption.

[0060] The method according to the invention can be actuated by a control module (U).

[0061] In a manner known in the industry, the control module (U) mentioned in this description and the appended claims is generally indicated as a single unit, but in fact it can be equipped with separate functional modules (memory modules or operating modules), each of which is designed to control a predetermined device or operating cycle.

[0062] In short, the control module (U) may consist of a single electronic device programmed to perform the described functions, and the multiple functional modules may correspond to hardware units and / or software programs forming part of the programmed device.

[0063] Alternatively or additionally, the function may be executed by multiple electronic devices (the above-mentioned functional modules may be distributed on the multiple electronic devices).

[0064] The multiple processing units may also have one or more processors for executing the instructions contained in the memory module. These units and the above functional modules may also be distributed locally or remotely on different computers based on the architecture of the network in which they are located.

[0065] The control module (U) is provided with a control algorithm configured to actuate the steps of the method according to the invention. Furthermore, the control module (U) is connected to the control valves and is designed to adjust the level of each control signal according to the action required by each actuator (A1, A2, A3, ...). In particular, the control module (U) is connected to the control means available to the operator and, according to the commands issued by the operator, it is set to adjust the level of each control signal according to the steps provided by the method according to the invention.

[0066] The control module (U) is also connected to one or more sensors known in the industry for detecting the above-mentioned operating conditions: the presence of an onboard operator; the use of one or more commands for the actuators; the driving or stopping state of the vehicle. In addition, the control module (U) is connected to the motor (M) and is designed to regulate the rotation speed in a manner known in the industry.

Claims

1. A method for controlling the speed of a motor, wherein: The motor (M) is connected to a pump (P), which in turn is connected to one or more hydraulic actuators (A1, A2, A3, ...); An electrically activated flow control valve (V1, V2, V3, ...) is interposed between the pump (P) and each actuator, the flow control valve being designed to deliver a flow proportional to the level of the control signal; Characterized in that the method comprises the following steps: preparing a first function that relates a flow rate that can be delivered by the pump to a rotational speed of the pump; preparing a second function for each flow control valve, the second function relating the flow rate that can be delivered by the flow control valve to the level of the received control signal; At a given moment in time: detecting the presence of one or more control signals and the level of each control signal; using the second function to calculate the flow rate that can be delivered by each flow control valve according to the level of the received control signal; Calculate the total demand flow, that is, the sum of the flows that can be delivered by each flow control valve; Calculate the required speed of the pump using the first function; The speed of the motor is adjusted according to the required speed of the pump.

2. The method according to claim 1, wherein: The step of preparing the second function comprises: for each flow control valve, experimentally measuring the flow rate that can be delivered at a plurality of predetermined opening positions, and interpolating the flow rate that can be delivered at the plurality of said predetermined opening positions using a predetermined mathematical method.

3. A method according to any one of the preceding claims, wherein: The step of preparing said first function comprises measuring an actual flow rate that can be delivered by said pump at one or more predetermined pressure values ​​and at one or more predetermined rotational speeds when delivering, and interpolating the measured actual flow rate using a predetermined mathematical method.

4. A method according to any one of the preceding claims, wherein: The control signals for the flow control valve are electrical signals, and wherein the level of each control signal is an electric current intensity.

5. The method according to claim 4, wherein: The level of each control signal can be adjusted by means of a control device which can be operated by an operator.

6. The method according to any one of the preceding claims, comprising the steps of: A priority index is assigned to each flow control valve, and if the total flow requested is greater than the flow that can be delivered by the pump, the level of the control signal of the flow control valve is modified according to the corresponding priority index to reduce the flow that can be delivered by one or more flow control valves.

7. A method according to any one of the preceding claims, wherein: The motor (M), the pump (P) and the actuators (A1, A2, A3, ...) are associated with an operator vehicle; Among them, there are the following steps: detecting one or more of the following operating conditions: presence of an onboard operator; use of one or more commands for the actuator; a moving state or a stopped state of the vehicle; The rotational speed of the motor (M) is increased in the presence of at least one of the operating conditions.

8. An operator vehicle comprising: Motor (M); a pump (P) connected to the motor (M); one or more hydraulic actuators (A1, A2, A3, ...), connected to said pump (P); wherein at least one flow control valve (V1, V2, V3, ...) electrically activated is interposed between the pump (P) and each actuator; A control device designed to send a control signal capable of adjusting a level to each flow control valve; a control module (U) connected to the control device, to the flow control valve and to the motor (M); Features: The control module (U) is programmed with: a first function that relates the flow rate that can be delivered by the pump to the rotation speed of the pump; a second function that, for each flow control valve, relates the flow rate that can be delivered by the flow control valve to the level of a received control signal; The control module (U) is programmed with a control algorithm which performs the following steps at predetermined times: detecting the presence of one or more control signals and the level of each control signal; using the second function to calculate the flow rate that can be delivered by each flow control valve according to the level of the received control signal; Calculate the total demand flow, that is, the sum of the flows that can be delivered by each flow control valve; Calculating a required speed of the pump using the first function, wherein the required speed is a minimum value required to deliver the total required flow rate; The speed of the motor is adjusted according to the required speed of the pump.

9. The operator vehicle of claim 8, wherein: The control algorithm is configured to detect one or more of the following operating conditions: the presence of an onboard operator; the use of one or more commands for the actuator; the driving state or the stopped state of the vehicle; In the presence of at least one of the operating conditions, the control algorithm is configured to increase the rotational speed of the motor (M).

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