Work vehicle

Abstract

The utility model relates to a working vehicle (100), which is provided with a control unit (114), a control unit (114) and a control unit (114), wherein the control unit is used for calculating the required flow of hydraulic oil based on the input of an operator; and a motor (104) for driving the hydraulic pump (116) in order to produce the calculated flow rate.

Description

Technical Field

[0001] The utility model relates to a work vehicle and a method for operating a work vehicle. Background Art

[0002] Conventional work vehicles, such as wheel loaders, use an internal combustion engine as the only drive source. The powertrain and the hydraulic pump are connected to the internal combustion engine via the same drive shaft. When the motor speed increases, the speed of the powertrain and the delivery volume of the hydraulic pump always increase. In order to specifically increase the delivery volume of the hydraulic pump, when the excavator bucket should move, the user operates a control pedal, for example. Summary of the Utility Model

[0003] The work vehicle according to the utility model includes: a control unit for calculating the required flow rate of hydraulic oil based on an operator input; and an electric machine for driving a hydraulic pump to generate the calculated flow rate. The electric machine includes, for example, an electric motor and / or a generator. The electric machine can achieve the technical advantage of reducing losses in the hydraulic system because the speed of the hydraulic pump is not coupled to the speed of the internal combustion engine. Moreover, due to the absence of coupling, the pump speed does not increase during the driving operation of the work vehicle, so that unnecessary circulation of hydraulic oil in the hydraulic system is prevented. Therefore, the hydraulic pump can operate independently in the hydraulic system at the required minimum speed and / or velocity.

[0004] In an advantageous embodiment, the work vehicle additionally includes an internal combustion engine for driving the hydraulic pump to generate the calculated flow rate. This can achieve the technical advantage that if the electric machine does not provide sufficient power, the internal combustion engine can assist the electric machine.

[0005] In another advantageous embodiment, the work vehicle includes a clutch for decoupling the internal combustion engine from the hydraulic pump. This can achieve the technical advantage that the hydraulic pump can operate independently of the internal combustion engine when needed.

[0006] In another advantageous embodiment, the electric machine is decoupled from the powertrain of the work vehicle. This can achieve the technical advantage that the pump speed can be set independently of the drive power.

[0007] In another advantageous embodiment, the work vehicle includes a detection device for detecting the deflection of a joystick and / or the angular velocity of a steering wheel. This can achieve the technical advantage that the deflection of the joystick and / or the angular velocity of the steering wheel can be transmitted to the control unit via a signal.

[0008] In another advantageous embodiment, the work vehicle includes a battery for storing energy for the electric machine. This can achieve the technical advantage that the electric machine can operate independently of an external energy source and independently of the internal combustion engine.

[0009] In another advantageous embodiment, the control unit is configured to calculate the speed or rotational speed of the hydraulic pump based on the required flow rate. This enables the technical advantage that the required flow rate can be provided quickly.

[0010] In another advantageous embodiment, the work vehicle includes an adjustment circuit for adjusting the speed or rotational speed of the hydraulic pump. This enables the technical advantage that the required flow rate can be provided in a simple manner with high precision.

[0011] In another advantageous embodiment, the work vehicle is a wheel loader or a dump loader. This enables the technical advantages of simplifying the operation of the wheel loader and reducing the operator's workload.

[0012] The method for operating a work vehicle according to the present invention includes the following steps: calculating the required flow rate of the hydraulic oil based on the operator input; and driving the hydraulic pump by an electric motor to generate the calculated flow rate. The same technical advantages as those of the work vehicle are achieved by the method. Description of the Drawings

[0013] Embodiments of the present invention are elaborated in detail according to the following drawings. Shown herein are:

[0014] Figure 1 A schematic diagram showing a work vehicle;

[0015] Figure 2 A schematic diagram showing the control of the work vehicle; and

[0016] Figure 3 A schematic diagram showing a method for driving a work vehicle. Detailed Description of the Invention

[0017] Figure 1 A schematic diagram showing a work vehicle 100 having an internal combustion engine 102 and an electric motor 104. The work vehicle 100 is, for example, a wheel loader or a dump loader. The work vehicle 100 includes a power train 106 for driving the work vehicle 100. An electric drive unit 118 is present in the power train 106. The drive unit 118 is formed, for example, by a motor equipped with an inverter. The drive unit 118 is supplied with electrical energy via a battery 122 or via the electric motor 104. The battery 122 is, for example, a high-voltage battery. The position of the control pedal 108 reflects the required driving torque and is used when controlling the electric drive unit 118.

[0018] However, specific components of the work vehicle 100 are moved via a hydraulic system. Here, pressure is generated by means of hydraulic oil and this pressure is converted into mechanical energy. For example, the work vehicle 100 includes a bucket, and the movement of the bucket is caused hydraulically. In this case, the user operates a joystick 110 in order to cause the movement of the bucket via the valve controller 124. The hydraulic oil is conducted into a hydraulic piston by the valve controller 124, and the hydraulic piston causes the corresponding movement of the bucket.

[0019] The hydraulic power is provided by a hydraulic pump 116. The hydraulic pump 116 can be driven by an electric motor 104 or by an internal combustion engine 102. For this purpose, a clutch 120 is used to controllably connect or disconnect the internal combustion engine 102. The internal combustion engine 102 can be used to drive the hydraulic pump 116 or to charge the battery 122 via the electric motor 104.

[0020] Furthermore, in the case of a hydraulic power steering device (Orbitrol-Steering), the steering position of the wheels can also be caused hydraulically. In this case, the user operates the steering wheel in order to likewise cause the movement and control of the wheels via the valve controller 112.

[0021] Depending on the operation of the joystick 110 and the steering wheel, the user requests the flow rate of the hydraulic oil for the valve control of the corresponding components. The hydraulic pump 116 is connected via a priority valve 126, which ensures an adequate supply of hydraulic oil and distributes the hydraulic oil between the steering system and the bucket. The greater the mechanical power to be generated, the greater the required flow rate of the hydraulic oil. The hydraulic oil is conveyed by the hydraulic pump 116, which provides the required flow rate via the pump speed.

[0022] The hydraulic pump 116 is driven by the electric motor 104 independently of the powertrain 106. The energy supply of the electric motor 104 is carried out by the battery 122, which also supplies current to the drive unit 118 having an electric motor. The battery 122 is connected to the electric motor 104 via a DC-AC converter 128. In this way, the battery 122 can be charged via the internal combustion engine 102.

[0023] The connection between the joystick 110 (and / or the steering wheel) and the hydraulic pump 116 is formed by a control unit 114, which calculates the required flow rate of the hydraulic oil and controls the hydraulic pump 116 such that the calculated flow rate of the hydraulic oil can be generated. The powertrain 106 is not mechanically connected to the hydraulic pump 116, such that the speed or rotational speed can be controlled independently of the drive power demand. Therefore, depending on the previously calculated flow rate, the control unit 114 can increase or decrease the pump speed of the hydraulic pump 116 independently of the rest of the powertrain 106.

[0024] Figure 2Schematic diagram showing the control of the work vehicle 100. The work vehicle includes a control unit 114, such as a hybrid control unit - HCU. The control unit 114 includes, for example, a microprocessor for running control programs and a digital memory for storing programs and other data. The control unit 114 processes input signals generated by a control pedal 108, a joystick 110, and a steering wheel 112. A detection device 132 (Joystick Controller) is used, for example, to detect the deflection of the joystick 110. The position of the steering wheel 112 is also transmitted to the control unit 114 via a signal, for example. In order to determine the required flow rate of the hydraulic oil, the deflection of the joystick 110 and / or the angular velocity of the steering wheel 112 are transmitted to the control unit 114 via electrical signals, for example.

[0025] The control unit 114 controls the activation, deactivation, and torque of the internal combustion engine 102. In addition, the control unit 114 calculates the speed or rotational speed of the hydraulic pump 116 based on the required flow rate. For this purpose, the control unit 114 controls an electric motor 104 that drives the hydraulic pump 116. The speed or rotational speed of the hydraulic pump 116 is regulated, for example, by a regulating circuit 130. Here, the desired rotational speed is transmitted to the electric motor 104 and the current actual rotational speed is fed back to the control unit 114. In this way, an effective regulation of the flow rate can be achieved.

[0026] Figure 3 Schematic diagram showing a method for operating the work vehicle 100. In step S101, the required flow rate of the hydraulic oil is calculated based on the operation of the joystick 110 and / or the steering wheel 112. In the subsequent method step S102, the hydraulic pump 116 is driven by the electric motor 104 in order to generate the calculated flow rate.

[0027] The method can achieve the following advantages, namely, reducing losses in the hydraulic system because the pump speed is not continuously coupled to the driving torque demand. The use of its own electric motor 104 for driving the hydraulic pump 116 allows the hydraulic pump 116 to operate as needed and prevents unnecessary circulation of the hydraulic oil. Therefore, the hydraulic pump 116 can operate at the minimum required rotational speed and / or speed. This not only results in fuel savings but also allows an increase in the service life of the pump.

[0028] In addition, the operation of the work vehicle 100 is simplified by the said control. By controlling the work vehicle 100, the required flow rate of the hydraulic oil can be calculated in a simple manner, so that the operation is simplified and the operator's load is reduced. The reason for the simplified operation is that the powertrain is decoupled from the working hydraulic system and the pump speed is automatically controlled based on the required flow rate. Different from the conventional control of work vehicles, in order to control the work vehicle, the operator does not need to operate multiple control elements. This is the case, for example, when the bucket of a wheel loader should be lifted and the vehicle should be braked at the same time.

[0029] All features described and illustrated in connection with the various embodiments of the present invention can be presented in different combinations in the subject matter according to the present invention in order to achieve its advantageous effects simultaneously.

[0030] All method steps can be implemented by a device suitable for performing the corresponding method steps. All functions implemented by the features of the subject matter can be a method step of a method.

Claims

1. A working vehicle (100), characterized in that: The working vehicle has: - a control unit (114) for calculating a required flow rate of hydraulic oil based on an operator input; and - an electric motor (104) for driving a hydraulic pump (116) in order to generate said calculated flow rate.

2. The work vehicle (100) of claim 1, wherein the work vehicle (100) additionally comprises an internal combustion engine (102) for driving the hydraulic pump (116) so as to generate the calculated flow rate.

3. The work vehicle (100) of claim 2, wherein the work vehicle (100) includes a clutch (120) for decoupling the internal combustion engine (102) from the hydraulic pump (116).

4. The work vehicle (100) according to any one of the above claims, wherein the electric machine (104) is decoupled from a powertrain (106) of the work vehicle (100).

5. The working vehicle (100) according to any one of claims 1 to 3, wherein the working vehicle (100) comprises a detection device (132) for detecting the deflection of the joystick (110) and / or the angular velocity of the steering wheel (112) as user input.

6. The work vehicle (100) according to any one of claims 1 to 3, wherein the work vehicle (100) comprises a battery (122) for storing energy for the motor (104).

7. The work vehicle (100) according to any one of claims 1 to 3, wherein the control unit (114) is configured to calculate a speed or rotational speed of the hydraulic pump (116) based on the required flow rate.

8. The work vehicle (100) according to claim 7, wherein the work vehicle (100) comprises a regulating circuit (130) for regulating the speed or rotation speed of the hydraulic pump (116).

9. The work vehicle (100) according to any one of claims 1 to 3, wherein the work vehicle (100) is a wheel loader or a dump loader.

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