Multi-speed pump with automatic gear control

Abstract

A multi-speed pump has a plurality of gears, including at least one high gear and one low gear. The multi-speed pump comprises a gear control module, the gear control module is integrated in a control board (3) or a frequency converter (4) of a drive motor of the multi-speed pump, and is configured to switch the gear of the multi-speed pump from a high gear to a low gear when a low gear condition is met within a control cycle, and to switch the gear of the multi-speed pump from a low gear to a high gear when a high gear condition is met within a control cycle.

Description

Technical Field

[0001] The present application relates to a multi-speed pump having an improved gear control function. Background Art

[0002] Multi-speed (multi-point) pumps have multiple shiftable displacements. In actual operation, the pump shifts according to the actual pump pressure and speed, so that the pump operates at the appropriate shift, thereby improving the pressure control level and system energy saving level.

[0003] In the prior art, a programmable controller (PLC) is usually used to control a multi-speed pump, and a switching signal is input to the multi-speed pump by the PLC to control the gear position of the multi-speed pump.

[0004] However, the users of multi-speed pumps do not know as much about pumps as the designers of multi-speed pumps. It is not easy for users to design a control program in PLC to control the gear position of multi-speed pumps according to actual working conditions, and many users are reluctant to do additional control programming in PLC.

[0005] Therefore, it is hoped that the manufacturers of multi-speed pumps will improve the control system of the pump itself to reduce the user's additional programming work. Summary of the invention

[0006] The purpose of the present application is to provide a multi-speed pump, which can add an automatic gear control function to the control system of the pump itself.

[0007] To achieve this object, the present application provides, in one aspect, a multi-speed pump (a specific form is a two-speed pump), having multiple gears, including at least one high gear and one low gear, the multi-speed pump comprising a gear control module, the gear control module being integrated in a control board or a frequency converter of a drive motor of the multi-speed pump, and being configured to switch the gear of the multi-speed pump from a high gear to a low gear when a low gear condition is met within a control cycle, and to switch the gear of the multi-speed pump from a low gear to a high gear when a high gear condition is met within a control cycle;

[0008] The low gear condition includes a low gear working condition A1, and the low gear working condition A1 is defined as:

[0009] The difference between the set output pressure and the actual output pressure of the pump is less than a set first pressure difference limit; and

[0010] The actual pump speed is lower than the set pump speed limit; and

[0011] The actual output pressure of the pump is higher than the set first pressure limit;

[0012] The high gear condition includes a high gear condition A2 corresponding to the low gear condition A1, and the high gear condition A2 is defined as:

[0013] The low gear operating condition A1 in the previous cycle is satisfied, and the low gear operating condition A1 in the current cycle is not satisfied; and:

[0014] The difference between the set output pressure and the actual output pressure of the pump is greater than the set second pressure difference limit, wherein the second pressure difference limit is greater than the first pressure difference limit; or the actual output pressure of the pump is lower than the first pressure selection value, wherein the first pressure selection value is lower than the first pressure limit.

[0015] According to one embodiment, the first selected pressure value is equal to the first pressure limit value minus a set pressure value; or, the first selected pressure value is a value set by a user.

[0016] According to an embodiment, the low gear condition further includes a low gear condition B1 in parallel with the low gear condition A1, and the low gear condition B1 is defined as:

[0017] The actual output pressure of the pump is higher than the set second pressure limit value, and the set output pressure of the pump is higher than the set third pressure limit value;

[0018] The high gear condition also includes a high gear condition B2 corresponding to the low gear condition B1, and the high gear condition B2 is defined as:

[0019] The low gear operating condition B1 in the previous cycle is satisfied, and the low gear operating condition B1 in the current cycle is not satisfied; and:

[0020] The actual output pressure of the pump is lower than the second pressure selection value, wherein the second pressure selection value is lower than the second pressure limit; or the set output pressure of the pump is lower than the third pressure selection value, wherein the third pressure selection value is lower than the third pressure limit.

[0021] According to one embodiment, the second pressure selected value is equal to the second pressure limit value minus a set pressure value; or, the second pressure selected value is a value set by a user;

[0022] The third pressure selection value is equal to the third pressure limit value minus a set pressure value; or, the third pressure selection value is a value set by the user.

[0023] According to an embodiment, the low gear condition further includes a low gear condition C1 in parallel with the low gear conditions A1 and B1, and the low gear condition C1 is defined as:

[0024] The set output flow of the pump is less than the set output flow limit;

[0025] The high gear condition also includes a high gear condition C2 corresponding to the low gear condition C1, and the high gear condition C2 is defined as:

[0026] The low gear operating condition C1 in the previous cycle is satisfied, and the low gear operating condition C1 in the current cycle is not satisfied; and

[0027] The set output flow rate of the pump is greater than the flow selection value, and the flow selection value is less than the output flow limit value.

[0028] According to one embodiment, the selected flow value is equal to the output flow limit value minus a set flow value; or, the selected flow value is a value set by a user.

[0029] According to one embodiment, the gear control module is configured to switch the gear of the multi-speed pump from a high gear to a low gear when any one of the low gear operating conditions A1, B1, and C1 is met, and to switch the gear of the multi-speed pump from a low gear to a high gear when any one of the high gear operating conditions A2, B2, and C2 is met.

[0030] According to one embodiment, the gear control module is configured to determine whether the gear was switched to a low gear due to the satisfaction of the corresponding low gear operating condition A1, B1, C1 when one of the high gear operating conditions A2, B2, C2 is met; if the gear was switched to a low gear due to the satisfaction of the corresponding low gear operating condition A1, B1, C1, switching to a high gear is allowed; if the gear was not switched to a low gear due to the satisfaction of the corresponding low gear operating condition A1, B1, C1, switching to a high gear is not allowed.

[0031] According to one embodiment, the multi-speed pump also includes a user signal interface, and the gear control module is configured to receive a signal input by a user via the user signal interface, wherein the signal input by the user includes a forced low gear signal; and the gear control module is configured to: based on the received forced low gear signal, switch the gear of the multi-speed pump from a high gear to a low gear, regardless of whether the low gear condition is met.

[0032] According to one embodiment, the signal input by the user also includes a prohibit low gear signal, and the prohibit low gear signal does not coexist with the forced low gear signal; and the gear control module is configured to: based on the received prohibit low gear signal, prohibit the gear of the multi-speed pump from switching from a high gear to a low gear, regardless of whether the low gear condition is met.

[0033] According to one embodiment, the signal input by the user includes a forced high gear signal; and the gear control module is configured to: based on the received forced high gear signal, switch the gear of the multi-speed pump from a low gear to a high gear, regardless of whether the high gear condition is met.

[0034] According to one embodiment, the signal input by the user also includes a prohibit high gear signal, and the prohibit high gear signal does not coexist with the forced high gear signal; and the gear control module is configured to: based on the received prohibit high gear signal, prohibit the gear of the multi-speed pump from switching from a low gear to a high gear, regardless of whether the high gear condition is met.

[0035] According to an embodiment, the forced low gear signal is also used as a prohibition high gear signal, and the forced high gear signal is also used as a prohibition low gear signal.

[0036] The gear control algorithm is added to the control system of the multi-speed pump of the present application, which is suitable for various speed / displacement applications, and the end user does not need to perform additional programming for this purpose. In addition, the end user can influence the control result through active input signals according to his wishes. The gear control algorithm is integrated into the drive system of the multi-speed pump, and the end user may even omit the PLC and save wiring. Therefore, the solution provided by the present application can save customers' time and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present application may be further understood by reading the following detailed description with reference to the accompanying drawings, in which:

[0038] Figure 1 is a schematic diagram of a double-speed pump according to the present application;

[0039] Figure 2 is a flow chart of an exemplary gear control algorithm that can be used in the dual-speed pump of the present application;

[0040] Figure 3 It is a graph showing the displacement of a two-speed pump without the gear control algorithm;

[0041] Figure 4 It is a graph showing the displacement of a two-speed pump when shifting gears purely based on physical conditions;

[0042] Figure 5 It is a graph showing the displacement of a dual-speed pump when the gear control algorithm is adopted according to the present application. DETAILED DESCRIPTION

[0043] The present application generally relates to a multi-speed (multi-point) pump. A multi-speed pump has a plurality of switchable gears, and each gear can be realized by an internal gear-changing structure of the multi-speed pump. For example, for a plunger-type multi-speed pump, each gear is realized by a different inclination of a metering head (inclined plate). Once the metering head is set at a certain inclination, the gear of the pump is determined, and the pump displacement corresponding to the gear (the amount of fluid output by the pump after one rotation of the pump rotor) is determined.

[0044] The multi-speed pump is generally Figure 1 It is schematically shown in that it can transport liquid media with a displacement of multiple gears. The multi-speed pump includes a pump unit 1 and a drive system for driving the pump unit 1. The drive system includes a motor 2, a control board 3 and a frequency converter 4. The control board 3 and the frequency converter 4 control the operation of the motor 2. The control board 3 also controls the operation of the pump unit 1 (such as gear switching, etc.). In addition, a sensor 5, such as a pressure sensor, is connected to the output end of the pump unit 1, and its signal can be obtained by the frequency converter 4 to realize the control of the pump unit 1 by the frequency converter 4.

[0045] The present application proposes to add a gear control module to the control board 3 or the frequency converter 4 to save the end user from the work of additionally programming the gear shifting of the multi-speed pump (such as in an external PLC). The gear control module is embedded in the control board 3 or the frequency converter 4. The control board 3 and the frequency converter 4 are hardware built into the pump drive system, so wiring can be saved and even an external PLC can be omitted.

[0046] The gear control module is configured to switch the gear of the pump according to the system state variable, and can affect the control result based on the active input signal of the customer at any time, and can even select the user's input signal as the only criterion. The multi-speed pump of the present application is provided with a user signal interface (in the form of hardware or software), and the user can independently choose to input the control signal through digital / analog / bus communication / Bluetooth input / set time or number of delay parameters.

[0047] The gear control module of the multi-speed pump is implemented through the PID circuit and algorithm inside the drive system. After the gear of the pump is switched, the appropriate PID parameters can be adjusted according to the new gear (displacement) to achieve better control effect.

[0048] The system state variables on which the gear control module is based may include: pump output pressure setting value, actual value, and the real-time difference between the two; pump speed setting value, actual value, and the real-time difference between the two; current pump displacement state feedback; gear switching execution speed; switching command signal delay; and the like.

[0049] One form of the multi-speed pump is a double-speed (double-point) pump, which has two gears, high and low. The following describes some feasible implementations of the present application using a double-speed pump as an example. It can be understood that the principles and features of the present application are also applicable to multi-speed pumps with other gear numbers.

[0050] The gear control module is configured to execute the gear control algorithm of the present application. Among them, preferably, the initial gear after the dual-stage pump is started is set to the high gear, and the conditions are detected in each cycle, and when the low gear condition is met, the gear is allowed to be switched from the high gear to the low gear in that cycle. Of course, the gear control module can also be configured to set the initial gear after the pump is started to the low gear.

[0051] The low gear conditions for realizing gear shifting applicable to the dual-stage pump include, as examples, operating conditions A1, B1, and C1.

[0052] Condition A1 is defined as:

[0053] |ΔP| < ΔP_threshold1; and

[0054] N_real < Nk; and

[0055] P_real > P_lim1.

[0056] Among them, ΔP is the difference between the set output pressure P_cmd of the pump and the detected actual output pressure P_real of the pump,

[0057] ΔP_threshold1 is the set first differential pressure limit value;

[0058] N_real is the detected actual speed of the pump;

[0059] Nk is the pump speed limit value, which is adjustable by the user;

[0060] P_lim1 is the set first pressure limit value.

[0061] Condition B1 is defined as:

[0062] P_real > P_lim2; and

[0063] P_cmd > P_lim3.

[0064] Among them, P_lim2 is the set second pressure limit value, and P_lim3 is the set third pressure limit value.

[0065] Condition C1 is defined as:

[0066] Q_cmd < Q_cmd_lim.

[0067] Among them, Q_cmd is the set output flow rate of the pump, and Q_cmd_lim is the set output flow rate limit value.

[0068] Conditions A1, B1, and C1 are three conditions that run in parallel with each other. When any one of them is met, the low gear condition is met. P_lim1, P_lim2, and P_lim3 are all set values, and there is no specific relationship between the three.

[0069] Other low gear conditions can also be set according to the specific working process.

[0070] For different working conditions, such as different processes in a working process (with different requirements for pump output pressure and displacement), each of the settable parameters in conditions A1, B1, C1... can be specifically set to meet the requirements of the specific working conditions. In addition, for a specific process, one or more of conditions A1, B1, C1... can be selected as the low gear condition.

[0071] According to an embodiment, in a certain cycle, if any one or more of the operating conditions A1, B1, C1, . . . are met, the gear control module can control the gear of the dual-speed pump to switch from a high gear to a low gear.

[0072] According to another embodiment, in addition to determining the downshifting scheme based on the above working conditions, the gear control module can also force downshifting based on the customer input signals DIA1, DIB1, DIC1... (regardless of whether the working conditions A1, B1, C1... are met). Within a certain period, if a certain user input signal DIA1, DIB1, DIC1... is received, the gear control module can control the gear of the dual-speed pump to switch from a high gear to a low gear. In this embodiment, the customer input signals DIA1, DIB1, DIC1... are used as forced low gear signals.

[0073] In addition, according to another embodiment, the gear control module can also determine whether to downshift based on a combination of operating conditions A1, B1, C1... and user input signals DIA1', DIB1', DIC1'... In this embodiment, the customer input signals DIA1', DIB1', DIC1'... are used as low gear prohibition signals. Specifically, within a certain cycle, even if a certain operating condition A1, B1, C1... is met, but there is a corresponding customer input signal DIA1', DIB1', DIC1'..., the gear control module does not perform a downshift operation; only when there is no customer input signal DIA1', DIB1', DIC1'..., the gear control module can perform a downshift operation.

[0074] The user input signals DIA1 (DIA1’), DIB1 (DIB1’), DIC1 (DIC1’)… are control signals corresponding to conditions A1, B1, C1… respectively, and can be input through corresponding user signal interfaces. The prohibited low gear signals DIA1’, DIB1’, DIC1’… are respectively inverse to the forced low gear signals DIA1, DIB1, DIC1… Each prohibited low gear signal and the corresponding forced low gear signal can be input through the same interface, but cannot be input simultaneously, which avoids misoperation by the user.

[0075] Further, the gear control module is configured to allow the gear to be switched from low gear to high gear in a certain cycle when the high gear condition is met in that cycle.

[0076] The high gear conditions applicable to the gear shift of the two-speed pump include, as examples, the operating conditions A2, B2, C2.

[0077] Condition A2 is defined as:

[0078] Condition A1 in the previous cycle is satisfied, and condition A1 in the current cycle is not satisfied, and there is no corresponding forced low gear signal DIA1; and

[0079] |ΔP|>ΔP_threshold2 or P_real<X1.

[0080] Where ΔP_threshold2 is the set second pressure difference limit value, and ΔP_threshold2>ΔP_threshold1.

[0081] X1 can be called the first pressure selection value, and X1 = P_lim1 - P1, where P1 is a set pressure value;

[0082] Or, X1 = P_min1, where P_min1 is a value that can be set by the user, and P_lim1 - P1 < P_min1 < P_lim1.

[0083] Condition B2 is defined as:

[0084] Condition B1 in the previous cycle is satisfied, and condition B1 in the current cycle is not satisfied, and there is no corresponding forced low gear signal DIB1;

[0085] And, P_real<X2 or P_cmd<X3.

[0086] Where X2 can be called the second pressure selection value, and X2 = P_lim2 - P2, where P2 is a set pressure value;

[0087] Alternatively, X2 = P_min2, where P_min2 is a value that can be set by the user, P_lim2-P2 <P_min2<P_lim2。

[0088] X3 can be called the third pressure selection value, X3 = P_lim3-P3, P3 is a set pressure value;

[0089] Alternatively, X3 = P_min3, where P_min3 is a value that can be set by the user, and P_lim3 - P3 <P_min3<P_lim3。

[0090] Condition C2 is defined as:

[0091] The condition C1 in the previous cycle is satisfied, and the condition C1 in the current cycle is not satisfied, and there is no corresponding forced low gear signal DIC1; and

[0092] Q_cmd>X4.

[0093] Among them, X4 can be called the flow selection value, take X4 = Q_cmd_lim-Q0, Q0 is a set flow value;

[0094] Alternatively, X4 = Q_min, where Q_min is a value that can be set by the user, Q_cmd_lim - Q0 <Q_min<Q_cmd_lim

[0095] Other high gear conditions can also be set according to the specific working process.

[0096] For different working conditions, such as different steps in a working process (with different requirements for pump output pressure and displacement), each of the settable parameters in conditions A2, B2, C2... can be specifically set to meet the requirements of the specific working conditions. In addition, for a specific process, one or more of conditions A2, B2, C2... (corresponding to the selected low-gear working conditions A1, B1, C1...) can be selected as the high-gear condition.

[0097] In a certain cycle, if at least one of the operating conditions A2, B2, C2, . . . is satisfied, the gear control module switches the pump gear from a low gear to a high gear.

[0098] In addition to determining the upshifting scheme based on the above working conditions, the gear control module can also force upshifting based on the customer input signals DIA2, DIB2, DIC2... (regardless of whether the working conditions A2, B2, C2... are met). Within a certain cycle, if a certain user input signal DIA2, DIB2, DIC2... is received, the gear control module can control the gear of the dual-speed pump to switch from a low gear to a high gear. In this embodiment, the customer input signals DIA2, DIB2, DIC2... are used as forced high gear signals.

[0099] In addition, the gear control module can also determine whether to shift up based on a combination of operating conditions A2, B2, C2... and user input signals DIA2', DIB2', DIC2'... In this embodiment, the customer input signals DIA2', DIB2', DIC2'... are used as high gear prohibition signals. Specifically, within a certain cycle, even if a certain operating condition A2, B2, C2... is met, but there is a corresponding customer input signal DIA2', DIB2', DIC2'..., the gear control module does not perform the upshift operation. Only when there is no corresponding customer input signal DIA2', DIB2', DIC2'..., the gear control module can perform the upshift operation.

[0100] The user input signals DIA2 (DIA2'), DIB2 (DIB2'), DIC2 (DIC2') ... are control signals corresponding to the conditions A2, B2, C2 ..., respectively, and can be input through the corresponding user signal interface. The prohibition high gear signals DIA2', DIB2', DIC2' ... are respectively inverse to the forced high gear signals DIA2, DIB2, DIC2 ..., and each prohibition high gear signal can be input through the same interface as the corresponding forced high gear signal, but cannot be input at the same time, which avoids user misoperation.

[0101] The forced low range signals DIA1, DIB1, DIC1, ... can be used to disable the high range signals DIA2', DIB2', DIC2', ..., and the forced high range signals DIA2, DIB2, DIC2, ... can be used to disable the low range signals DIA1', DIB1', DIC1', ...

[0102] According to a further feasible solution, when one of the high gear working conditions A2, B2, and C2 is met, it is also necessary to determine whether the previous switch to low gear was due to the corresponding low gear working conditions A1, B1, and C1 being met. If the previous switch to low gear was due to the corresponding low gear working conditions A1, B1, and C1 being met, then switching to high gear is allowed. If not, then switching to high gear is not allowed. For example, when the high gear working condition A2 is met, it is also necessary to determine whether the previous switch to low gear was due to the corresponding low gear working condition A1 being met. If the previous switch to low gear was due to the corresponding low gear working condition A1 being met, then switching to high gear is allowed. If the switch to low gear was not due to the corresponding low gear working condition A1 being met (for example, it was due to the low gear working conditions B1 and C1 being met or due to a user forced signal), then switching to high gear is not allowed.

[0103] Refer to the following Figure 2 An exemplary process of a gear control algorithm executable in the gear control module of the dual-speed pump is described.

[0104] See also Figure 2 , First, in step S1, the double-speed pump is started.

[0105] Next, in step S2, the driving system of the dual-speed pump is initialized, and the user inputs the set pressure, flow, speed, pump operating mode, pump technical data, etc. The dual-speed pump initially pumps liquid in high gear and monitors the downshift operating conditions SA1, SB1, SC1 in the current cycle and the optional user input signals SDIA1, SDIB1, SDIC1, SDIA1', SDIB1', SDIC1' related to the low gear.

[0106] Next, in step S3, the gear control module determines whether the low gear operating condition A1 in the current cycle is satisfied, and optionally, whether there is a corresponding user input signal (SDIA1, SDIA1') related to the low gear, thereby determining whether the low gear is suitable in the current cycle.

[0107] If it is determined in step S3 that the current cycle is suitable for the low gear, then go to step S4; if it is determined that the current cycle is not suitable for the low gear, then go to step S5.

[0108] In step S4, the pump gear is set to a low gear, and then the process goes to step S15.

[0109] In step S5, the gear control module determines whether the low gear operating condition B1 in the current cycle is satisfied, and optionally, whether there is a corresponding user input signal (SDIB1, SDIB1') related to the low gear, thereby determining whether the low gear is suitable in the current cycle.

[0110] If it is determined in step S5 that the current cycle is suitable for the low gear, then go to step S6; if it is determined that the current cycle is not suitable for the low gear, then go to step S7.

[0111] In step S6, the pump gear is set to a low gear, and then the process goes to step S15.

[0112] In step S7, the gear control module determines whether the low gear operating condition C1 in the current cycle is satisfied, and optionally, whether there is a corresponding user input signal (SDIC1, SDIC1') related to the low gear, thereby determining whether the low gear is suitable in the current cycle.

[0113] If it is determined in step S7 that the current cycle is suitable for the low gear, then go to step S8; if it is determined that the current cycle is not suitable for the low gear, then go to step S9.

[0114] In step S8, the pump gear is set to a low gear, and then the process goes to step S15.

[0115] In step S9, the gear control module determines whether the high gear operating condition A2 in the current cycle is met and whether the low gear operating condition A1 in the current cycle is not met, and optionally, whether there is a corresponding user input signal (SDIA2, SDIA2') related to the high gear, thereby determining whether the high gear condition is met in the current cycle.

[0116] If it is determined in step S9 that the high gear condition is met in the current cycle, then go to step S10; if it is determined that the high gear condition is not met in the current cycle, then go to step S11.

[0117] In step S10, the pump gear is set to a high gear, and then the process goes to step S15.

[0118] In step S11, the gear control module determines whether the high gear operating condition B2 in the current cycle is met and whether the low gear operating condition B1 in the current cycle is not met, and optionally, whether there is a corresponding user input signal (SDIB2, SDIB2') related to the high gear, thereby determining whether the high gear condition is met in the current cycle.

[0119] If it is determined in step S11 that the high gear condition is met in the current cycle, then go to step S12; if it is determined that the high gear condition is not met in the current cycle, then go to step S13.

[0120] In step S12, the pump gear is set to a high gear, and then proceed to step S15.

[0121] In step S13, the gear control module determines whether the high gear operating condition C2 in the current cycle is met and whether the low gear operating condition C1 in the current cycle is not met, and optionally, whether there is a corresponding user input signal (SDIC2, SDIC2') related to the high gear, thereby determining whether the high gear condition is met in the current cycle.

[0122] If it is determined in step S13 that the high gear condition is met in the current cycle, then go to step S14; if it is determined that the high gear condition is not met in the current cycle, then go back to step S3.

[0123] In step S14, the pump gear is set to a high gear, and then proceed to step S15.

[0124] In step S15, the dual-speed pump is controlled to operate at the set gear, and then the process returns to step S3 to execute the next cycle of monitoring and gear setting.

[0125] It is understood that those skilled in the art can Figure 2 Make various modifications to the various steps in the process, such as adding judgment conditions and so on.

[0126] In order to verify the technical effect of the gear control algorithm of this application, different dual-speed pump gear control technologies were tested using the corresponding test bench. The test results can be seen from Figures 3 to 5 In these figures, the horizontal axis represents the time t after the dual-speed pump is started, and the vertical axis represents the pump displacement Vg, that is, the displacement per revolution, which typically includes a high displacement Vh in high gear and a low displacement Vl in low gear.

[0127] Figure 3 The figure shows the displacement of the two-speed pump when the gear control algorithm is not added, where the two-speed pump maintains a high displacement Vh at a high gear, that is, the two-speed pump maintains a fixed displacement. This solution has poor stability in the low-speed pressure holding stage.

[0128] Figure 4 The figure shows the displacement of a two-speed pump when shifting gears solely based on physical conditions, where the two-speed pump frequently switches between a high displacement Vh in the high gear and a low displacement Vl in the low gear. This frequent switching is often unnecessary and will cause output pressure fluctuations.

[0129] Figure 5 The figure shows the displacement of a dual-speed pump using the gear control algorithm of the present application in combination with user input, wherein when the conditions are met, the dual-speed pump is automatically switched to a low-gear, low-displacement Vl for a period of time, and the pressure loop parameters are adaptively adjusted at the same time, and the pressure remains stable. Figure 5 The test results in show that the gear control algorithm of the present application can be stably applied to different working conditions.

[0130] The gear control algorithm of the present application is applicable to various multi-gear pumps, and is not limited to the two-gear pump described above. In general, a multi-gear pump includes multiple gears, among which there is at least one pair of relatively high gear and low gear (the displacement in the high gear is greater than the displacement in the low gear), such as the third gear and the second gear, the second gear and the first gear. The gear control algorithm of the present application can realize the automatic control of the pump gear switching between the high gear and the low gear. For the switching between different high and low gears, it is sufficient to set the corresponding control conditions.

[0131] The multi-speed pump of the present application has a gear control algorithm added to its own control system, which is suitable for various variable speed / variable displacement applications. The end user does not need to perform additional programming for this purpose, thus saving the user's time and cost.

[0132] In addition, an external signal interface is reserved, and the end user can actively input the control signal through the external signal interface according to his wishes to affect the gear control result, thereby having higher practicality.

[0133] In addition, the gear control algorithm is integrated into the drive system of the multi-speed pump, and the end user may even omit the PLC, saving wiring and costs.

[0134] In addition, according to the gear control algorithm of the present application, the multi-speed pump can realize automatic gear switching, so that the displacement of the multi-speed pump is suitable for specific working conditions, thereby improving the operation accuracy and pump discharge accuracy.

[0135] In addition, by setting various parameters in gear switching, for example, the second pressure difference limit set in the high gear operating condition A2 is greater than the first pressure difference limit set in the corresponding low gear operating condition A1, the working stability can be improved and excessive gear switching and pressure fluctuations can be avoided.

[0136] Although the present application is described herein with reference to specific embodiments, the scope of the present application is not limited to the details shown. Various modifications may be made to these details without departing from the basic principles of the present application.

Claims

1. A multi-speed pump, having a plurality of gears, including at least one high gear and one low gear, the multi-speed pump comprising a gear control module, the gear control module being integrated in a control board (3) or a frequency converter (4) of a drive motor of the multi-speed pump, and being configured to switch the gear of the multi-speed pump from a high gear to a low gear when a low gear condition is satisfied within a control cycle, and to switch the gear of the multi-speed pump from a low gear to a high gear when a high gear condition is satisfied within a control cycle; in, The low gear condition includes a low gear operating condition A1, and the low gear operating condition A1 is defined as: The difference (ΔP) between the set output pressure (P_cmd) and the actual output pressure (P_real) of the pump is less than a set first pressure difference limit (ΔP_threshold1); and The actual pump speed (N_real) is lower than the set pump speed limit; and The actual output pressure (P_real) of the pump is higher than the set first pressure limit (P_lim1); The high gear condition includes a high gear condition A2 corresponding to the low gear condition A1, and the high gear condition A2 is defined as: The low gear operating condition A1 in the previous cycle is satisfied, and the low gear operating condition A1 in the current cycle is not satisfied; and: The difference (ΔP) between the set output pressure and the actual output pressure of the pump is greater than the set second pressure difference limit (ΔP_threshold2), wherein the second pressure difference limit (ΔP_threshold2) is greater than the first pressure difference limit (ΔP_threshold1); or the actual output pressure (P_real) of the pump is lower than the first pressure selection value (X1), wherein the first pressure selection value is lower than the first pressure limit (P_lim1); The low gear condition also includes a low gear condition B1 in parallel with the low gear condition A1. The low gear condition B1 is defined as: The actual output pressure (P_real) of the pump is higher than the set second pressure limit (P_lim2), and the set output pressure (P_cmd) of the pump is higher than the set third pressure limit (P_lim3); The high gear condition also includes a high gear condition B2 corresponding to the low gear condition B1, and the high gear condition B2 is defined as: The low gear operating condition B1 in the previous cycle is satisfied, and the low gear operating condition B1 in the current cycle is not satisfied; and: The actual output pressure (P_real) of the pump is lower than the second pressure selection value (X2), wherein the second pressure selection value is lower than the second pressure limit (P_lim2); or the set output pressure (P_cmd) of the pump is lower than the third pressure selection value (X3), wherein the third pressure selection value is lower than the third pressure limit (P_lim3).

2. The multi-speed pump according to claim 1, wherein: The first selected pressure value (X1) is equal to the first pressure limit value (P_lim1) minus a set pressure value; or, the first selected pressure value (X1) is a value set by a user.

3. The multi-speed pump according to claim 1, wherein: The second selected pressure value (X2) is equal to the second pressure limit value (P_lim2) minus a set pressure value; or, the second selected pressure value (X2) is a value set by a user; The third pressure selection value (X3) is equal to the third pressure limit value (P_lim3) minus a set pressure value; or, the third pressure selection value is a value set by the user.

4. The multi-speed pump according to claim 1, wherein: The low gear condition also includes a low gear condition C1 which is parallel to the low gear conditions A1 and B1. The low gear condition C1 is defined as: The set output flow rate (Q_cmd) of the pump is less than the set output flow rate limit (Q_cmd_lim); The high gear condition also includes a high gear condition C2 corresponding to the low gear condition C1, and the high gear condition C2 is defined as: The low gear operating condition C1 in the previous cycle is satisfied, and the low gear operating condition C1 in the current cycle is not satisfied; and The set output flow rate (Q_cmd) of the pump is greater than the flow selection value (X4), and the flow selection value is less than the output flow limit value.

5. The multi-speed pump according to claim 4, wherein: The flow selection value (X4) is equal to the output flow limit value (Q_cmd_lim) minus a set flow value; or, the flow selection value is a value set by the user.

6. The multi-speed pump according to claim 4, wherein: The gear control module is configured to switch the gear of the multi-speed pump from a high gear to a low gear when any one of the low gear operating conditions A1, B1, and C1 is met, and to switch the gear of the multi-speed pump from a low gear to a high gear when any one of the high gear operating conditions A2, B2, and C2 is met.

7. The multi-speed pump according to claim 6, wherein: The gear control module is configured to determine whether the gear was switched to a low gear due to the satisfaction of the corresponding low gear operating condition A1, B1, C1 when one of the high gear operating conditions A2, B2, C2 is met; if the gear was switched to a low gear due to the satisfaction of the corresponding low gear operating condition A1, B1, C1, switching to a high gear is allowed; if the gear was not switched to a low gear due to the satisfaction of the corresponding low gear operating condition A1, B1, C1, switching to a high gear is not allowed.

8. The multi-speed pump according to any one of claims 1 to 7, wherein: It also includes a user signal interface, and the gear control module is configured to receive a signal input by a user via the user signal interface, and the signal input by the user includes a forced low gear signal; and the gear control module is configured to: based on the received forced low gear signal, switch the gear of the multi-speed pump from a high gear to a low gear, regardless of whether the low gear condition is met.

9. The multi-speed pump according to claim 8, wherein: The signal input by the user also includes a prohibit low gear signal, which does not coexist with the forced low gear signal; and the gear control module is configured to: based on the received prohibit low gear signal, prohibit the gear of the multi-speed pump from switching from a high gear to a low gear, regardless of whether the low gear condition is met.

10. The multi-speed pump according to claim 8, wherein: The signal input by the user includes a forced high gear signal; and the gear control module is configured to: based on the received forced high gear signal, switch the gear of the multi-speed pump from a low gear to a high gear, regardless of whether the high gear condition is met.

11. The multi-speed pump according to claim 10, wherein: The signal input by the user also includes a prohibit high gear signal, which does not coexist with the forced high gear signal; and the gear control module is configured to: based on the received prohibit high gear signal, prohibit the gear of the multi-speed pump from switching from a low gear to a high gear, regardless of whether the high gear condition is met.

12. The multi-speed pump according to claim 10, wherein: The forced low range signal is also used as a prohibit high range signal, and the forced high range signal is also used as a prohibit low range signal.

13. The multi-speed pump according to any one of claims 1 to 7, wherein: The multi-speed pump is a double-speed pump.

Images