An electric push rod with a bottom floating structure

Abstract

This invention proposes an electric actuator with a bottom-floating structure, comprising a housing, a lead screw, bearings, a nut, an inner actuator, an outer actuator, an actuator sleeve, a locking / unlocking mechanism, and a bottom fulcrum. When the electric actuator is retracted to its shortest position, it remains in a free-floating state for a certain distance before reaching this position, meaning its axial movement is free. This allows the actuator to float when retracted to the bottom, changing the characteristic of a rigid connection throughout the entire stroke of an electric mechanical actuator. It overcomes the contradiction between reverse transmission self-locking and the requirement for bottom floating, making it possible to drive suspended loads. The floating resistance of the floating structure in this invention is negligible, lower than that of existing hydraulic expansion cylinders, and has less impact on load suspension. The locking / unlocking mechanism is implemented using a purely mechanical structure, requiring no electric components, making it simple, reliable, and safe even in the event of a power outage.

Description

Technical Field

[0001] This invention belongs to the technical field of electric mechanical linear actuators, specifically relating to an electric push rod with a bottom floating structure. Background Technology

[0002] Current electromechanical telescopic pushrod technology maintains a rigid connection at all points throughout its stroke. However, some loads are not fixed to the base in their working position; they exhibit some degree of floating in multiple directions. Therefore, the lifting pushrod connecting to this load must also possess a floating function; otherwise, it will hinder load floating. For example, to achieve comfortable vibration reduction, a truck cab may float by tens of millimeters in three degrees of freedom in its normal operating position. Since the cab tilting lifting pushrod connects the cab and the chassis, it must be freely floating when retracted to its shortest length—a feature known as bottom floating. Because current electromechanical pushrods lack bottom floating functionality, hydraulic expansion cylinders are used in such cases. This involves increasing the diameter of the bottom section of the hydraulic cylinder to create a larger gap between the piston and the cylinder wall, allowing for smoother free flow of hydraulic oil and thus enabling floating. The characteristics of the hydraulic system ensure that the expansion cylinder still possesses a certain thrust; during lifting, pressure at the bottom can still push the piston to the non-expansion section, thus maintaining the lifting function. However, the hydraulic expansion cylinders used in this method suffer from common problems such as leakage, high floating resistance, and negatively impacting the comfort of the cab's floating mechanism. Summary of the Invention

[0003] (a) Technical problems to be solved This invention proposes an electric actuator with a bottom floating structure to solve the technical problem that the electric actuator needs to have a certain amount of free displacement when connected to a suspended load.

[0004] (II) Technical Solution To address the aforementioned technical problems, this invention proposes an electric actuator with a bottom-floating structure. This electric actuator includes a housing, a lead screw, a bearing, a nut, an inner actuator, an outer actuator, an actuator sleeve, a locking / unlocking mechanism, and a bottom fulcrum. The bottom support and push rod sleeve are fixed to the outer sides of the housing, and the housing is equipped with bearings. The rear end of the lead screw is supported by the bearings. A nut is installed on the lead screw, and the front end of the nut is fixedly connected to the rear end of the inner push rod. The outer push rod is sleeved on the outer circumference of the inner push rod and is set inside the push rod sleeve. The rear section of the inner push rod is provided with a shoulder, and the front end of the shoulder can abut against the rear end of the outer push rod. The outer wall of the push rod sleeve has guide grooves and pin grooves. The guide wheel is mounted on the side trunnion of the nut. The guide wheel can roll in the guide groove, so that the nut can only move axially and cannot rotate. The outer periphery of the outer push rod is provided with a pin hole, in which a spring-loaded pin is installed. The spring force keeps the pin in a depressed state. The outer periphery of the inner push rod is provided with a pin insertion hole for the pin to be inserted. The distance between the pin and the pin insertion hole is the floating distance. The locking and unlocking mechanism is mounted on the outer wall of the outer push rod via a central pivot point. The tail of the locking and unlocking mechanism is inserted into the control hole on the pin. The head of the locking and unlocking mechanism is pressed down when it enters the push rod sleeve. The tail of the locking and unlocking mechanism is raised via the pivot point and can push the pin out of the pin insertion hole and extend into the pin groove on the push rod sleeve. The outer push rod is connected to the load.

[0005] Furthermore, a guide key is provided on the outer periphery of the inner push rod, and a guide keyway is provided at the corresponding position of the outer push rod; the outer push rod and the inner push rod adopt a clearance fit, and the guide key allows the outer push rod and the inner push rod to retain only the axial movement degree of freedom.

[0006] Furthermore, a rubber sheath is installed at the end of the outer push rod and the push rod sheath.

[0007] Furthermore, the rubber sheath has a folding structure that extends and retracts with the outer push rod and the inner push rod.

[0008] Furthermore, the position of the latch is controlled by a spring that maintains an upward thrust and by rigidly pressing down on the shape of the push rod sleeve.

[0009] (III) Beneficial Effects This invention proposes an electric linear actuator with a bottom-floating structure, comprising a housing, a lead screw, bearings, a nut, an inner push rod, an outer push rod, a push rod sleeve, a locking / unlocking mechanism, and a bottom fulcrum. When the electric linear actuator is retracted to its shortest position, it remains in a free-floating state for a certain distance before reaching this position, meaning its axial movement is free. This allows the actuator to float when retracted to the bottom, changing the characteristic of a rigid connection throughout the entire stroke of an electric mechanical linear actuator, overcoming the contradiction between reverse transmission self-locking and the requirement for bottom floating, and making it possible to drive suspended loads. The floating resistance of the floating structure in this invention is negligible, lower than that of existing hydraulic expansion cylinders, and has less impact on load suspension. The locking / unlocking mechanism is implemented using a purely mechanical structure, requiring no electric components, making it simple, reliable, and safe even in the event of a power outage. This invention solves the bottom-floating problem of mechanical linear actuators, enabling electric mechanical telescopic linear actuators to have a bottom-floating function with lower resistance than hydraulic cylinders, thereby expanding the application range of electric mechanical linear actuators. Attached Figure Description

[0010] Figure 1This is a schematic diagram of the overall structure of the electric actuator with a bottom floating structure according to the present invention; Figure 2 This is a partial radial sectional view in the vertical direction of the electric actuator with a bottom floating structure according to the present invention; Figure 3 This is a partial radial cross-sectional view in the horizontal direction of the electric actuator with a bottom floating structure according to the present invention.

[0011] In the diagram: 1-Rubber sheath; 2-Outer push rod; 3-Guide key; 4-Inner push rod; 5-Sheath; 6-Nut; 7-Lead screw; 8-Bearing; 9-Box body; 10-Bottom fulcrum; 11-Guide wheel; 12-Locking hole; 13-Pin; 14-Locking and unlocking mechanism. Detailed Implementation

[0012] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0013] This embodiment proposes an electric actuator with a bottom floating structure, the overall structure of which is as follows: Figure 1 As shown, it mainly includes a housing 9, a lead screw 7, a bearing 8, a nut 6, an inner push rod 4, an outer push rod 2, a push rod sleeve 5, a locking / unlocking mechanism 14, a bottom support point 10, and a rubber sleeve 1.

[0014] The housing 9 has a rectangular structure. The bottom support 10 and the push rod sleeve 5 are fixed to the outer sides of the housing 6, respectively. A bearing 8 is installed inside the housing 6, and the rear end of the lead screw 7 is supported by the bearing 8. A nut 6 is installed on the lead screw 7, and the front end of the nut 6 is fixedly connected to the rear end of the inner push rod 4. The outer push rod 2 is sleeved on the outer circumference of the inner push rod 4, and both are located inside the push rod sleeve 5. A guide key 3 is provided on the outer circumference of the inner push rod 4, and a guide keyway is provided at the corresponding position of the outer push rod 2. The outer push rod 2 and the inner push rod 4 are fitted with a clearance of less than 0.05mm, and the guide key 3 ensures that only axial movement freedom is maintained between the outer push rod 2 and the inner push rod 4. A shoulder is provided at the rear end of the inner push rod 4, and the front end face of the shoulder can abut against the rear end face of the outer push rod 2.

[0015] A rubber sleeve 1 is installed at the ends of the outer push rod 2 and the push rod sleeve 5, serving as a dustproof function. The rubber sleeve 1 has a folding structure, allowing it to extend and retract with the outer push rod 2 and the inner push rod 4. The outer wall of the push rod sleeve 5 has guide grooves and pin grooves. A guide wheel 11 is mounted on a trunnion on the side of the nut 6. The guide wheel 11 can roll within the guide groove, allowing the nut 6 to move only axially and not rotate. The outer periphery of the outer push rod 2 has a pin hole, in which a spring-loaded pin 13 is installed. The spring force keeps the pin 13 in a pressed-down state. The outer periphery of the inner push rod 4 has a pin insertion hole 12 for inserting the pin 13. The distance between the pin 13 and the pin insertion hole 12 is the distance it can float to the right.

[0016] The locking / unlocking mechanism 14 is mounted on the outer wall of the outer push rod 2 via the central pivot point. The tail of the locking / unlocking mechanism 14 is inserted into the control hole on the pin 13. The head of the locking / unlocking mechanism 14 is pressed down when it enters the push rod sleeve 5. The tail of the locking / unlocking mechanism 14 is raised by the pivot point and can push the pin 13 out of the pin insertion hole 12 and extend into the pin groove on the push rod sleeve 5.

[0017] The outer push rod 2 is connected to the load. Figure 1 The outer push rod 2 shown is now at its shortest position. The locking / unlocking mechanism 14 has entered the push rod sleeve 5 ahead of time. The compression of the locking / unlocking mechanism 14 causes the pin 13 to be pulled out of the pin hole 12, while the inner push rod 4 and nut 6 continue to move inward until the nut 6 abuts against the housing 9. At this time, the pin 13 on the outer push rod 2 and the pin hole 12 on the inner push rod 4, as well as the shoulder of the inner push rod 4 and the end face of the outer push rod 2, are all offset by a distance. This distance allows the outer push rod 2 and the load to gain axial freedom relative to the inner push rod 4 and nut 6, and the entire electric push rod gains a floating distance. In this state, if the load has a suspension buffer structure, the outer push rod 2 can freely extend and retract when the load is suspended and shaken. This function is called bottom floating. The smaller the bottom floating resistance, the smaller the impact on the load suspension effect.

[0018] When the outer push rod 2 needs to extend to drive the load, the lead screw 7 rotates, and the nut 6 moves in the direction of extension under the constraint of the guide wheel 11. When the shoulder of the inner push rod 4 reaches the end face of the outer push rod 2, the locking and unlocking mechanism 14 has already disengaged from the push rod sleeve 5. Under the action of spring pressure, the pin 13 is inserted downward into the locking hole 12, and the outer push rod 2 and the inner push rod 4 are fixed together. Regardless of whether the load is pressure or tension, the entire electric push rod can be driven normally.

[0019] In addition, such as Figure 2 As shown, the position of the pin 13 can also be controlled by a spring that maintains an upward thrust and by rigidly pressing down the push rod sleeve 5 based on its shape.

[0020] Figure 3 The cross section shown is Figure 2 Vertically, this shows the relationship between the guide wheel 11 on the nut 6 and the push rod sleeve 5. The push rod sleeve 5 is fixedly connected to the housing 9. The guide wheel 11 moves in the guide groove of the push rod sleeve 5, so that when the screw 7 rotates, the nut 6 only moves axially and does not rotate.

[0021] The bottom floating structure of this invention is applied to an electromechanical lifting push rod in the cab tilting design of a heavy-duty truck. The outer diameter is Φ68mm, the lifting stroke is 680mm, and the bottom floating distance is 100mm. It can not only fully meet the functions required for cab tilting, but also has a lower weight and higher reliability than hydraulic push rods, and the performance is good.

[0022] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An electric actuator with a bottom floating structure, characterized in that, The electric actuator with a bottom floating structure includes a housing, a lead screw, a bearing, a nut, an inner actuator, an outer actuator, an actuator sleeve, a locking / unlocking mechanism, and a bottom fulcrum; wherein, The bottom support and push rod sleeve are fixed to the outer sides of the housing, and the housing is equipped with bearings. The rear end of the lead screw is supported by the bearings. A nut is installed on the lead screw, and the front end of the nut is fixedly connected to the rear end of the inner push rod. The outer push rod is sleeved on the outer circumference of the inner push rod and is set inside the push rod sleeve. The rear section of the inner push rod is provided with a shoulder, and the front end of the shoulder can abut against the rear end of the outer push rod. The outer wall of the push rod sleeve has guide grooves and pin grooves. The guide wheel is mounted on the side trunnion of the nut. The guide wheel can roll in the guide groove, so that the nut can only move axially and cannot rotate. The outer periphery of the outer push rod is provided with a pin hole, in which a spring-loaded pin is installed. The spring force keeps the pin in a depressed state. The outer periphery of the inner push rod is provided with a pin insertion hole for the pin to be inserted. The distance between the pin and the pin insertion hole is the floating distance. The locking and unlocking mechanism is mounted on the outer wall of the outer push rod via a central pivot point. The tail of the locking and unlocking mechanism is inserted into the control hole on the pin. The head of the locking and unlocking mechanism is pressed down when it enters the push rod sleeve. The tail of the locking and unlocking mechanism is raised via the pivot point and can push the pin out of the pin insertion hole and extend into the pin groove on the push rod sleeve. The outer push rod is connected to the load.

2. The electric actuator with a bottom floating structure as described in claim 1, characterized in that, The inner push rod is provided with a guide key on its outer periphery, and the corresponding position of the outer push rod is provided with a guide keyway; the outer push rod and the inner push rod adopt a clearance fit, and the guide key allows the outer push rod and the inner push rod to retain only the axial movement degree of freedom.

3. The electric actuator with a bottom floating structure as described in claim 1, characterized in that, The rubber sheath is installed at the end of the outer push rod and the push rod sheath.

4. The electric actuator with a bottom floating structure as described in claim 3, characterized in that, The rubber sheath has a folding structure and extends and retracts with the outer push rod and the inner push rod.

5. The electric actuator with a bottom floating structure as described in claim 1, characterized in that, The position of the pin is controlled by a spring that maintains an upward pushing force and by rigidly pressing down on the shape of the push rod sleeve.

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