Method for controlling a construction machine pump

Abstract

A method for controlling a construction machine pump, including a control system, a construction machine, and a computer program implementing this control method, the method comprising the following steps: setting (82) the pump to a first pumping speed (V1) according to a user-defined setpoint, determining (83) the product output flow rate of the construction machine, progressively reducing (84) the pumping speed while the product output flow rate remains stable, until a second pumping speed (V2) is reached, from which point the product output flow rate begins to decrease, and stabilizing (87) the pumping speed. Fig. 3

Description

Title of the invention: Method for controlling a construction machine pump technical field

[0001] The present exposition relates to a method of controlling a construction machine pump as well as a control system, a construction machine and a computer program implementing this control method.

[0002] Such a control method can be used for any type of pump and any type of construction machine used in the building and construction sector, and in particular pumping and / or mixing machines for pasty or viscous products such as mortars, concretes and liquid screeds. Previous technique

[0003] Known machines for pumping and / or mixing pasty or viscous products in the building and construction sector suffer from a fairly low yield and rapid wear.

[0004] Indeed, most of the pumps used by these machines include components made of deformable materials, such as elastomers, which deteriorate rapidly due to the viscosity and abrasiveness of the pumped products. This is particularly true of peristaltic pumps and progressive cavity pumps (PCPs). Thus, these pumps, whose initial efficiency is already quite low, see their efficiency decrease rapidly as these components wear out, until they can no longer perform their function.

[0005] A second reflux phenomenon further aggravates the situation. Indeed, the viscosity of the pumped products leads to a significant increase in pressure at the pump outlet, an increase that is all the more significant as the transport pipes connected to the pump outlet are generally of small diameter (50 mm most often), of great length (frequently greater than 20 m), with high coefficients of friction, and therefore lead to significant pressure losses.

[0006] The pressure thus obtained at the pump outlet can then significantly exceed the material resistance characteristics of the pumps, resulting in reflux which hinders the progression of the product and, given the abrasiveness of the latter, rapidly deteriorates the moving parts of the pump as well as its sealing segments.

[0007] There is therefore a real need for a method of controlling a construction machine pump, as well as a control system, a construction machine, and a computer program, making it possible to reduce the drawbacks inherent in the configurations known figures mentioned above. Description of the invention

[0008] The present description relates to a method for controlling a construction machine pump, said pump being configured to pump fluid, pasty and / or viscous products such as mortars, concretes or self-leveling screeds, comprising the following steps: controlling the pump to a first pumping speed according to a setting desired by the user, determination of the product output flow rate of the construction machine, progressive reduction of the pump speed as long as the product output flow rate remains stable, until a second pumping speed is reached from which the product output flow rate begins to decrease, and stabilization of the pumping speed.

[0009] For the reasons explained above, the outlet pressures of such construction equipment pumps are very high, typically exceeding 10 bar, and therefore cause these pumps to operate beyond their theoretical operating range. The inventors then observed that, in such pressure ranges, beyond a certain rotational speed, the product output flow rate no longer increases linearly with the rotational speed: indeed, in this operating range, the effort required to increase the product output flow rate becomes increasingly greater. Consequently, the pump efficiency decreases more and more as one attempts to achieve a high output flow rate.

[0010] However, probably due to the viscosity of the pumped product, the inventors found that while a significant effort was required to establish a given output flow rate, it was then possible, once this flow rate was established, to maintain it by applying less effort. In other words, the inventors discovered that the relationship between the pump's output flow rate and its rotational speed exhibited a hysteresis phenomenon within such an operating range.

[0011] Thus, thanks to the control method described herein, it is possible to take advantage of this hysteresis phenomenon to reduce the pump's rotational speed once an output flow rate has been established, while maintaining that output flow rate. This allows for an increase in pump efficiency.

[0012] Furthermore, by reducing the pump's rotational speed for a given output flow rate, unnecessary stress on the pump's internal components is avoided. This limits the impact of this overpressure regime on the pump's internal components, particularly its deformable parts, thereby increasing the pump's lifespan. Indeed, it is clear that, without the speed reduction step proposed by this In this process, the energy differential associated with this speed differential, which is unproductive since it occurs at a constant output flow rate, contributes to the deterioration of the pump's internal components. Consequently, a reduction in backflow phenomena is also observed.

[0013] In particular, the pumped products may have a viscosity greater than 500 Pa.s, preferably between 500 and 5000 Pa.s.

[0014] In some embodiments, the pump is a positive displacement pump. Indeed, these positive displacement pumps often include deformable parts and are therefore particularly sensitive to overpressures and backflow phenomena.

[0015] In some embodiments, the pump includes at least one deformable element capable of causing reflux in the pump.

[0016] In some embodiments, the pump is a progressive cavity pump or a peristaltic pump. Both types of pump include deformable elements. In particular, progressive cavity pumps are frequently used in construction machinery designed to pump and / or mix pasty or viscous products.

[0017] In some embodiments, the pump is hydraulically controlled.

[0018] In some embodiments, the pump is controlled by a hy motor variable flow draulic.

[0019] In some embodiments, the speed of the pump is determined by measuring the hydraulic flow rate of the hydraulic pump.

[0020] In some embodiments, the speed of the pump is determined by measuring the rotational speed of its shaft.

[0021] In certain embodiments, the pump is used in a pressure range exceeding its nominal pressure range. This nominal pressure range is the pressure range specified by the pump manufacturer. Consequently, the pump is used outside its optimal efficiency range. The proposed method then makes it possible to limit the decrease in efficiency necessarily observed outside this optimal range.

[0022] In certain embodiments, the construction machine includes a product outlet pipe connected to the pump outlet. This outlet pipe, due to its considerable length and small diameter, contributes significantly to the pressure losses generated by the pumped product and therefore to the increase in pressure at the pump outlet.

[0023] In some embodiments, the product outlet pipe has a diameter less than or equal to 100 mm, preferably less than or equal to 50 mm.

[0024] In some embodiments, the product outlet pipe has a length greater than or equal to 10 m, preferably greater than or equal to 20 m.

[0025] In some embodiments, the product exit process is flexible. It It can be made of elastomer, among other materials. This further increases the pressure losses generated by the pumped product.

[0026] In certain embodiments, the output flow rate of the construction machine is determined by direct measurement at the machine's outlet using a flow meter. If the construction machine is equipped with an outlet pipe, this output flow rate measurement can be taken at the outlet of the outlet pipe. For example, this flow meter can be an electromagnetic flow meter.

[0027] In certain embodiments, the output flow rate of the construction machine is determined by calculation from the pressure measurement at the pump outlet. In particular, a pressure sensor, for example a diaphragm sensor, may be provided at the pump outlet. Such a calculation may be based on Poiseuille's law, along the outlet pipe, which is expressed as follows: Q = ir.AP.U / Sql where Q is the volumetric flow rate, that is to say the output flow rate. AP is the differential pressure between the pressure at the pump outlet and atmospheric pressure. r is the inside radius of the outlet pipe, q is the dynamic viscosity of the pumped product, and 1 is the length of the outlet pipe.

[0028] In certain embodiments, the construction machine includes a human-machine interface allowing the input of at least one parameter of the outlet pipe and / or the pumped product. In particular, it is possible to input the values ​​of r, q, and / or 1. It is also possible to select the product name from a list or to choose a pre-recorded configuration.

[0029] In certain embodiments, a new second pumping speed is determined each time a new setpoint is configured by the user. Thus, each time the user changes the flow rate setpoint, either directly or by manually adjusting the pump speed, the control method automatically adapts the pump speed to achieve the same output flow rate, corresponding to the user's setpoint, at a lower speed. The pump efficiency is therefore optimized at all times.

[0030] In certain embodiments, the step of progressively reducing the pumping speed is carried out in increments, i.e., discontinuously. The value of these increments can be fixed and predetermined or variable depending on the pump's rotational speed. For example, this reduction is carried out in increments of 2% of the setpoint speed with continuous monitoring of the effects of this reduction. This control loop repeats at regular intervals, for example, every 10 seconds.

[0031] In certain embodiments, the step of progressively reducing the speed of Pumping is carried out continuously, preferably in a linear fashion.

[0032] In some embodiments, the step of progressively reducing the pumping speed is carried out along a slope between 100 t / min2 and 200 t / min2.

[0033] In some embodiments, during the pumping speed stabilization step, the pumping speed is stabilized at the value of the second pumping speed.

[0034] In certain embodiments, during the pumping speed stabilization step, the pumping speed is stabilized at a value between the second and first pumping speeds. In other words, during the pumping speed stabilization step, the pumping speed is raised above the second pumping speed. This is useful, for example, if the outlet flow rate has decreased too significantly before the stabilization step.

[0035] Control method, wherein, during the pumping speed stabilization step, the pumping speed is stabilized at a value V3 established according to the following equation: V3 = V2 + e, where V2 is the second pumping speed, and e is a strictly positive value less than 10% of V2. This value e can be fixed and predetermined or variable and a function of the value of V2.

[0036] In some embodiments, the value e is between 1 rpm and 30 rpm.

[0037] In certain embodiments, the product output rate is monitored by The pumping speed is constantly adjusted to find the lowest speed that achieves the desired product output flow rate. In this case, the stabilization phase is performed dynamically, allowing for optimal pump efficiency at all times.

[0038] The present disclosure also relates to a control system for a construction machine comprising a pump configured to pump fluid, pasty and / or viscous products such as mortars, concretes or self-leveling screeds, comprising a sensor, configured to measure the product output flow rate of the machine or a parameter representative of this product output flow rate, a control unit, configured to operate the pump and impose a pumping speed, in which the control unit is configured to initially control the pump at a first pumping speed, in which the control unit is configured to, in a second step, gradually reduce the pumping speed of the pump as long as the product output flow rate remains stable, until a second pumping speed is reached at which the product output flow rate begins to decrease, and in which the control unit is configured to, in a third step, stabilize the pumping speed.

[0039] All or part of the additional features described above with respect to the control method can be applied to this control system, and vice versa. In particular, this control system benefits from all the advantages of the control method described above.

[0040] The present description also relates to a construction machine, comprising a pump, configured to pump fluid, pasty and / or viscous products such as mortars, concretes or self-leveling screeds, and a system according to any one of the preceding embodiments.

[0041] The present exposition also relates to a computer program, comprising instructions for executing the steps of the control process of any of the preceding embodiments.

[0042] The aforementioned features and advantages, as well as others, will become apparent from the following detailed description, examples of implementations of the control method, the control system, and the proposed construction machine. This detailed description refers to the accompanying drawings. Brief description of the drawings

[0043] The attached drawings are schematic and are intended primarily to illustrate the principles of the exposition.

[0044] On these drawings, from one figure to another, identical elements (or parts of elements) are identified by the same reference signs.

[0045] [Fig. 1] The [Fig. 1] is a perspective view of an example of a construction machine according to the exposition.

[0046] [Fig.2] Fig.2 is a diagram of the control system of this machine construction site.

[0047] [Fig.3] Fig.3 schematically illustrates the control method implemented work by this control system. Description of the implementation methods

[0048] To make the explanation more concrete, an example of a control method and control system equipping a construction machine is described in detail below, with reference to the accompanying drawings. It should be noted that the invention is not limited to this example.

[0049] Figure 1 illustrates an example of a construction machine 1 as described. This construction machine 1 takes the form of a trailer equipped with wheels 2 and a coupling system 3. It comprises a chassis 10, a pump 20, and a dis- module contribution 30.

[0050] The construction machine 1 includes a hopper 11, mounted in the frame 10. This hopper 11 is intended to receive a fluid product to be distributed on a construction site, for example, a screed. Typically, the hopper will be supplied with the fluid product using a mixer truck. A grid 12, acting as a screen or sieve, is provided at the top of the hopper 11 to retain any large, undesirable particles such as pebbles.

[0051] The pump 20 is here a progressive cavity pump. It comprises a stator made of elastomeric material, enclosed in a metal casing 21 and forming a succession of axial cavities, and a rotor engaged in the cavities of the stator.

[0052] The construction machine 1 also includes a drive unit 13 mounted in the frame 10 (shown schematically in [Fig. 2]), combining a thermal engine, for example a diesel engine, with a hydraulic machine. The output shaft of this drive unit 13 is coupled to a transmission shaft extending through the hopper 11 and carrying conveying elements, for example an Archimedes screw, which convey the fluid product to an outlet in the hopper 11 connected to the pump 20. The conveying shaft is itself coupled to the rotor of the pump 20. Thus, the drive unit 13 is able to impose the rotational speed V of the pump 20, i.e., its pumping speed. In this regard, a speed sensor 14 is mounted on one of these shafts to measure the rotational speed V of the pump 20 in real time.

[0053] The distribution module 30 is cone-shaped, comprising an upstream end plate 31, connected to the outlet of the pump 20, and a downstream end plate 32, for connecting an outlet pipe. The distribution module 30 further comprises a diaphragm-type pressure sensor 33 for measuring the pressure of the fluid product at the outlet of the pump 20.

[0054] The construction machine 1 also includes a computer 40 receiving, in particular, the pressure measurements at the outlet of the pump 20, transmitted by the pressure sensor 33, and the measurements of the rotation speed of the pump 20, transmitted by the speed sensor 14, and capable of controlling the drive device 13 in order to control the speed of the pump 20.

[0055] The computer 40 is also equipped with a human-machine interface 41 comprising at least one screen and several buttons. Among other possible functions, this human-machine interface 41 allows, on the one hand, the parameters of the configuration in which the machine 1 is intended to operate to be entered. In particular, the human-machine interface 41 allows the diameter and length of the outlet pipe currently connected to the outlet of the machine 1 to be entered. It also allows the nature of the fluid product currently present to be entered. in machine 1: calculator 40 then extracts the viscosity value of this product from its memory.

[0056] Furthermore, the human-machine interface 41 allows the user to set a speed setpoint or, depending on the embodiment of the machine 1, a flow rate setpoint. In the present example, the human-machine interface 41 thus includes a "+" button to accelerate the pump 20, and therefore increase the output flow rate, and a "-" button to slow down the pump 20, and therefore decrease the output flow rate.

[0057] The construction machine 1 thus includes a control system 50, schematically represented in [Fig.2], implementing the computer 40, the speed sensor 14, the pressure sensor 33 and the human-machine interface 41, and capable of controlling the drive device 13 and therefore the pump 20.

[0058] The control method used by the control system 50 will now be described with reference to [Fig.3].

[0059] This control method begins with a step 81 in which the computer 40 checks whether the user has changed the setpoint via the human-machine interface 4L. When this is the case, particularly when starting the machine 1, the computer proceeds to step 82 and controls the drive device 13 to satisfy the user's setpoint. The resulting rotational speed V, measured by the speed sensor 14, is recorded by the computer as the first speed VL.

[0060] The computer 40 then determines, during step 83, the outlet flow rate Q of the machine 1. In this example, this outlet flow rate Q is calculated by the computer 40 based on the pressure measurement P at the outlet of the pump 20, transmitted by the pressure sensor 33, using Poiseuille's law. The dynamic viscosity q of the conveyed product, as well as the radius r and the length 1 of the outlet pipe, have been entered using the human-machine interface 4L. The computer 40 then records this outlet flow rate as the reference flow rate Qref associated with the first speed VL

[0061] Next, during step 84, the computer 40 reduces the rotational speed V of the pump 20 by a certain increment and then, during step 85, checks whether the output flow rate Q has decreased relative to the reference flow rate Qref. If this decrease AQ is negligible, i.e., less than a predetermined threshold value e, the computer repeats steps 84 and 85 in a loop until the output flow rate Q exhibits a deviation AQ from the reference output flow rate Qref greater than the threshold value e. This threshold value is preferably between 2 and 3% of the reference flow rate Qref.

[0062] When this condition is met, the computer determines, during step 86, the rotation speed V of the pump 20 and records it as the second speed V2.

[0063] Finally, during step 87, the computer 40 stabilizes the rotational speed V of the pump 20. In the present example, this stabilization consists of increasing the rotational speed to a third speed V3 slightly higher than V2. More precisely, in this example, the stabilization aims to recover the reference flow rate Qref to within e.

[0064] Once the rotation speed V has stabilized, the computer resumes the process from the beginning and waits until the user requests a speed change again.

[0065] However, during this interval, the computer can also continuously or at regular intervals monitor the rotational speed V of the pump 20 and the output flow rate Q of the machine 1 in order to adjust the rotational speed V to the minimum speed required to ensure the reference output flow rate Qref. This allows the speed, and therefore the efficiency, of the pump 20 to continue to be optimized, without any user intervention, even in the event of instability or transient disturbances in the operation of the pump 20.

[0066] 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.

[0067] 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. A method for controlling a construction machine pump, said pump (20) being configured to pump fluid, pasty and / or viscous products such as mortars, concretes or self-leveling screeds, comprising the following steps: controlling (82) the pump (20) at a first pumping speed (VI) according to a user-desired setpoint, determining (83) the product output flow rate (Q) of the construction machine and recording this flow rate as a reference flow rate (Qref), progressively reducing (84) the pumping speed (V) of the pump (20) as long as the product output flow rate (Q) remains stable, i.e., as long as the decrease (AQ) of the product output flow rate (Q) relative to the reference flow rate (Qref) remains below a predetermined threshold value (e), until a second pumping speed (V2) is reached, from which the product output flow rate (Q) begins to decrease,that is to say from which said decrease (AQ) of the product outlet flow rate (Q) relative to the reference flow rate (Qref) exceeds said predetermined threshold value (e), stabilization (87) of the pumping speed (V).,

2. A control method according to claim 1, wherein the pump (20) is a progressive cavity pump or a peristaltic pump.

3. A control method according to claim 1 or 2, wherein the pump (20) is used in a pressure range beyond its nominal pressure range.

4. A control method according to any one of claims 1 to 3, wherein the construction machine (1) comprises a product outlet line connected to the outlet of the pump (20).

5. A control method according to any one of claims 1 to 4, wherein the output flow rate of product (Q) of the construction machine (1) is determined by direct measurement at the outlet of the construction machine (1) using a flow meter.

6. A control method according to any one of claims 1 to 5, wherein the product output flow rate (Q) of the construction machine (1) is determined by calculation from the pressure measurement (P) at the outlet of the pump (20).

7. A control method according to any one of claims 1 to 6, in which the step of progressively reducing the pumping speed (84) is carried out by increments or continuously, preferably linearly.

8. A control method according to any one of claims 1 to 7, wherein, during the stabilization step (87) of the pumping speed (V), the pumping speed (V) is stabilized at a value V3 = V2 + e, where V2 is the second control speed, and e is a strictly positive value less than 10% of V2.

9. A control method according to any one of claims 1 to 8, wherein the product output flow rate (Q) is continuously monitored and the pumping speed (V) is continuously adjusted to find the lowest speed that achieves the desired product output flow rate (Qref).

10. Control system for a construction machine comprising a pump configured for pumping fluid, pasty and / or viscous products such as mortars, concretes or self-leveling screeds, comprising a sensor (33) configured for measuring the product output flow rate of the machine or a representative parameter (P) of this product output flow rate (Q), a control unit (40) configured for operating the pump (20) and imposing a pumping speed (V) on it, wherein the control unit (40) is configured to, initially (82), command the pump (20) to a first pumping speed (VI), determine the product output flow rate (Q) and record it as a reference flow rate (Qref), wherein the control unit (40) is configured to, subsequently (84), progressively reduce the pumping speed (V) of the pump (20) as long as the product output flow rate (Q) remains stable,that is, as long as the decrease (AQ) in the product outlet flow rate (Q) relative to the reference flow rate (Qref) remains below a predetermined threshold value (e), until a second pumping speed (V2) is reached at which the product outlet flow rate (Q) begins to decrease, that is, from which the said decrease (AQ) in the product outlet flow rate (Q) relative to the reference flow rate (Qref) exceeds the said predetermined threshold value (e), and in which the control unit (40) is configured to, in a,

11. third step (87), stabilize the pumping speed (V). Construction machine, comprising a pump (20) configured to pump fluid, pasty and / or viscous products such as mortars, concretes or self-leveling screeds, and a system (50) according to claim 10.

12. Computer program, comprising instructions for executing the steps of the method for controlling any one of claims 1 to 9 when said program is executed on a computer.

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