Steering system of four-wheel forklift

Abstract

The utility model relates to a steering system of a four-wheel forklift. The steering system comprises a power mechanism and an oil way switching mechanism connected with the power mechanism. The front steering mechanism is connected with the power mechanism and the oil way switching mechanism; the rear steering mechanism is connected with the oil way switching mechanism; the power mechanism comprises a steering oil can, a steering oil pump connected and communicated with the steering oil can, a steering gear connected with the steering oil pump, a steering wheel connected with the steering gear in a matched mode and a steering component (15) with one end connected with the steering gear, and the other end of the steering component is connected with the front steering mechanism. The steering gear is provided with a first additional power port and a second additional power port which provide hydraulic oil with the same pressure and direction as an oil cylinder in the steering gear for the outside. The steering mode of the forklift can be flexibly converted, the reliability is high, and the driving performance and the operation performance of the forklift are remarkably improved.

Description

Technical Field

[0001] The utility model relates to a wheeled vehicle, in particular to a steering system for a four-wheel forklift. Background Art

[0002] The essence of the steering system of a wheeled vehicle is to reflect the degree of coincidence between the vehicle's driving trajectory and the driver's intention in time and space, as well as the stability of the vehicle's driving state, based on the vehicle's turning radius. Therefore, steering maneuverability is a decisive factor affecting vehicle maneuverability. The coordinated use of the vehicle's front-wheel steering, all-wheel steering and crab steering can achieve flexible and varied movement modes. On a multi-axle steering vehicle with steering mode conversion, the reliability and flexibility of the mode conversion directly affects the vehicle's driving performance and the convenience of operation. According to the changing operating scenarios, timely select a reasonable front-wheel steering, four-wheel steering or crab driving mode to complete the forklift operation efficiently and quickly.

[0003] CN107985392A discloses a "forklift steering system", which includes a bridge body, a steering cylinder, and a first steering knuckle and a second steering knuckle arranged on the bridge body. The steering cylinder includes a cylinder body, a first piston rod for controlling the rotation of the first steering knuckle, and a second piston rod for controlling the rotation of the second steering knuckle. The steering cylinder also includes a first piston connected to the first piston rod and a second piston connected to the second piston rod. The first piston and the second piston are located inside the cylinder body. The cylinder body has a first rodless cavity, a second rodless cavity, a first rod cavity for accommodating the first piston rod, and a second rod cavity for accommodating the second piston rod. The first rodless cavity and the second rodless cavity are not connected. It realizes independent control of the two steering machines through the steering cylinder, and the steering is more accurate on demand. It can eliminate the tire eccentric wear, slippage, early wear and other conditions caused by the angle problem, and improve the service life of the forklift and the tire. Undoubtedly, the technical solution disclosed in the patent document is a beneficial attempt in the relevant technical field. Utility Model Content

[0004] The utility model aims to provide a four-wheel forklift steering system, which can flexibly convert the steering mode of the forklift and has high reliability, thereby significantly improving the driving performance and operating performance of the vehicle.

[0005] The utility model discloses a steering system for a four-wheel forklift, comprising a power mechanism, an oil circuit conversion mechanism connected to the power mechanism through an oil circuit; further comprising a front steering mechanism connected to the power mechanism and the oil circuit conversion mechanism, and a rear steering mechanism connected to the oil circuit conversion mechanism; the power mechanism comprises a steering oil pot for storing hydraulic oil of a steering system, a steering oil pump connected to and in communication with the steering oil pot, a steering gear connected to the steering oil pump, a steering wheel connected to the steering gear, and a steering component connected to the steering gear at one end, the other end of the steering component being connected to the front steering mechanism; the steering gear is arranged on a forklift beam, and has a first additional power port and a second additional power port, which provide the outside with hydraulic oil of the same pressure and direction as the internal oil cylinder of the steering gear.

[0006] Furthermore, the oil circuit conversion mechanism includes a first solenoid valve, a second solenoid valve, a third solenoid valve and a hydraulically controlled one-way valve group. The first solenoid valve is connected to the first additional power port and the second additional power port of the steering gear, and the second solenoid valve and the third solenoid valve are connected to the first solenoid valve through the hydraulically controlled one-way valve group; the second solenoid valve is also connected to the front steering mechanism, and the third solenoid valve is also connected to the rear steering mechanism.

[0007] Furthermore, the front steering mechanism includes a front steering cylinder and a front wheel center position sensor arranged thereon; the cylinder and piston of the front steering cylinder are made of non-magnetic materials, and a magnetic ring is provided on the piston; the position of the front wheel center position sensor arranged on the front steering cylinder corresponds to the state when the front wheel is centered; the front wheel center position sensor is a PNP type proximity switch.

[0008] Furthermore, the rear steering mechanism includes a rear steering cylinder and a rear wheel median position sensor arranged thereon; the cylinder and piston of the rear steering cylinder are made of non-magnetic materials, and a magnetic ring is provided on the piston; the position of the rear wheel median position sensor arranged on the rear steering cylinder corresponds to the state when the rear wheel is centered; the rear wheel median position sensor is of the same model as the front wheel median position sensor and has the same function.

[0009] Furthermore, the rear steering mechanism is also provided with a piston locking device and an unlocking oil circuit for controlling its opening and closing. The piston locking device is arranged inside the rear steering cylinder and is fixedly connected to the piston rod and moves with the piston rod; the unlocking oil circuit is arranged at the center of the piston rod and is connected to the steering gear.

[0010] Furthermore, the steering oil pump is a vane-type power-assisting pump, which obtains power from the engine of the forklift, obtains low-pressure oil from the steering oil tank, and converts it into high-pressure oil to supply to the steering gear.

[0011] Furthermore, the steering component includes a steering rocker arm and a steering tie rod.

[0012] Beneficial effects of the utility model:

[0013] Since the front and rear steering cylinders are respectively provided with front and rear wheel median position sensors, they have the function of detecting the median position of the front and rear wheels, and can be clearly displayed on the driving instrument. The driver can easily and quickly align the front and rear wheels to the median position by operating the steering wheel, and then switch the steering mode according to the needs of the site, so that the front and rear wheel angles are always the same during the steering process, and the steering conversion operation is accurate and fast.

[0014] Since a piston locking device is provided in the rear steering cylinder of the rear steering mechanism, the piston locking device is composed of a disc spring and a wedge block cooperating therewith; the unlocking oil circuit is arranged at the center of the piston rod, when the elastic force of the disc spring acts on the wedge block, the wedge block is pushed to move, so that the piston locking device is tightly combined with the inner wall of the cylinder to lock the cylinder piston, which can ensure accurate and reliable front steering. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the principle of the utility model;

[0016] Figure 2 It is a schematic diagram of the principle of the power mechanism;

[0017] Figure 3 It is a schematic diagram of the principle of the oil circuit conversion mechanism;

[0018] Figure 4 It is a schematic diagram of the principle of the front steering cylinder mechanism;

[0019] Figure 5 It is a schematic diagram of the principle of the rear steering cylinder mechanism.

[0020] In the figure (technical features indicated by marks):

[0021] 1—power mechanism, 11—steering oil pot, 12—steering oil pump, 13—steering gear, 14—steering wheel, 15—steering member; 131—first additional power port, 132—second additional power port;

[0022] 2—oil circuit conversion mechanism, 21—first solenoid valve, 22—second solenoid valve, 23—third solenoid valve, 24—hydraulic control one-way valve group;

[0023] 3—front steering mechanism, 31—front axle steering cylinder, 32—front wheel mid-position sensor;

[0024] 4—rear steering mechanism, 41—rear axle steering cylinder, 42—rear wheel mid-position sensor, 43—cylinder locking structure, 44—unlocking oil circuit. DETAILED DESCRIPTION

[0025] The technical solution of the utility model is described in detail below in conjunction with the accompanying drawings:

[0026] See also Figures 1 to 5 A four-wheel forklift steering system shown in the figure includes a power mechanism 1, an oil circuit conversion mechanism 2 connected to the power mechanism through an oil circuit; it also includes a front steering mechanism 3 connected to the power mechanism 1 and the oil circuit conversion mechanism 2, and a rear steering mechanism 4 connected to the oil circuit conversion mechanism 2; the power mechanism provides thrust for the front and rear steering wheels, the oil circuit conversion mechanism can change the front and rear steering wheels to rotate in the same direction or in different directions, the front steering mechanism can drive the front axle to steer, and the rear steering mechanism can drive the front axle to steer.

[0027] The power mechanism 1 includes a steering oil pot 11 for storing hydraulic oil of the steering system, a steering oil pump 12 connected to the steering oil pot 11, a steering gear 13 connected to the steering oil pump 12, a steering wheel 14 connected to the steering gear 13, and a steering member 15 connected to the steering gear 13 at one end, and the other end of the steering member 15 is connected to the front steering mechanism 3. The steering oil pump is a vane-type booster pump powered by the engine, sucking hydraulic oil from the steering oil pot, and then discharging high-pressure oil to the steering gear; the rotation signal of the driver rotating the steering wheel is transmitted to the output shaft of the steering gear after the hydraulic boost of the steering gear is increased, driving the steering tie rod to move.

[0028] The steering gear 13 is arranged on the forklift beam, and has a first additional power port 131 and a second additional power port 132, which provide the outside with hydraulic oil of the same pressure and direction as the internal cylinder of the steering gear. The steering gear is a circulating ball hydraulic power steering gear. When the steering wheel turns right, the first additional power port 131 outputs high-pressure oil, and the second additional power port 132 outputs low-pressure oil; when the steering wheel turns left, the second additional power port 132 outputs high-pressure oil, and the first additional power port 131 outputs low-pressure oil.

[0029] The oil circuit conversion mechanism 2 includes a first solenoid valve 21, a second solenoid valve 22, a third solenoid valve 23 and a hydraulically controlled one-way valve group 24. The first solenoid valve 21 is connected to the first additional power port 131 and the second additional power port 132 of the steering gear 13. The second solenoid valve 22 and the third solenoid valve 23 are connected to the first solenoid valve 21 through the hydraulically controlled one-way valve group 24. The second solenoid valve 22 is also connected to the front steering mechanism 3, and the third solenoid valve 23 is also connected to the rear steering mechanism 4.

[0030] The front steering mechanism 3 includes a front steering oil cylinder 31 and a front wheel center position sensor 32 arranged thereon; the oil cylinder and piston of the front steering oil cylinder 31 are made of non-magnetic materials, and a magnetic ring is arranged on the piston; the position of the front wheel center position sensor 32 arranged on the front steering oil cylinder 31 corresponds to the state when the front wheel is centered; the front wheel center position sensor 32 is a PNP type proximity switch. The characteristics of this proximity switch are that high potential is effective, positive output, when an object is sensed, the output is a high voltage (system voltage), when no object is detected, the output is a low voltage, and the system voltage signal is transmitted to the combination instrument, so that the front wheel centering signal light on the combination instrument lights up to remind the driver that the front wheel has been centered.

[0031] The rear steering mechanism 4 includes a rear steering oil cylinder 41 and a rear wheel center position sensor 42 disposed thereon; the oil cylinder and piston of the rear steering oil cylinder 41 are made of non-magnetic materials, and a magnetic ring is disposed on the piston; the position of the rear wheel center position sensor 42 disposed on the rear steering oil cylinder 41 corresponds to the state when the rear wheel is centered; the rear wheel center position sensor 42 is of the same model and function as the front wheel center position sensor 32. The rear wheel centering signal light on the instrument cluster can be turned on to remind the driver that the rear wheel has been centered.

[0032] The rear steering mechanism 4 is also provided with a piston locking device 43 and an unlocking oil circuit 44 for controlling the opening and closing thereof. The piston locking device 43 is arranged inside the rear steering oil cylinder 41 and is fixedly connected to the piston rod and moves with the piston rod; the unlocking oil circuit 44 is arranged at the center of the piston rod and is connected to the steering gear 13. The locking device is a combination of a disc spring and a wedge block. The elastic force of the disc spring is used to push the wedge block to move, so that the locking device is tightly combined with the inner wall of the oil cylinder to limit the movement of the piston. The opening and closing of the locking device is controlled by the unlocking oil circuit. When the unlocking oil circuit is high pressure, the thrust generated by the high pressure oil overcomes the elastic force of the disc spring, so that the wedge block is not subjected to force, that is, the piston locking device is separated from the inner wall of the oil cylinder, and the oil cylinder piston can move freely; when the unlocking oil circuit is low pressure, the elastic force of the disc spring acts on the wedge block, pushing the wedge block to move, so that the piston locking device is tightly combined with the inner wall of the oil cylinder to lock the oil cylinder piston.

[0033] The steering oil pump 12 is a vane-type power pump, which obtains power from the forklift engine, obtains low-pressure oil from the steering oil pot 11, converts it into high-pressure oil and supplies it to the steering gear 13. The steering oil pot is the low-pressure oil source of the steering oil pump and stores the low-pressure oil flowing back from the oil circuit conversion mechanism.

[0034] The steering member 15 includes a steering rocker arm and a steering tie rod.

[0035] When only the front wheel of the forklift is turned, the first solenoid valve 21, the second solenoid valve 22 and the third solenoid valve 23 are all powered off, the P and T oil ports of the first solenoid valve 21 are in a closed state, and the hydraulic oil in the first additional power port 131 and the second additional power port 132 of the steering gear 14 does not flow into the oil circuit conversion mechanism 2; the P and T oil ports of the second solenoid valve 22 are in an open state, the oil ports at both ends of the front axle cylinder 31 are connected and connected to the steering oil pot 11, and the front axle cylinder 31 can freely telescope with the front axle; the B and A oil ports of the third solenoid valve 23 are in a closed state, the oil ports at both ends of the rear axle cylinder 41 are not connected, the rear axle cylinder 41 cannot telescope and is in a locked state, and the rear wheel cannot rotate.

[0036] When the forklift performs four-wheel steering, the TD3 ends of the first solenoid valve 21, the second solenoid valve 22 and the third solenoid valve 23 are all energized, the P and T oil ports of the first solenoid valve 21 are opened, and the hydraulic oil of the first additional power port 131 and the second additional power port 132 of the steering gear 13 passes through the first solenoid valve 21 and the hydraulically controlled one-way valve group 24, and first enters one end oil port of the front steering cylinder 31, and the oil discharged from the other end oil port passes through the hydraulically controlled one-way valve group 24 and enters the rear axle cylinder 41, and the oil port end on the different side of the oil discharge port of the front axle cylinder 31, thereby realizing the four-wheel steering of the vehicle.

[0037] When the vehicle crab-turns, the first solenoid valve 21, the TD4 end of the second solenoid valve 22 and the third solenoid valve 23 are all energized, the P and T oil ports of the first solenoid valve 21 are opened, and the hydraulic oil of the first additional power port 131 and the second additional power port 132 of the steering gear 13 passes through the first solenoid valve 21 and the hydraulically controlled one-way valve group 24, and first enters one end oil port of the front steering cylinder 31. The oil discharged from the other end oil port passes through the hydraulically controlled one-way valve group 24 and enters the rear steering cylinder 41, and the oil port end on the same side as the oil discharge port of the front steering cylinder 31, thereby realizing the crab-turn of the vehicle.

Claims

1. A four-wheel forklift steering system, comprising a power mechanism (1), and an oil circuit conversion mechanism (2) connected to the power mechanism via an oil circuit, wherein: It also comprises a front steering mechanism (3) connected to the power mechanism (1) and the oil circuit conversion mechanism (2), and a rear steering mechanism (4) connected to the oil circuit conversion mechanism (2); the power mechanism (1) comprises a steering oil pot (11) for storing steering system hydraulic oil, a steering oil pump (12) connected to the steering oil pot (11), a steering gear (13) connected to the steering oil pump (12), a steering wheel (14) connected to the steering gear (13), and a steering member (15) connected to the steering gear (13) at one end, the other end of the steering member (15) being connected to the front steering mechanism (3); the steering gear (13) is arranged on the forklift beam, and has a first additional power port (131) and a second additional power port (132) for providing the outside with hydraulic oil of the same pressure and direction as the internal cylinder of the steering gear.

2. The four-wheel forklift steering system according to claim 1, characterized in that: The oil circuit conversion mechanism (2) comprises a first solenoid valve (21), a second solenoid valve (22), a third solenoid valve (23) and a hydraulically controlled one-way valve group (24); the first solenoid valve (21) is connected to a first additional power port (131) and a second additional power port (132) of the steering gear (13); the second solenoid valve (22) and the third solenoid valve (23) are connected to the first solenoid valve (21) via the hydraulically controlled one-way valve group (24); the second solenoid valve (22) is also connected to the front steering mechanism (3); and the third solenoid valve (23) is also connected to the rear steering mechanism (4).

3. The four-wheel forklift steering system according to claim 1 or 2, characterized in that: The front steering mechanism (3) comprises a front steering oil cylinder (31) and a front wheel mid-position sensor (32) arranged thereon; the oil cylinder and piston of the front steering oil cylinder (31) are made of non-magnetic materials, and a magnetic ring is arranged on the piston; the position of the front wheel mid-position sensor (32) arranged on the front steering oil cylinder (31) corresponds to the state when the front wheel is centered; the front wheel mid-position sensor (32) is a PNP type proximity switch.

4. The four-wheel forklift steering system according to claim 3 is characterized in that: The rear steering mechanism (4) comprises a rear steering oil cylinder (41) and a rear wheel mid-position sensor (42) arranged thereon; the oil cylinder and piston of the rear steering oil cylinder (41) are made of non-magnetic materials, and a magnetic ring is arranged on the piston; the position of the rear wheel mid-position sensor (42) arranged on the rear steering oil cylinder (41) corresponds to the state of the rear wheel when it is centered; the rear wheel mid-position sensor (42) is of the same model as the front wheel mid-position sensor (32) and has the same function.

5. The four-wheel forklift steering system according to claim 4, characterized in that: The rear steering mechanism (4) is further provided with a piston locking device (43) and an unlocking oil circuit (44) for controlling the opening and closing of the piston locking device (43). The piston locking device (43) is arranged inside the rear steering cylinder (41) and is fixedly connected to the piston rod and moves with the piston rod. The unlocking oil circuit (44) is arranged at the center of the piston rod and is in communication with the steering gear (13).

6. The four-wheel forklift steering system according to claim 1, characterized in that: The steering oil pump (12) is a vane-type power-assisting pump, which obtains power from the engine of the forklift, obtains low-pressure oil from the steering oil pot (11), converts it into high-pressure oil and supplies it to the steering gear (13).

7. The four-wheel forklift steering system according to claim 1, characterized in that: The steering component (15) comprises a steering rocker arm and a steering tie rod.

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