A method for accounting for the hydraulic system of a special vehicle for environmental sanitation

Abstract

The application discloses a method for accounting for a hydraulic system of a special vehicle for environmental sanitation, fully understands the superstructure and functional principle, combines chassis related parameters, determines the oil pump, the hydraulic valve, the oil cylinder, the oil tank specification model and size, calculates the flow of the hydraulic oil pump, the oil tank volume, the oil cylinder driving execution mechanism related parameters, and checks whether the operation cycle time of each mechanism meets the use requirement. Through the stress analysis of the barrel turning and lifting mechanism and the parameter checking calculation of the hydraulic system configuration, the calculation result of the barrel turning and lifting mechanism loading operation speed or time is obtained, the matching rationality of the hydraulic components and the execution mechanism is verified on how to improve the work efficiency, the hydraulic components are preferably selected to meet the practicality, reliability and economy of the execution mechanism, and the deficiency and excess phenomenon between the configurations is avoided.

Description

Technical Field

[0001] This invention mainly relates to the technical field of hydraulic systems for sanitation vehicles, specifically a method for calculating the hydraulic system of the superstructure of sanitation vehicles. Background Technology

[0002] Specialized sanitation vehicles, also known as sanitation special operation vehicles, refer to sanitation vehicles equipped with specialized equipment and functions, mounted on chassis with specific power take-off devices, used for garbage collection and transportation. Examples include self-loading and unloading garbage trucks, kitchen waste collection and transportation vehicles, and rear-loading compactor garbage trucks. Their hydraulic power source is typically a power take-off unit mounted on the chassis engine and gearbox, driving a hydraulic pump. This pump, through hydraulic pipelines, hydraulic tanks, and hydraulic valve groups, reaches the actuators driven by hydraulic cylinders to perform the specialized functions. Sanitation vehicles generally have a tipping and lifting mechanism, with corresponding hydraulic cylinders executing a dedicated bucket-lifting and loading mechanism. Whether the hydraulic cylinder parameters are reasonably matched and whether they meet the technical parameter requirements for the specialized mechanism to complete specific operations in the most economical and practical way requires stress analysis and hydraulic system calculation of the tipping and lifting mechanism.

[0003] The inventors discovered that the lifting mechanisms of sanitation vehicles of the same type but different specifications often follow or borrow the same set of hydraulic system components (hydraulic oil pump, hydraulic oil tank, hydraulic valve group, hydraulic cylinder, etc.). This often results in a mismatch between "small horse pulling a large cart" and "large horse pulling a small cart," which can easily cause the special mechanism to move too fast or too slow, fatigue damage, and hydraulic system failure, thus greatly reducing the service life of the vehicle. Summary of the Invention

[0004] To address the shortcomings of current technologies, this invention, based on existing technologies and practical applications, provides a method for calculating the hydraulic system of the superstructure of sanitation vehicles. It verifies the matching rationality of hydraulic components and actuators by analyzing the parameters of hydraulic system components (hydraulic pumps, hydraulic tanks, hydraulic valve groups, hydraulic cylinders, etc.) and the stress on the functional modules of the special mechanisms, and optimizes the selection of hydraulic components to meet the practicality and reliability of the actuators, avoiding both deficiencies and excesses in the configuration.

[0005] The technical solution of the present invention is as follows:

[0006] A method for calculating the hydraulic system of the superstructure of a sanitation vehicle includes the following steps;

[0007] S1. Based on the structure and function of the special vehicle, determine its engine idle speed, PTO speed and gearbox power take-off ratio;

[0008] S2. Determine the parameters, specifications and model of the hydraulic oil pump, and calculate the PTO speed and the corresponding hydraulic oil pump flow rate under idle conditions based on the engine idle speed, PTO speed and the speed ratio of the transmission power take-off.

[0009] S3. Based on the hydraulic principle, determine the action and number of hydraulic cylinders of each functional actuator, and determine the flow distribution;

[0010] S4. Based on the cylinder parameters, calculate the cylinder area. At the same time, based on the cylinder speed formula and flow formula, calculate the cylinder rod extension and retraction time, which is the corresponding actuator operation time.

[0011] S5. Compare and analyze the working time under idling and throttle acceleration conditions with the actual working requirements to determine the appropriate working mode;

[0012] S6. Based on the motion analysis of the actuator of the upper structure, determine the key points of the action and perform performance verification;

[0013] S7. Perform force analysis on the upper structure functional actuator under various working states, calculate the cylinder thrust of the actuator under various actions, find the state point where the mechanism is under the greatest force and compare it with the pressure set by the system, and judge whether the selection of the hydraulic system is reasonable based on the calculation results.

[0014] Furthermore, in step S2, the formula for calculating the hydraulic oil pump flow rate is as follows:

[0015] Qj=q×n×92% / 1000

[0016] In the formula, q is the geometric displacement of the pump or motor, n is the speed, n = nj / i, i is the power take-off ratio, nj is n1 or n2, n1 is the speed at which the PTO is set to accelerate, and n2 is the engine idle speed.

[0017] Furthermore, in step S4, the extension and retraction times of the hydraulic cylinder are determined using the following formula:

[0018] t1=6A1×S / Qj

[0019] t2=6A2×S / Qj

[0020] In the above formula, A1 is the cross-sectional area of ​​the rodless chamber of the hydraulic cylinder, A2 is the cross-sectional area of ​​the rod chamber of the hydraulic cylinder, and S is the stroke of the hydraulic cylinder.

[0021] Furthermore, the special vehicle is a self-dumping garbage truck, and the actuator is a tipping and lifting mechanism, which includes a sliding frame, a support frame, a lifting frame, a lifting rod, a tipping cylinder, a lifting frame, and a garbage bin.

[0022] Furthermore, in step S7, the force analysis of the tipping and lifting mechanism under various working states is performed. The hydraulic cylinder thrust of the tipping and lifting mechanism is calculated when lifting the trash can, tipping the trash can, and tipping the trash can to a certain angle. The state point where the mechanism is under the greatest force is found and compared with the pressure set by the system to verify whether the selection of the hydraulic system is reasonable.

[0023] Furthermore, the calculation method for the hydraulic cylinder thrust when lifting the trash can is as follows:

[0024] Determine the mass of each entity, the corresponding gravity variables, and the location of each hinge point.

[0025] First, taking the lifting tie rod as the research object, we calculate the torque at the connection between the lifting tie rod and the swing arm of the lifting frame.

[0026] Secondly, taking the lifting frame as the research object, the torque at the weld between the lifting frame and the box body is calculated.

[0027] The thrust of a single tipping cylinder is determined by the torque balance relationship, and the pressure of a single cylinder when the trash can just starts to lift is obtained.

[0028] Furthermore, the calculation method for the hydraulic cylinder thrust when tipping over the trash can is as follows:

[0029] When the trash can is about to tip over, calculate the torque at the rotation point of the front roller of the bucket lifting frame, and obtain the lifting rod pulling force from the torque balance relationship;

[0030] Taking the lifting frame as the research object, the torque at the rotation point of the welded connection between the lifting frame and the box body is calculated.

[0031] The thrust of a single tipping cylinder is obtained from the torque balance relationship, and the pressure of a single cylinder is obtained when the trash can is tipped over.

[0032] Furthermore, the calculation method for the hydraulic cylinder thrust when the trash can is tilted to a certain angle is as follows:

[0033] When the trash can is flipped to a certain angle, the torque is calculated about the rotation point of the front roller of the lifting frame, and the lifting force of the lifting rod is obtained from the torque balance relationship.

[0034] Taking the lifting frame as the research object, the torque at the rotation point of the welded connection between the lifting frame and the box body is calculated.

[0035] The thrust of a single tipping cylinder is obtained from the torque balance relationship, and the pressure of a single cylinder is obtained when the trash can is tipped to a certain angle.

[0036] Furthermore, the special vehicle is a self-dumping garbage truck, and the actuator is a hydraulic rear door actuator. In step S7, when the hydraulic rear door is checked and calculated, the force analysis is performed on three states: the rear door is about to open, the rear door is opened to the maximum angle, and the rear door is closed and locked.

[0037] Furthermore, the special vehicle is a dump truck, and the actuator is a multi-stage pusher cylinder actuator. In step S7, the verification calculation of the multi-stage pusher cylinder requires force analysis of each stage of the cylinder based on the cylinder diameter, rod diameter, and stroke. The cylinder pressure in each state is calculated step by step and compared with the hydraulic system pressure to verify whether the rear door and the pusher cylinder can meet the operational requirements.

[0038] The beneficial effects of this invention are:

[0039] 1. The working time parameters of the same superstructure installed on different chassis vehicles are accurately calculated. By considering the engine speed and power take-off ratio of different chassis, the working time of the superstructure lifting mechanism functional module will be different. The present invention adjusts the parameters by calculation to meet the user's requirements. In contrast, traditional methods often do not perform theoretical calculations. For the same superstructure on different chassis or with different engines, the whole vehicle often uses the same working parameters, resulting in large errors in vehicle operation, deviating from reality, causing dissatisfaction to users, and affecting the authenticity and reliability of vehicle parameters.

[0040] 2. This invention utilizes force analysis on functional mechanism modules to determine the key points of maximum force on the mechanism, providing a theoretical basis for the parameter selection of hydraulic cylinders and the structural optimization of mechanical mechanisms, reducing the failure rate of hydraulic systems and mechanical components, and improving the safety and practicality of the entire mechanism. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the bucket tipping and lifting mechanism in an embodiment of the present invention. Figure 1 ;

[0042] Figure 2 This is a schematic diagram of the bucket tipping and lifting mechanism in an embodiment of the present invention. Figure 2 ;

[0043] Figure 3 This is a schematic diagram of the trash can lifting mechanism in an embodiment of the present invention.

[0044] Figure 4 This is a schematic diagram illustrating the torque analysis of the pull rod when the trash can is lifted in an embodiment of the present invention;

[0045] Figure 5 This is a torque analysis diagram of the lifting frame when the trash can is lifted according to the present invention;

[0046] Figure 6 This is a schematic diagram of the trash can about to tip over in an embodiment of the present invention;

[0047] Figure 7 This is a schematic diagram illustrating the torque analysis of the rotation point of the front roller of the bucket lifting frame in an embodiment of the present invention;

[0048] Figure 8 This is a torque analysis diagram of the lifting frame when the trash can is about to tip over in an embodiment of the present invention;

[0049] Figure 9 This is a torque analysis diagram of the lifting frame when the trash can is flipped to 31° in an embodiment of the present invention;

[0050] Figure 10 This is the trash can being flipped to its maximum angle (47°) in this embodiment of the invention;

[0051] Figure 11 This is a hydraulic principle diagram in an embodiment of the present invention. Detailed Implementation

[0052] The present invention will be further described in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined in this application.

[0053] This application embodiment is a verification calculation for the hydraulic lifting mechanism of a side-loading self-unloading garbage truck. This method is also applicable to the verification calculation of hydraulic systems of other lifting mechanisms with the same structure for food waste collection and transportation or other similar structures.

[0054] As described in the background section, the tipping and lifting mechanisms of existing sanitation vehicles are generally standardized. Even with the same superstructure on different chassis, or even different superstructures on different chassis, the same hydraulic system is used. This lacks theoretical calculation basis, leading to unreasonable matching between hydraulic components and frequent hydraulic system failures. To address these technical problems, this embodiment proposes a method for calculating the hydraulic system of the tipping and lifting mechanism of a sanitation vehicle. The embodiment uses the hydraulic system calculation of the tipping and lifting mechanism of a ZTQ5040ZZZHFG28F self-loading and unloading garbage truck as an example. Its structure consists of a dedicated superstructure and a chassis. The main functions of a self-loading and unloading garbage truck are garbage collection, transportation, and unloading; the corresponding dedicated function is the lifting and lowering of the side-loading lifting mechanism. The main calculation method is as follows.

[0055] 1. Consult relevant vehicle technical data and determine the relevant parameters such as chassis engine idle speed, PTO speed and transmission PTO ratio based on product model ZTQ5040ZZZHFG28F and the chassis used (as shown in Table 1).

[0056] Table 1. Relevant parameters for verification calculation of the tipping and lifting mechanism.

[0057]

[0058] 2. Determination of relevant performance parameters of gear oil pump

[0059] By analyzing the principle of the vehicle's hydraulic system, the specification and model of the hydraulic oil pump, CBN-F525-BFHL, were determined. By consulting the supplier's catalog, the relevant performance parameters of the gear oil pump in Table 1 can be calculated. The relevant gear oil pump flow rate Q... j The calculation formula is:

[0060] Q j =q×n×92% / 1000 (1)

[0061] In the formula, q is the geometric displacement of the pump or motor, taken as q = 25 ml / r; the power take-off speed ratio i = 1.5; n is the rotational speed (n = n j Let n1 be the engine speed at which the PTO throttle accelerates (take n1 = 1500 r / min n), and let n2 be the engine idle speed (take n2 = 800 r / min n).

[0062] The gear pump flow rate of PTO can be calculated as Q1 = 23 L / min from equation (1). Similarly, the gear pump flow rate at idle speed is Q2 = 12.27 L / min.

[0063] 3. Determining the action and number of hydraulic cylinders in the tipping bucket lifting mechanism.

[0064] By calculating the flow rate of the hydraulic oil pump, the corresponding action and number of cylinders in the tipping bucket lifting mechanism can be determined, and the flow rate can be distributed accordingly. Figure 10 As can be seen from the hydraulic principle: when the tipping cylinder rod extends, the lifting mechanism moves upward; when the tipping cylinder rod retracts, the corresponding lifting mechanism falls; the tipping cylinders are used in pairs symmetrically on the left and right, with each cylinder accounting for 1 / 2 of the flow rate.

[0065] 4. Determination of hydraulic cylinder parameters for the bucket tipping and lifting mechanism

[0066] The parameters of the tipping cylinder are shown in Table 2. The cross-sectional areas of the rodless and rod chambers of the cylinder are calculated, and the working time of the tipping cylinder driving the actuator is derived based on the cylinder speed and flow formula.

[0067] Table 2. Parameters of the Tilting Cylinder

[0068]

[0069] a. Relationship between hydraulic cylinder speed V and other formulas

[0070] V=10Q / A (2)

[0071] In the formula, Q is the hydraulic cylinder flow rate, L / min.

[0072] b. Relationship between hydraulic cylinder flow rate Q and other related formulas

[0073] Q=V×A / 10=60A×S / (10t) (3)

[0074] In the formula, V is the speed of the hydraulic cylinder, m / min; S is the stroke of the hydraulic cylinder, m; and t is the reciprocating time of the hydraulic cylinder, s.

[0075] c. The relationship between the extension and retraction times t of the hydraulic cylinder piston rod

[0076] The following can be derived from equations (2) and (3):

[0077] t=A×S / (10Q)×60=6A×S / Q (4)

[0078] d. The relationship between the time t1 for the bucket to flip upwards and the time t2 for the bucket to flip downwards.

[0079] t1=A1×S / (10Q)×60=6A1×S / Q (5)

[0080] t2=A2×S / (10Q)×60=6A2×S / Q (6)

[0081] From equations (5) and (6), we can obtain that when PTO is under throttle acceleration (Q1 = 23 L / min, two cylinders are used in pairs, and the flow rate of each cylinder accounts for 1 / 2), the time for the bucket to tip upward is: t1 = 6A1 × S / (Q1 / 2) = 6.02 s; the time for the bucket to tip downward is: t2 = 6A2 × S / (Q1 / 2) = 3.59 s.

[0082] Similarly, at idle speed (Q2 = 12.27 L / min, with each cylinder accounting for 1 / 2 of the flow), t1 = 6A1 × S / (Q2 / 2) = 11.28 s; t2 = 6A2 × S / (Q2 / 2) = 6.73 s.

[0083] 5. Practicality and economic analysis

[0084] By comparing the operating time at idle speed and under throttle acceleration with actual parameters, it can be determined whether the requirements for practicality and economy are met.

[0085] As shown in Table 1, the theoretical calculation results are very close to the actual measurement results, and the theoretical values ​​can be used as the basis for the parameters of the vehicle's special mechanism. In actual operation, the falling speed of the tipping bin should not be too fast, otherwise it may damage the trash can. Therefore, a one-way throttle valve is installed in its circuit to adjust to the satisfactory speed requirement. It should be noted that, to improve operational reliability, low-speed operation is suitable; to improve vehicle economy and reduce operating costs, the tipping mechanism is best operated at idle speed.

[0086] Taking all factors into consideration, the ideal time for the bucket to rise is around 12 seconds, and the ideal time for it to fall is around 7 seconds.

[0087] 6. Upper Structure and Motion Analysis

[0088] The hydraulic lifting mechanism of a self-loading garbage truck mainly consists of lifting, dumping, and lowering of the bins. Whether these three actions can operate smoothly will directly affect the performance of the superstructure.

[0089] Upgrading the organizational structure, such as Figure 1 , 2 As shown. The lifting mechanism mainly includes a sliding frame 1, a support frame 2, a bucket lifting frame 3, a pull rod 4, a guide rail 5, a tipping cylinder 6, a lifting frame 7, a bucket blocking frame 8, and a trash can 9.

[0090] The action is divided into four key points:

[0091] a. When starting to move, all parts should move smoothly;

[0092] b. When the top plate of the hanging buckets is in contact, all four hanging buckets must simultaneously touch the top plate;

[0093] c. When the pull rod is closest to the cabinet, the pull rod must not come into contact with the cabinet;

[0094] d. When raising to the highest point, the components must not interfere with each other.

[0095] 7. Calculation of the hydraulic system

[0096] In the design process of special-purpose vehicles, in addition to making correct designs for mechanical and structural components, the hydraulic components that provide power for the movement also need to be carefully selected and designed. Therefore, a force analysis was performed on the tipping and lifting mechanism under various working states. The cylinder thrust of the tipping and lifting mechanism was calculated when lifting the trash can, tipping the trash can, and tipping the trash can to a certain angle. The point where the mechanism experiences the maximum force was found and compared with the system's set pressure to verify whether the selection of the hydraulic system was reasonable.

[0097] 7.1 Hydraulic pressure calculation when lifting the trash can

[0098] In this example, the mass of each entity is set as follows: M1 = 100kg (garbage including plastic garbage can), M2 = 26.79kg (lifting frame), M3 = 25.70kg (sliding frame), M4 = 11.79kg (support frame), M5 = 7.30kg (tie rod) and M6 = 74.98kg (lifting frame). The mass point positions of each mechanism assembly are calculated by 3D software, and the maximum system working pressure is 16MPa.

[0099] To simplify the subsequent force analysis and torque calculation, based on the structure and motion characteristics, the mass of the lifting frame and the sliding frame is represented by M7, then M7 = M2 + M3; the mass of the waste, lifting frame, sliding frame and support frame is represented by M0, then M0 = M1 + M2 + M3 + M4.

[0100] The corresponding gravity variables are set as follows: G1 (garbage), G2 (lifting frame), G3 (sliding frame), G4 (support frame), G5 (pull rod), G6 (lifting frame); let G0 = G1 + G2 + G3 + G4, G7 = G2 + G3.

[0101] The corresponding forces for G=Mg are set as follows: F1 (pull rod tension); F2 (cylinder thrust); F1' (lifting frame tension); F0 (horizontal thrust of the sliding frame on the pull rod).

[0102] The hinge points are set as follows: A (rotation point of the pull rod and the lifting frame); B (rotation point of the welded connection between the lifting frame and the box); C (rotation point of the front roller of the bucket lifting frame).

[0103] When the trash can is in its initial position (e.g.) Figure 1 When the tipping cylinder rod is closed, the lifting frame, support frame, and sliding frame are located at the bottom of the guide rail, and the trash can does not contact the hanging plate on the sliding frame.

[0104] When the trash can is first lifted (e.g.) Figure 3 The cylinder rod of the tipping cylinder extends a certain distance, the bucket lifting frame and support frame are located at the bottom of the guide rail, and the sliding frame rises to the bucket hanging plate on it and contacts the garbage can. The force analysis is as follows.

[0105] First, taking the lifting tie rod as the research object, the torque at the connection between the tie rod and the lifting frame boom is calculated. The schematic diagram of the tie rod torque analysis is shown below. Figure 4 As shown.

[0106] Find the torque about point A (L0:G0, L1:F0, L5:G5 are the lever arms about point A):

[0107] M0 = M1 + M2 + M3 + M4 = 164.276 kg

[0108] G0 = M0 × g = 1609.9 N

[0109] G5 = 2M5 × g = 143.08 N

[0110] From the torque balance relationship: F0×L1=G5×L5+G0×L0F0×1861=G5×59+G0×121, we can get F0=109.21N.

[0111] By F 2 =F0 2 +G0 2 Therefore, F = 1613.6 N.

[0112] Therefore, the tension F1 = 1470.8 N on the tie rod can be obtained from the force triangle diagram of the tie rod. At the same time, the angle of 0.329° shows that the weight of the tie rod itself is very small compared to the forces at both ends of the tie rod, and it can be simplified as a two-force member.

[0113] Secondly, taking the lifting frame as the research object, the torque at the welded connection between the lifting frame and the box body is calculated. The schematic diagram of the lifting frame torque analysis is shown below. Figure 5 As shown.

[0114] Calculate the torque about point B (L6':G6, L2':F1" and L:F2 are the lever arms about point B):

[0115] F1' = F1

[0116] G6=M6×g=74.98×9.8=734.804N

[0117] Based on the torque balance relationship:

[0118] F2×L=G6×L6’+F1×L2’

[0119] exist Figure 5 In the example: L = 198mm, L6' = 510mm, L2' = 1324mm.

[0120] Therefore, F2 = 11.728kN, so the thrust of a single tipping cylinder is: F = F2 / 2 = 5.86kN.

[0121] Given a tipping cylinder diameter of 63mm and a rodless cavity cross-sectional area A1 = πD 2 / 4=3115.67mm 2 Therefore, the pressure of a single hydraulic cylinder when the trash can is first lifted is: P = F / A1 = 1.882 MPa.

[0122] 7.2 Hydraulic pressure calculation when tipping over the trash can

[0123] a. When the trash can is about to tip over (e.g.) Figure 6 The hydraulic pressure verification method for the bucket-tipping cylinder is as follows. The torque is calculated at the rotation point C of the front roller of the bucket-lifting frame, and the torque analysis diagram is shown below. Figure 7 As shown.

[0124] Calculate the torque about point C (L":F1, L1":G1, L4":G4, L7":G7 are the lever arms about point C):

[0125] exist Figure 6Among them, G1=M1×g=980N, G7=(M2+M4)×g=514.363N, G3=M3×g=115.542N; L″=96mm, L1″=577mm, L7″=259mm, L4″=215mm.

[0126] Based on the torque balance relationship:

[0127] F1×L1"=G1×L1"+G7×L7"+G4×L4"

[0128] The pulling force applied to the lever is: F1 = 7536.683 N.

[0129] b. Taking the lifting frame as the research object, calculate the torque at the rotation point B at the welded connection between the lifting frame and the box body. The torque analysis diagram is shown below. Figure 8 As shown.

[0130] Calculate the torque about point B (L:F2, L1':F1', L5':G5, L6':G6 are the lever arms about point B):

[0131] exist Figure 8 China G 拉杆 =2M5×g=143.08N, G6=M6×g=74.98×9.8=734.804N, F1"=F1=7536.683N,

[0132] L=163mm, L5'=848mm, L6'=92mm, L1'=976mm

[0133] Based on the torque balance relationship:

[0134] F2×L=G5×L5'+G6×L6'+F1'×L1'

[0135] The calculated value is F2 = 46286.726 N. Therefore, the thrust of a single tipping cylinder is F = 23143.363 N.

[0136] The cross-sectional area of ​​the tipping drum is A1 = πD 2 / 4, so the pressure of a single hydraulic cylinder when the trash can tip over is:

[0137] P = F / A1 = 7.428 MPa.

[0138] 7.3 Hydraulic pressure calculation when the trash can is tilted to a certain angle

[0139] When the trash can is tilted to a certain angle (e.g.) Figure 9 The hydraulic pressure verification method for the tipping cylinder is as follows.

[0140] This embodiment Figure 9Center: L"=227mm, L1"=691mm, L7"=355mm, L4"=236mm, L=153mm, L5'=838mm, L6'=45mm, L1'=1019mm

[0141] Similarly, calculate the torque using the rotation point C, following the steps and methods described above.

[0142] Based on the torque balance relationship:

[0143] F1×L"=G1×L1"+G7×L7"+G4×L4"

[0144] We deduce that F1 = 3907.695 N

[0145] Calculate the torque using the point of rotation B:

[0146] F2×L=G5×L5'+G6×L6'+F1'×L1'

[0147] We derive F2 = 27025.545 N and F = 13512.773 N.

[0148] The cross-sectional area of ​​the tipping drum is A1 = πD 2 / 4 gives the pressure of a single hydraulic cylinder when the trash can is flipped to a certain angle:

[0149] P = F2 / A1 = 4.337 MPa.

[0150] 7.4 Hydraulic pressure calculation when the trash can is tilted to its maximum angle

[0151] When the trash can is tilted to its maximum angle (e.g.) Figure 10 Find the pressure of the tipping cylinder.

[0152] at this time, Figure 10 The diagram shows the lifting frame torque analysis for the maximum stroke of the tilting cylinder. Similarly, calculate using the steps described above.

[0153] This embodiment Figure 10 In the middle: L" = 350mm, L1" = 33mm, L7" = 92mm, L4" = 193mm

[0154] L = 79 mm, L5' = 347 mm, L6' = 236 mm, L1' = 844 mm. Calculate the torque at the point of rotation C.

[0155] Based on the torque balance relationship:

[0156] F1×L"=G1×L1"+G7×L7"+G4×L4"

[0157] We deduce that F1 = 291.317 N.

[0158] Calculate the torque using the point of rotation B:

[0159] F2×L=G5×L5′+F1×L1′-G6×L6′

[0160] We deduce that F2 = 1545.653 N and F = 772.826 N.

[0161] Based on the cross-sectional area of ​​the tipping drum: A1=πD 2 / 4, which gives the pressure of a single hydraulic cylinder when the trash can is flipped to a certain angle:

[0162] P = F / A1 = 0.248 MPa

[0163] In summary, the pressure of the tipping cylinder is 1.882 MPa when the trash can is first lifted, 7.428 MPa when the trash can is about to tip over, 4.337 MPa when the trash can has tipped over to a certain angle, and 0.248 MPa when the trash can has tipped over to its maximum angle. It is evident that the cylinder pressure is highest when the trash can is about to tip over and lowest when it has tipped over to its maximum angle. The maximum working pressure of the hydraulic system is set to 16 MPa (approximately twice the actual operating pressure), thus meeting the requirements of the lifting mechanism's hydraulic system.

[0164] 7.5 Calculation of the minimum cylinder diameter for the drum tilting cylinder

[0165] Based on the above analysis, when F is at its maximum (F = 23143.363 N), the system pressure is at its maximum, and the minimum allowable cylinder diameter can be determined by: P = F 缸 / A, A=πD 2 / 4; Launch D 2 =4F 缸 / (Pπ), i.e., D=43mm; if a 50mm cylinder is selected, the calculation using the above method shows that, at idle speed, the time for the bucket to rise and fall is 7.1s and 2.6s respectively. It is evident that the bucket falling time is relatively fast, which is not conducive to actual operation. The speed would be even faster under throttle acceleration, which is impractical. In this example, the cylinder diameter for the bucket-tilting mechanism is 63mm, which meets the operational requirements of the hydraulic mechanism. Simultaneously, considering the universality of other vehicle models and the requirement for consistency in mass production by cylinder manufacturers, the standard parameters of existing vehicle cylinders are optimized to improve the universality of cylinder parameters and save on cylinder manufacturing or procurement costs.

[0166] Similarly, this method can be used to perform verification calculations for other mechanisms in the hydraulic system, such as the hydraulic rear door and multi-stage pusher cylinders in this example. The hydraulic rear door verification calculation requires force analysis for three states: the rear door is about to open, the rear door is open to its maximum angle, and the rear door is closed and locked. The multi-stage pusher cylinder verification calculation requires force analysis for each cylinder stage based on its cylinder diameter, rod diameter, and stroke, calculating each stage sequentially. The cylinder pressure for each state is then calculated and compared with the hydraulic system pressure to verify whether the rear door and pusher cylinders can meet the operational requirements. This ensures the entire hydraulic system is well-matched and coordinated, better meeting performance requirements.

[0167] In this embodiment, the force analysis method and derivation approach for each key operating state of the hydraulic lifting mechanism driven by the tipping cylinder are also applicable to special vehicles with similar lifting and loading mechanisms (such as the hydraulic lifting mechanism of a food waste collection and transportation vehicle). The verification calculation of the hydraulic system can be performed in reverse. Based on the pressure set by the hydraulic system and the force analysis of the cylinder-driven mechanism, the position of the maximum force state can be found. The maximum thrust of the cylinder at this time can be calculated from the force analysis of the mechanism, and the minimum allowable cylinder diameter can be calculated. This allows for the optimization of existing standard cylinder diameters, improves the generalization of cylinder parameters, and saves cylinder manufacturing costs.

[0168] This embodiment, through force analysis of the tipping and lifting mechanism and parameter verification calculations of the hydraulic system configuration, yields the calculated loading speed or time of the tipping and lifting mechanism. It provides a practical and effective theoretical verification calculation method for improving work efficiency, verifying the rationality of the matching between hydraulic components and actuators, and optimizing hydraulic components to meet the practicality, reliability, and economy of the actuators, avoiding deficiencies and excesses in configuration. This method is currently widely used in the force analysis and hydraulic system verification calculations of self-loading and unloading garbage trucks and food waste truck collection devices.

Claims

1. A method for calculating the hydraulic system of the superstructure of sanitation vehicles, characterized in that, Includes the following steps; S1. Based on the structure and function of the special vehicle, determine its engine idle speed, PTO speed and gearbox power take-off ratio; S2. Determine the parameters, specifications and model of the hydraulic oil pump, and calculate the PTO speed and the corresponding hydraulic oil pump flow rate under idle conditions based on the engine idle speed, PTO speed and the speed ratio of the transmission power take-off. S3. Based on the hydraulic principle, determine the action and number of hydraulic cylinders of each functional actuator, and determine the flow distribution; S4. Based on the cylinder parameters, calculate the cylinder area. At the same time, based on the cylinder speed formula and flow formula, calculate the cylinder rod extension and retraction time, which is the corresponding actuator operation time. S5. Compare and analyze the working time under idling and throttle acceleration conditions with the actual working requirements to determine the appropriate working mode; S6. Based on the motion analysis of the actuator of the upper structure, determine the key points of the action and perform performance verification; S7. Perform force analysis on the upper structure functional actuator under various working states, calculate the cylinder thrust of the actuator under various actions, find the state point where the mechanism is under the greatest force and compare it with the pressure set by the system, and judge whether the selection of the hydraulic system is reasonable based on the calculation results.

2. The method for calculating the hydraulic system of the superstructure of sanitation vehicles according to claim 1, characterized in that, In step S2, the formula for calculating the hydraulic oil pump flow rate is as follows: Q j =q×n×92% / 1000 In the formula, q is the geometric displacement of the pump or motor, n is the rotational speed, and n = n j / i, where i is the power take-off ratio, n j It can be either n1 or n2, where n1 is the engine speed at which the PTO throttle is set to accelerate, and n2 is the engine idle speed.

3. The method for calculating the hydraulic system of the superstructure of sanitation vehicles according to claim 2, characterized in that, In step S4, the extension and retraction times of the hydraulic cylinder are determined by the following formula: t1=6A1×S / Q j t2=6A2×S / Q j In the above formula, A1 is the cross-sectional area of ​​the rodless chamber of the hydraulic cylinder, A2 is the cross-sectional area of ​​the rod chamber of the hydraulic cylinder, and S is the stroke of the hydraulic cylinder.

4. The method for calculating the hydraulic system of the superstructure of sanitation vehicles according to claim 1, characterized in that, The special vehicle is a self-dumping garbage truck, and the actuator is a tipping and lifting mechanism, which includes a sliding frame, a support frame, a lifting frame, a lifting rod, a tipping cylinder, a lifting frame, and a garbage bin.

5. The method for calculating the hydraulic system of the superstructure of sanitation vehicles according to claim 4, characterized in that, In step S7, the force analysis of the tipping and lifting mechanism under each working state is performed. The hydraulic cylinder thrust of the tipping and lifting mechanism is calculated when lifting the trash can, tipping the trash can, and tipping the trash can to a certain angle. The state point where the mechanism is under the greatest force is found and compared with the pressure set by the system to verify whether the selection of the hydraulic system is reasonable.

6. The method for calculating the hydraulic system of the superstructure of sanitation vehicles according to claim 5, characterized in that, The calculation method for the hydraulic cylinder thrust when lifting the trash can is as follows: Determine the mass of each entity, the corresponding gravity variables, and the location of each hinge point. First, taking the lifting tie rod as the research object, we calculate the torque at the connection between the lifting tie rod and the swing arm of the lifting frame. Secondly, taking the lifting frame as the research object, the torque at the weld between the lifting frame and the box body is calculated. The thrust of a single tipping cylinder is determined by the torque balance relationship, and the pressure of a single cylinder when the trash can just starts to lift is obtained.

7. The method for calculating the hydraulic system of the superstructure of sanitation vehicles according to claim 6, characterized in that, The calculation method for the hydraulic cylinder thrust when tipping over the trash can is as follows: When the trash can is about to tip over, calculate the torque at the rotation point of the front roller of the bucket lifting frame, and obtain the lifting rod pulling force from the torque balance relationship; Taking the lifting frame as the research object, the torque at the rotation point of the welded connection between the lifting frame and the box body is calculated. The thrust of a single tipping cylinder is obtained from the torque balance relationship, and the pressure of a single cylinder is obtained when the trash can is tipped over.

8. The method for calculating the hydraulic system of the superstructure of sanitation vehicles according to claim 7, characterized in that, The calculation method for the hydraulic cylinder thrust when the trash can is tilted to a certain angle is as follows: When the trash can is flipped to a certain angle, the torque is calculated about the rotation point of the front roller of the lifting frame, and the lifting force of the lifting rod is obtained from the torque balance relationship. Taking the lifting frame as the research object, the torque at the rotation point of the welded connection between the lifting frame and the box body is calculated. The thrust of a single tipping cylinder is obtained from the torque balance relationship, and the pressure of a single cylinder is obtained when the trash can is tipped to a certain angle.

9. The method for calculating the hydraulic system of the superstructure of sanitation vehicles according to claim 1, characterized in that, The special vehicle is a self-dumping garbage truck, and the actuator is a hydraulic rear door actuator. In step S7, when the hydraulic rear door is checked and calculated, the force analysis is performed on three states: the rear door is about to open, the rear door is opened to the maximum angle, and the rear door is closed and locked.

10. The method for calculating the hydraulic system of the superstructure of sanitation vehicles according to claim 1, characterized in that, The special vehicle is a dump truck, and the actuator is a multi-stage pusher cylinder actuator. In step S7, the verification calculation of the multi-stage pusher cylinder requires force analysis of each stage of the cylinder based on the cylinder diameter, rod diameter, and stroke. The cylinder pressure in each state is calculated step by step and compared with the hydraulic system pressure to verify whether the rear door and the pusher cylinder can meet the operation requirements.

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