Articulated frame steering mechanism and engineering machine

Abstract

The present application relates to a steering mechanism, in order to solve the problem of poor buffering effect of the elastic collision buffering device in the existing articulated frame steering mechanism, the present application constructs an articulated frame steering mechanism and engineering machinery, the steering cylinder in the steering mechanism has an annular buffering oil channel and a buffering sleeve; the circumferential side surface of the buffering sleeve is sequentially provided with a variable cross-section section and an extension section from the first end to the last end; the minimum cross-section area of the gap between the buffering sleeve and the cylinder cover decreases with the increase of the insertion depth of the variable cross-section section, and the first end of the extension section does not change after being inserted; the distance between the two rotating centers AB of the oil cylinder at the maximum rotating angle of the front and rear frames is greater than or equal to the distance between the AB points when the last end of the variable cross-section section is inserted into the annular buffering oil channel, and is less than the distance between the AB points when the piston contacts the cylinder cover. The present application reduces the impact during steering through the oil cylinder buffering and deceleration, the elastic collision buffering device collision contact limiting, and improves the comfort.

Description

Technical Field

[0001] This invention relates to a steering mechanism, and more specifically, to an articulated frame steering mechanism and engineering machinery. Background Technology

[0002] In the field of construction machinery, some machines such as loaders, graders, and road rollers use articulated frames. An articulated frame consists of a front frame and a rear frame hinged together by a pivot pin. A steering cylinder is installed on each side of the hinge point between the front and rear frames, with its two ends connected to the front and rear frames respectively. The extension and retraction of the steering cylinders causes the front and rear frames to rotate relative to each other around the pivot pin, thus enabling the construction machinery to steer.

[0003] In existing articulated chassis steering mechanisms, to prevent severe collisions between the front and rear frames when they reach their maximum steering angle, a resilient impact damper is typically installed between the front and rear frames. The elastic element in this damper is usually a rubber block. During use, this rubber block can easily lose its elasticity and damping function due to excessive compression. Furthermore, in a resilient impact damper, the elastic force is directly proportional to the degree of compression of the rubber block; the greater the compression, the greater the elastic force and the greater the steering impact damping acceleration. During steering, at the end of the steering stroke, the steering impact damping acceleration increases with the steering angle, reaching its maximum value at the end, indicating the maximum intensity of the collision. It is difficult to design the elastic element to achieve a steering impact damping acceleration curve that provides a comfortable deceleration effect. Summary of the Invention

[0004] The technical problem to be solved by the present invention is the poor effect of the existing articulated frame steering mechanism in terms of the steering limit and buffering effect of the front and rear frames by installing elastic collision buffer devices. The present invention provides an articulated frame steering mechanism and engineering machinery to improve the limit and buffering effect.

[0005] The technical solution of this invention to achieve its objective is as follows: An articulated vehicle frame steering mechanism is constructed, comprising an articulated front frame and a rear frame, steering cylinders respectively arranged on the left and right sides of the frame hinge point, and elastic collision buffer devices mounted on the front and rear frames to limit the maximum rotation angle of the front and rear frames. The rotation center points of the two ends of the steering cylinders, which are hinged to the front and rear frames, are points A and B, respectively. The steering cylinder is characterized by having an annular buffer oil passage connecting small chambers to oil ports between the cylinder head and the piston rod. A buffer sleeve, capable of being inserted into the annular buffer oil passage and fitting with the cylinder head with a clearance, is fitted on the piston rod near the piston. The circumferential side of the buffer sleeve consists of a variable cross-section section and an extended section from the first end to the last end. The minimum cross-sectional area of ​​the fit clearance between the buffer sleeve and the cylinder head decreases from the first end of the variable cross-section section to the last end as the insertion depth of the buffer sleeve increases. After insertion from the first end of the extended section, the minimum cross-sectional area of ​​the fit clearance does not change with the increasing insertion depth of the buffer sleeve.

[0006] When the front and rear frames rotate relative to each other to the maximum rotation angle, the distance between points A and B is greater than or equal to the distance between points A and B when the end of the variable cross-section section of the buffer sleeve is inserted into the annular buffer oil passage, and less than the distance between points A and B when the piston of the steering cylinder contacts the cylinder head.

[0007] In this invention, when the relative rotation angle between the front and rear frames approaches the maximum rotation angle, the piston rod of the corresponding steering cylinder extends into the annular buffer oil passage through the buffer sleeve. This reduces the flow area between the small chambers and their connecting ports, decreasing the piston rod extension speed and achieving hydraulic buffering. Before the extended section is inserted into the annular buffer oil passage, the flow area between the small chambers and their connecting ports decreases with the increasing insertion depth of the buffer sleeve, and correspondingly, the piston rod extension speed also decreases. When the variable cross-section section is fully inserted into the annular buffer oil passage, the flow area between the small chambers and their connecting ports remains constant with the increasing insertion depth of the buffer sleeve, and the piston rod extension speed also remains constant, extending at the speed reduced during the insertion of the variable cross-section section. During the insertion of the extended section of the buffer sleeve into the annular buffer oil passage, the front and rear frames stop rotating due to elastic collision limiting by the elastic collision buffer device. During the collision-stopped rotation process of the front and rear frames, the piston of the steering cylinder does not contact the cylinder head, thus preventing damage to the steering cylinder due to rigid contact collision between the piston and the cylinder head. The front and rear frames achieve contact limit stop at the end of rotation through the elastic collision buffer device. Since the collision is decelerated and buffered by the cooperation of the buffer sleeve and cylinder head, the elastic components in the elastic collision buffer device are slightly compressed, resulting in less damage to the elastic collision buffer device. At the same time, the impact intensity is low, improving the steering operation comfort of the machine.

[0008] In this invention, the distance between points A and B when the front and rear frames rotate relative to each other to the maximum rotation angle is the distance between points A and B, the rotation center points at both ends of the steering cylinder, when the front and rear frames stop rotating due to the collision limit of the elastic collision buffer device.

[0009] The distance between points A and B when the end of the variable cross-section section of the buffer sleeve is inserted into the annular buffer oil passage refers to the distance between points A and B, the rotation center points at both ends of the steering cylinder, when the minimum cross-sectional area of ​​the clearance fit between the buffer sleeve and the cylinder head no longer changes during the process of the buffer sleeve being inserted into the annular buffer oil passage. This distance is usually also the distance between points A and B, the rotation center points at both ends of the steering cylinder, when the beginning of the extended section of the buffer sleeve is inserted into the annular buffer oil passage.

[0010] The distance between points A and B when the piston of the steering cylinder contacts the cylinder head refers to the distance between points A and B, the rotation center points at both ends of the steering cylinder, when the front and rear ends of the steering cylinder are not connected to the front and rear frames, and the large chamber of the cylinder is continuously filled with oil until the piston contacts the cylinder head. In other words, it is the distance between points A and B, the rotation center points at both ends of the steering cylinder, when the piston rod reaches its maximum extension stroke. In this invention, when the front and rear frames are stopped by the collision limit device, the piston rod extension stroke of the steering cylinder has not yet reached its maximum.

[0011] In the articulated frame steering mechanism of this invention, the inner wall of the cylinder head that mates with the circumferential side of the buffer sleeve is a cylindrical surface. The variable cross-section section of the circumferential side of the buffer sleeve is composed of a conical section and a chamfered section at the beginning of the conical section. The extended section of the circumferential side of the buffer sleeve is a cylindrical surface with a diameter equal to or smaller than the diameter of the end of the conical section. During the initial insertion of the buffer sleeve into the annular buffer oil passage, the cross-sectional area of ​​the mating clearance between the circumferential side of the buffer sleeve and the cylinder head gradually decreases, and the piston rod extension speed gradually decreases. During the complete insertion of the variable cross-section section and the gradual insertion of the extended section into the annular buffer oil passage, the cross-sectional area of ​​the mating clearance between the circumferential side of the buffer sleeve and the cylinder head remains constant, and the piston rod extension speed remains correspondingly constant.

[0012] In the articulated frame steering mechanism of the present invention, the piston rod is provided with a limiting step for limiting the contact of the first end face of the buffer sleeve. The buffer sleeve is floatingly fitted between the limiting step and the piston. There is a rod-sleeve fitting gap between the inner wall of the buffer sleeve and the piston rod, which allows oil to flow. The end of the buffer sleeve has a radial channel that radially connects the rod-sleeve fitting gap with the small cavity. The first end face of the buffer sleeve and the end face of the limiting step are planes that can fit tightly against each other.

[0013] A floating sleeve refers to a system where the distance between the limiting step and the piston is greater than the axial length of the buffer sleeve, allowing the buffer sleeve to move axially between the limiting step and the piston. Simultaneously, the inner diameter of the buffer sleeve is greater than the diameter at the buffer sleeve mounting position on the piston rod, enabling the buffer sleeve to have a certain amount of radial movement relative to the piston rod. A rod-sleeve fit clearance exists between the buffer sleeve and the piston rod to allow oil flow. When the floating sleeve is inserted into the annular buffer oil passage, it adaptively adjusts to the clearance fit with the piston rod and cylinder head.

[0014] When the buffer sleeve is inserted into the annular buffer oil passage, the pressure in the small cavity is greater than the pressure at the oil port connecting the small cavity. The buffer sleeve moves under the action of the oil pressure in the small cavity. The end face of the buffer sleeve is in contact with the end face of the limiting step. There is no flow gap between the end face of the buffer sleeve and the limiting step for the oil in the rod sleeve fitting gap to flow to the annular buffer oil passage.

[0015] When the buffer sleeve retracts from the annular buffer oil passage (during piston rod retraction), the hydraulic pressure at the small cavity connection port is greater than the pressure in the small cavity. The first end of the buffer sleeve disengages from the end face of the limiting step, allowing the oil from the small cavity connection port to enter the rod sleeve fitting clearance through the gap between the first end face of the buffer sleeve and the end face of the limiting step. The oil from the small cavity connection port flows to the small cavity through the fitting clearance between the buffer sleeve and the annular buffer oil passage, and also flows to the small cavity through the rod sleeve fitting clearance. The throttle valve does not dampen the oil flowing to the small cavity, allowing the steering cylinder to start quickly.

[0016] The above structure allows for different flow areas between the small chambers and the connecting ports when the buffer sleeve is inserted into and withdrawn from the annular buffer oil passage. When the buffer sleeve is inserted, the flow area is small, resulting in a low piston rod extension speed; when the buffer sleeve is withdrawn, the flow area is large, resulting in a fast piston rod retraction start speed.

[0017] In the articulated frame steering mechanism of the present invention, a flow area regulating oil passage is provided on the cylinder head, connecting the small cavity and the oil port of the small cavity, and a throttle valve installed in the flow area regulating oil passage is provided in the flow area regulating oil passage through threaded engagement; or a flow area regulating oil passage is provided on the piston rod, connecting the rod sleeve engagement clearance and the oil port of the small cavity; the flow area regulating oil passage is L-shaped, with its radial section outlet located on the cylindrical surface of the piston rod, its axial section outlet located on the end face of the limiting step, and a throttle valve installed in the radial section through threaded engagement is provided.

[0018] The oil in the small cavity flows to the small cavity connection port through the fit gap between the buffer sleeve and the annular buffer oil passage, and also flows to the small cavity connection port through the flow area adjustment oil passage. By selecting different specifications of throttle valves, the flow area of ​​the flow area adjustment oil passage can be adjusted, thereby adjusting the rate of change of the piston rod extension speed when the buffer sleeve is inserted into the annular buffer oil passage, so as to adapt to different models and achieve different buffering effects.

[0019] In the articulated frame steering mechanism of this invention, an annular groove is provided at the end of the piston rod near the piston end face, communicating with the radial channel and the rod sleeve mating clearance. The radial channel is formed by multiple radial notches on the end face of the extended section of the buffer sleeve, or by multiple radial through holes on the end face of the extended section of the buffer sleeve. The rod sleeve mating clearance is a cylindrical channel, and the radial channels are discretely distributed along the circumference of the buffer sleeve. The annular groove at the end connects the rod sleeve mating clearance with the radial channels, allowing for better oil flow.

[0020] In the articulated frame steering mechanism of this invention, a first-end annular groove is provided on the cylindrical surface of the piston rod near the end face of the limiting step, communicating with the flow area adjusting oil passage and the clearance between the piston rod sleeve and the piston rod sleeve. The first-end annular groove serves to connect the clearance between the piston rod sleeve and the flow area adjusting oil passage, allowing for better oil flow.

[0021] The technical solution of this invention to achieve its objective is as follows: Constructing an engineering machine characterized by having the aforementioned articulated frame steering mechanism. This type of engineering machine has an articulated frame, which can be a loader, grader, road roller, etc.

[0022] Compared with the prior art, the present invention buffers and decelerates the steering cylinder when the steering stroke is close to the end, reduces the relative rotation speed of the front and rear frames, reduces the intensity of the collision between the front and rear frames at the end of the steering stroke, improves steering operation comfort and the service life of the elastic collision buffer device. When the steering stroke is close to the end, the cylinder piston and cylinder head will not make rigid contact, and the steering cylinder will not be damaged by rigid impact. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the articulated frame steering mechanism of the present invention.

[0024] Figure 2 This is a schematic diagram of the state when the front and rear frames of the vehicle are rotated to the maximum steering angle in this invention.

[0025] Figure 3 This is a schematic diagram of the steering cylinder in this invention.

[0026] Figure 4This is a schematic diagram of the engagement state between the buffer sleeve and the cylinder head when the front and rear frames rotate to the maximum steering angle in this invention.

[0027] Figure 5 This is a schematic diagram of the structure of the buffer sleeve in this invention.

[0028] Figure 6 This is a schematic diagram of the second embodiment of the steering cylinder in this invention.

[0029] Component names and serial numbers in the diagram:

[0030] Steering cylinder 100, rear frame 101, front frame 102, pin 103.

[0031] 1. Cylinder head; 2. Cylinder barrel; 3. Cylinder head; 4. Piston; 5. Piston rod; 6. Large chamber; 7. Small chamber; 8. Small chamber connecting oil port; 9. Large chamber connecting oil port; 10. Buffer sleeve; 11. Flow area adjusting oil passage; 12. Throttle valve; 13. Rod sleeve fitting clearance; 14. End annular groove; 15. Head annular groove; 16. Radial through hole; 17. Annular buffer oil passage; 18. Radial notch. Detailed Implementation

[0032] The specific implementation plan is described below with reference to the attached diagram.

[0033] Figure 1 Figure 2 This is a schematic diagram of an articulated frame steering mechanism provided in an embodiment of the present invention. The articulated frame steering mechanism includes a front frame 102, a rear frame 101, and two steering cylinders 100. The front frame 102 and the rear frame 101 are hinged together by a pin 103. The two steering cylinders 100 are respectively arranged on the left and right sides of the hinge point between the front and rear frames. One end of the steering cylinder 100 is hinged to the front frame 102, with the hinge rotation center at point B; the other end of the steering cylinder 100 is hinged to the rear frame 101, with the hinge rotation center at point A.

[0034] The front frame 102, driven by two steering cylinders, can rotate relative to the rear frame 101 around the pivot pin 103, thereby achieving frame swing steering. Figure 2 As shown, when the front frame 102 rotates to the right relative to the rear frame 101, the right steering cylinder piston rod retracts and the left steering cylinder piston rod extends. Correspondingly, when the front frame 102 rotates to the left relative to the rear frame 101, the left steering cylinder piston rod retracts and the right steering cylinder piston rod extends.

[0035] Elastic collision buffer devices (not shown in the figure) are installed on the front frame 102 and the rear frame 101. The elastic collision buffer device typically includes an elastomer (usually an elastic rubber column) and a collision plate. The elastomer is fixedly installed on the rear frame 101, and the collision plate is fixed on the front frame 102. When the front frame 102 rotates relative to the rear frame 101 to the maximum steering angle, the collision plate collides with and squeezes the elastomer, restricting the front frame from continuing to rotate relative to the rear frame, thereby limiting the maximum steering angle of the front and rear frames.

[0036] In articulated frame steering mechanisms, there are usually two elastic collision buffer devices, which are arranged on the left and right sides of the front and rear frame hinge points, respectively, to limit the collision between the front and rear frames when the frame rotates to its maximum angle when turning left and right.

[0037] The large chamber of the left steering cylinder is connected to the small chamber of the right steering cylinder through a pipeline, and the lower chamber of the left steering cylinder is connected to the large chamber of the right steering cylinder through a pipeline, thereby enabling the two steering cylinders to extend and retract synchronously in opposite directions.

[0038] Figure 3 This is a schematic diagram of a steering cylinder according to an embodiment of the present invention. The steering cylinder includes a cylinder barrel 2, a cylinder head 1 and a cylinder cover 3 fixedly connected to both ends of the cylinder barrel, and a piston 4 located inside the cylinder barrel 2. The cylinder barrel 2, cylinder cover 3, and cylinder head 1 divide the inner cavity into a large cavity 6 and a small cavity 7. A large cavity connection port 9 communicating with the large cavity 6 is provided on the cylinder head 1, and a small cavity connection port 8 is provided at the position where the cylinder barrel 2 and cylinder cover 3 are connected. One end of the piston rod 5 extends into the cylinder barrel 2 through a hole in the cylinder cover 3 and is fixedly connected to the piston 4.

[0039] like Figure 3 Figure 5 As shown, a buffer sleeve 10 is floatingly fitted on the piston rod 5 near the piston 4. An annular buffer oil passage 17 is formed between the inner hole of the cylinder head 3 and the piston rod 5. The small cavity connecting oil port 8 is connected to the small cavity 6 through the annular buffer oil passage 17. When the piston rod 5 extends to near the end of its stroke, the buffer sleeve 10 is inserted into the annular buffer oil passage 17, reducing the flow area of ​​the annular buffer oil passage 17 and reducing the speed at which the oil flows out of the small cavity 7, thereby slowing down the extension speed of the piston rod 5 and realizing cylinder buffering.

[0040] like Figure 4 As shown, the circumferential side surface of the buffer sleeve 10 consists of a chamfered section C, a conical section B, and a cylindrical section A from the first end to the last end. The chamfered section C and the conical section B constitute a variable interface section, and the cylindrical section A constitutes an extension section.

[0041] The diameter of the conical section B gradually increases from the beginning to the end, while the diameter of the cylindrical section A remains constant, equal to the diameter of the end of the conical section B. When the piston rod 5 extends and moves to near the end of its extension stroke, the chamfered section C, the conical section B, and the cylindrical section A on the buffer sleeve 10 sequentially enter the annular buffer oil passage. The chamfered side of the buffer sleeve 10 has a large gap with the inner wall of the cylinder head, facilitating the insertion of the floating buffer sleeve 10 into the inner hole of the cylinder head (i.e., the annular buffer oil passage). As the conical section B of the buffer sleeve 10 enters the annular buffer oil passage 13, the minimum gap between the buffer sleeve 10 and the inner wall of the cylinder head 3 decreases, the minimum cross-sectional area of ​​the fit decreases, and correspondingly, the piston rod extension speed gradually decreases. After the cylindrical section of the buffer sleeve enters the annular buffer oil passage, the gap between the buffer sleeve 10 and the inner hole of the cylinder head 3 remains constant. Under the condition that the pressure in the large cavity of the cylinder remains constant, the operating speed of the steering cylinder remains constant.

[0042] In this embodiment, when the conical section B of the buffer sleeve 10 is fully engaged in the annular buffer oil passage during steering, the piston 4 has not yet reached the end of its stroke (the piston 4 has not yet contacted the cylinder head 3). As the steering angle further increases, the cylindrical section A of the buffer sleeve 10 enters the annular buffer oil passage 17. The flow area between the small cavity 7 and the small cavity connecting port 8 remains constant, and the piston rod 5 extends at a constant speed until the front and rear frames stop due to the limiting contact of the elastic collision buffer device. Because the steering cylinder achieves buffer deceleration through the engagement of the conical section B of the buffer sleeve 10 with the inner hole of the cylinder head 3, the relative rotational speed between the front and rear frames is low when the elastic collision buffer device on the front and rear frames contacts and collides, resulting in a minor collision. When the elastic collision buffer device on the front and rear frames contacts and collides, the distance between the rotation center points A and B at both ends of the steering cylinder is less than the distance between points A and B when the piston of the steering cylinder contacts the cylinder head. Therefore, the piston does not contact the cylinder head, meaning that at the end of the steering stroke, the steering cylinder will not be damaged due to the collision between the piston and the cylinder head. The length of the extended section on the buffer sleeve is greater than the maximum deviation of the steering stroke during the manufacturing of the articulated frame. This ensures that the steering cylinder stroke is not fully utilized when the front and rear frames stop at the end of the steering stroke due to the limiting contact of the elastic collision buffer device, thus avoiding rigid contact and limiting between the piston and the cylinder head.

[0043] In this embodiment, during the process from the front and rear frames of the articulated frame steering mechanism rotating to near their maximum steering angle until they stop rotating due to the impact of the elastic collision buffer device, the conical section B of the buffer sleeve enters the annular buffer oil passage, achieving buffer deceleration. Before the conical section B of the buffer sleeve fully enters the annular buffer oil passage, the elastic collision buffer device is at its collision-non-collision limit; when the conical section B of the buffer sleeve is fully entered into the annular buffer oil passage and a portion of the cylindrical section of the buffer sleeve enters the annular buffer oil passage, the elastic collision buffer device is at its collision contact limit, and the front and rear frames stop rotating relative to each other.

[0044] like Figure 5 As shown, a limiting step is provided at the position of piston rod 5 near piston 4, and buffer sleeve 10 is located between the limiting step and piston 4. The inner diameter of buffer sleeve 10 is larger than the diameter at the installation position of buffer sleeve 10 on piston rod 5, and the fitting clearance between buffer sleeve 10 and piston rod 5 is rod-sleeve fitting clearance 13.

[0045] The distance between the limiting step and the piston 4 is greater than the axial length of the buffer sleeve 10. Under the action of oil pressure, the buffer sleeve 10 can move axially between the piston and the limiting step. When the buffer sleeve 10 moves in the direction of piston rod extension, the end face of the buffer sleeve 10 abuts against the end face of the limiting step. When the buffer sleeve 10 moves in the direction of piston rod retraction, the end face of the buffer sleeve 10 abuts against the end face of the piston 4. The buffer sleeve 10 can move relative to the piston rod 5 within a certain range in the radial and axial directions, and is in a floating state. When the buffer sleeve 10 enters the annular buffer oil passage, it adapts to the annular buffer oil passage under the action of pressure oil.

[0046] A flow area regulating oil passage 11 is provided on the piston rod 5 at the position of the limiting step. The flow area regulating oil passage 11 is L-shaped, with its radial section opening located on the cylindrical surface of the piston rod 5 and its axial section opening located on the end face of the limiting step. A throttle valve 12 is installed in the radial section. When the buffer sleeve 10 enters the annular buffer oil passage 17, the end face of the buffer sleeve 10 and the end face of the limiting step are in close contact, and the radial section outlet of the flow area regulating oil passage is connected to the annular buffer oil passage 17.

[0047] The end face of the buffer sleeve 10 and the end face of the limiting step are mating planes. When the buffer sleeve 10 moves in the direction of piston rod extension and comes into contact with the end face of the limiting step, there is no gap between the buffer sleeve 10 and the limiting step for oil flow. The oil in the rod sleeve mating gap 13 flows to the small cavity connecting oil port through the flow area adjusting oil passage 11 and the throttle valve 12.

[0048] An annular groove 15 is provided on the cylindrical surface of the piston rod 5 near the end face of the limiting step, which communicates with the axial section opening of the flow area adjusting oil passage and the rod sleeve fitting clearance 13. The annular groove 15 connects the L-shaped oil passage 11 and the rod sleeve fitting clearance 13, allowing for better oil flow.

[0049] The throttle valve 12 is cylindrical and has an axial inner bore for oil flow. The throttle valve 12 is fixed within the radial section of the flow area adjusting oil passage by engaging with the piston rod via an external thread. Different models of throttle valves have different inner bore diameters, resulting in different flow areas. By selecting and installing different models and specifications of throttle valves, the oil flow capacity varies.

[0050] In this embodiment, when the articulated frame steering mechanism is steering, taking left steering as an example, when the left steering angle is close to the maximum left steering angle, when the piston rod 5 of the right steering cylinder extends to almost the end of its stroke, the first end of the buffer sleeve 10 enters the annular buffer oil passage, causing the hydraulic oil flow area of ​​the annular buffer oil passage to decrease sharply. The pressure in the small cavity 7 increases sharply under the compression of the piston. The buffer sleeve 10 moves relative to the piston rod 5 in the direction of piston rod extension. The end face of the first end of the buffer sleeve 10 contacts and engages with the end face of the limiting step on the piston rod 5. There is no gap for oil flow between the buffer sleeve 10 and the limiting step. Part of the hydraulic oil in the small cavity 7 flows to the small cavity connecting port 8 through the rod sleeve engagement gap 13, the flow area adjustment oil passage 11, and the throttle valve 12. The flow area of ​​the flow area adjustment oil passage depends on the flow area of ​​the throttle valve 12.

[0051] The moving speed of piston rod 5 depends on the flow area between small chamber 7 and oil port 8. Different speeds are required in different applications, which means corresponding flow areas are needed.

[0052] like Figure 4 As shown, the end face of the buffer sleeve 10 has multiple radial notches 18 that penetrate the buffer sleeve wall. The end of the rod-sleeve mating clearance communicates with the small cavity 7 through the radial notches 18. An annular groove 14, communicating with the radial notches and the rod-sleeve mating clearance, is provided on the cylindrical surface of the piston rod 5 near the piston end face. The rod-sleeve mating clearance is a cylindrical channel, and the radial channels are discretely distributed along the circumference on the buffer sleeve. The annular groove at the end connects the rod-sleeve mating clearance with the radial channels, allowing for better oil flow.

[0053] In another embodiment provided by the present invention, such as Figure 5 As shown, the rear part of the buffer sleeve 10 is provided with a plurality of radial through holes 16 communicating with the small cavity, and an annular groove 14 is provided on the cylindrical surface of the piston rod 5 near the piston end face, communicating with the radial through holes 16 and the fitting clearance of the rod sleeve. In this embodiment, the radial through holes 16 can be used to replace the radial notch 18 on the end face.

[0054] In this embodiment, the flow area between the small cavity 7 and the connecting port 8 is equal to the sum of the flow area between the buffer sleeve 10 and the inner wall of the cylinder head 3 and the flow area of ​​the throttle valve 12. The flow area between the buffer sleeve 10 and the inner wall of the cylinder head depends on the minimum cross-sectional area of ​​the fit clearance between the circumferential side of the buffer sleeve 10 and the inner hole of the cylinder head. Designing and manufacturing a set of buffer sleeve and cylinder head for each application increases the manufacturer's production and management costs. In this embodiment of the steering cylinder, the buffer sleeve 10 and cylinder head 3 have the same fit clearance, i.e., the same flow area, regardless of the application. The appropriate model of throttle valve 12 is selected according to the application requirements, ensuring that the sum of the flow area between the buffer sleeve 10 and the inner wall of the cylinder head and the flow area of ​​the throttle valve meets the piston rod's deceleration requirement at the end of its extension stroke. Compared to changing the fit clearance between the buffer sleeve and the inner hole of the cylinder head to adapt to different application requirements, this embodiment achieves lower costs by replacing the throttle valve.

[0055] When the piston rod 5 starts to retract at the end of its extended stroke, the pressure at the small cavity connecting port 8 is higher than the pressure in the small cavity 7. The buffer sleeve 10 moves backward under the force of the hydraulic oil, and its end contacts the end face of the piston 4. There is a gap between the buffer sleeve 10 and the end face of the upper limit step of the piston rod 5. The pressurized oil in the front section of the annular buffer oil passage enters the rod-sleeve fitting gap 13 between the buffer sleeve 10 and the piston rod 5 through the gap between the buffer sleeve and the limit step, and flows into the small cavity 7 through the end of the rod-sleeve fitting gap 13. The throttle valve 12 in the flow area regulating oil passage 11 does not dampen the oil, allowing the hydraulic oil to quickly enter the small cavity through the rod-sleeve fitting gap, causing the hydraulic cylinder piston rod to retract quickly. When the piston rod retracts, the flow area between the small cavity 7 and the small cavity connecting port 8 is greater than the flow area between the small cavity 7 and the small cavity connecting port 8 when the buffer sleeve is inserted into the annular buffer oil passage to decelerate and buffer the piston rod.

[0056] This embodiment also provides a piece of construction machinery, which may have an articulated frame, such as a loader, grader, or road roller. Due to manufacturing errors, the articulated frame, consisting of a front frame and a rear frame, will exhibit a certain angular deviation when turning left and right. This results in a discrepancy between the piston rod extension stroke of the right steering cylinder when turning left to its maximum left turning angle and the extension stroke of the left steering cylinder when turning right to its maximum right turning angle.

[0057] Figure 6 This is a schematic diagram of another steering cylinder provided in an embodiment of the present invention. Figure 6 In the technical solution shown, the flow area adjustment oil passage is set on the cylinder head, and the two ends of the oil passage are connected to the small cavity and the small cavity connection port, respectively.

Claims

1. An articulated vehicle frame steering mechanism, comprising an articulated front frame and a rear frame, steering cylinders respectively arranged on the left and right sides of the frame articulation point, and elastic collision buffer devices mounted on the front and rear frames to limit the maximum rotation angle of the front and rear frames, wherein the rotation center points of the two ends of the steering cylinders that are articulated with the front and rear frames are points A and B, respectively, characterized in that... The steering cylinder has an annular buffer oil passage connecting the small chambers between the cylinder head and the piston rod. A buffer sleeve is fitted on the piston rod near the piston, which can be inserted into the annular buffer oil passage and fits with the cylinder head with a clearance. The circumferential side of the buffer sleeve is divided into a variable cross-section section and an extended section from the first end to the last end. The minimum cross-sectional area of ​​the fit clearance between the buffer sleeve and the cylinder head decreases from the first end of the variable cross-section section to the last end of the variable cross-section section as the insertion depth of the buffer sleeve increases. After insertion from the first end of the extended section, the minimum cross-sectional area of ​​the fit clearance does not change with the increase of the insertion depth of the buffer sleeve. When the front and rear frames rotate relative to each other to the maximum rotation angle, the distance between points A and B is greater than or equal to the distance between points A and B when the end of the variable cross-section section of the buffer sleeve is inserted into the annular buffer oil passage, and less than the distance between points A and B when the piston of the steering cylinder contacts the cylinder head.

2. The articulated frame steering mechanism according to claim 1, characterized in that... The inner wall of the cylinder head that mates with the circumferential side of the buffer sleeve is a cylindrical surface. The variable cross-section section of the circumferential side of the buffer sleeve is composed of a conical section and a chamfered section at the beginning of the conical section. The extended section of the circumferential side of the buffer sleeve is a cylindrical surface with a diameter equal to or smaller than the diameter at the end of the conical section.

3. The articulated frame steering mechanism according to claim 1, characterized in that... The piston rod is provided with a limiting step for limiting the contact of the first end face of the buffer sleeve. The buffer sleeve is floatingly fitted between the limiting step and the piston. There is a rod-sleeve fitting gap between the inner wall of the buffer sleeve and the piston rod, which allows oil to flow. The end of the buffer sleeve has a radial channel that connects the rod-sleeve fitting gap to the small cavity. The first end face of the buffer sleeve and the end face of the limiting step are planes that can fit tightly against each other.

4. The articulated frame steering mechanism according to claim 3, characterized in that... The cylinder head is provided with a flow area regulating oil passage that connects the small cavity to the oil port of the small cavity, and a throttle valve is installed in the flow area regulating oil passage by means of threaded connection.

5. The articulated frame steering mechanism according to claim 3, characterized in that... An oil passage for adjusting the flow area is provided on the piston rod, which connects the piston rod sleeve clearance with the oil port of the small cavity; the oil passage for adjusting the flow area is L-shaped, with its radial section outlet located on the cylindrical surface of the piston rod and its axial section outlet located on the end face of the limiting step, and a throttle valve installed in the radial section by means of threaded engagement.

6. The articulated frame steering mechanism according to claim 4 or 5, characterized in that... An annular groove is provided on the cylindrical surface of the piston rod near the piston end face, which communicates with the radial channel and the clearance between the sleeve and the end face.

7. The articulated frame steering mechanism according to claim 6, characterized in that... The radial channel is composed of multiple radial notches on the end face of the extended section of the buffer sleeve.

8. The articulated frame steering mechanism according to claim 6, characterized in that... The radial channel is composed of multiple radial through holes located on the end face of the extended section of the buffer sleeve.

9. The articulated frame steering mechanism according to claim 4 or 5, characterized in that... An annular groove is provided at the beginning of the piston rod cylindrical surface near the end face of the limiting step, which communicates with the flow area adjusting oil passage and the clearance of the rod sleeve.

10. An engineering machinery, characterized in that... The vehicle has an articulated frame steering mechanism as described in any one of claims 1 to 9.

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