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EP-4735698-A1 - SYSTEMS AND METHODS FOR CONTROL OF EXCAVATORS AND OTHER POWER MACHINES

EP4735698A1EP 4735698 A1EP4735698 A1EP 4735698A1EP-4735698-A1

Abstract

A power machine (100, 200, 400, 500) can include a lift arm assembly (502) that includes a hydraulic actuator (520), a hydraulic pump (504), an electric motor (506) configured to power rotation of the hydraulic pump (504), and a control system (508). The hydraulic pump (504) can be in hydraulic communication with the hydraulic actuator (520) to power movement of the lift arm assembly. The control system (508) can include one or more processor devices configured to selectively control operation of the hydraulic actuator in a flow control mode and a power control mode. In a flow control mode, the electric motor (506) can be controlled based on a target flow rate for flow of hydraulic fluid from the hydraulic pump to the hydraulic actuator. In a power control mode, the electric motor (506) can be controlled based one or more of on a target power consumption for the electric motor or a threshold motor speed.

Inventors

  • MIYALOU, Pierre Rode Surech

Assignees

  • Doosan Bobcat North America, Inc.

Dates

Publication Date
20260506
Application Date
20241104

Claims (15)

  1. 1. A power machine (100) compri sing : a lift arm assembly (502) that includes a hydraulic actuator (520); a hydraulic pump (504) in hydraulic communication with the hydraulic actuator (520) and configured to power movement of the lift arm assembly (502); an electric motor (506) configured to power rotation of the hydraulic pump (504); and a control system (508) that includes one or more processor devices configured to selectively control the electric motor (506) for operation of the hydraulic actuator (520), by: in a flow control mode, controlling the electric motor (506) based on a target flow rate for flow of hydraulic fluid from the hydraulic pump (504) to the hydraulic actuator (520); and in a power control mode, controlling the electric motor (506) based on one or more of a target power consumption for the electric motor (506) or a threshold motor speed.
  2. 2. The power machine (100) of claim 1, wherein the control system (508) is further configured to: while controlling operation of the electric motor (506) in the flow control mode, determine a first power consumption of the electric motor (506); and transition to controlling operation of the electric motor (506) in the power control mode in response to determining that the first power consumption exceeds a first threshold power consumption.
  3. 3. The power machine (100) of claim 2, wherein the control system (508) is further configured to: while controlling operation of the electric motor (506) in the power control mode, determine a second power consumption of the electric motor (506); and transition to controlling operation of the electric motor (506) in the flow control mode in response to determining that the first power consumption does not exceed a second threshold power consumption.
  4. 4. The power machine (100) of any of the preceding claims, wherein the control system (508) is configured to selectively control operation of the hydraulic actuator (520) by: determining a first target motor speed for the flow control mode; determining a second target motor speed for the power control mode; and controlling the electric motor (506) based on the smaller of the first and second target motor speeds, and optionally or preferably wherein one or more of: the first target motor speed for the flow control mode is determined based on the target flow rate for flow of hydraulic fluid from the hydraulic pump (504) to the hydraulic actuator (520); or the second target motor speed for the power control mode is determined based on one or more of the target power consumption for the electric motor (506) or the threshold motor speed.
  5. 5. The power machine of claim 4, wherein the first target motor speed is determined based on the target flow rate and a difference between a pump pressure and a load pressure associated with the hydraulic actuator (520), and wherein the second target motor speed is determined based on the pump pressure for the hydraulic pump (504).
  6. 6. The power machine of any of the preceding claims, wherein, in the flow control mode, the target flow rate is based on an operator input that commands operation of the hydraulic actuator (520).
  7. 7. The power machine of any of the preceding claims, wherein, in the flow control mode, the one or more processor devices control the electric motor (506) based on the target flow rate and a difference between a pump pressure and a load pressure associated with the hydraulic actuator (520).
  8. 8. The power machine of claim 7, wherein, in the flow control mode, the one or more processor devices control the electric motor (506) to reduce motor speed in response to determining that the difference between the pump and load pressures exceeds a threshold pressure drop.
  9. 9. The power machine of either of claims 7 or 8, wherein the control system further comprises: a control valve (510) configured to control flow from the hydraulic pump (504) to the hydraulic actuator (520); a first pressure sensor (512) configured to sense a fluid pressure corresponding to an inlet (522) to the control valve (510) for flow from the hydraulic pump (504); and a second pressure sensor (514) configured to sense a fluid pressure corresponding to an outlet (524) from the control valve (510) to the hydraulic actuator (520); and wherein the one or more processor devices are configured to determine the pump pressure based on signals from the first pressure sensor (512) and determine the load pressure based on signals from the second pressure sensor (514), and optionally or preferably wherein the first and second pressure sensors (512, 514) are integrated into the control valve (510).
  10. 10. The power machine of any of the preceding claims, wherein the lift arm assembly (502) is an excavator lift arm assembly, including a boom (232) and an arm (234) pivotally supported by the boom (232); and wherein the hydraulic actuator (520) is configured to move the boom (232) relative to a frame (210) of the power machine (100) or to move the arm (234) relative to the boom (232).
  11. 11. The power machine of claim 1, wherein the hydraulic pump (504) is a constant displacement pump.
  12. 12. A method of controlling operation of a work element of a power machine (100), the method comprising: selectively controlling operation of an electric motor (506), with one or more processor devices, in a flow control mode or a power control mode, the electric motor (506) being arranged to power rotation of a hydraulic pump (504), the hydraulic pump (504) being arranged to power a hydraulic actuator (520) to move the work element; wherein, in the power control mode, the electric motor (506) is controlled based on a target power consumption for the electric motor (506); and wherein, in the flow control mode, the electric motor (506) is controlled based on a target pressure differential between (i) a pump pressure corresponding to an outlet (524) from the hydraulic pump (504) and (ii) a load pressure corresponding to the hydraulic actuator (520).
  13. 13. The method of claim 12, further comprising: determining a present pressure differential between the pump pressure and the load pressure based on (i) data from a first pressure sensor (512) configured to sense a fluid pressure upstream of or at an inlet (522) to a control valve (510) and (ii) data from a second pressure sensor (514) configured to sense a fluid pressure downstream of or at an outlet (524) from the control valve (510); wherein in the flow control mode, controlling the electric motor (506) based on the target pressure differential includes controlling the electric motor (506) based on a comparison between the present pressure differential and the target pressure differential.
  14. 14. The method of claim 13, wherein, in the power control mode, controlling the electric motor (506) based on the target power consumption includes controlling the electric motor (506) based on data from the either of the first pressure sensor (512) or the second pressure sensor (514).
  15. 15. The method of claim 12, wherein selectively controlling operation of the electric motor (506) in the flow control mode or the power control mode includes: determining a first target motor speed for the flow control mode; determining a second target motor speed for the power control mode; and controlling the electric motor (506) based on the smaller of the first and second target motor speeds.

Description

SYSTEMS AND METHODS FOR CONTROL OF EXCAVATORS AND OTHER POWER MACHINES CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. provisional patent application no. 63/595,579, filed November 2, 2023, the entirety of which is incorporated herein by reference. BACKGROUND [0002] This disclosure is directed toward power machines. More particularly, this disclosure is directed to excavators and control systems for excavators and workgroups thereof. [0003] Power machines, for the purposes of this disclosure, include any type of machine that generates power to accomplish a particular task or a variety of tasks. One type of power machine is a work vehicle. Work vehicles are generally self-propelled vehicles that have a work device, such as a lift arm (although some work vehicles can have other work devices) that can be manipulated to perform a work function. Work vehicles include excavators, loaders, utility vehicles, tractors, and trenchers, to name a few examples. [0004] Excavators are a known type of power machine that generally have an undercarriage and a house that selectively rotates on the undercarriage. A lift arm, to which an implement can be attached, is operably coupled to the house and moveable under power with respect to the house. Excavators are also typically self-propelled vehicles. Typical excavators include one or more operator input devices (e.g., joysticks or pedals) that are physically moved by an operator to directly adjust hydraulic fluid flow through a particular component of the excavator (e.g., a control valve for an actuator for a lift arm) thereby adjusting the movement of a particular component (e.g., the lift arm). For example, a joystick can be physically coupled to a hydraulic valve through mechanical cables or linkages between the joystick and the hydraulic valve, or through hydraulic signals that are controlled by the joystick (i.e., the use of what is commonly known as pilot operated joysticks). Thus, for example, movement of the joystick can directly change the hydraulic valve position and thereby cause movement of an actuator and a component that is coupled to the actuator. [0005] The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. SUMMARY OF THE DISCLOSURE [0006] Some embodiments of the invention provide a power machine. The power machine can include a lift arm assembly, a hydraulic pump, an electric motor, and a control system. The lift arm assembly can include a hydraulic actuator. The hydraulic pump can be in hydraulic communication with the hydraulic actuator and configured to power movement of the lift arm assembly. The electric motor is configured to power rotation of the hydraulic pump. The control system includes one or more processor devices that is configured to selectively control operation of the hydraulic actuator. When in a flow control mode, the electric motor is controlled based on a target flow rate for flow of hydraulic fluid from the hydraulic pump to the hydraulic actuator. When in a power control mode, the electric motor is controlled based on a target power consumption for the electric motor. [0007] In some examples, a power machine can include a lift arm assembly, a hydraulic pump, and a control system. The lift arm assembly can include a hydraulic actuator. The hydraulic pump can be in hydraulic communication with the hydraulic actuator and configured to power movement of the lift arm assembly. The electric motor can be arranged to power the rotation of the hydraulic pump. The control system can include a first pressure sensor, a second pressure sensor, and one or more processor devices. The first pressure sensor can be arranged to a sense a pump pressure. The second pressure sensor can be arranged to sense a load pressure. The one or more processor devices can be configured to control the electric motor based on a difference between the sensed pump pressure and the sensed load pressure in response to a requested movement of the lift arm assembly. [0008] In some examples, a method of controlling operation of a work element of a power machine can include selectively controlling operation of an electric motor with one or more processor devices. The controlling operation of the electric motor can be in a flow control mode or a power control mode and the electric motor is arranged to power rotation of a hydraulic pump. The hydraulic pump is arranged to power a hydraulic actuator to move the work element. When in the flow control mode, the electric motor is controlled based on a target pressure differential between (i) a pump pressure that corresponds to an outlet from the hydraulic pump and (ii) a load pressure corresponding to a sensed load pressure of a main control valve. While in the power control mode, the electric motor is controlled based on a target power consumption for the electric motor. [0009] I