阅读说明：本技术 一种用于提高平衡重式叉车转向稳定性的控制方法 (Control method for improving steering stability of counter-weight forklift ) 是由 夏光 张洋 于星海 李嘉诚 纵华宇 张亮 王跃强 夏岩 陈建杉 于 2020-05-22 设计创作，主要内容包括：本发明公开了一种用于提高平衡重式叉车转向稳定性的控制方法,是通过陀螺仪采集的叉车运动参数计算叉车动态稳定点并对比叉车支撑平面的变化以判断叉车的运动状态,并根据不同的运动状态采取不同的稳定性控制方法：当叉车处于稳定状态时,动平衡块锁定在初始位置且液压支撑油缸处于自由状态；当叉车处于基本稳定状态时,将动平衡块沿固定轨道向方向盘转动方向移动且液压支撑油缸处于半自由状态；当叉车处于失稳状态时,将动平衡块沿固定轨道向方向盘转动方向移动到极限位置且液压支撑油缸处于锁止状态。本发明能有效提高叉车在不同转向工况下的稳定性。(The invention discloses a control method for improving the steering stability of a balance weight type forklift, which is characterized in that a dynamic stability point of the forklift is calculated through forklift motion parameters acquired by a gyroscope, the change of a forklift supporting plane is compared to judge the motion state of the forklift, and different stability control methods are adopted according to different motion states: when the forklift is in a stable state, the dynamic balance block is locked at an initial position and the hydraulic support oil cylinder is in a free state; when the forklift is in a basic stable state, the dynamic balance block moves to the rotation direction of the steering wheel along the fixed track, and the hydraulic support oil cylinder is in a semi-free state; when the forklift is in a destabilizing state, the dynamic balance block is moved to the limit position along the fixed track in the rotating direction of the steering wheel, and the hydraulic support oil cylinder is in a locking state. The invention can effectively improve the stability of the forklift under different steering working conditions.)

1. A control method for improving the steering stability of a counterweight type forklift is applied to a forklift provided with an actuating mechanism, and the actuating mechanism comprises the following steps: the hydraulic support oil cylinder, the dynamic balance block and the dynamic balance block actuating mechanism; the hydraulic support cylinder includes: a first electromagnetic valve and an oil cylinder; the dynamic balance block executing mechanism comprises: the second electromagnetic valve, the movable oil cylinder and the fixed track;

the first electromagnetic valve is connected with an oil inlet of an oil cylinder, and two ends of the oil cylinder are respectively connected with a forklift body and a steering axle of a forklift; the movable oil cylinder is fixed on the static balance block, the movable balance block is connected with the movable oil cylinder, and the movable balance block is arranged on the fixed track through a pulley, so that the movable balance block can move left and right along the fixed track under the action of the movable oil cylinder;

a gyroscope sensor is also arranged at the position of the mass center of the forklift;

taking the center of mass of a chassis of the forklift as an original point O, the center of mass of the bottom of the forklift as the original point O, the advancing direction of the forklift as an X axis, a Y axis which is vertical to the X axis and is positioned in a horizontal plane passing through the original point O, and a Z axis which is vertical to a plane XOY formed by the X axis and the Y axis, thereby establishing a three-dimensional coordinate system O-XYZ; the method is characterized in that: the control method comprises the following steps:

step 1, acquiring vehicle body roll angle, lateral acceleration and roll angle acceleration signals by using a gyroscope sensor, and calculating to obtain a component y of a dynamic stable point of the forklift along the transverse direction of the forklift; the dynamic stable point is a point which enables the resultant moment of the forklift body and the chassis to be 0 along the forklift transverse direction component in the forklift supporting plane;

step 2, judging the motion state of the forklift according to the component y of the dynamic stability point of the forklift in the transverse direction of the forklift and a forklift supporting plane;

step 3, when the forklift is in a stable state, locking the dynamic balance block at an initial position through a dynamic balance block executing mechanism, and controlling the first electromagnetic valve to enable the hydraulic support oil cylinder to be in a free state;

when the forklift is in a basic stable state, according to different steering working conditions, the dynamic balance block is moved by different distances to the rotation direction of the steering wheel along the fixed track through the dynamic balance block executing mechanism, and the first electromagnetic valve is controlled to enable the hydraulic support oil cylinder to be in a semi-free state;

when the forklift is in a destabilizing state, the dynamic balance block is moved to a limit position along the fixed track to the rotation direction of the steering wheel through the dynamic balance block executing mechanism, and the first electromagnetic valve is controlled to enable the hydraulic support oil cylinder to be in a locking state.

2. The control method according to claim 1, characterized in that: the component y of the dynamic stability point of the forklift in the step 1 along the transverse direction of the forklift is calculated by using the formula (1):

in the formula (1), m,Respectively the whole truck mass, the truck body mass and the chassis mass of the forklift; h is_sThe distance from the center of mass of the vehicle body to the hinged point of the rear axle of the forklift along the Z-axis direction is obtained; phi is the vehicle body side inclination angle; a is_yIs the lateral acceleration of the forklift; i is_xThe moment of inertia of the whole vehicle around the X axis; and y is the coordinate of the dynamic stable point of the forklift along the transverse direction of the forklift.

3. The control method according to claim 1, characterized in that: in the step 2, the judgment is carried out according to the following steps:

when the dynamic stable point exists in the supporting plane of the forklift, the forklift is in a stable state;

when the dynamic stable point exists outside the supporting plane of the forklift, the forklift is in a dangerous state;

the hazardous condition includes a substantially steady condition and a destabilized condition.

4. The control method according to claim 3, characterized in that: the forklift supporting plane is determined according to the following method:

when the hydraulic support oil cylinder does not provide lateral support force, the vehicle body is in a free state, and the forklift support plane is an isosceles triangle support plane formed by the left and right connecting points of the vehicle body and the front axle and the hinge point of the rear axle;

when the hydraulic support oil cylinder provides lateral support force for the vehicle body, the forklift support plane is an isosceles trapezoid support plane formed by left and right connection points of the vehicle body and the front axle, connection points of the hydraulic support oil cylinder and the rear axle and symmetrical points of the oil cylinder relative to the X axis and the rear axle.

5. The control method according to claim 4, characterized in that: whether the dynamic stable point exists in the forklift supporting plane is judged according to the following method:

when y is less than or equal to l₁If so, indicating that the dynamic stable point exists in the supporting plane of the forklift; wherein l₁Representing the distance from the center of mass of the forklift body to the waist of the isosceles triangular support plane;

when y > l₁+l₂If the dynamic stable point does not exist in the forklift supporting plane; wherein l₂And the distance from the center of mass of the forklift body to the waist of the isosceles trapezoid supporting plane is represented.

6. The control method according to claim 5, characterized in that: the dangerous state is subdivided according to the following method:

when the dynamic stable point satisfies l along the transverse direction component y of the forklift₁＜|y|≤l₂When the forklift is in a basic stable state;

when it is dynamicThe component y of the stable point along the transverse direction of the forklift satisfies | y | ≧ l₂In time, the forklift is in a destabilizing state.

7. The control method according to claim 1, characterized in that: and 3, when the forklift is in a basic stable state, enabling the moving distance of the dynamic balance block to be in direct proportion to the absolute value of the lateral component y of the dynamic stable point along the forklift.

8. The control method according to claim 1, characterized in that: the working process of the hydraulic support oil cylinder in the step 3 is as follows:

when the hydraulic support oil cylinder is in a free state, the first electromagnetic valve controls the hydraulic support oil cylinder to enable an upper oil cavity and a lower oil cavity to be completely communicated, the oil cylinder is in a free motion state, and the hydraulic support oil cylinder enables a steering axle to be freely connected with a vehicle body;

when the hydraulic support oil cylinder is in a semi-free state, the first electromagnetic valve controls the hydraulic support oil cylinder to enable an upper oil cavity and a lower oil cavity to be throttled and communicated, the oil cylinder is in a damping motion state, and the hydraulic support oil cylinder enables a steering axle to be in damping connection with a vehicle body;

when the hydraulic support oil cylinder is in a locked state, the first electromagnetic valve controls the hydraulic support oil cylinder to disconnect the upper oil chamber and the lower oil chamber, and the oil cylinder enables the steering axle to be fixedly connected with the vehicle body.

Technical Field

The invention relates to the field of stability control of forklifts, in particular to a control method for improving steering stability of a forklift.

Background

Along with among each big trade such as counter-balanced formula fork truck wide application in mill, harbour, station, warehouse, its operational environment is also more and more complicated, in fork truck turns to the in-process, if appear turning to the radius undersize, turn to the speed of a motor vehicle too big or turn to the time the goods barycenter of fork and transport higher, then can cause fork truck automobile body inclination grow, cause fork truck to roll emergence accident, consequently fork truck its steering security in the course of the work awaits the opportune moment and improves.

The front part of the balance weight type forklift is provided with a portal fork device for loading and unloading goods, the front wheels of the forklift are driving wheels, the rear wheels of the forklift are steering wheels, and a double-trapezoid steering mechanism is adopted. A hinged point is arranged in the middle of the steering axle and connected with the frame, and the frame can swing up and down relative to the steering axle through the hinged point. Due to the hinging, a forklift supporting plane is composed of two front wheel supporting points and a hinging point of the rear axle and the frame, and a forklift driving plane is composed of two front wheel supporting points and a middle point of a connecting line of the two rear wheel supporting points. Although the hinge connection mode of the forklift improves the flexibility of operation of the forklift and the stability of the forklift when the forklift passes through a concave road surface and a convex road surface, the forklift is swung due to the inclined angle of the supporting plane, so that the supporting plane of the forklift and the driving plane are not overlapped, and the forklift is easily subjected to lateral instability or even rollover under the influence of centrifugal force during steering, thereby causing potential safety hazards of operators and goods.

Disclosure of Invention

In order to avoid the defects of the prior art, the invention provides a control method for improving the steering stability of a forklift, so that the forklift is expected to be prevented from tilting due to an overlarge roll angle in the operation process, and the transverse stability and the active safety of the forklift are improved.

The invention adopts the following technical scheme for solving the technical problems:

the invention discloses a control method for improving the steering stability of a balance weight type forklift, which is applied to the forklift provided with an actuating mechanism, wherein the actuating mechanism comprises the following components: the hydraulic support oil cylinder, the dynamic balance block and the dynamic balance block actuating mechanism; the hydraulic support cylinder includes: a first electromagnetic valve and an oil cylinder; the dynamic balance block executing mechanism comprises: the second electromagnetic valve, the movable oil cylinder and the fixed track;

the first electromagnetic valve is connected with an oil inlet of an oil cylinder, and two ends of the oil cylinder are respectively connected with a forklift body and a steering axle of a forklift; the movable oil cylinder is fixed on the static balance block, the movable balance block is connected with the movable oil cylinder, and the movable balance block is arranged on the fixed track through a pulley, so that the movable balance block can move left and right along the fixed track under the action of the movable oil cylinder;

a gyroscope sensor is also arranged at the position of the mass center of the forklift;

taking the center of mass of a chassis of the forklift as an original point O, the center of mass of the bottom of the forklift as the original point O, the advancing direction of the forklift as an X axis, a Y axis which is vertical to the X axis and is positioned in a horizontal plane passing through the original point O, and a Z axis which is vertical to a plane XOY formed by the X axis and the Y axis, thereby establishing a three-dimensional coordinate system O-XYZ; the method is characterized in that: the control method comprises the following steps:

step 1, acquiring vehicle body roll angle, lateral acceleration and roll angle acceleration signals by using a gyroscope sensor, and calculating to obtain a component y of a dynamic stable point of the forklift along the transverse direction of the forklift; the dynamic stable point is a point which enables the resultant moment of the forklift body and the chassis to be 0 along the forklift transverse direction component in the forklift supporting plane;

step 2, judging the motion state of the forklift according to the component y of the dynamic stability point of the forklift in the transverse direction of the forklift and a forklift supporting plane;

step 3, when the forklift is in a stable state, locking the dynamic balance block at an initial position through a dynamic balance block executing mechanism, and controlling the first electromagnetic valve to enable the hydraulic support oil cylinder to be in a free state;

when the forklift is in a basic stable state, according to different steering working conditions, the dynamic balance block is moved by different distances to the rotation direction of the steering wheel along the fixed track through the dynamic balance block executing mechanism, and the first electromagnetic valve is controlled to enable the hydraulic support oil cylinder to be in a semi-free state;

when the forklift is in a destabilizing state, the dynamic balance block is moved to a limit position along the fixed track to the rotation direction of the steering wheel through the dynamic balance block executing mechanism, and the first electromagnetic valve is controlled to enable the hydraulic support oil cylinder to be in a locking state.

The control method of the invention is also characterized in that: the component y of the dynamic stability point of the forklift in the step 1 along the transverse direction of the forklift is calculated by using the formula (1):

in the formula (1), m,Respectively the whole truck mass, the truck body mass and the chassis mass of the forklift; h is_sThe distance from the center of mass of the vehicle body to the hinged point of the rear axle of the forklift along the Z-axis direction is obtained; phi is the vehicle body side inclination angle; a is_yIs the lateral acceleration of the forklift; i is_xThe moment of inertia of the whole vehicle around the X axis; and y is the coordinate of the dynamic stable point of the forklift along the transverse direction of the forklift.

In the step 2, the judgment is carried out according to the following steps:

when the dynamic stable point exists in the supporting plane of the forklift, the forklift is in a stable state;

when the dynamic stable point exists outside the supporting plane of the forklift, the forklift is in a dangerous state;

the hazardous condition includes a substantially steady condition and a destabilized condition.

The forklift supporting plane is determined according to the following method:

when the hydraulic support oil cylinder does not provide lateral support force, the vehicle body is in a free state, and the forklift support plane is an isosceles triangle support plane formed by the left and right connecting points of the vehicle body and the front axle and the hinge point of the rear axle;

when the hydraulic support oil cylinder provides lateral support force for the vehicle body, the forklift support plane is an isosceles trapezoid support plane formed by left and right connection points of the vehicle body and the front axle, connection points of the hydraulic support oil cylinder and the rear axle and symmetrical points of the oil cylinder relative to the X axis and the rear axle.

Whether the dynamic stable point exists in the forklift supporting plane is judged according to the following method:

when y is less than or equal to l₁If so, indicating that the dynamic stable point exists in the supporting plane of the forklift; wherein l₁Representing the distance from the center of mass of the forklift body to the waist of the isosceles triangular support plane;

when y > l₁+l₂If the dynamic stable point does not exist in the forklift supporting plane; wherein l₂And the distance from the center of mass of the forklift body to the waist of the isosceles trapezoid supporting plane is represented.

The dangerous state is subdivided according to the following method:

when the dynamic stable point satisfies l along the transverse direction component y of the forklift₁＜|y|≤l₂When the forklift is in a basic stable state;

when the dynamic stability point satisfies the condition that the component y is greater than or equal to l along the transverse direction of the forklift₂In time, the forklift is in a destabilizing state.

And 3, when the forklift is in a basic stable state, enabling the moving distance of the dynamic balance block to be in direct proportion to the absolute value of the lateral component y of the dynamic stable point along the forklift.

The working process of the hydraulic support oil cylinder in the step 3 is as follows:

when the hydraulic support oil cylinder is in a free state, the first electromagnetic valve controls the hydraulic support oil cylinder to enable an upper oil cavity and a lower oil cavity to be completely communicated, the oil cylinder is in a free motion state, and the hydraulic support oil cylinder enables a steering axle to be freely connected with a vehicle body;

when the hydraulic support oil cylinder is in a semi-free state, the first electromagnetic valve controls the hydraulic support oil cylinder to enable an upper oil cavity and a lower oil cavity to be throttled and communicated, the oil cylinder is in a damping motion state, and the hydraulic support oil cylinder enables a steering axle to be in damping connection with a vehicle body;

when the hydraulic support oil cylinder is in a locked state, the first electromagnetic valve controls the hydraulic support oil cylinder to disconnect the upper oil chamber and the lower oil chamber, and the oil cylinder enables the steering axle to be fixedly connected with the vehicle body.

Compared with the prior art, the invention has the beneficial effects that:

1. the dynamic stability point of the forklift is calculated by collecting the kinematic parameters of the forklift body, and the dynamic stability point is compared with the forklift supporting plane to judge the forklift attitude.

2. According to the invention, the judgment of the steering state of the forklift is carried out through the relation between the dynamic stable point of the forklift and the supporting plane of the forklift, the change of the supporting plane in the steering process of the forklift is considered, the state of the forklift is divided into three stages of stable, basic stable and unstable, different steering stability control strategies are adopted according to different stages, when the forklift is in the stable state, the dynamic balance block is locked at the initial position, the hydraulic supporting oil cylinder is in a free state, and the road surface profiling function of the forklift frame and frame hinge structure can be effectively exerted; when the forklift is in a basic stable state, the dynamic balance block moves towards the rotation direction of the steering wheel along the fixed track, and the hydraulic support oil cylinder is in a semi-free state, so that the posture of the forklift body can be effectively adjusted; when the forklift is in a destabilizing state, the dynamic balance block is moved to the limit position along the fixed track in the rotating direction of the steering wheel, the hydraulic support oil cylinder is in a locking state, and the steering stability of the forklift is improved.

3. The invention makes the balance weight type forklift keep a stable running state at different steering stages by the simultaneous work of the hydraulic support oil cylinder and the dynamic balance block. The stability area of the counter weight type forklift is enlarged through the locking frame and the rear axle of the hydraulic support oil cylinder in the unstable state, meanwhile, the movable balance block can change the mass center position of the counter weight type forklift to the maximum extent through moving to the limit position along the fixed track, and the steering stability of the forklift is improved.

Drawings

FIG. 1 is a rear elevational view of the fork lift truck of the present invention;

FIG. 2 is a schematic view of the centroid position of the present invention;

FIG. 3 is a plan view of the forklift support of the present invention;

reference numbers in the figures: 1, hydraulically supporting an oil cylinder; 2, a static balance block; 3, a hinged point of the frame and the steering axle; 4, a dynamic balance block; 5, a frame; 6 a steering axle.

Detailed Description

In this embodiment, a control method for improving steering stability of a counter weight type forklift is applied to a forklift provided with an actuator, and the actuator includes: the hydraulic support oil cylinder, the dynamic balance block and the dynamic balance block actuating mechanism; the hydraulic support cylinder includes: a first electromagnetic valve and an oil cylinder; the dynamic balance block actuating mechanism comprises: the second electromagnetic valve, the movable oil cylinder and the fixed track;

the first electromagnetic valve is connected with an oil inlet of an oil cylinder, and two ends of the oil cylinder are respectively connected with a forklift body and a steering axle of a forklift; the movable oil cylinder is fixed on the static balance block, the movable balance block is connected with the movable oil cylinder, and the movable balance block is arranged on the fixed track through a pulley, so that the movable balance block can move left and right along the fixed track under the action of the movable oil cylinder;

taking the center of mass of a chassis of the forklift as an original point O, the center of mass of the bottom of the forklift as the original point O, the advancing direction of the forklift as an X axis, a Y axis which is vertical to the X axis and is positioned in a horizontal plane passing through the original point O, and a Z axis which is vertical to a plane XOY formed by the X axis and the Y axis, thereby establishing a three-dimensional coordinate system O-XYZ; the control method comprises the following steps:

the method comprises the following steps that 1, a gyroscope sensor is fixed at the position of the center of mass of a forklift, and an output signal of a forklift gyroscope is collected in the movement process of the forklift; as shown in fig. 1, a hydraulic support cylinder 1 is vertically arranged between a forklift frame 5 and a steering axle 6; this hydraulic support hydro-cylinder 1 includes: a first electromagnetic valve and an oil cylinder; the first electromagnetic valve is connected with an oil inlet of an oil cylinder, and two ends of the oil cylinder are respectively connected with a frame 5 of a forklift and a steering axle 6; acquiring the roll angle, the lateral acceleration and the roll angle acceleration signals of the vehicle body by using a gyroscope sensor, and calculating by using the formula (1) to obtain the component y of the dynamic stable point of the forklift along the transverse direction of the forklift;

in the formula (1), m,Respectively the whole truck mass, the truck body mass and the chassis mass of the forklift; h is_sThe distance from the center of mass of the vehicle body to the hinged point of the rear axle of the forklift along the Z-axis direction is obtained; phi is the vehicle body side inclination angle; a is_yIs the lateral acceleration of the forklift; i is_xThe moment of inertia of the whole vehicle around the X axis; y is a coordinate of the dynamic stable point of the forklift along the transverse direction of the forklift;

as shown in fig. 2, the dynamic stable point is a point in the forklift supporting plane, which makes the resultant moment of the forklift body and chassis 0 along the forklift transverse direction;

step 2, judging the motion state of the forklift according to the component y of the dynamic stability point of the forklift in the transverse direction of the forklift and a forklift supporting plane; as shown in figure 3, when the hydraulic support cylinder is in a free state, the supporting plane of the forklift is a plane ABE, and the distance from the center of mass of the forklift body to the waist of the isosceles triangle supporting plane is l₁(ii) a When the hydraulic support oil cylinder provides support force for the forklift body, the forklift support plane is ABGF (equivalent body height), and the distance from the center of mass of the forklift body to the waist of the isosceles trapezoid support plane is l₂；

If y is less than or equal to l₁Then it means that the forklift is stableSetting the state;

if l₁＜|y|＜l₂Then, the forklift is in a basic stable state;

if l₁+l₂Y, the forklift is in a basic stable state;

step 3, when the forklift is in a stable state, locking the dynamic balance block at an initial position through a dynamic balance block executing mechanism, and controlling the first electromagnetic valve to enable the hydraulic support oil cylinder to be in a free state; the dynamic balance block is locked at an initial position, namely the dynamic balance block is positioned on an X-axis extension line, the free state of the hydraulic support oil cylinder is a free state, namely a PWM signal with a 100% duty ratio is used as a first electromagnetic valve control signal, the first electromagnetic valve controls the hydraulic support oil cylinder to enable an upper oil cavity and a lower oil cavity to be completely communicated, and the hydraulic support oil cylinder enables a steering axle to be freely connected with an automobile body.

When the forklift is in a basic stable state, according to different steering working conditions, the dynamic balance block is moved by different distances to the rotation direction of the steering wheel along the fixed track through the dynamic balance block executing mechanism, and the first electromagnetic valve is controlled to enable the hydraulic support oil cylinder to be in a semi-free state; wherein, the moving distance s of the dynamic balance block is in direct proportion to the absolute value of the dynamic stable point of the forklift along the Y-axis component Y, the proportionality coefficient is k, i.e. s is k | Y |, wherein,the dynamic stability point is the absolute value of the Y-axis component Y when β is in an unstable state, the semi-free state of the hydraulic support oil cylinder means that the control signal of an oil cylinder electromagnetic valve is a PWM duty ratio signal of 0-70%, the first electromagnetic valve controls the hydraulic support oil cylinder to enable an upper oil cavity and a lower oil cavity to be connected in a throttling mode, the oil cylinder is in a damping motion state, and the hydraulic support oil cylinder enables a steering axle to be connected with an automobile body in a damping mode.

When the forklift is in a destabilizing state, the dynamic balance block is moved to a limit position along the fixed track to the rotation direction of the steering wheel through the dynamic balance block executing mechanism, and the first electromagnetic valve is controlled to enable the hydraulic support oil cylinder to be in a locking state. The locking state of the hydraulic support oil cylinder refers to a PWM duty ratio signal of 0% of an oil cylinder electromagnetic valve control signal, the first electromagnetic valve controls the hydraulic support oil cylinder to enable an upper oil cavity and a lower oil cavity to be connected in a throttling mode, and the hydraulic support oil cylinder enables a steering axle to be connected with a vehicle body in a damping mode;