An energy-saving control method for a concrete pump truck

Abstract

The present invention relates to the technical field of mechanical engineering, and discloses an energy-saving control method for a concrete pump truck, which includes the following steps: calculating the required pumping flow according to the user's desired pumping frequency, the displacement and speed of the main pump; calculating the average pumping pressure during the pumping stroke according to the instantaneous pressure sampled during one pumping stroke; estimating the load power according to the average pumping pressure and the required pumping flow; inversely calculating the engine output power according to the load power and mechanical efficiency, and calculating the optimal engine speed corresponding to this power, and setting the engine speed to the optimal engine speed; calculating the required main pump displacement according to the required pumping flow and the set engine speed; calculating the required main pump current according to the required main pump displacement. The beneficial effect of the present invention is that by real-time monitoring of different working conditions during the pumping operation, the matching relationship between the engine speed and the main pump displacement is automatically adjusted to achieve the purpose of saving fuel consumption while ensuring the working efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical engineering, and particularly to an energy-saving control method for a concrete pump truck. Background Art

[0002] Concrete pump truck: A concrete pump truck is a device that integrates a pumping system for pumping concrete and a boom system for placing concrete on an automotive chassis. Among them, the pumping system is driven by the engine of the automotive chassis, pressurizes the concrete and feeds it into the pipeline, and then the boom system delivers the concrete in the pipeline to the construction site.

[0003] Main pump: As the power oil source for the main cylinder's movement, the main pump selected for the concrete pump truck is a high-pressure swashplate piston variable pump. The displacement control method of this pump is electro-hydraulic proportional positive control, simply referred to as the main pump.

[0004] A concrete pump truck is a construction machinery that uses pressure to transport pre-mixed concrete along a laid pipeline to a certain height and distance, and is widely used in modern construction projects. Since a concrete pump truck is a high-power and high-energy-consuming construction machinery, its energy-saving performance has a crucial impact on aspects such as environmental protection and construction costs. Meeting the energy-saving requirements of a concrete pump truck can not only greatly reduce the engineering operation cost, but also reduce the pollution to the environment during the building construction process. In addition, as an important selling point of a concrete pump truck, energy-saving performance directly reflects the core competitiveness of the product and affects the product's sales volume.

[0005] However, due to the diverse working conditions and loads during the pumping operation of a concrete pump truck, the current control system cannot adjust the engine speed and the main pump displacement in real time. Generally, a fixed speed and a fixed main pump displacement are determined according to the input pumping frequency requirement. In this way, the utilization efficiency of the engine power is very low under light loads, resulting in a large amount of energy waste. On the other hand, under heavy loads and overloading, the engine power will be insufficient, leading to unstable engine speed or even stalling. Therefore, it is very necessary to adjust the engine speed and the main pump displacement according to the actual working conditions of the concrete pump truck, which can not only make the most of the fuel-saving economic speed of the engine but also ensure that the engine will not stall and flame out due to overloading.

[0006] Currently, generally, multi-stage speed control is adopted for the engine speed according to different input displacement requirements, that is, regardless of the load size, the engine speed remains constant under a certain displacement requirement. The engine always has enough surplus power to adapt to the load change. Although this can ensure the stable operation of the system under most working conditions, the energy-saving effect is not obvious; the main pump displacement cannot be adjusted in real time according to the load change, and in the case of a major load, the load exceeds the engine power, resulting in a speed drop and flameout. Summary of the Invention

[0007] In view of the deficiencies of the prior art, the present invention provides an energy-saving control method for a concrete pump truck, which automatically adjusts the matching relationship between the engine speed and the main pump displacement by real-time monitoring of different working conditions during the pumping operation, so as to achieve the purpose of saving fuel consumption while ensuring work efficiency.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] The concrete pump truck uses a diesel engine to provide mechanical power. After mechanical transmission through a gearbox, a drive shaft, a transfer case, etc., it drives hydraulic oil pumps such as the main pump, the swing pump, the boom pump, and the auxiliary pump to convert mechanical energy into hydraulic energy, and then drives the corresponding hydraulic cylinders to realize functions such as pumping, boom movement, swinging, stirring, and outrigger retraction. This energy-saving control technology only considers the energy-saving effect during the pumping operation. Since the power consumed by actions such as the boom and outriggers accounts for a very small proportion and is included within the safety factor used when calculating the engine power by back-calculating from the load power, the energy-saving effect of actions such as the boom and outriggers is not considered.

[0010] An energy-saving control method for a concrete pump truck includes the following steps:

[0011] Directly obtain the maximum net torque output by the engine and the maximum net power output by the engine according to the technical parameters and the universal characteristic curve of the engine of the concrete pump truck;

[0012] Directly obtain the maximum main pump displacement, the minimum main pump displacement, the rated pressure, the maximum main pump flow rate, the minimum main pump flow rate, the maximum main pump current, and the minimum main pump current according to the parameters of the main pump;

[0013] According to the desired pumping frequency of the user, calculate the required pumping flow rate based on the main pump displacement and speed;

[0014] Calculate the average pumping pressure during the pumping stroke based on the instantaneous pressure sampled during one pumping stroke;

[0015] Estimate the load power based on the average pumping pressure and the required pumping flow rate;

[0016] Back-calculate the engine output power based on the load power and the mechanical efficiency, and calculate the optimal engine speed corresponding to this power, and set the engine speed to the optimal engine speed; the engine speed is optimally matched according to the load power, and the load power is calculated through the average pumping pressure and the required pumping flow rate. Therefore, the engine speed is adjusted according to the average pumping pressure of the pumping pressure in the previous stroke. In this way, the adjustment of the engine speed is carried out in the way of adjusting once per commutation cycle, avoiding frequent adjustment of the engine speed caused by drastic pressure fluctuations during the pumping process.

[0017] Calculate the required main pump displacement based on the required pumping flow rate and the set engine speed;

[0018] Calculate the required main pump current based on the required main pump displacement.

[0019] Adjust the main pump according to the calculated required main pump current. Make full use of the fast response characteristic of the electronic control adjustment of the main pump. While the engine speed is set to the optimal engine speed, adjust the current of the main pump in real time according to the required main pump current to adapt to the instantaneous pressure change and keep the engine speed stable.

[0020] Further, the desired pumping frequency f is 2.5 times / minute to 25 times / minute, which can be adjusted by the user according to the user's expectation.

[0021] Further, the desired pumping efficiency f 1 takes values from 0.1 to 1.0, and f 1 corresponds to the knob value of the remote control from 0 - 100%, which is the input set by the user. When the knob input is below 10%, it is all 10%.

[0022]

[0023] Further, the main pump is a high - pressure swash - plate piston variable pump, and its displacement control method is electro - proportional positive control.

[0024] Further, according to the desired pumping efficiency f 1 calculate and return the required pumping flow rate Q 需 , the required pumping flow rate Q 需 The calculation formula is:

[0025]

[0026] where Q 需 is the required pumping flow rate, unit: L / min; f 1 is the desired pumping efficiency, taking values from 0.1 to 1.0; n is the rated speed, which is a fixed value, unit: rpm; V max is the maximum main pump displacement of the main pump, which is a fixed value, unit: mL / r.

[0027] Further, the instantaneous pressure is obtained by sampling through a pressure sensor, and the average pumping pressure is calculated by averaging the collected instantaneous pressure after removing the impact during the commutation process.

[0028] Further, the calculation formula for the load power is:

[0029]

[0030] where P load is the load power, unit: KW; P ave is the average pumping pressure, unit: MPa; Q需 is the required pumping flow rate, in L / min.

[0031] Furthermore, the specific calculation method of the optimal engine speed is as follows:

[0032] Based on the load power and mechanical efficiency, the required engine output power is deduced backwards, and its calculation formula is:

[0033]

[0034] where P represents the required engine output power, in KW; P load represents the load power, in KW; E represents the mechanical efficiency, which is a fixed value, an empirical value determined according to tests and can be adjusted according to the actual situation; S represents the safety factor, which is a fixed value;

[0035] Based on the required engine output power, the optimal engine speed is obtained. The specific method is as follows:

[0036] When the required engine output power is less than the threshold TH, the optimal engine speed is set to the minimum allowable engine speed N min , N min is a fixed value obtained from the universal characteristic curve;

[0037] When it is greater than the threshold TH, it is calculated according to the following formula:

[0038] N opt = p1×P 2 + p2×P + p3 (5)

[0039] where N opt represents the optimal engine speed, in rpm; p1, p2, and p3 represent the coefficients of the polynomial, which are constants. They are fitted using experimental data through a fitting tool. The load pressure, flow rate, and engine speed in the experimental data can be used to fit the relationship between power and speed. When fitting the curve, different determination coefficients can be selected to obtain different fitting curves. At this time, the three constants p1, p2, and p3 of the fitting curve are different values (automatically generated by the fitting tool). By comparing the sum of squared errors and the root mean square error between the fitting curve and the actual data points under different determination coefficients, the optimal determination coefficient is selected, and thus p1, p2, and p3 are determined.

[0040] At the same time, the calculated optimal engine speed needs to meet the main pump displacement requirements. The specific requirements are as follows:

[0041] When N opt is less than N Eng ×f 1 then N opt = N Eng ×f1 ;

[0042] N Eng represents the engine speed corresponding to the maximum net power output of the engine, which is a fixed value; f 1 is the desired pumping efficiency, with a value range of 0.1 to 1.0.

[0043] Thirdly, the calculated optimal engine speed should satisfy the minimum engine speed n required for the output power min : When N opt is less than the minimum engine speed, N opt is directly taken as the minimum engine speed n min , and the minimum engine speed n min is the speed obtained when the torque T takes the maximum value, which is the minimum engine speed n min .

[0044] Set the engine speed according to the calculated optimal engine speed;

[0045] When the calculated optimal engine speed N opt differs from the currently set engine speed N set by more than 10 revolutions, adjust the set engine speed to the optimal engine speed.

[0046] Conduct test experiments through the parameters of the engine and the main pump. According to the corresponding relationship between the load power and the engine speed obtained from the experiments, fit the curve of the relationship between the load power and the optimal engine speed, and then obtain the optimal engine speed corresponding to the engine output power.

[0047] The experimental method is as follows: Install a throttle valve on the concrete pump truck to conduct a water injection test to simulate the load pressure during actual concrete pumping. In each test, fix the displacement percentage and the pumping pressure, start from a higher speed and gradually reduce the main pump speed. After each change in speed, wait for the main pump to run smoothly; when the engine speed drops to idle speed or cannot meet the pumping frequency requirement or the engine speed stalls, stop the current test and obtain the critical values corresponding to the load power and the engine speed. Change the displacement percentage and the pumping pressure, and start the next test. During the operation of the main pump, detect and record parameters such as the main pump flow rate, hydraulic oil temperature, fuel consumption, number of pumpings per minute, main pump current, engine speed, and pumping pressure.

[0048] Through the implementation, obtain the data such as the main pump flow rate, hydraulic oil temperature, fuel consumption, number of pumpings per minute, main pump current, engine speed, and pumping pressure under each displacement percentage and pumping pressure. Import the data into MATLAB. There is a fitting tool in its toolbox. Use the discrete data points to fit the curve, and thus p1, p2, and p3 can be obtained.

[0049] Further, it also includes real-time monitoring of the error between the current engine speed and the set engine speed to ensure that the engine does not stall;

[0050] When the set engine speed remains unchanged and the current engine speed N act is less than N set - 10, the required main pump displacement and the required main pump current are adjusted according to the following rules:

[0051] I 需 = I 需 - KK × (I 需 - I min ) (6)

[0052] where, I 需 represents the required main pump current; KK is an adjustment coefficient, with a default value of 0.1; N act represents the current engine speed, in units of rpm, and is collected by a speed sensor.

[0053] Further, the calculation method of the required main pump displacement is: calculate and return the single main pump displacement according to the required pumping flow and the set engine speed; its calculation formula is:

[0054]

[0055] where, Q 需 represents the required pumping flow, in units of L / min; N set is the set engine speed, in units of rpm; i represents the transmission ratio from the engine to the main pump, which is one of the pump truck parameters and is a fixed value; V 需 represents the required main pump displacement, in units of mL / r; V lost represents the main pump displacement loss, with a default value of 0.

[0056] Further, the calculation method of the required main pump current is:

[0057]

[0058] where, I 需 represents the required main pump current, in units of mA; I min represents the minimum main pump current, in units of mA, which is one of the main pump parameters and is a fixed value; I max represents the maximum main pump current, in units of mA, which is one of the main pump parameters and is a fixed value; V 需 represents the required main pump displacement, in units of mL / r; V min represents the minimum main pump displacement, in units of mL / r, which is one of the main pump parameters and is a fixed value; V max represents the maximum main pump displacement, in units of mL / r, which is one of the main pump parameters and is a fixed value.

[0059] Compared with the prior art, the present invention provides an energy-saving control method for a concrete pump truck, which has the following beneficial effects:

[0060] (1) On the premise of ensuring that the load requirements and the set pumping speed are met, according to the current working condition requirements and the engine universal characteristic curve, the matching adjustment of the engine speed and the main pump displacement is carried out, so that the engine works at the most economical fuel consumption under the current working condition, thereby achieving the energy-saving effect.

[0061] (2) The engine speed of the present invention can be adjusted according to the average pumping pressure of the pumping pressure in the previous stroke, so that the engine power and the load power reach the best match. When the load is light, the engine speed is adjusted to the optimal energy-saving range, ensuring the energy-saving effect.

[0062] (3) By setting the minimum speed to meet the displacement requirement and the minimum speed to meet the output power requirement, the engine speed is limited to above the minimum speed, ensuring that the pumping frequency meets the requirements and the power meets the requirements under heavy load, and preventing the engine from stalling due to insufficient power.

[0063] (4) The adjustment of the engine speed is carried out once per commutation cycle, avoiding frequent adjustment of the engine speed caused by violent pressure fluctuations during the pumping process.

[0064] (5) Taking full advantage of the fast response of the main pump electronic control adjustment, while setting the optimal working speed of the engine, the main pump current is adjusted in real time to adapt to the instantaneous pressure change and keep the engine speed stable. Description of the Drawings

[0065] Figure 1 It is the universal characteristic curve diagram of the engine model MC11.44-60 in Embodiment 1;

[0066] Figure 2 It is the fitting curve diagram of the engine power and the optimal speed in Embodiment 1;

[0067] Figure 3 It is the universal characteristic curve diagram of the engine model MC13.54-61 in Embodiment 2;

[0068] Figure 4 It is the fitting curve diagram of the engine power and the optimal speed in Embodiment 2. Detailed Embodiments

[0069] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0070] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn according to the actual proportional relationship. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific value should be construed as merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments may also include different values. It should be noted that: like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0071] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation on the protected content of the present invention.

[0072] Embodiment 1

[0073] As Figure 1 shown, the engine model selected is: MC11.44 - 60, and the energy-saving control method of the present invention includes the following steps:

[0074] Step 1: Directly obtain the maximum net torque T Eng output by the engine and the maximum net power P Eng output by the engine.

[0075] Step 1-1, the maximum net torque T Eng output by the engine:

[0076] As Figure 1 shown, Figure 1The horizontal axis represents the engine speed, the left vertical axis represents the engine output power, and the right vertical axis represents the torque. Power represents power and Torque represents torque. In the engine speed range of 1000 rpm to 1400 rpm, the maximum output net torque is basically constant at 2100 Nm; outside this engine speed range, the maximum output net torque gradually decreases. Among them, when the engine speed increases from 1400 rpm to 1450 rpm, the corresponding maximum output net torque approximately linearly decreases from 2100 Nm to about 2060 Nm.

[0077] Therefore, the maximum output torque T of the engine Eng is 2100 Nm, which is determined according to the external characteristics.

[0078] Step 1-2, the engine outputs the maximum net power P Eng :

[0079] According to the power calculation formula: Power = Torque * Angular velocity W = Torque * 2 * 3.14 * Engine speed / 60, the maximum output power at an engine speed of 1000 rpm (when the maximum net torque is 2100 Nm) is 219.8 KW; the power at an engine speed of 1400 rpm (when the maximum net torque is 2100 Nm) is 307.7 KW; the power at an engine speed of 1450 rpm (when the maximum net torque is approximately 2060 Nm) is approximately 312 KW.

[0080] Therefore, the maximum net power P output by the engine Eng is 312 KW (the power corresponding to 1450 rpm is calculated according to the external characteristics).

[0081] Step 2: Directly obtain the maximum main pump displacement, minimum main pump displacement, rated pressure, maximum main pump flow rate, minimum main pump flow rate, maximum main pump current, and minimum main pump current according to the main pump parameters.

[0082] The maximum main pump displacement V max : unit mL / r, one of the main pump parameters, is a fixed value, and the value is 193 mL / r;

[0083] The minimum main pump displacement V min : unit mL / r, one of the main pump parameters, is a fixed value, and the value is 8.8 mL / r;

[0084] The maximum main pump flow rate Q min : unit L / min, one of the main pump parameters, is a fixed value, and the value is 428 L / min;

[0085] The minimum main pump flow rate Q min : unit L / min, one of the main pump parameters, is a fixed value, and the value is 20 L / min;

[0086] The minimum main pump current Imin : Unit: mA, one of the main pump parameters, a fixed value, calibrated (default 200 mA);

[0087] Maximum main pump current I max : Unit: mA, one of the main pump parameters, a fixed value, calibrated (default 600 mA);

[0088] Rated speed n: Unit: rpm, value: 2200;

[0089] Transmission ratio i from engine to main pump: 0.659;

[0090] Average pumping pressure F during pumping process ave : Unit: MPa, measure the instantaneous pressure through a sensor and then calculate it;

[0091] Maximum allowable working pressure F max : Unit: MPa, specified as 35 MPa;

[0092] Engine idle speed n idl : Unit: rpm, specified as 600 rpm;

[0093] Highest allowable engine speed n max : Unit: rpm, 1450 rpm, calculated from the rated speed n of the main pump (variable pump) with a value of 2200 rpm;

[0094] Required pumping flow rate Q 需 : Unit: L / min, determined by calculation using formula (2);

[0095] Load power P load : Unit: KW, determined by calculation using formula (3);

[0096] Mechanical efficiency E: 0.667;

[0097] Safety factor S: Tentatively set as 0.95;

[0098] Actual engine speed (i.e., the current engine speed) N act : Unit: rpm, collected and determined by a speed sensor.

[0099] Step 3: According to the user's desired pumping frequency, calculate the required pumping flow rate based on the main pump displacement and speed. The calculation formula for the required pumping flow rate is:

[0100]

[0101]

[0102] Q 需 = f × 836

[0103] Among them, the expected pumping frequency f is 2.5 times / minute to 25 times / minute; Q 需 is the required pumping flow rate, with the unit of L / min; f 1 is the expected pumping efficiency, with a value range of 0.1 to 1.0; n is the rated speed, which is a fixed value, with the unit: rpm; V max is the maximum displacement of the main pump, which is a fixed value, with the unit: mL / r.

[0104] Step 4: Calculate the average pumping pressure during this pumping stroke based on the instantaneous pressure sampled during one pumping stroke. The instantaneous pressure is sampled by a pressure sensor, and the average pumping pressure is calculated by taking the average of the sampled instantaneous pressure after removing the impact during the commutation process.

[0105] Step 5: Estimate the load power based on the average pumping pressure and the required pumping flow rate.

[0106] The calculation formula for the load power is:

[0107]

[0108] Among them, P load is the load power, with the unit of KW; P ave is the average pumping pressure, with the unit of MPa; Q 需 is the required pumping flow rate, with the unit of L / min.

[0109] Step 6: Calculate the engine output power by reverse deduction based on the load power and the mechanical efficiency, and calculate the optimal engine speed corresponding to this power, and set the engine speed to the optimal engine speed.

[0110] The specific calculation method for the optimal engine speed is:

[0111] Step 6-1: Calculate the required engine output power by reverse deduction based on the load power and the mechanical efficiency. The calculation formula is:

[0112]

[0113] Among them, P represents the required engine output power, with the unit of KW; P load represents the load power, with the unit of KW; E represents the mechanical efficiency, with a value of 0.667, which is an empirical value determined through tests and can be adjusted according to the actual situation; S represents the safety factor, with a value of 0.95;

[0114] Step 6-2: Obtain the optimal engine speed based on the required engine output power. The specific method is:

[0115] When the required engine output power is less than the threshold TH, where the threshold is 150KW, the optimal engine speed is set to the minimum allowable engine speed N during pumping min , N min which is 1000rpm, obtained from the universal characteristic curve;

[0116] When it is greater than 150KW, it is calculated according to the following formula:

[0117] N opt = p1×P 2 + p2×P + p3

[0118] where, N opt represents the optimal engine speed, in units of rpm; p1, p2, p3 represent the coefficients of the polynomial and are constants; as Figure 2 shown, Figure 2 in the vertical axis represents the engine speed and the horizontal axis represents the maximum net engine output power, p1 is 0.01257; p2 is -2.676; p3 is 1120.

[0119] Step 6-3: The calculated optimal engine speed needs to meet the main pump displacement requirements, and the specific requirements are:

[0120] When N opt is less than 1450×f 1 , N opt = 1450×f 1 ;

[0121] where, 1450 is the engine speed corresponding to the maximum net engine output power; f 1 is the desired pumping efficiency, with a value range of 0.1 - 1.0;

[0122] Step 6-4: The calculated optimal engine speed should meet the minimum engine speed n required for the output power min ;

[0123] According to the power calculation formula:

[0124] Power (W) = Torque T (NM) * 2 * 3.14 * Rotational speed (rpm) / 60

[0125] Rotational speed (rpm) = Power (W) * 60 / (6.28 * Torque T)

[0126] When the torque T takes the maximum torque of 2100NM, the minimum engine speed n is obtained min = Power (KW) * 1000 * 60 / 6.28 / 2100 = Power (KW) * 4.55.

[0127] The optimal engine speed cannot be lower than the minimum speed, otherwise the required power cannot be met: When Nopt Less than n min When, N opt = n min .

[0128] Step 6-5: Set the engine speed according to the calculated optimal engine speed: When the calculated optimal engine speed N opt And the currently set engine speed N set The difference exceeds 10 revolutions, adjust the set engine speed to the optimal engine speed.

[0129] Step 7: Monitor the current engine speed N act And the set engine speed N set Error, ensure that the engine does not stall;

[0130] When the set engine speed remains unchanged and the current engine speed N act Less than N set -10, then adjust the required main pump displacement and required main pump current according to the following rules:

[0131] I 需 = I 需 - KK × (I 需 - I min )

[0132] Among them, I 需 Represents the required main pump current; KK is the adjustment coefficient, default 0.1; N act Represents the current engine speed, unit rpm, collected by the speed sensor.

[0133] Step 8: Calculate and return the single main pump displacement according to the required pumping flow and the set engine speed; its calculation formula is:

[0134]

[0135] Among them, Q 需 Represents the required pumping flow, unit L / min; N set Is the set engine speed, unit rpm; i represents the transmission ratio from the engine to the main pump, taking the value 0.659; V 需 Represents the required main pump displacement, unit mL / r; V lost Represents the main pump displacement loss, default 0.

[0136] Step 9: The calculation method of the required main pump current is:

[0137]

[0138]

[0139] Step 10: Adjust the main pump according to the calculated required main pump current.

[0140] Embodiment 2

[0141] As Figure 3 shown, the selected engine model is: MC13.54 - 61. The difference in its energy-saving control method from that of Embodiment 1 lies in the different engine model and individual parameters. Specifically, the differences are as follows: During the control process, only the coefficients p1, p2, and p3 in the maximum torque and the fitted optimal engine speed of the calculated data are different, and the others are the same.

[0142] In this embodiment, the maximum net torque T Eng output by the engine is 2500 NM, which is determined according to the external characteristics:

[0143] As Figure 3 shown, Figure 3 the horizontal axis represents the engine speed, the left vertical axis represents the engine output power, the right vertical axis represents the torque, Power represents power, and Torque represents torque. In the range of 1000 rpm to 1400 rpm, the maximum output net torque is basically constant at 2500 NM; outside this speed range, the maximum output net torque gradually decreases. Among them, when the speed increases from 1400 rpm to 1450 rpm, the corresponding maximum output net torque approximately linearly decreases from 2500 NM to about 2460 NM.

[0144] In this embodiment, the maximum net power P Eng output by the engine is 373 KW (the power corresponding to 1450 rpm calculated according to the external characteristics).

[0145] According to the power calculation formula: Power = Torque * Angular velocity W = Torque * 2 * 3.14 * Speed / 60, the maximum output power when the speed is 1000 rpm (at this time the maximum net torque is 2500 NM) is 260 KW; the power when the speed is 1400 rpm (at this time the maximum net torque is 2500 NM) is 366.3 KW; the power when the speed is 1450 rpm (at this time the maximum net torque is about 2460 NM) is about 373 KW.

[0146] Other different parameters are:

[0147] The maximum main pump displacement V max : unit mL / r, with a value of 190 mL / r;

[0148] The minimum main pump displacement V min : unit mL / r, with a value of 8.8 mL / r;

[0149] The maximum main pump flow rate Q min: Unit: L / min, value: 428 L / min;

[0150] Minimum main pump flow rate Q min : Unit: L / min, value: 20 L / min;

[0151] Minimum main pump current I min : Unit: mA, one of the main pump parameters, a fixed value, calibrated (default: 200 mA);

[0152] Maximum main pump current I max : Unit: mA, one of the main pump parameters, a fixed value, calibrated (default: 600 mA);

[0153] In this embodiment, when the maximum output torque T of the engine takes the maximum torque of 2500 N·m, the lowest engine speed n is obtained min = Power (kW) * 1000 * 60 / 6.28 / 2500 = Power (kW) * 3.82.

[0154] In this embodiment, as Figure 4 shown, Figure 4 The vertical axis represents the engine speed, the horizontal axis represents the maximum net power output of the engine, p1 is -0.005525; p2 is 3.895; p3 is 684.1.

[0155] It should be noted that in this application, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variation thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0156] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made therein without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An energy-saving control method for a concrete pump truck, characterized in that, it includes the following steps: directly obtain the maximum net torque output by the engine and the maximum net power output by the engine according to the technical parameters and the universal characteristic curve of the engine of the concrete pump truck; directly obtain the maximum main pump displacement, the minimum main pump displacement, the rated pressure, the maximum main pump flow rate, and the minimum main pump flow rate according to the parameters of the main pump; calculate the required pumping flow rate according to the desired pumping frequency, the main pump displacement, and the rotational speed; calculate the average pumping pressure during the pumping stroke according to the instantaneous pressure sampled during one pumping stroke; estimate the load power according to the average pumping pressure and the required pumping flow rate; inversely deduce the engine output power according to the load power and the mechanical efficiency, calculate the optimal engine speed corresponding to this power, and set the engine speed to the optimal engine speed; calculate the required main pump displacement according to the required pumping flow rate and the set engine speed; calculate the required main pump current according to the required main pump displacement; adjust the main pump according to the calculated required main pump current.

2. The energy-saving control method for a concrete pump truck according to claim 1, characterized in that: the desired pumping frequency f is 2.5 times / minute to 25 times / minute.

3. The energy-saving control method for a concrete pump truck according to claim 1, characterized in that: the main pump is a high-pressure swashplate piston variable pump, and its displacement control method is electro-hydraulic proportional positive control.

4. The energy-saving control method for a concrete pump truck according to claim 1, characterized in that: According to the desired pumping efficiency f 1 Calculate and return the required pumping flow rate Q 需 , where the required pumping flow rate Q 需 is calculated by the formula: Among them, Q 需 is the required pumping flow rate, with the unit of L / min; f 1 is the desired pumping efficiency, with a value range of 0.1 to 1.0; n is the rated speed, which is a fixed value, with the unit: rpm; V max is the maximum main pump displacement of the main pump, which is a fixed value, with the unit of mL / r.

5. The energy-saving control method for a concrete pump truck according to claim 1, characterized in that: the instantaneous pressure is obtained by sampling with a pressure sensor, and the average pumping pressure is calculated by averaging the collected instantaneous pressure after removing the impact during the commutation process.

6. The energy-saving control method for a concrete pump truck according to claim 1, characterized in that: the calculation formula for the load power is: Among them, P load is the load power, with the unit of KW; P ave is the average pumping pressure, with the unit of MPa; Q 需 is the required pumping flow rate, with the unit of L / min.

7. The energy-saving control method for a concrete pump truck according to claim 1, characterized in that: the specific calculation method for the optimal engine speed is: inversely deduce the required engine output power according to the load power and the mechanical efficiency, and its calculation formula is: Among them, P represents the required engine output power, in KW; P load represents the load power, in KW; E represents the mechanical efficiency, which is a fixed value, an empirical value determined according to tests and can be adjusted according to the actual situation; S represents the safety factor, which is a fixed value; obtain the optimal engine speed according to the required engine output power, and its specific method is: When the required engine output power is less than the threshold TH, the optimal engine speed is set to the minimum allowable engine speed N during pumping min , N min is a fixed value obtained from the universal characteristic curve; when it is greater than the threshold TH, calculate according to the following formula: N opt = p1 × P 2 + p2 × P + p3 (5) Among them, N opt represents the optimal engine speed, with the unit of rpm; p1, p2, and p3 represent the coefficients of the polynomial and are constants; At the same time, the calculated optimal engine speed needs to meet the main pump displacement requirement, and the specific requirement is: When N opt is less than N Eng × f 1 then, N opt = N Eng × f 1 ; Among them, N Eng represents the engine speed corresponding to the maximum net power output of the engine, which is a fixed value; f 1 is the desired pumping efficiency, and its value ranges from 0.1 to 1.0; Thirdly, the calculated optimal engine speed shall meet the minimum engine speed required for the output power: when N opt is less than the minimum engine speed, N opt shall be directly taken as the minimum engine speed; set the engine speed according to the calculated optimal engine speed of the engine; When the calculated optimal engine speed N opt differs from the currently set engine speed N set by more than 10 revolutions, adjust the set engine speed to the optimal engine speed.

8. The energy-saving control method for a concrete pump truck according to claim 7, characterized in that: it also includes real-time monitoring of the error between the current engine speed and the set engine speed to ensure that the engine does not stall; When the engine speed is set to be constant and the current engine speed N act is less than N set by -10, the required main pump displacement and the required main pump current are adjusted according to the following rules: I 需 = I 需 - KK×(I 需 - I min ) (6) Among them, I 需 represents the required main pump current; KK is the adjustment coefficient, with a default value of 0.1; N act represents the current engine speed, in rpm, which is collected by a speed sensor.

9. The energy-saving control method for a concrete pump truck according to claim 1, characterized in that: the calculation method for the required main pump displacement is: calculate and return the single main pump displacement according to the required pumping flow rate and the set engine speed; its calculation formula is: Among them, Q 需 represents the required pumping flow rate, with the unit of L / min; N set is the set engine speed, with the unit of rpm; i represents the transmission ratio from the engine to the main pump, which is one of the parameters of the pump truck and is a fixed value; V 需 represents the required main pump displacement, with the unit of mL / r; V lost represents the main pump displacement loss, and the default value is 0.

10. The energy-saving control method for a concrete pump truck according to claim 1, characterized in that: The calculation method of the required main pump current is as follows: Among them, I 需 represents the required main pump current, in mA; I min represents the minimum main pump current, in mA, which is one of the main pump parameters and is a fixed value; I max represents the maximum main pump current, in mA, which is one of the main pump parameters and is a fixed value; V 需 represents the required main pump displacement, in mL / r; V min represents the minimum main pump displacement, in mL / r, which is one of the main pump parameters and is a fixed value; V max represents the maximum main pump displacement, in mL / r, which is one of the main pump parameters and is a fixed value.

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