KR102275211B1 - Three-wheel electric forklift having steering type dual drive unit and, driving method thereof - Google Patents

Abstract

The three-wheel electric forklift according to the present invention drives and steers the left and right wheels of the front wheels using a steering dual drive unit, and steers the rear wheels using the steering unit. Accordingly, it is possible to implement a minimum turning radius driving, in-place rotation driving, and crab driving in a narrow space.

Description

Three-wheel electric forklift having steering type dual drive unit and driving method thereof

The present invention relates to a three-wheel electric forklift, and more specifically, driving and steering the left and right wheels of the front wheels using a steering dual drive unit and steering the rear wheels using the steering unit, thereby driving the minimum turning radius; It is about a three-wheeled electric forklift that can efficiently work even in a narrow space by implementing in-situ rotational driving and crab driving.

In addition, the present invention includes a driving method of such a three-wheel electric forklift.

An electric forklift is a forklift that uses an electric power source and is a logistics vehicle that mainly performs work indoors, such as factories and warehouses.

The electric forklift includes a fork unit for performing work and a power transmission system for driving, and a front wheel drive rear wheel steering method is generally used to facilitate work and logistics transport of the fork unit.

In particular, the power transmission system is divided into a four-wheel system and a three-wheel system depending on the number of wheels. Forklifts with a three-wheel power transmission system with a smaller turning radius than the four-wheel power transmission system can be operated in a narrow space such as indoor logistics work. is commonly used.

The power transmission system of the 3-wheel electric forklift is divided into a dual drive unit at the front wheel and a steering unit at the rear wheel. The dual drive unit drives the electric forklift and the steering unit at the rear determines the direction of movement of the forklift.

As shown in FIG. 1, the main components of the dual drive unit are an electric motor, a gearbox, and a wheel (front wheel), and since the front axle is fixed to the frame, steering of the wheel (front wheel) is impossible and forward and backward driving only possible

In addition, the steering unit performs a steering function that determines the traveling direction of the electric forklift, and unlike general industrial vehicles, the wheel (rear wheel) can rotate 360°, so it has a smaller turning radius than the existing four-wheel power transmission system.

As such, the 3-wheel power transmission system has a smaller turning radius than the 4-wheel power transmission system, but because the front axle is fixed to the frame, it is difficult to operate efficiently when the working space is narrow, and various driving conditions are not satisfied. there are many

The turning radius of the four-wheel power transmission system and the turning radius of the three-wheel power transmission system can be compared through the following equation. The turning radius is determined according to the steering angle and wheel base of the front and rear axles, and is as follows.

In the above formula,

As shown in FIG. 2 , as for the turning radius R ₄ of the four-wheel dynamometer, since the frame is fixed to the front wheel, the front wheel steering angle is δ _f = 0, and the turning radius is determined according to _{the sinδ r of the rear wheel steering angle.}

However, in the 4-wheel power transmission system, the range of _{sinδ r} is limited because the rear wheel steering angle is limited to the maximum steering angle by the axle structure.

On the other hand, as shown in Figure 3, the turning radius (R ₃ ) of the three-wheel dynamometer is the same as the wheelbase when the rear wheel steering angle is up to 90˚ (sinδ _r = 1), so the four-wheel power transmission system It can be seen that the turning radius of the three-wheel power transmission system is smaller.

As such, the 3-wheel power transmission system has a smaller turning radius than the 4-wheel power transmission system, but because the front axle is fixed to the frame, it is difficult to operate efficiently when the working space is narrow, and the minimum turning radius driving and in-place rotation driving And, in many cases, various driving conditions such as crab driving are not satisfied.

Therefore, the present invention can steer the front wheels (left and right wheels) and thus efficiently drive in a narrow working space and satisfy various driving conditions such as minimum turning radius driving, in-situ rotation driving, and crab driving. It aims to provide a wheel electric forklift.

Another object of the present invention is to provide a method of driving such a three-wheeled electric forklift.

In order to achieve the above object, the three-wheel electric forklift 200 according to the present invention includes a steering-type dual drive unit 100 . The steering-type dual drive unit 100 drives and steers the left and right wheels FLW (FRW) of the front wheels.

The steering-type dual drive unit 100 includes: an electric motor 110 for driving that is respectively installed to correspond to the left and right wheels (FLW) (FRW) of the front wheels and provides a driving force; Steering knuckles 130 respectively installed on the left and right wheels (FLW) (FRW); and an actuator 140 installed to push or pull the steering knuckle 130 . _{The steering angle δ f of the} front wheel is adjusted by the retraction and withdrawal of the actuator 140 . And, the steering angle δ _r of the rear wheel RW is adjusted by the steering unit.

The maximum steering angle of the front wheel is less than 90˚, and preferably the front wheel steering angle (δ _f ) is 0˚ to 55˚.

The actuator 140 is preferably a linear actuator driven by an electric motor for steering. The encoder 145 may measure the rotation angle and the rotation direction of the electric motor for steering, and estimate the steering _{angle δ f and the steering direction of the front wheel using the measured values.}

The driving force of the electric motor 110 for driving is transmitted to the left wheel FLW or the right wheel FRW through the gearbox 120 and the universal joint 125 and the wheel shaft (hub). The gearbox 120 adjusts the R.P.M. and rotational force of the electric motor 110 for driving, and the universal joint 125 is connected to the output shaft of the gearbox 120 and may change the direction of power transmission by front wheel steering.

The minimum turning radius driving of the three-wheel electric forklift 200 may include: (a) selecting a minimum turning radius driving mode; (b) detecting _{steering angles (δ f} ) (δ _r ) of the front and rear wheels according to the driver's manipulation of the steering wheel; And, (c) driving to the minimum turning radius after (b); may include. In step (b), when the rear wheel steering angle is 55˚ or less, the left and right steering angles are the same as the rear wheel steering angles, but the steering direction is reversed. When the rear wheel steering angle exceeds 55˚, the left and right steering angles are set to 55˚. However, the steering direction is opposite to that of the rear wheel.

In step (c), the rear wheel steering angle (δ _r ) is preferably 70˚ or less.

The in-place rotation of the three-wheeled electric forklift 200 may include: (a) selecting an in-place rotation mode; (b), but determines the steering angle (δ _f) of the left and right wheel (FLW) (FRW) using the following formula, the same is left, the steering angle (δ _f) of the right wheel (FLW) (FRW) and a steering direction is to the contrary step; (c) the driver manipulates the steering wheel so that the rear wheel RW is perpendicular to the _{wheelbase L wb;} (d) determining the rotation direction according to the rotation direction of the handle; And, (e) the step of rotating in place; may include.

[expression]

In the above formula,

L _wb : wheelbase

L _tread : tread

For example, when the handle is rotated to the right, the electric motor 110 for driving the left wheel FLW rotates in the forward direction and the electric motor 110 for driving the right wheel FRW rotates in the reverse direction to rotate the three-wheeled electric forklift 200. can be rotated clockwise. And, when the handle is rotated to the left, the electric motor 100 for driving the left wheel FLW rotates in the reverse direction and the electric motor 100 for driving the right wheel FRW rotates in the forward direction, so that the three-wheel electric forklift turns counterclockwise. can be rotated.

Here, the forward rotation of the driving electric motor 110 refers to a rotation direction when the electric forklift moves forward, and the reverse rotation of the driving electric motor 110 refers to a rotation direction when the electric forklift moves backward.

The crab driving of the three-wheeled electric forklift 200 may include: (a) selecting a crab driving mode; _{(b) The steering angle (δ r} ) and steering direction of the rear wheel are determined in response to the steering wheel rotation, but when the rear _{wheel steering angle (δ r} ) is less than or equal to the maximum steering angle of the front wheel (for example, 55˚), the steering angle of the front wheel (δ _f ) and the steering direction are _{determined to be the same as the rear wheel steering angle (δ r} ) and the steering direction, and when the rear wheel steering angle (δ _r ) exceeds the maximum steering _{angle, the front and rear wheel steering angles (δ f} ) (δ _r ) are set to the maximum steering angle. and making the front and rear wheel steering directions the same; and, (c) driving the crab.

The present invention has the following effects.

First, it is possible to steer the front wheels (left and right wheels) and accordingly, various driving conditions such as minimum turning radius driving, in-place rotation driving, and crab driving can be satisfied. can be easily applied.

Second, it can be extended to a four-wheel electric forklift, and it can also be applied to an in-wheel type steering system.

1 is a front view showing a dual drive unit of a three-wheeled electric forklift according to the prior art.
2 is a view showing a turning radius of a four-wheel power transmission system according to the prior art.
3 is a view showing a turning radius of a three-wheel power transmission system according to the prior art.
4 is a perspective view showing a three-wheeled electric forklift having a steered dual drive unit according to a preferred embodiment of the present invention;
Fig. 5 is a front view of Fig. 4;
Figure 6 is an enlarged view of part A of Figure 4;
7 is a view showing the main configuration of a steerable dual drive unit.
8 is a view showing a case in which the actuator of the steering-type dual drive unit is withdrawn.
9 is a view showing a case in which the actuator of the steering-type dual drive unit is retracted;
10 is a view showing a case in which a three-wheel electric forklift according to a preferred embodiment of the present invention is driven with a minimum turning radius;
11 is a graph showing a turning radius according to a front wheel steering angle (δ _f ) and a rear wheel steering angle (δ _{r ).}
Fig. 12 is a flow chart showing an operation sequence for driving with a minimum turning radius;
13 is a view showing a case of driving in place.
Fig. 14 is a flowchart showing an operation sequence when driving in place;
15A is a view showing the crab driving, showing a case where the steering angles of the front and rear wheels are the same;
15B is a view showing crab driving, and is a view showing a case in which a rear wheel steering angle is greater than a front wheel steering angle;
16 is a flowchart showing an operation sequence when the crab is driven.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to conventional or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. Based on the principle that it can be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention. Accordingly, since the embodiments described in the present specification and the configurations shown in the drawings are merely embodiments of the present invention and do not represent all the technical spirit of the present invention, various equivalents that can be substituted for them at the time of the present application It should be understood that there may be variations and examples.

I. Structure of 3 wheel electric forklift with steered dual drive unit

4 is a perspective view showing a three-wheeled electric forklift according to a preferred embodiment of the present invention, FIG. 5 is a front view of FIG. 4 , and FIG. 6 is an enlarged view of part A of FIG. 4 .

As shown in the drawing, the three-wheel electric forklift 200 includes a steering dual drive unit 100 and a steering unit.

The steering-type dual drive unit 100 drives the front wheels (left, right, FLW, and FRW) and adjusts _{the steering angle δ f of the front wheels FLW (FRW).} Specifically, the steering-type dual drive unit 100 includes a frame 101 , a driving electric motor 110 installed on the frame 101 , and a gearbox for controlling the rotational speed and rotational force of the driving electric motor 110 . 120, a universal joint 125 connected to the output shaft of the gearbox 120, a wheel axle (hub) connected to the universal joint 125, and a steering knuckle installed in each of the left and right wheels (FLW) (FRW) ( 130 , and an actuator 140 installed to push or pull the steering knuckle 130 .

The frame 101 is a part of the vehicle body, and the left and right electric motors 110 for driving are installed in the frame 101 .

The driving electric motor 110 is installed on the left and right wheels (FLW) (FRW), respectively. The right driving electric motor 110 provides driving force to the right wheel FRW, and the left driving electric motor 110 provides driving force to the left wheel FLW.

The driving force provided from the electric motor 110 for driving is transmitted to the left wheel FLW or the right wheel FRW through the gearbox 120 , the universal joint 125 , and the wheel shaft (hub). The gearbox 120 controls the rotational speed (RPM) and rotational force and transmits it to the universal joint 125, and the universal joint 125 changes the power transmission direction according to the steering angle of the front wheels (FLW) (FRW) to change the direction of the wheel axle (Herb) to pass.

The steering knuckles 130 are respectively installed on the left and right wheels FLW (FRW). The steering knuckle 130 is supported by two supports 132 and its direction (steering angle) is adjusted by the actuator 140, and is connected to the front wheel (FLW) (FRW) by a hub bearing or the like, so the front wheel (FLW) ( Even if FRW) is rotated, it is not rotated.

The two supports 132 are installed on the upper and lower portions of the output shaft of the gearbox 120 . The rear end of the support 132 is installed on the frame 101 so as to be rotatable in the vertical direction, and the front end of the support 132 is installed on the steering knuckle 130 by a kingpin so that it can rotate in the left and right direction.

Actuator 140 is installed on the left and right wheels (FLW) (FRW), respectively, the left and right actuators 140 are driven by an electric motor for steering, the steering angle (δ _f ) of the front wheel (FLW) (FRW) Adjust. The front end of the actuator 140 is installed on the steering knuckle 130 so as to be rotatable in the left and right direction, and the rear end of the actuator 140 is installed in the frame 101 so as to be rotatable in the left and right direction.

Preferably, the actuator 140 is a linear actuator and the encoder 145 is installed in the actuator 140 . As shown in FIG. 7 , when the driver manipulates the steering wheel, the driver's will to steer is transmitted to the inverter with controller through a command signal, and the inverter controls the electric motor for steering in response to the actuator ( 140) is driven. Then, the encoder 145 measures the rotation angle and the rotation direction of the electric motor for steering, estimates the steering position of the actuator 140 using the measured values, and transmits the signal (estimated displacement) transmitted to the inverter.

8 shows a case in which the actuator 140 is withdrawn, and FIG. 9 shows a case where the actuator 140 is retracted. Due to constraints such as a structure in which the actuator 140 and the steering knuckle 130 are connected, the maximum steering angle of the front wheel FLW (FRW) is less than 90˚, and preferably, the steering angle range of the front wheel FLW (FRW) is 0˚ ~ 55 degrees.

Meanwhile, the steering unit adjusts _{the steering angle δ r of the rear wheel RW.} In the three-wheeled electric forklift 200 according to the present invention, the rear wheel RW is responsible for only steering. As the steering unit, a well-known steering device such as EPS may be used.

II. Driving method of 3-wheel electric forklift with steered dual drive unit

1. Minimum turning radius driving

The minimum turning radius driving is performed when, as shown in FIG. 10 , the front wheel steering angle δ _f and the rear wheel steering angle δ _r are the same but the steering directions are opposite. Therefore, in Equation (1), the proportional constant (ξ) becomes 1, so Equations (1) and (2) become as follows, and the minimum turning radius is 1/2 of the turning radius of the existing dual drive three-wheel electric forklift.

On the other hand, as described above, _{the range of the front wheel steering angle (δ f} ) is 0˚ to 55˚, whereas the range of the rear wheel steering angle (δ _r ) is 0˚ to 90˚, so the front wheel steering angle (δ _f ) and the rear wheel steering angle ( The turning radius (R) when δ _r ) is steered at the same angle in the range of 0˚ to 55˚, and the rear wheel steering angle (δ _r ) _{at the maximum steering angle of the front wheel (δ f = 55˚)} When the turning radius (R) when 56˚ ~ 90˚ is shown in a graph, it is as shown in FIG.

11, it can be seen that there is no significant change in the turning radius when the front wheel steering angle (δ _f ) is 55˚ and the rear wheel steering angle (δ _{r ) is 56˚ to 90˚, which is the front wheel steering angle (δ f} ) is relatively larger than the effect of the rear wheel steering angle (δ _{r ).}

In addition, when the rear wheel steering angle δ _r is greater than 70˚, the turning radius R slightly increases, because it exceeds the turning radius of the forklift 200 and slippage of the rear wheel RW occurs. Therefore, it can be seen that the rear wheel steering angle (δ _r ) should be controlled to 70˚ or less when driving the minimum turning radius.

Then, each step of driving the minimum turning radius will be sequentially described with reference to FIG. 12 .

First, the driver selects the minimum turning radius driving mode (S10). Subsequently, when the driver turns the steering wheel, the front wheel steering device and the rear wheel steering unit operate simultaneously, and the front wheel steering angle δ _f and the rear wheel steering angle δ _r of the rear wheel steering unit are detected ( S20 ).

As described above, when the minimum turning radius is driven, the front and rear wheel _{steering angles (δ f} ) (δ _r ) are the same, but the steering directions are opposite, and the front wheel steering angle (δ _f ) ranges from 0˚ to 55˚. Therefore, if the rear wheel steering angle (δ _{r ) is 55˚ or less, the steering angle (δ f} ) of the left and right wheels (FLW) (FRW) is the same as the rear wheel steering angle (δ _r ), but the rotation direction is reversed (S30), and the rear wheel steering angle If (δ _r ) is greater than 55˚ and less than or equal to 70˚, the steering angle (δ _f ) of the left and right wheels (FLW) (FRW) is set to 55˚, and the rear wheel steering angle (δ _r ) is the actual steering angle (S40).

On the other hand, as shown in FIG. 11 , when the steering angle δ _f of the left and right wheels FLW (FRW) is 55˚, when the rear wheel steering angle δ _r exceeds 70˚, the turning radius R slightly increases. Therefore, the rear wheel steering angle (δ _r ) should be 70˚ or less. For example, the inverter (Inverter with controller) maintains the rear wheel steering angle δ _r at 70˚ when the rotation angle of the handle exceeds 70˚ (S50).

When the inverter with controller drives the electric motor for steering after the front and rear wheel steering angles δ _f (δ _r ) are set, the actuator 140 is drawn in or out, and the left and right wheels (FLW) (FRW) are set above. It is steered at a steering angle, and then the driving electric motor 110 is driven to drive the left and right wheels (FLW) (FRW) ( S60 ).

2. In-situ rotation drive

In order to rotate in place, as shown in FIG. 13 , the left and right wheel _{steering angles δ f} should be the same, but the steering directions should be opposite.

And, in order to rotate in place, it is necessary to select the steering angle so that the center _{of the turning radius becomes the center of the wheelbase (L wb} ), and the front wheel steering angle using the _{wheelbase (L wb} , wheel base) and the tread (L _{tread , tread)} (δ _f ) can be calculated.

When the wheelbase (L _wb ) and the tread (L _tread ) are the same, the front wheel steering angle (δ _f ) is 45˚, but in general, the wheelbase (L _{wb ) is longer than the tread (L tread} ), so the front wheel steering angle by Equation 3 below Calculate (δ _f ).

[expression]

At this time, the rear wheel steering angle (δ _r ) is set to be perpendicular to the wheelbase (L _{wb ).}

When driving in place, the rotation directions of the electric motor 110 for driving the left and right wheels should be opposite to each other, and the rotation direction is determined according to the operation direction of the driver's handle. For example, when the electric forklift 200 is intended to rotate in the clockwise direction (CW), when the driver rotates the handle to the right, the electric motor 110 for driving the left wheel FLW rotates in the forward direction and The driving electric motor 110 rotates in the reverse direction. Here, the forward direction refers to the rotation direction of the electric motor 110 for driving when the electric forklift 200 moves forward, and the reverse direction refers to the rotation direction of the electric motor 110 for driving when the electric forklift 200 moves backward. do.

And, when the electric forklift 200 is to be rotated counterclockwise (CCW), when the driver rotates the handle to the left, the electric motor 110 for driving the left wheel rotates in the reverse direction and the electric motor for driving the right wheel ( 110) is rotated in the forward direction. 13 shows a case in which the electric forklift 200 is rotated in a counterclockwise direction (CCW).

Then, each step of the in-situ rotation driving will be sequentially described with reference to FIG. 14 .

First, the driver selects the in-place rotation driving mode (S110). Then, the inverter calculates the front wheel steering angle δ _f using Equation 3 and steers the rear wheel RW to be perpendicular to the wheelbase (S120). At this time, the left wheel FLW and the right wheel FRW of the front wheel have the same steering angle δ _{f but the} steering direction is opposite.

Then, when the driver turns the handle, the electric forklift 200 rotates in place (S130). That is, when the driver rotates the handle to the right, the electric forklift 200 rotates in place clockwise, and when the driver rotates the handle to the left, the electric forklift 200 rotates in place in the counterclockwise direction.

3. Crab Drive

As shown in FIG. 15A , the crab driving controls so that the front and rear wheel _{steering angles δ f} (δ _r ) are the same and driven in the same steering direction, and the rear wheel steering angle δ _r does not exceed the front wheel steering angle δ _{f .} should be limited

In particular, as shown in FIG. 15B , when the rear wheel steering angle δ _r exceeds the range of the front wheel steering angle δ _f , the driving direction of the vehicle changes, so the tires of the steering unit may be damaged and the stability of the electric forklift may be problematic. have.

Then, each step of crab driving will be sequentially described with reference to FIG. 16 .

First, the driver selects the crab driving mode (S210).

Then, when the driver turns the steering wheel, the rear wheel steering angle δ _r and the steering direction are sensed by the steering unit ( S220 ).

At this time, since the maximum value of the front wheel steering angle (δ _f ) is 55˚, when the rear wheel steering angle (δ _r ) is equal to or less than the maximum steering angle (55˚), the front wheel steering angle (δ _f ) and the steering direction are the rear wheel steering angle (δ _r ) and It is set to be the same as the steering direction (S230). And, when the rear wheel steering angle (δ _r ) exceeds the maximum steering angle (55˚), the front and rear wheel steering angles (δ _f ) (δ _r ) are set to the maximum steering angle of 55˚ (S240).

After the front and rear wheel _{steering angles δ f} (δ _r ) and the steering direction are determined, the crab driving is started ( S250 ).

100: steered dual drive unit
101: frame 110: electric motor for driving
120: gearbox 125: universal joint
130: steering knuckle 132: support
140: actuator 145: encoder
δ _f : Front wheel steering angle δ _r : Rear wheel steering angle
L, L _wb : Wheelbase L _tread : Track
R : Turn radius ξ : Proportional constant between front and rear wheel steering angles
FLW : Left wheel of front wheel FRW : Right wheel of front wheel
RW: rear wheel
200: 3-wheel electric forklift equipped with a steering dual drive unit

Claims (12)

It is a three-wheeled electric forklift equipped with a steered dual drive unit,
The steered dual drive unit is
an electric motor for driving that is respectively installed to correspond to the left and right wheels of the front wheel and provides driving force;
Steering knuckles installed on the left and right wheels of the front wheel respectively;
an actuator installed to push or pull the steering knuckle;
a gearbox for controlling RPM and rotational force by receiving the driving force of the electric motor for driving;
universal joint connected to the output shaft of the gearbox; and;
Including; a wheel shaft that is connected to the universal joint and rotates;
The steering angle of the front wheel is controlled by the actuator's retraction and withdrawal, and the maximum steering angle of the front wheel is less than 90˚,
The steering angle of the rear wheels is controlled by the steering unit,
The driving force is transmitted to the front wheel through the gearbox and the universal joint,
The actuator is a linear actuator driven by an electric motor for steering, and the encoder measures the rotation angle and rotation direction of the electric motor for steering, and uses the measured values to estimate the steering angle and steering direction of the front wheel. 3 wheel electric forklift. According to claim 1,
A three-wheeled electric forklift, characterized in that the steering angle of the front wheels is 0˚ to 55˚. delete According to claim 1,
In order for the electric forklift to be driven with the minimum turning radius, the front wheel steering angle and the rear wheel steering angle are set to be the same according to the steering intention of the driver, and the steering directions of the front and rear wheels are controlled to be opposite. It is a three-wheeled electric forklift equipped with a steering dual drive unit,
The steered dual drive unit is
an electric motor for driving that is respectively installed to correspond to the left and right wheels of the front wheel and provides driving force;
Steering knuckles installed on the left and right wheels of the front wheel respectively; and;
an actuator installed to push or pull the steering knuckle;
The steering angle of the front wheel is controlled by the actuator's retraction and withdrawal, and the maximum steering angle of the front wheel is less than 90˚,
The steering angle of the rear wheels is controlled by the steering unit,
For the in-place rotation of the electric forklift, the left and right wheels of the front wheel have the same steering angle but the steering direction is controlled in the opposite direction, and the front wheel steering angle is set by the following equation and the rear wheel steering angle is set to be perpendicular to the wheelbase. fork lift.
[expression]

In the above formula,
L _wb : wheelbase
L _tread : tread According to claim 1,
For the crab driving of the electric forklift, the steering angle of the front wheel and the rear wheel is controlled to be driven in the same direction, and the steering angle of the rear wheel is less than or equal to the steering angle of the front wheel. The left and right wheels of the front wheel are driven by electric motors and actuators for driving, respectively, the steering angle is controlled, and the steering angle of the rear wheel is controlled by the steering unit.
(a) selecting a minimum turning radius driving mode;
(b) detecting steering angles of the front and rear wheels according to the driver's manipulation of the steering wheel; and;
(c) driving with a minimum turning radius after (b); including,
In (b) above, when the rear wheel steering angle is 55˚ or less, the left and right steering angles are the same as the rear wheel steering angles, but the steering direction is reversed. When the rear wheel steering angle exceeds 55˚, the left and right steering angles are set to 55˚. However, a driving method of a three-wheeled electric forklift, characterized in that the steering direction is opposite to the rear wheel. 8. The method of claim 7,
In the step (c), the rear wheel steering angle is a driving method of a three-wheel electric forklift, characterized in that less than 70˚. The left and right wheels of the front wheel are driven by electric motors and actuators for driving, respectively, the steering angle is controlled, and the steering angle of the rear wheel is controlled by the steering unit.
(a) selecting an in-place rotation mode;
(b), but it determines the steering angle (δ _f) of the left and right wheels by using the following formula, the left and the steering angle (δ _f) is identical to the steering direction of the right wheels comprising the other hand;
(c) the driver manipulates the steering wheel so that the rear wheels are perpendicular to the wheelbase;
(d) setting the rotation direction according to the rotation direction of the handle; and;
(e) driving the three-wheeled electric forklift in place;
[expression]

In the above formula,
L _wb : wheelbase
L _tread : tread 10. The method of claim 9,
When the handle is rotated to the right, the electric motor for driving the left wheel rotates in the forward direction and the electric motor for driving the right wheel rotates in the reverse direction, causing the 3-wheel electric forklift to rotate clockwise.
When the handle is rotated to the left, the electric motor for driving the left wheel rotates in the reverse direction and the electric motor for driving the right wheel rotates in the forward direction, so that the three-wheel electric forklift rotates counterclockwise.
A method of driving a three-wheel electric forklift, characterized in that the forward rotation of the electric motor for driving the left and right wheels is the rotation direction when the electric forklift moves forward, and the reverse rotation is the rotation direction when the electric forklift moves backward. The left and right wheels of the front wheel are driven by electric motors and actuators for driving, respectively, the steering angle is controlled, and the steering angle of the rear wheel is controlled by the steering unit.
(a) selecting a crab driving mode;
_{(b) The rear wheel steering angle (δ r} ) and the steering direction are determined in response to the steering wheel rotation, but when the rear wheel steering _{angle (δ r} ) is less than or equal to the maximum steering angle of the front wheel, the front wheel steering angle (δ _f ) and the steering direction are the rear wheel steering angle (δ _r) ) and the steering direction, and when the rear wheel steering angle (δ _r ) exceeds the _{maximum steering angle, the front and rear wheel steering angles (δ f} ) (δ _r ) are the maximum steering angles and the front and rear wheel steering directions are the same. step; and;
(c) driving the crab; a driving method of a three-wheeled electric forklift comprising: a. 12. The method according to any one of claims 7 to 11,
The actuator is a linear actuator driven by an electric motor for steering, and the encoder measures the rotation angle and rotation direction of the electric motor for steering, and uses the measured values to estimate the steering angle and steering direction of the front wheel. Driving method of 3-wheel electric forklift.

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