CA2269350A1 - A split power, differential aided cvt - Google Patents
A split power, differential aided cvt Download PDFInfo
- Publication number
- CA2269350A1 CA2269350A1 CA 2269350 CA2269350A CA2269350A1 CA 2269350 A1 CA2269350 A1 CA 2269350A1 CA 2269350 CA2269350 CA 2269350 CA 2269350 A CA2269350 A CA 2269350A CA 2269350 A1 CA2269350 A1 CA 2269350A1
- Authority
- CA
- Canada
- Prior art keywords
- belt
- cvt
- ratio
- transmission
- force
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H37/00—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00
- F16H37/02—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings
- F16H37/06—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts
- F16H37/08—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing
- F16H37/0833—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing with arrangements for dividing torque between two or more intermediate shafts, i.e. with two or more internal power paths
- F16H37/084—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing with arrangements for dividing torque between two or more intermediate shafts, i.e. with two or more internal power paths at least one power path being a continuously variable transmission, i.e. CVT
- F16H37/0846—CVT using endless flexible members
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H37/00—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00
- F16H37/02—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings
- F16H37/06—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts
- F16H37/08—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing
- F16H37/0833—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing with arrangements for dividing torque between two or more intermediate shafts, i.e. with two or more internal power paths
- F16H37/084—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing with arrangements for dividing torque between two or more intermediate shafts, i.e. with two or more internal power paths at least one power path being a continuously variable transmission, i.e. CVT
- F16H2037/088—Power split variators with summing differentials, with the input of the CVT connected or connectable to the input shaft
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Transmissions By Endless Flexible Members (AREA)
- Transmission Devices (AREA)
Abstract
In building a continuously variable transmission (CVT), it is beneficial to find some way to extend the continuous range of the transmission into the negative transmission ratios. It would also be of benefit if the load that is transmitted through the friction-based portion of the transmission were reduced. This invention, a variation of the regular belt driven continuously variable transmission, does both of these. It works by coupling a belt type CVT to a differential.
Claims (4)
1. By varying the belt ratio, the final transmission ratio as altered, and it is possible for the belt ratio to remain positive while producing a negative transmission ratio. Again, refer to equations 5a and 5b, and graphs 1 through 3 for the exact relationship between the transmission ratio and the belt ratio and gear ratio.
2. Having the transmission operate at and below the ratio of zero allows for the elimination of a device to disengage the transmission from the engine, such as a clutch, or a torque converter. This also eliminates the reversing gear set that is needed to make regular CVTs reverse the output shaft. Eliminating these things also allows for the reduction in the transmissions total size and weight. Also, since the transmission is never disconnected from the engine, the mass of the gears and pulleys inside the transmission can substitute for some of the mass in the engine's flywheel. This further reduces the total weight of the engine and transmission.
3. The differential and gear set used shares the power that is to be transmitted from the source to the destination with the belt, thereby reducing the load on the belt. This effectively increases the total load that the transmission as a whole can handle. The force analysis is done for the regular CVT, and then my CVT for comparison. The calculations and plotting were done between the belt ratios of 1:4 and 4:1, or .25 to 4.
From figure 3.1, we can obtain the mathematical relationship:
F T = T~ (6a) Where:
F T is the tension force in belt T in is the input torque from engine For my version of the CVT, the force is transmitted differently.
From figure 3.2, the belt force can be calculated by:
As shown in figure 3.2, for my variation of the CVT, the torque is shared between the belt and the gear set. To create formulae to display the reduction in belt force the following formula is needed Where R B is the belt ratio, r1 is the input pulley radius and r2 is the output pulley radius.
For a unit r1 and r2, r2 can be obtained as a function of r1:
r2 = 2 - r1 (8) Substituting equation 7, 8 and R B = R T into equation 6a, the belt force as a function of transmission ratio for a regular CVT can be obtained.
Substituting equations 7, 8 and 5b into equation 6b we obtain the belt force as a function of transmission ratio for my CVT.
We can then plot these results for a unit-input torque, or T in = 1. Graph 4 is a comparison of the belt force in a regular CVT to the belt force in my CVT. The regular CVT is plotted in a dotted line, while my CVT is plotted with a gear ratio of 1, in a thin single line, and 1.5, shown in a thick single line.
We can see that by increasing the gear ratio, the force transferred through the belt is further reduced somewhat.
For a vehicle to accelerate at a constant rate, a constant output torque is required.
For all transmissions, the output torque varies inversely to the transmission ratio for a constant input torque, as seen in the following formula.
or:
T in = R T * T out (12) Where:
T out is the output torque applied to the application R TQ is the torque ratio Applying equation 12 to equation 9, we can obtain the relationship between the force in the belt and the transmission ratio for a constant output torque in a regular CVT.
Also, applying equation 12 to equation 10, we can obtain the relationship between the force in the belt and the transmission ratio for a constant output torque in my CVT.
We again plot these relationships between the belt ratio range of 1:4 to 4:1, this time with a unit output torque. Again, the standard CVT is in a dotted line, while my CVT is plotted with a gear ratio of 1 in a thin line and the gear ratio of 1.5 in a thick line.
It is clear in this graph, that my transmission has a lot less force in the belt as compared to a regular CVT.
From figure 3.1, we can obtain the mathematical relationship:
F T = T~ (6a) Where:
F T is the tension force in belt T in is the input torque from engine For my version of the CVT, the force is transmitted differently.
From figure 3.2, the belt force can be calculated by:
As shown in figure 3.2, for my variation of the CVT, the torque is shared between the belt and the gear set. To create formulae to display the reduction in belt force the following formula is needed Where R B is the belt ratio, r1 is the input pulley radius and r2 is the output pulley radius.
For a unit r1 and r2, r2 can be obtained as a function of r1:
r2 = 2 - r1 (8) Substituting equation 7, 8 and R B = R T into equation 6a, the belt force as a function of transmission ratio for a regular CVT can be obtained.
Substituting equations 7, 8 and 5b into equation 6b we obtain the belt force as a function of transmission ratio for my CVT.
We can then plot these results for a unit-input torque, or T in = 1. Graph 4 is a comparison of the belt force in a regular CVT to the belt force in my CVT. The regular CVT is plotted in a dotted line, while my CVT is plotted with a gear ratio of 1, in a thin single line, and 1.5, shown in a thick single line.
We can see that by increasing the gear ratio, the force transferred through the belt is further reduced somewhat.
For a vehicle to accelerate at a constant rate, a constant output torque is required.
For all transmissions, the output torque varies inversely to the transmission ratio for a constant input torque, as seen in the following formula.
or:
T in = R T * T out (12) Where:
T out is the output torque applied to the application R TQ is the torque ratio Applying equation 12 to equation 9, we can obtain the relationship between the force in the belt and the transmission ratio for a constant output torque in a regular CVT.
Also, applying equation 12 to equation 10, we can obtain the relationship between the force in the belt and the transmission ratio for a constant output torque in my CVT.
We again plot these relationships between the belt ratio range of 1:4 to 4:1, this time with a unit output torque. Again, the standard CVT is in a dotted line, while my CVT is plotted with a gear ratio of 1 in a thin line and the gear ratio of 1.5 in a thick line.
It is clear in this graph, that my transmission has a lot less force in the belt as compared to a regular CVT.
4. It should also be mentioned that reducing belt force also reduces the belts wear rate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2269350 CA2269350C (en) | 1999-04-14 | 1999-04-14 | A split power, differential aided cvt |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2269350 CA2269350C (en) | 1999-04-14 | 1999-04-14 | A split power, differential aided cvt |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2269350A1 true CA2269350A1 (en) | 2000-10-14 |
| CA2269350C CA2269350C (en) | 2012-10-16 |
Family
ID=29588805
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2269350 Expired - Lifetime CA2269350C (en) | 1999-04-14 | 1999-04-14 | A split power, differential aided cvt |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2269350C (en) |
-
1999
- 1999-04-14 CA CA 2269350 patent/CA2269350C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2269350C (en) | 2012-10-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |
Effective date: 20190415 |