Constant-force spring energy storage power-assisted wheelchair and energy recovery method thereof

Abstract

The invention discloses a constant-force spring energy storage power-assisted wheelchair and an energy recovery method thereof, and belongs to the technical field of walking aids. For a half-floor home-entry scene of an old community, a steel wire rope is pulled out through the gravity of a human body when going downstairs to wind a constant-force spring to store energy, and the constant-force spring is rolled back to pull a star wheel to rotate to release energy when going upstairs, so that energy recycling is realized. The core innovation comprises a scroll constant-force spring-steel wire rope-ratchet mechanism, a coil spring for storing energy when going downstairs and an energy release for assisting when going upstairs; the lock is mechanically held, the lock is unlocked by holding, and the lock is unlocked by loosening hands, so that the safety is ensured; and by adopting the design of 180-degree turning-around when going downstairs, the accompanying and nursing front guide is realized, and the sight According to the technical scheme, a pure mechanical structure is adopted, zero power and zero leakage are achieved, the service life of the constant-force spring exceeds 100 thousand times, the constant tension is 150-250 N, and 50-70% assisting power can be provided for going upstairs. The system is low in cost, and is suitable for high-frequency, high-safety, low-cost and extreme-temperature environment demand scenes of half-floor home entry.

Description

Technical Field

[0001] This invention relates to the field of mobility aids, specifically to a semi-floor accessible wheelchair that utilizes gravitational potential energy recovery and constant force spring energy storage, and its energy recovery method. Through a purely mechanical scheme of storing energy when going downstairs and releasing energy when going upstairs, it achieves safe, labor-saving, and maintenance-free access to a semi-floor staircase for life. Background Technology

[0002] 1.1 Social Pain Points of Half-Floor Entry

[0003] As my country's population ages, the installation of elevators in older buildings often adopts a "half-floor access" solution, where there are 4-8 steps (a height difference of 0.8-1.2 meters) between the elevator floor and the resident's entrance door. This "last half-floor" has become the biggest obstacle for wheelchair users and elderly people with mobility difficulties.

[0004] 1.2 Deficiencies of the prior art

[0005] Currently available stair-climbing wheelchairs are mainly divided into three categories:

[0006] (1) Electric wheelchairs: rely on batteries and motors, and have problems such as heavy weight, high cost, many faults, and difficult maintenance. They also become completely ineffective once the power is cut off.

[0007] (2) Pure human-powered wheelchair: without power assist device, it is difficult to go upstairs and dangerous to go downstairs, and it requires high physical strength from the caregiver.

[0008] (3) Pneumatic / hydraulic assisted wheelchairs: Some use pneumatic springs or hydraulic cylinders for assistance, but there are problems such as aging of seals, air and liquid leakage, frequent maintenance, and limited service life.

[0009] 1.3 Technological Development Trends

[0010] A constant force spring is a special type of spiral spring that can provide constant tension over a large range of strokes. It is widely used in automotive seat belts, elevator balancing systems, and medical devices. However, its purely mechanical structure, maintenance-free operation, and long lifespan have not yet been applied to assist wheelchairs in climbing stairs. Summary of the Invention

[0011] 2.1 Technical problems to be solved

[0012] The technical problem to be solved by the present invention is to provide a constant force spring energy storage power-assisted wheelchair and its energy recovery method, which recovers the gravitational potential energy of the human body when going downstairs and releases the constant force spring energy when going upstairs, so as to achieve safe, labor-saving and convenient passage through half a flight of stairs, while realizing a pure mechanical structure, zero electricity, zero leakage and lifetime maintenance-free.

[0013] 2.2 Technical Solution

[0014] To achieve the above objectives, the present invention adopts the following technical solution:

[0015] A constant-force spring energy storage power wheelchair, comprising:

[0016] The chassis frame serves as the supporting structure for the entire machine.

[0017] The front swivel casters are mounted on the front of the chassis frame and are used for steering when traveling on flat ground.

[0018] The rear wheels are mounted at the rear of the chassis frame and are used for support when walking on flat ground.

[0019] The star wheel stair-climbing mechanism is installed at the rear of the chassis frame and includes a Y-shaped bracket and three small wheels installed at the ends of the bracket, with a ratchet mechanism connected in the center; the three small wheels of the star wheel stair-climbing mechanism are distributed at 100°-140°, the diameter of the small wheels is 60-100mm, and the overall diameter of the star wheel is 150-250mm, ensuring that at least two points are in contact with the steps;

[0020] The constant force spring energy storage system, installed on the chassis frame, includes a spiral constant force spring, a wire rope drum, and a ratchet locking mechanism. The free end of the constant force spring is connected to a wire rope, which is wound around the drum and connected to the star wheel mechanism. The constant tension of the constant force spring is 150-250N, adjustable according to the elderly person's weight of 50-100kg. When going downstairs, the wire rope is pulled out, the constant force spring is wound up to store energy, and the ratchet locks the energy. When going upstairs, the ratchet is unlocked, the constant force spring is wound back up, and the star wheel is rotated through the wire rope to provide assistance.

[0021] The mechanical grip lock is installed on the control armrest and connected to the ratchet locking mechanism via a steel cable; it includes an ungripped state (spring extended, pawl locks the ratchet, constant force spring retains energy and locks) and a gripped state (spring compressed, pawl retracts to unlock, constant force spring can retract to release energy);

[0022] The seat is mounted on the chassis frame and connected to the chassis frame via a tilt adjustment mechanism. It can be adjusted to be horizontal, reclined 3°-8°, or tilted forward 3°-8°.

[0023] The control armrest is installed behind the seat and has a built-in mechanical grip lock.

[0024] The three modes include:

[0025] Flat ground mode: The seat is horizontal, the rear wheels are on the ground, the star wheel is raised, the constant force spring is in the initial relaxed state, and it is pushed from behind by the caregiver;

[0026] Stairs climbing mode: The seat reclines 3°-8°, the rear wheels rise, the star wheel descends to contact the step, the caregiver moves to the rear to hold the control armrest, the mechanical grip lock unlocks, the ratchet unlocks, the constant force spring rolls back and pulls the star wheel to rotate through the steel wire rope, providing constant force assistance;

[0027] Descending mode: The seat tilts forward 3°-8°, the rear wheels rise, the star wheel descends to contact the step, the wheelchair turns 180° so that the star wheel faces down the stairs, the caregiver moves to the front to hold the control handrail, the mechanical grip lock unlocks, the person's weight drives the star wheel to rotate and pull out the steel cable, the constant force spring coils and stores energy, and the ratchet automatically locks to retain energy.

[0028] A method for energy recovery in a constant-force spring-assisted wheelchair includes the following steps:

[0029] S1: Equipment inspection to confirm that the constant force spring is in its initial relaxed state;

[0030] S2: Before going downstairs, turn the wheelchair 180°, tilt the seat forward 3°-8°, with the star wheel facing downstairs, and move the caregiver to the front;

[0031] S3: The caregiver holds the control armrests with both hands, unlocks the mechanical grip lock, and gently pulls the wheelchair down slowly;

[0032] S4: The human body's gravity drives the star wheel to rotate, the steel wire rope is pulled out, the constant force spring is wound to store energy, and the ratchet automatically locks to retain energy;

[0033] S5: After reaching the lower platform, release the control handrail, the mechanical grip lock will lock, and the constant force spring will maintain the energy storage state;

[0034] S6: Before going upstairs, recline the seat 3°-8°, move the caregiver to the back, hold the control armrests with both hands, and unlock the mechanical grip lock;

[0035] S7: Ratchet unlocks, constant force spring rewinds, steel wire rope pulls star wheel to rotate, providing constant force to assist upward movement;

[0036] S8: The constant force spring has finished rewinding, and the wheelchair has reached the upper platform, completing the energy recovery and reuse cycle.

[0037] 2.3 Beneficial Effects

[0038] Compared with the prior art, the present invention has the following significant advantages:

[0039] (1) "Gravitational potential energy recovery + constant force spring energy storage" - energy recycling

[0040] Traditional wheelchairs rely entirely on human power or electricity to go up and down stairs, resulting in one-way energy consumption. This invention utilizes the user's weight to pull a steel cable when going downstairs, with a constant-force spring storing energy; when going upstairs, the constant-force spring automatically rewinds, pulling a star wheel to provide assistance. Energy recovery efficiency reaches 85%, and effort is reduced by 50-70% when going upstairs.

[0041] (2) "Purely mechanical structure + zero leakage" - Lifetime maintenance-free

[0042] It does not rely on easily damaged components such as batteries, motors, or pneumatic / hydraulic systems, but instead relies entirely on purely mechanical structures such as constant force springs, wire ropes, and ratchet wheels. The constant force springs have a lifespan of over 100,000 cycles, equivalent to using it 10 times a day for more than 20 years, truly achieving lifetime maintenance-free operation.

[0043] (3) "Constant force output + linear controllability" - contributing to smooth and comfortable operation

[0044] Unlike the non-linear variable force of gas springs, constant force springs provide constant tension throughout the entire stroke range, providing smooth and even assistance when climbing stairs without sudden shocks. This makes the ride more comfortable for the elderly and allows for more controllable operation for caregivers.

[0045] (4) "U-turn front-mounted + mechanical grip lock" - double safety protection

[0046] When going downstairs, the wheelchair turns 180°, and the caregiver naturally moves to the front, so that both parties can see the edge of the steps directly, completely eliminating blind spots; the mechanical grip lock ensures that "it is unlocked when gripped and locked when released", and in conjunction with the ratchet energy retention mechanism, it can brake immediately even in case of an emergency.

[0047] (5) "Half-floor dedicated + minimalist design" - extremely low cost

[0048] Optimized for half-floor scenarios with 4-8 steps and a height difference of 0.8-1.2 meters, all parts are standard or simply machined, costing about 400 yuan, which is 87% lower than the electric version and 20% lower than the gas spring version, truly achieving inclusive elderly care. Attached Figure Description

[0049] Figure 1 Overall side view of a constant force spring energy-storage power wheelchair: (a) flat ground mode, (b) going upstairs mode, (c) going downstairs mode; Labels in the figures: 1-front wheel (swivel wheel), 2-rear wheel, 3-star wheel mechanism (Y-type three-star wheel + ratchet), 4-seat, 5-control armrest, 6-mechanical grip lock, 7-constant force spring box, 8-wire rope drum, 9-foot pedal

[0050] Figure 2 This is a schematic diagram of a constant force spring energy storage system;

[0051] The diagram is labeled as follows: 1-Coiled constant force spring, 2-Wire rope, 3-Drum, 4-Ratchet, 5-Pawl, 6-Spring box.

[0052] Figure 3 Schematic diagram of star wheel-ratchet-wire rope transmission mechanism:

[0053] Figure 3 (a) Downstairs mode: The ratchet rotates freely, the steel wire rope is pulled out, and the constant force spring is wound up to store energy;

[0054] Figure 3 (b) Upstairs mode: ratchet locking, constant force spring rewinding, steel wire rope pulling star wheel to rotate and release energy.

[0055] The diagram is labeled as follows: 1-Star wheel Y-shaped bracket, 2-Ratchet, 3-Pawl, 4-Wire rope, 5-Drum.

[0056] Figure 4 A schematic diagram of the mechanically gripped lock:

[0057] The diagram shows: 1- Grip cover, 2- Inner slide, 3- Compression spring, 4- Steel cable, 5- Pawl control lever.

[0058] Figure 5 This is a flowchart of an energy recovery method.

[0059] Figure 6 Schematic diagram of star wheel type lifting clutch mechanism:

[0060] The diagram is labeled as follows: ① Foot lever (pressed position), ② Foot lever (released position), ③ Foot lever (middle position), 2-Connecting rod, 3-Star wheel bracket, 4-Ratchet clutch, 5-Constant force spring drum, 8-Bearing seat / support, 120-120° included angle.

[0061] Figure 6 (a) (Section along the clutch centerline): Ratchet clutch (4) detail: outer ring with 12 internal teeth (triangular teeth), inner hub with three pawls (spring omitted for clarity, pawl position indicated by diagonal lines), engagement depth dimension line marked with arrow 2.5mm, constant force spring drum (5): helical coil shown in section with 8 turns visible, cable connection point marked with X, drum wall thickness exaggerated for visibility. Shaft bearing: simple rectangle with section lines.

[0062] Figure 6 (b): Pawl mechanism: Pawl body, pivot pin, return spring (coil with hook end), tooth meshing geometry with 15° working angle marking.

[0063] Figure 6 (c): Cable termination: crimp connector, drum groove profile, incident angle marked 12° Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0065] Example 1: Flat Ground Modal Operation

[0066] like Figure 1 As shown in (a), when a wheelchair user is walking on a flat surface:

[0067] 1. Adjust the seat to a level position, raise the star wheel off the ground, and keep the rear wheels on the ground;

[0068] 2. The constant force spring is in its initial relaxed state, and the mechanical grip lock is in its locked state;

[0069] 3. The caregiver should push the child from behind;

[0070] 4. The front swivel wheels are used for steering, just like a regular wheelchair.

[0071] Example 2: Downstairs Modal Operation (Energy Storage Stage)

[0072] like Figure 1 As shown in (c), when a wheelchair user needs to move from the upper level to the lower level:

[0073] 1. Push the wheelchair to the top of the stairs and adjust the seat to tilt forward 5 degrees;

[0074] 2. Key step: Turn the wheelchair 180° in place so that the star wheels are facing down the stairs;

[0075] 3. The caregiver moves from the back to the front and holds the control handle with both hands;

[0076] 4. Unlock the mechanical grip lock, and step on the lifting pedal (if any) to lower the star wheel to contact the step;

[0077] 5. Gently pull the control armrests, and the wheelchair will slowly descend, driven by the weight of the person;

[0078] 6. The rotation of the star wheel drives the drum, the wire rope is pulled out, and the constant force spring is wound up to store energy;

[0079] 7. The ratchet automatically locks to prevent rewinding, and the constant force spring maintains its stored energy.

[0080] 8. After reaching the lower platform, release the control handrail and lock the mechanical grip lock;

[0081] 9. Step on the pedal to raise the star wheel and return to the flat ground mode.

[0082] Example 3: Upstairs Modal Operation (Energy Release Phase)

[0083] like Figure 1 As shown in (b), when a wheelchair user needs to move from the lower level to the upper level:

[0084] 1. Adjust the seat to recline 5 degrees and move the caregiver to the back;

[0085] 2. Hold the control armrests with both hands and use the mechanical grip lock to unlock;

[0086] 3. The ratchet unlocks, and the constant force spring automatically rewinds;

[0087] 4. The wire rope pulls the drum, driving the star wheel to rotate;

[0088] 5. The rotating star wheel propels the wheelchair upwards, while the constant force spring provides a constant pulling force of approximately 200N, equivalent to 60% assistance when climbing stairs;

[0089] 6. The caregiver only needs to provide the remaining 40% of the pushing force to easily complete the ascent upstairs;

[0090] 7. The constant force spring has finished rewinding and reached the upper platform;

[0091] 8. The mechanical grip lock automatically locks, restoring the flat ground mode.

[0092] Example 4: Security Protection Scenario

[0093] Scenario A: Suddenly letting go while going downstairs

[0094] - The mechanical grip lock locks immediately, and the pawl locks the ratchet;

[0095] - The constant force spring maintains its energy storage state, and the wheelchair stops immediately;

[0096] - Prevents falls and is safe and reliable.

[0097] Scenario B: The constant force spring fails when going upstairs.

[0098] - The tension of a constant force spring gradually decreases after fatigue, which can provide an early warning;

[0099] Even if it completely fails, the ratchet can still be unlocked manually, allowing you to go upstairs entirely by human effort.

[0100] - No risk of sudden failure, progressive safety.

[0101] Scenario C: Extreme temperature environment

[0102] - The constant force spring operates at a temperature of -40℃ to 150℃ and is unaffected by temperature.

[0103] - It can be used normally in both the severe cold of the north and the scorching heat of the south;

[0104] - Superior temperature sensitivity compared to gas springs.

[0105] Industrial applicability

[0106] The constant-force spring energy-storage power wheelchair of this invention has a simple structure, low cost, and requires no maintenance for its entire lifespan, making it suitable for large-scale production and widespread adoption. It is particularly suitable for:

[0107] - Renovation of half-floor entrances in old residential communities;

[0108] - Extreme temperature environments (severe cold, extreme heat);

[0109] - Short staircases for access in institutions such as hospitals and nursing homes.

[0110] By utilizing gravitational potential energy recovery and constant force spring energy storage technology, a half-floor staircase access system with zero electricity consumption, zero leakage, lifetime maintenance-free operation, and extremely low cost is achieved while ensuring safety, demonstrating promising market prospects and social benefits.

Claims

1. A constant-force spring energy storage power-assisted wheelchair, characterized in that, include: Chassis frame; Front swivel casters, mounted on the front of the chassis frame; The rear wheel is installed at the rear of the chassis frame; the star wheel stair-climbing mechanism is installed at the rear of the chassis frame, including a Y-shaped bracket and three small wheels installed at the ends of the bracket, with a ratchet mechanism connected at the center; the constant force spring energy storage system is installed on the chassis frame, including a spiral constant force spring, a wire rope drum, and a ratchet locking mechanism; the constant force spring is connected to the star wheel mechanism through a wire rope; when going downstairs, the wire rope is pulled out, the constant force spring is wound up to store energy, and the ratchet locks to retain energy; when going upstairs, the ratchet is unlocked, the constant force spring is wound back, and the star wheel is rotated through the wire rope to provide assistance; the mechanical grip lock is installed on the control handrail and is connected to the ratchet locking mechanism through a steel cable; The seat is mounted on top of the chassis frame and connected to the chassis frame via a tilt adjustment mechanism; the control armrests are mounted behind the seat and have built-in mechanical grip locks.

2. The constant force spring energy storage power wheelchair according to claim 1, characterized in that, It also includes a star wheel lifting clutch mechanism, comprising a foot lever, a connecting rod, a star wheel bracket, a ratchet clutch, and a return spring; the foot lever is connected to the star wheel bracket and the ratchet clutch shift fork via the connecting rod; Flat ground mode: When the foot pedal is released, the return spring pulls up the star wheel bracket, the star wheel rises off the ground, the ratchet clutch disengages, and the constant force spring disconnects from the star wheel; Upstairs mode: When the foot pedal is pressed down and pushed forward, the star wheel descends to the ground, the ratchet clutch engages in both directions, and the constant force spring rewinds to drive the star wheel; Descending mode: When the foot pedal is pressed down and pushed, the star wheel descends and touches the ground. The ratchet clutch engages in one direction, the constant force spring is wound up to store energy, and the ratchet rotates freely to allow downward movement.

3. The constant force spring energy storage power-assisted wheelchair according to claim 1, characterized in that, The constant force spring energy storage system includes: Descending: The steel cable is pulled out, the constant force spring is wound up to store energy, the ratchet locks to retain energy, and the wheelchair descends slowly. Upstairs status: The ratchet is unlocked, the constant force spring is retracted, and the steel wire rope pulls the star wheel to rotate, providing constant force to assist in the upward movement.

4. The constant force spring energy storage power-assisted wheelchair according to claim 1, characterized in that, The mechanical grip lock includes: Unheld state: Spring extends outward, pawl locks the ratchet, constant force spring retains energy and locks; Grip state: Spring is compressed, pawl retracts to unlock, constant force spring can retract to release energy.

5. The constant force spring energy storage power wheelchair according to claim 1, characterized in that, The seat is connected to the chassis frame via a tilt adjustment mechanism and can be adjusted to be horizontal, tilted back 3°-8°, or tilted forward 3°-8°, corresponding to the flat ground mode, the upstairs mode, and the downstairs mode, respectively.

6. The constant force spring energy storage power wheelchair according to claim 1, characterized in that, The three small wheels of the star wheel stair-climbing mechanism are distributed at 100°-140°, with a diameter of 60-100mm and an overall diameter of 150-250mm, ensuring that at least two points are in contact with the steps.

7. The constant force spring energy storage power wheelchair according to claim 1, characterized in that, The downstairs mode includes: the seat tilts forward 3°-8°, the wheelchair turns 180° so that the star wheel faces downstairs, the caregiver moves to the front to hold the control handrail, the steel cable is pulled out, the constant force spring is wound up to store energy, and the ratchet locks to retain energy.

8. The constant force spring energy storage power wheelchair according to claim 1, characterized in that, The upstairs mode includes: the seat reclines 3°-8°, the caregiver moves to the back to hold the control armrest, the ratchet unlocks, the constant force spring rewinds, and the star wheel is pulled to rotate via the steel cable to provide constant force assistance, with the caregiver assisting in providing the remaining thrust.

9. A method for energy recovery in a constant-force spring-assisted wheelchair, characterized in that, Includes the following steps: S1: Equipment inspection to confirm that the constant force spring is in its initial relaxed state; S2: Before going downstairs, turn the wheelchair 180°, tilt the seat forward 3°-8°, with the star wheel facing downstairs, and move the caregiver to the front; S3: The caregiver holds the control armrests with both hands, unlocks the mechanical grip lock, and gently pulls the wheelchair down slowly; S4: The star wheel rotates under the force of human body gravity, the steel wire rope is pulled out, the constant force spring is wound up to store energy, and the ratchet automatically locks to retain energy; S5: After reaching the lower platform, release the control handrail, the mechanical grip lock will lock, and the constant force spring will maintain the energy storage state; S6: Before going upstairs, recline the seat 3°-8°, move the caregiver to the back, hold the control armrests with both hands, and unlock the mechanical grip lock; S7: Ratchet unlocks, constant force spring rewinds, steel wire rope pulls star wheel to rotate, providing constant force to assist upward movement; S8: The constant force spring has finished rewinding, and the wheelchair has reached the upper platform, completing the energy recovery and reuse cycle.

10. The energy recovery method according to claim 9, characterized in that, The constant force spring has a constant tension of 150-250N and an energy storage efficiency of 85%. It can provide 50-70% of the energy required to go upstairs, with the remaining 30-50% provided by the caregiver.

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