FIELD OF THE INVENTION

The present invention relates generally to drive systems and more particularly, embodiments of the invention relate to a shifting mechanism for a two speed axle assembly.

BACKGROUND OF THE INVENTION

Two speed axles' assemblies are frequently employed in the drive train of motor vehicles to enable the driver to choose between any two desired speed ratios depending on the changing load, route profile & the speed requirements. The speed ratios chosen can be direct mode, overdrive mode or a shift from a low speed mode to a high speed mode. The speed axle assembly includes a planetary gear arrangement and a shifting means for selectively locking the planetary gear arrangement in a desired mode. The shifting means can be achieved either electrically or mechanically.

Electrically operated shifting means employ solenoid actuated mechanism or Use the electrical Motor for shifting between desired speeds ratios. Although the electrically operated shifting means achieves switching between ratios, the electrically operated shifter units results in additional power requirement, additional cost and the repair requirement due to working conditions and also the Smooth shift is not possible due to the Matching requirements of speed and linier movement of the Planetary Gear. Hence there is a need for a shifting means that helps in smooth shift, less maintenance and less additional power to drive the means.

OBJECTS OF THE INVENTION

One of the basic objects of the present invention is to overcome the drawbacks of the prior art.

Another object of the present invention is to provide a shifting mechanism for a two speed axle assembly.

Another object of the present invention is to provide shifting mechanism which is cost effective.

SUMMARY OF THE INVENTION

According to one of the aspect of the present invention there is provided a shifting mechanism for a two speed axle assembly, said mechanism comprising:

a casting means comprising a housing and a cover;

a pneumatic port placed substantially on said cover of said housing;

a planetary gear arrangement coupled with said housing means, said gear arrangement comprising a sun means;

a spring means connected with said housing means;

a shaft means operatively connected with said spring means and said planetary gear arrangement;

a ring means connected substantially on the top of housing means to avoid air leakage;

a quick release valve means adapted for quick release of air pressure for repositioning the ratio to original speed ratio;

a solenoid valve operatively connected with said release valve through a pipe means;

a bolt means adapted to lock the cover on said housing means;

a switch means located in the drivers cabin connected operatively with said solenoid valve through wiring means adapted to perform shift of ratios based on drivers requirement; and

an air tank means operatively connected with said solenoid valve means to enable compressed air to shifter assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to various embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

FIG. 1 illustrates a ratio shifter unit for a two speed axle according to an embodiment of the invention.

Fig 2 illustrates the quick release valve with the other components of the ratio shifter unit.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a shifting mechanism for a two speed axle assembly.
According to one of the embodiments of the present invention there is provided a shifting mechanism for a two speed axle assembly. The mechanism comprises a casting means comprising a housing and a cover, a pneumatic port placed substantially on the cover of the housing, a planetary gear arrangement coupled with the housing means where the gear arrangement comprises a sun means , a spring means connected with the housing means , a shaft means operatively connected with the spring means and the planetary gear arrangement, a ring means connected substantially on the top of housing means to avoid air leakage , a quick release valve means for quick release of air pressure for repositioning the ratio to original speed ratio , a solenoid valve operatively connected with the release valve through a pipe means, a bolt means to lock the cover on the housing means, a switch means located in the drivers cabin connected operatively with the solenoid valve through wiring means to perform shift of ratios based on drivers requirement and an air tank means operatively connected with the solenoid valve means to enable compressed air to shifter assembly.

The shaft means movement is initiated by the air delivered from the air compressor of the motor vehicle through the pneumatic port provided on the Cover of the Housing for the Engagement/Disengagement. The shaft means is configured for a linear movement which subsequently engages/disengages a particular speed ratio. The speed ratio is available in a Carrier means. For example the speed ratio may be from 4.56 to 6.21.

The ring means comprises O-ring. The housing is open for easy maintenance. The spring means movement enables the engaging/disengaging movement of the shaft means. The two speed axle assembly gets its power derived from the air released from the compressor of the motor vehicle. The shaft means optionally is made of hard material.

The fork shift means having two Arms joined to the shaft for the positioning of the Sun Gear in the planetary system. The fork shift comprises a pivot means to retain the position of fork shift and to have a proper shift during shifting process.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Various embodiments of the invention provide an air shifter for a two speed axle.

FIG.1 shows a ratio shifter unit /mechanism for a two speed axle according to an embodiment of the invention. The ratio shifter unit 100 comprises of a housing 101.The housing 101 includes a spring 103 and a shaft 105. The Shaft 105 is operably coupled to a planetary gear arrangement (not shown).The movement of the shaft 105 for the Engagement/Disengagement is initiated by the air delivered from the air compressor of the motor vehicle through the pneumatic port provided on the Cover of the Housing 102.

The shaft 105 is configured for a linear movement which subsequently engages/disengages a particular speed ratio available in the Carrier means ( Not Shown) for example change of ratio from 4.56 to 6.21.

The engage/disengage movement of the shaft 105 is enabled by the movement of the spring 103 & discontinuation of the Compressed Air through the Pneumatic Port. An O ring 107 is provided on the top of the housing 101 to avoid air leakage between the Housing 101 & the Cover 102 which would subsequently cause improper engage/disengage of a particular speed ratio.

Bolt 109 is used for locking the cover 102 on the housing 101 with a proper
sealant to ensure no leakage of compressed air during the functioning.

Figure 2 shows the Quick release valve 111 is introduced for the quick release of Air pressure incase required for repositioning the Ratio to the Original Speed Ratio. The Quick release valve is connected to the Solenoid valve 110 through the pneumatic/Air pipe and again the Solenoid valve is connected to the Switch 112 in the driver's cabin through the electrical wiring enabling the Shift of ratios based on the driver's requirement. The Solenoid valve is connected to the Air tank 113 to enable the compressed air to the Shifter assembly.

The ratio switchover is made simpler by the aforesaid mechanism. Further, maintenance of the ratio shifter is made easier by construction of an easily openable housing. The ratio shifter does not require any additional power for driving the shifting and advantageously utilizes the power derived from the air released from the compressor of the motor vehicle.

ADVANTAGES:

• Air Shifter Unit is designed to use the available Air output from the vehicle air compressor

• Spring is used for the quick positioning of the Shaft to the original position based on the Drivers requirement

• Fork Shift with two Arms joined to the. shifter shaft for the positioning of the Sun Gear in the planetary system. Shift Fork is connected to Shaft (not shown)

• Shift Shaft coated with the hardened material with smooth surface for the hassle free shift and also to improve the durability of shifter shaft with the repeated operations
Two Piece Cast housing design ( Housing & Cover) enables the quick opening incase of any requirements for service

• O-ring to avoid the potentials of the Air Leakage causing the improper shift of the ratios

• Fork shift with the Pivot to retain the position of the Fork shift and to have a proper shift during the shifting process

WE CLAIM

1. A shifting mechanism for a two speed axle assembly, said mechanism comprising:

(i) a casting means comprising a housing and a cover;

(ii) a pneumatic port placed substantially on said cover of said housing;

(iii) a planetary gear arrangement coupled with said housing means, said gear arrangement comprising a sun means;

(iv) a spring means connected with said housing means;

(v) a shaft means operatively connected with said spring means and said planetary gear arrangement;

(vi) a ring means connected substantially on the top of housing means to avoid air leakage;

(vii) a quick release valve means adapted for quick release of air pressure for repositioning the ratio to original speed ratio ;

(viii) a solenoid valve operatively connected with said release valve through a pipe means;

(ix) a bolt means adapted to lock the cover on said housing means;

(x) a switch means located in the drivers cabin connected operatively with said solenoid valve through wiring means adapted to perform shift of ratios based on drivers
requirement; and

(xi) an air tank means operatively connected with said solenoid
valve means to enable compressed air to shifter assembly.

2. Mechanism as claimed in claim 1 wherein said shaft means movement is initiated by the air delivered from the air compressor of the motor vehicle through said pneumatic port provided on said Cover of the Housing for the Engagement/Disengagement.

3. Mechanism as claimed in claim 2 wherein said shaft means is configured for a linear movement which subsequently engages/disengages a particular speed ratio.

4. Mechanism as claimed in claim 1 wherein said speed ratio is available in a Carrier means.

5. Mechanism as claimed in claim 4 wherein said speed ratio is as per the application requirements.

6. Mechanism as claimed in claim 1 wherein said ring means comprises O-ring.

7. Mechanism as claimed in claim 1 wherein said housing is open for easy maintenance.

8. Mechanism as claimed in claim 1 wherein said spring means movement enables the engaging/disengaging movement of the shaft means.

9. Mechanism as claimed in claim 1 wherein two speed axle assembly gets its power derived from the air released from the compressor of the motor vehicle.

10. Mechanism as claimed 1 further comprises fork shift means having two Arms joined to said shaft for the positioning of the Sun Gear in the planetary system.

11. Mechanism as claimed in claim 10 wherein said fork shift comprises a pivot means to retain the position of fork shift and to have a proper shift during shifting process.

12. Mechanism as claimed in claims 1 wherein said shaft means optionally is made of hard material.